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  • 1.
    Akkarasamiyo, Sunisa
    et al.
    Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Sawadjoon, Supaporn
    Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Samec, Joseph S. M.
    Stockholm Univ, Dept Organ Chem, S-10691 Stockholm, Sweden..
    Tsuji-Trost Reaction of Non-Derivatized Allylic Alcohols2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 14, p. 3488-3498Article in journal (Refereed)
    Abstract [en]

    Palladium-catalyzed allylic substitution of non-derivatized enantioenriched allylic alcohols with a variety of uncharged N-, S-, C- and O-centered nucleophiles using a bidentate BiPhePhos ligand is described. A remarkable effect of the counter ion (X) of the XPd[kappa(2)-BiPhePhos][kappa(3)-C3H5] was observed. When ClPd[kappa(2)-BiPhePhos][eta(3)-C3H5] (complexI) was used as catalyst, non-reproducible results were obtained. Study of the complex by X-ray crystallography, (PNMR)-P-31 spectroscopy, and ESI-MS showed that a decomposition occurred where one of the phosphite ligands was oxidized to the corresponding phosphate, generating ClPd[kappa(1)-BiPhePhosphite-phosphate][eta(3)-C3H5] species (complexII). When the chloride was exchanged to the weaker coordinating OTf- counter ion the more stable Pd[kappa(2)-BiPhePhos][eta(3)-C3H5](+)+[OTf] (-) (complexIII) was formed. ComplexIII performed better and gave higher enantiospecificities in the substitution reactions. ComplexIII was evaluated in Tsuji-Trost reactions of stereogenic non-derivatized allylic alcohols. The desired products were obtained in good to excellent yields (71-98%) and enantiospecificities (73-99%) for both inter- and intramolecular substitution reactions with only water generated as a by-product. The methodology was applied to key steps in total synthesis of (S)-cuspareine and (+)-lentiginosine. A reaction mechanism involving a palladium hydride as a key intermediate in the activation of the hydroxyl group is proposed in the overall transformation.

  • 2.
    Arkhypchuk, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Novel Approaches to Phosphorus-containing Heterocycles and Cumulenes2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Fast development in all areas of life and science over the last 50 years demands versatile, energy efficient and cheap materials with specific but easily tuneable properties which can be used for example in organic light emitting diodes (OLEDs), thin-film transistors, photovoltaic cells, etc. This thesis is devoted to the development of novel synthetic approaches to molecules with potential applications in the field of molecular electronics.  The acquisition of a detailed mechanistic understanding of the newly developed reactions is central to the work presented in this thesis.

    The first chapter is dedicated to the development of a new procedure for the preparation of phospha-Wittig-Horner (pWH) reagents, i.e. a reagents that has been known to convert carbonyl compounds into compounds with P=C double bonds. Each step of the synthetic sequence, i.e. preparation of the starting P,P-dichlorophosphines, their phosphorylation using the Michaelis-Arbuzov protocol, coordination to the metal centre and final hydrolysis, are presented in detail. A possible route to uncoordinated pWH reagents is also discussed.

    The second chapter focuses on the reactivity of the pWH reagents with acetone under different reaction conditions. The results show how changes in the ratio of starting material vs. base as well as reaction time or structure of the pWH reagent can influence the reaction outcome and the stability of the obtained products. The possibility to prepare unusual phosphaalkenes with unsaturated P-substituents is presented.

    The third chapter of the thesis is dedicated to the reactivity of pWH reagents towards symmetric and asymmetric ketones which contain one or two acetylene units. The proposed mechanisms of the reactions are studied by means of in situ FTIR spectroscopy as well as theoretical calculations. Physical-chemical properties of oxaphospholes, cumulenes and bisphospholes are presented.

    The last chapter is dedicated to reactivity studies of pWH reagents towards ketenes, and the exploration of a reliable route to 1-phosphaallenes. Detailed mechanistic studies of the pWH reaction that are based on the isolation and crystallographic characterization of unique reaction intermediates are presented. The reactivity of phosphaallenes towards nucleophiles such as water and methanol are examined.

    In summary, this thesis presents synthetic routes to novel phosphorus-containing molecules, together with detailed studies of the reaction mechanisms of the observed transformations.

    List of papers
    1. Revisiting the Phospha-Wittig - Horner Reaction
    Open this publication in new window or tab >>Revisiting the Phospha-Wittig - Horner Reaction
    2012 (English)In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 31, no 3, p. 1118-1126Article in journal (Refereed) Published
    Abstract [en]

    P,P-Dichlorophosphines 2a-c (RPCl2, R = Ph (a), t-Bu (b), 2,4,6-Me3Ph (c)) and P,P-dibromophosphines 4d,e (RPBr2, R = (i-Pr)(3)SiC C (d) and H2C=CH (e)) react with triethylphosphite under Michaelis-Arbuzov conditions to give phosphinodiphosphonates 3a-e in quantitative yields. After complexation to W(CO)(5) and treatment with CH3ONa, phospha-Wittig-Horner reagents 9a,b are obtained on a multigram scale in good overall yield. Phospha-Wittig-Horner reagents with unsaturated, substituents at P-III (10d,e) can be prepared in analogous procedures; however, their prevail in an unusual ylide form that allows conjugation between the lone pair and the acetylene and vinyl pi-systems, respectively. Phosphinophosphonate 9a has been characterized by X-ray crystallography and is shown to react smoothly with acetone within minutes. The resulting W(CO)(5)-coordinated phosphaalkene is shown to dimerize to a 1,2-diphosphitane or to undergo a 1,3-proton shift depending on the reaction conditions. In addition, a one-pot synthetic sequence starting from W(CO)(5)-coordinated phosphinodiphosphonates 5d,e has been developed to engage compounds with vinyl and acetylene substituents in phospha-Wittig-Horner reactions.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-170346 (URN)10.1021/om201158k (DOI)000300116100046 ()
    Available from: 2012-03-12 Created: 2012-03-12 Last updated: 2017-12-07Bibliographically approved
    2. Cascade Reactions Forming Highly Substituted, Conjugated Phospholes and 1,2-Oxaphospholes
    Open this publication in new window or tab >>Cascade Reactions Forming Highly Substituted, Conjugated Phospholes and 1,2-Oxaphospholes
    2012 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 51, no 31, p. 7776-7780Article in journal (Refereed) Published
    Abstract [en]

    The reaction of a phospha-Wittig–Horner reagent with diacetylenic ketones (see scheme) results in a cascade of reactions that can lead to both an oxaphosphole-terminated cumulene system and an alkene-bridged bis-phosphole. The reaction outcome is determined by the nature of the acetylene termini, with phenyl groups stabilizing a carbene intermediate that dimerizes to give the bis-phosphole product.

    Keywords
    acetylenes, conjugation, cumulenes, phospha-Wittig, reaction mechanisms
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-182042 (URN)10.1002/anie.201202153 (DOI)000306757900029 ()
    Available from: 2012-10-05 Created: 2012-10-02 Last updated: 2017-12-07Bibliographically approved
    3. Phosphorus Heterocylces from Phosphinophosphonates and α,β-Unsaturated Ketones
    Open this publication in new window or tab >>Phosphorus Heterocylces from Phosphinophosphonates and α,β-Unsaturated Ketones
    Show others...
    (English)Manuscript (preprint) (Other academic)
    National Category
    Organic Chemistry Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-198753 (URN)
    Available from: 2013-04-25 Created: 2013-04-24 Last updated: 2013-08-30
    4. Mechanism of the Phospha-Wittig-Horner Reaction
    Open this publication in new window or tab >>Mechanism of the Phospha-Wittig-Horner Reaction
    2013 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 25, p. 6484-6487Article in journal (Refereed) Published
    Keywords
    ketenes; phosphaallenes; phospha-Wittig-Horner reaction; reaction mechanisms
    National Category
    Organic Chemistry Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-198754 (URN)10.1002/anie.201301469 (DOI)000320378800024 ()
    Available from: 2013-04-25 Created: 2013-04-24 Last updated: 2017-12-06Bibliographically approved
  • 3.
    Arkhypchuk, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Mihali, Viorica Alina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Ehlers, Andreas
    VU University Amsterdam.
    Lammertsma, Koop
    VU University Amsterdam.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Phosphorus Heterocylces from Phosphinophosphonates and α,β-Unsaturated KetonesManuscript (preprint) (Other academic)
  • 4.
    Arkhypchuk, Anna
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Svyaschenko, Yurii
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Mechanism of the Phospha-Wittig-Horner Reaction2013In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 52, no 25, p. 6484-6487Article in journal (Refereed)
  • 5.
    Ayub, Rabia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    El Bakouri, Ouissam
    Univ Girona, IQCC, C Maria Aurelia Capmany 6, Girona 17003, Catalonia, Spain..
    Jorner, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Sola, Miguel
    Univ Girona, IQCC, C Maria Aurelia Capmany 6, Girona 17003, Catalonia, Spain..
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Can Baird's and Clar's Rules Combined Explain Triplet State Energies of Polycyclic Conjugated Hydrocarbons with Fused 4n pi- and (4n+2)pi-Rings?2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 12, p. 6327-6340Article in journal (Refereed)
    Abstract [en]

    Compounds that can be labeled as "aromatic chameleons" are pi-conjugated compounds that are able to adjust their pi-electron distributions so as to comply with the different rules of aromaticity in different electronic states. We used quantum chemical calculations to explore how the fusion of benzene rings onto aromatic chameleonic units represented by biphenylene, dibenbzocyclooctatetraene, and dibenzo[a,e]pentalene modifies the first triplet excited states (T-1) of the compounds. Decreases in T-1 energies are observed when going from isomers with linear connectivity of the fused benzene rings to those with cis- or transbent connectivities. The T-1 energies decreased down to those of the parent (isolated) 4n pi-electron units. Simultaneously, we observe an increased influence of triplet State aromaticity of the central 4n ring as given by Baird's rule and evidenced by geometric, magnetic, and electron density based aromaticity indices (HOMA, NICS-XY, ACID, and FLU). Because of an influence of,triplet state aromaticity in the central 4n pi-electron units,, the most stabilized, compounds, retain the triplet excitation in Baird pi-quartets or octets, enabling the outer benzene rings to adapt closed-shell singlet Clar pi-sextet character. Interestingly, the T-1 energies go down as the total number of aromatic cycles within a molecule in the T-1 state increases.

  • 6.
    Ayub, Rabia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. uppsala university.
    El Bakouri, Ouissam
    Univ Girona, IQCC, C Maria Aurelia Capmany 6, Girona 17003, Catalonia, Spain.
    Jorner, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. uppsala university.
    Sola, Miquel
    Univ Girona, IQCC, C Maria Aurelia Capmany 6, Girona 17003, Catalonia, Spain.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. uppsala university.
    Can Baird’s and Clar’s Rules Combined Explain Triplet State Energies of Polycyclic Conjugated Hydrocarbons with Fused 4nπ- and (4n + 2)π-Rings?2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 12, p. 6327-6340Article in journal (Refereed)
  • 7.
    Ayub, Rabia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Papadakis, Raffaello
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Jorner, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. uppsala university.
    Zietz, Burkhard
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. uppsala university.
    Cyclopropyl Group: An Excited-State Aromaticity Indicator?2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 55, p. 13684-13695Article in journal (Refereed)
    Abstract [en]

    The cyclopropyl (cPr) group, which is a well-known probe for detecting radical character at atoms to which it is connected, is tested as an indicator for aromaticity in the first * triplet and singlet excited states (T-1 and S-1). Baird's rule says that the -electron counts for aromaticity and antiaromaticity in the T-1 and S-1 states are opposite to Huckel's rule in the ground state (S-0). Our hypothesis is that the cPr group, as a result of Baird's rule, will remain closed when attached to an excited-state aromatic ring, enabling it to be used as an indicator to distinguish excited-state aromatic rings from excited-state antiaromatic and nonaromatic rings. Quantum chemical calculations and photoreactivity experiments support our hypothesis; calculated aromaticity indices reveal that openings of cPr substituents on [4n]annulenes ruin the excited-state aromaticity in energetically unfavorable processes. Yet, polycyclic compounds influenced by excited-state aromaticity (e.g., biphenylene), as well as 4n-electron heterocycles with two or more heteroatoms represent limitations.

  • 8.
    Bornhof, Anna-Bea
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Xiong, Ruisheng
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Borbas, K. Eszter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Rational Synthesis of 2-Bromoporphyrins and 2,12-Dibromoporphyrins2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 23, p. 12908-12913Article in journal (Refereed)
    Abstract [en]

    Bromoporphyrins were prepared by the metal-mediated self-condensation of brominated 1-formyldipyrromethanes. Depending on the conditions, Mg(II)-2,12-dibromoporphyrin and Mg(II)-2-bromoporphyrin could be obtained in up to 11% and 17% isolated yield, respectively. Zn(II) was also a viable templating metal. The positions of the bromine substituents were confirmed by 2D-NMR spectroscopic analysis and the X-ray crystal structure of a derivative. Suzuki and Sonogashira reactions of the bromoporphyrins yielded 2-substituted or 2,12-disubstituted porphyrins with red-shifted absorption and emission spectra. This method provides access to the minimalist core of beta-mono- and beta,beta'-disubstituted porphyrins from readily available starting materials.

  • 9.
    Denisova, Aleksandra
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Hyperconjugation in Group 14 Organic Compounds: Design and Property Investigations2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Nowadays π-conjugated molecules are widely used as materials for devices in organic and molecular electronics. This is due to the ability of such molecules to conduct electricity. However, π-conjugation leads to molecular rigidness and associated lower solubility, which limits possible applications. Meanwhile, there are other types of conjugation that do not cause molecular rigidness but still provide conductivity. One of them is so called hyperconjugation. While π-conjugation involves only p atomic orbitals, hyperconjugation is characterized by interaction of π and σ orbitals. Hyperconjugation is normally weaker than π-conjugation, thus, in order to get strongly hyperconjugated molecules they should be enhanced in some way.

    In this thesis, I describe methods for design of strongly hyperconjugated molecules. It is possible to increase the strength of hyperconjugation by various methods and some of them are discussed. We performed quantum chemical calculations in order to investigate optical and geometric properties of the hyperconjugated molecules and evaluate the relative strength of hyperconjugation. In some cases, results of calculations were compared with experimental results aiming to confirm the relevance of the calculations. First, we have investigated how the change of group 14 elements in the 1,4-ditetrelocyclohexa-2,5-dienes influence the hyperconjugation strength. Next, the substituent effect was considered in fulvenes and their hyperconjugated analogs. We showed this effect from the perspective of the substituents influence on the aromatic properties of molecules in the ground and first electronically excited states. Further, the gradual shift when going from monomer to oligomers were investigated. For this hyperconjugated oligomers were constructed from 1,4-disilacyclohexa-2,5-diene and cyclobutadisilole fragments. Additionally we showed the influence of electron withdrawing and electron donating groups on hyperconjugation in siloles and 1,4-disilacyclohexa-2,5-dienes. Finally, hyperconjugation was investigated in a set of silicon-containing omni-hyperconjugated compounds.

    The results obtained from this research showed that hyperconjugation strength can be increased significantly up to levels comparable to purely π-conjugated molecules. We hope that these results will be useful in development of other hyperconjugated small molecules, oligomers, and polymers, which can be further used as material for electronic devices.

    List of papers
    1. Optimization of the Cyclic Cross-Hyperconjugation in 1,4-Ditetrelcyclohexa-2,5-dienes
    Open this publication in new window or tab >>Optimization of the Cyclic Cross-Hyperconjugation in 1,4-Ditetrelcyclohexa-2,5-dienes
    2014 (English)In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 33, no 12, p. 2997-3004Article in journal (Refereed) Published
    Abstract [en]

    Cyclic cross-hyperconjugation can exist to variable extents in 1,4-ditetrelcyclohexa-2,5-dienes, i.e., all-carbon cyclohexa-1,4-dienes and 1,4-disila/digerma/distanna/diplumbacyclohexa-2,5-dienes. In this study we first use density functional theory (DFT) computations to optimize the conjugation strength by seeking the optimal atom E and substituent group E'Me-3 in the two saturated E(E'Me-3)(2) moieties (E and E' as the same or different tetrel (group 14) elements). We reveal that the all-carbon cyclohexadienes with gradually heavier E'Me-3 substituents at the two saturated carbon atoms display significant cross-hyperconjugation. The first electronic excitations in these compounds, which formally have two isolated C=C bonds, are calculated to reach wavelengths as long as 400 nm (excitation energies of 3.1 eV). These transitions are mostly forbidden, and the lowest allowed transitions are found at 387 nm (3.2 eV). The silicon analogues are also cross-hyperconjugated, while a decline is observed in the 1,4-digerma/distanna/diplumbacyclohexa-2,5-diene. Experiments on two substituted 1,4-disilacyclohexa-2,5-dienes confirm the effect of the E'Me3 substituents, with regard to both electronic excitations and geometries as determined by UV absorption spectroscopy and X-ray crystallography, respectively. At the end, we reveal through computations how electron-donating and electron-withdrawing substituents at the C=C double bonds influence the electronic properties of the all-carbon ring. We find that the first calculated excitation, which is forbidden, can be shifted to 440 nm (2.83 eV). This shows to what extent cyclic cross-hyperconjugation can affect the electronic and optical properties of a compound with two formally isolated C=C double bonds.

    National Category
    Organic Chemistry
    Research subject
    Chemistry with specialization in Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-221022 (URN)10.1021/om5001875 (DOI)000337936800008 ()
    Available from: 2014-03-24 Created: 2014-03-24 Last updated: 2017-12-12Bibliographically approved
    2. Impact of Ground- and Excited-State Aromaticity on Cyclopentadiene and Silole Excitation Energies and Excited-State Polarities
    Open this publication in new window or tab >>Impact of Ground- and Excited-State Aromaticity on Cyclopentadiene and Silole Excitation Energies and Excited-State Polarities
    Show others...
    2014 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 20, no 30, p. 9295-9303Article in journal (Refereed) Published
    Abstract [en]

    A new qualitative model for estimating the properties of substituted cyclopentadienes and siloles in their lowest pi pi* excited states is introduced and confirmed through quantum chemical calculations, and then applied to explain earlier reported experimental excitation energies. According to our model, which is based on excited-state aromaticity and antiaromaticity, siloles and cyclopentadienes are cross-hyperconjugated "aromatic chameleons" that adapt their electronic structures to conform to the various aromaticity rules in different electronic states (Huckel's rule in the pi(2) electronic ground state (S-0) and Baird's rule in the lowest pi pi* excited singlet and triplet states (S-1 and T-1)). By using pen-and-paper arguments, one can explain polarity changes upon excitation of substituted cyclopentadienes and siloles, and one can tune their lowest excitation energies by combined considerations of ground-and excited-state aromaticity/antiaromaticity effects. Finally, the "aromatic chameleon" model can be extended to other monocyclic compound classes of potential use in organic electronics, thereby providing a unified view of the S-0, T-1, and S-1 states of a range of different cyclic cross-pi-conjugated and cross-hyperconjugated compound classes.

    Keywords
    aromaticity, conjugation, density functional calculations, electronic structure, organic electronics
    National Category
    Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-231122 (URN)10.1002/chem.201402577 (DOI)000339568800022 ()
    Available from: 2014-09-04 Created: 2014-09-04 Last updated: 2018-04-23Bibliographically approved
    3. Expanding the (Cross-)Hyperconjugation of 1,4-Disilacyclohexa-2,5-dienes to Larger Monomers and Oligomers: A Computational Investigation
    Open this publication in new window or tab >>Expanding the (Cross-)Hyperconjugation of 1,4-Disilacyclohexa-2,5-dienes to Larger Monomers and Oligomers: A Computational Investigation
    2016 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 43, p. 36961-36970Article in journal (Refereed) Published
    Abstract [en]

    We used density functional theory calculations to examine molecules that can be regarded as expanded 1,4-disilacyclohexa-2,5-dienes as well as oligomers based on these or 1,4-disilacyclohexa-2,5-diene with the aim to identify systems with extended (cross-)hyperconjugation. Among the three "expanded 1,4-disilacyclohexa-2,5-dienes" considered cyclobutadisilole is the most interesting as it has a higher thermodynamic stability than the isomeric 1,6-disilacyclodeca-2,3,4,7,8,9-hexaene and significantly lower first electronic excitation energy than 1,6-disilacyclodeca-2,4,7,9-tetraene. Cyclobutadisilole with trimethylsilyl substituents at Si shows particularly low excitations with the first strong transition at 3.46 eV (358 nm), i.e., similar to 1.1 eV lower than in 1,4-disilacyclohexa-2,5-diene. The monomers were connected into oligomers via their Si atoms using bis(dimethylsilanediyl) linkers, and some extended hyperconjugation was revealed. The first allowed UV/Vis excitation in the cyclobutadisilole-based tetramers is calculated at 2.57 eV (482 nm), although the lowering in excitation energies when going from monomer to tetramer is merely similar to 0.5 eV and hyperconjugation has modest impact on geometries. Yet, the tetra(cyclobutadisilole) has a significantly lower first allowed excitation when compared to a previously studied tetra(1,4-disilacyclohexadiene) with first excitation at 3.9 eV (318 nm).

    National Category
    Organic Chemistry Engineering and Technology
    Research subject
    Chemistry with specialization in Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-293564 (URN)10.1039/C6RA02732F (DOI)000374561300088 ()
    Funder
    Swedish Research Council
    Available from: 2016-05-13 Created: 2016-05-13 Last updated: 2017-12-12Bibliographically approved
    4. A Computational Investigation of the Substituent Effects on Geometric, Electronic, and Optical Properties of Siloles and 1,4-Disilacyclohexa-2,5-dienes
    Open this publication in new window or tab >>A Computational Investigation of the Substituent Effects on Geometric, Electronic, and Optical Properties of Siloles and 1,4-Disilacyclohexa-2,5-dienes
    2017 (English)In: Molecules, ISSN 1420-3049, E-ISSN 1420-3049, Vol. 22, no 3, article id 370Article in journal (Refereed) Published
    Abstract [en]

    Thirty two differently substituted siloles 1a–1p and 1,4-disilacyclohexa-2,5-dienes 2a–2p were investigated by quantum chemical calculations using the PBE0 hybrid density functional theory (DFT) method. The substituents included σ-electron donating and withdrawing, as well as π-electron donating and withdrawing groups, and their effects when placed at the Si atom(s) or at the C atoms were examined. Focus was placed on geometries, frontier orbital energies and the energies of the first allowed electronic excitations. We analyzed the variation in energies between the orbitals which correspond to HOMO and LUMO for the two parent species, here represented as ΔεHL, motivated by the fact that the first allowed transitions involve excitation between these orbitals. Even though ΔεHL and the excitation energies are lower for siloles than for 1,4-disilacyclohexa-2,5-dienes the latter display significantly larger variations with substitution. The ΔεHL of the siloles vary within 4.57–5.35 eV (ΔΔεHL = 0.78 eV) while for the 1,4-disilacyclohexa-2,5-dienes the range is 5.49–7.15 eV (ΔΔεHL = 1.66 eV). The excitation energy of the first allowed transitions display a moderate variation for siloles (3.60–4.41 eV) whereas the variation for 1,4-disilacyclohexa-2,5-dienes is nearly doubled (4.69–6.21 eV). Cyclobutadisiloles combine the characteristics of siloles and 1,4-disilacyclohexa-2,5-diene by having even lower excitation energies than siloles yet also extensive variation in excitation energies to substitution of 1,4-disilacyclohexa-2,5-dienes (3.47–4.77 eV, variation of 1.30 eV).

    National Category
    Nano Technology
    Research subject
    Engineering Science with specialization in Nanotechnology and Functional Materials
    Identifiers
    urn:nbn:se:uu:diva-335095 (URN)10.3390/molecules22030370 (DOI)000398743500031 ()
    Note

    Title of manuscript in list of papers in Julius Tibbelin´s thesis: A comparative computational investigation of the substituent effects on geometric, electronic, and optical properties of 1,4-disilacyclo-hexa-2,5- dienes and siloles

    Available from: 2017-11-30 Created: 2017-11-30 Last updated: 2018-02-16Bibliographically approved
    5. Computational Design of Strongly σ/π-Conjugated Compounds with a Start at the Omni-Conjugated [3]Radialene
    Open this publication in new window or tab >>Computational Design of Strongly σ/π-Conjugated Compounds with a Start at the Omni-Conjugated [3]Radialene
    (English)Manuscript (preprint) (Other academic)
    National Category
    Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-336170 (URN)
    Available from: 2017-12-12 Created: 2017-12-12 Last updated: 2017-12-20
  • 10.
    Denisova, Aleksandra
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Emanuelsson, Rikard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Expanding the (Cross-)Hyperconjugation of 1,4-Disilacyclohexa-2,5-dienes to Larger Monomers and Oligomers: A Computational Investigation2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 43, p. 36961-36970Article in journal (Refereed)
    Abstract [en]

    We used density functional theory calculations to examine molecules that can be regarded as expanded 1,4-disilacyclohexa-2,5-dienes as well as oligomers based on these or 1,4-disilacyclohexa-2,5-diene with the aim to identify systems with extended (cross-)hyperconjugation. Among the three "expanded 1,4-disilacyclohexa-2,5-dienes" considered cyclobutadisilole is the most interesting as it has a higher thermodynamic stability than the isomeric 1,6-disilacyclodeca-2,3,4,7,8,9-hexaene and significantly lower first electronic excitation energy than 1,6-disilacyclodeca-2,4,7,9-tetraene. Cyclobutadisilole with trimethylsilyl substituents at Si shows particularly low excitations with the first strong transition at 3.46 eV (358 nm), i.e., similar to 1.1 eV lower than in 1,4-disilacyclohexa-2,5-diene. The monomers were connected into oligomers via their Si atoms using bis(dimethylsilanediyl) linkers, and some extended hyperconjugation was revealed. The first allowed UV/Vis excitation in the cyclobutadisilole-based tetramers is calculated at 2.57 eV (482 nm), although the lowering in excitation energies when going from monomer to tetramer is merely similar to 0.5 eV and hyperconjugation has modest impact on geometries. Yet, the tetra(cyclobutadisilole) has a significantly lower first allowed excitation when compared to a previously studied tetra(1,4-disilacyclohexadiene) with first excitation at 3.9 eV (318 nm).

  • 11.
    Esfandiarfard, Keyhan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Uppsala University.
    Novel Organophosphorus Compounds for Materials and Organic Synthesis2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis is devoted to the development of new organophosphorus compounds for potential uses in material science and as reagents in Organic Chemistry. Organophosphorus compounds in a single molecule or organic electronics context are appealing as the phosphorous centers perturb the electronic properties of the π-conjugated systems while at the same time provide synthetic handles for subsequent synthetic modifications. As such, new synthetic methodology to such compounds and the exploration of new building blocks is of considerable interest. In a different study, novel organophosphorus compounds are synthesized and shown to promote a reaction in Organic Chemistry that has previously not been possible, i.e. the stereoselective reductive coupling of aldehydes to alkenes. Such developments enlarge the toolkit of reactions that are available to Organic Chemists, and may impact the synthetic routes to pharmaceuticals and other important commodity chemicals.

    A general introduction of the key structural unit of this thesis, phosphaalkenes, is given in the first chapter. The synthesis, reactivity, properties and applications of these P=C double bond containing compounds are highlighted. The Wittig reaction and its variations as well as the phosphorus analogues that produce phosphaalkenes are outlined in detail.

    The second chapter is dedicated to the synthesis of a precursor that is used for the preparation of novel π-conjugated, organophosphorus compounds. C,C-Dibromophosphaalkenes are prepared and the halide substituents are used for the selective introduction of acetylene units. Besides the phosphaalkenes, the successful syntheses of two new diphosphenes is presented, indicating a broad applicability of the precursors.

    The third chapter is dedicated to the isolation of a metal-free phosphanylphosphonate that transforms aldehydes quantitatively to their corresponding E-phosphaalkenes in a transition metal-free phospha-HWE (Horner-Wadsworth-Emmons) reaction. The reaction benefits from mild conditions, high E-stereoselectivity, and a broad substrate scope.

    In the last chapter, a novel method for the reductive coupling of aldehydes to olefins is introduced. The reaction, which is a vast improvement over the McMurry coupling, allows for the selective synthesis of symmetrical and most importantly unsymmetrical E-alkenes. The phosphanylphosphonate mentioned above is the reagent that facilitates the coupling of the aldehydes via a phosphaalkene intermediate. This one-pot reaction benefits from mild conditions, good conversions, and high E-stereoselectivity.

    In summary, the thesis presents novel aspects of organophosphorus chemistry. These include the preparations and exploration of interesting precursors for the construction of π-conjugated organophosphorus compounds, and the use of organophosphorus reagents for unprecedented transformations in Organic Chemistry.

    List of papers
    1. Synthesis of 2,6-Dimesitylphenyl-C,C-dibromophosphaalkene
    Open this publication in new window or tab >>Synthesis of 2,6-Dimesitylphenyl-C,C-dibromophosphaalkene
    2015 (English)In: Phosphorus Sulfur and Silicon and the Related Elements, ISSN 1042-6507, E-ISSN 1563-5325, Vol. 190, no 5-6, p. 816-820Article in journal (Refereed) Published
    Abstract [en]

    A facile one-pot transformation of Dmp-I to Dmp-P=CBr2 (Dmp = 2,6-dimesitylphenyl), a valuable precursor for other unsaturated phosphorus compounds, is described. VT-1H-NMR experiments reveal a hindered rotation of the m-terphenyl structure with a rotational barrier of approx. 14 kcal/mol. Bromination of Dmp-I gives selective substitution of all aromatic protons of the mesityl substituents.

    Place, publisher, year, edition, pages
    Taylor & Francis Group, 2015
    National Category
    Inorganic Chemistry Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-257682 (URN)10.1080/10426507.2014.984030 (DOI)000357323000038 ()
    Funder
    Swedish Research Council, 2013-4763
    Available from: 2015-07-07 Created: 2015-07-07 Last updated: 2017-12-04
    2. Synthesis of Novel Precursors for the Development of Low-valent Phosphorus Compounds
    Open this publication in new window or tab >>Synthesis of Novel Precursors for the Development of Low-valent Phosphorus Compounds
    (English)Manuscript (preprint) (Other academic)
    National Category
    Organic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-328291 (URN)
    Available from: 2017-08-21 Created: 2017-08-21 Last updated: 2017-08-21
    3. Direct, Sequential, and Stereoselective Alkynylation of C,C-Dibromophosphaalkenes
    Open this publication in new window or tab >>Direct, Sequential, and Stereoselective Alkynylation of C,C-Dibromophosphaalkenes
    Show others...
    2016 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 22, no 30, p. 10614-10619Article in journal (Refereed) Published
    Abstract [en]

    The first direct alkynylation of C,C-dibromophosphaalkenes by a reaction with sulfonylacetylenes is reported. Alkynylation proceeds selectively in the trans position relative to the P substituent to afford bromoethynylphosphaalkenes. Owing to the absence of transition metals in the procedure, the previously observed conversion of dibromophosphaalkenes into phosphaalkynes through the phosphorus analog of the Fritsch-Buttenberg-Wiechell rearrangement is thus suppressed. The bromoethynylphosphaalkenes can subsequently be converted to C,C-diacetylenic, cross-conjugated phosphaalkenes by following a Sonogashira coupling protocol in good overall yields. By using the newly described method, full control over the stereochemistry at the P=C double bond is achieved. The substrate scope of this reaction is demonstrated for different dibromophosphaalkenes as well as different sulfonylacetylenes.

    Keywords
    alkynylation, cross-conjugation, phosphaalkenes, Sonogashira coupling, sulfonyl coupling
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-302705 (URN)10.1002/chem.201601955 (DOI)000380273300043 ()27310813 (PubMedID)
    External cooperation:
    Funder
    Swedish Research CouncilCarl Tryggers foundation
    Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2017-11-21Bibliographically approved
    4. Synthesis of the first metal-free phosphanylphosphonate and its use in the "phospha-Wittig-Horner" reaction
    Open this publication in new window or tab >>Synthesis of the first metal-free phosphanylphosphonate and its use in the "phospha-Wittig-Horner" reaction
    2016 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 45, no 5, p. 2201-2207Article in journal (Refereed) Published
    Abstract [en]

    The synthesis of the first phophanylphosphonate, Mes*PH-PO(OEt)(2) (2-H), in which the P(III) centre is not coordinated by a M(CO)(5) (M = W, Mo, Cr) fragment is reported. The title compound reacts with LDA under the formation of 2-Li which is best described as the enolate form with a high double bond character between the two phosphorus centres. 2-Li is shown to engage in the phospha-Wittig-Horner reaction and converts aldehydes into phosphaalkenes that are metal-free and thus available for future manipulations at the phophorus lone pair. Using a selection of aldehydes with aliphatic, aromatic or vinylic substituents as substrates, phosphaalkene formation proceeds in high yields and high E-selectivity. The selectivity is however compromised during purification on standard silica which was found to promote E/Z isomerization.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-280913 (URN)10.1039/c5dt03686k (DOI)000369413700046 ()26574885 (PubMedID)
    Funder
    Swedish Research Council
    Available from: 2016-03-16 Created: 2016-03-16 Last updated: 2017-11-30Bibliographically approved
    5. Unsymmetrical E-Alkenes from the Stereoselective Reductive Coupling of Two Aldehydes
    Open this publication in new window or tab >>Unsymmetrical E-Alkenes from the Stereoselective Reductive Coupling of Two Aldehydes
    2017 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 139, no 8, p. 2940-2943Article in journal (Refereed) Published
    Abstract [en]

    The unprecedented formation of unsymmetrical alkenes from the intermolecular reductive coupling of two different aldehydes is described. In contrast to the McMurry reaction which affords statistical product mixtures, selectivity in the reported procedure is achieved by a sequential ionic mechanism in which a first aldehyde is reacted with a phosphanylphosphonate to afford a phosphaalkene intermediate which, upon activation by hydroxide, reacts with a second aldehyde to the unsymmetrical E-alkenes. The described reaction is free of transition metals and proceeds under ambient temperature within minutes in good to excellent overall yields. It is a new methodology to use feedstock aldehydes for the direct production of C=C double bond-containing products and may impact how chemists think of multistep synthetic sequences in the future.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2017
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-320411 (URN)10.1021/jacs.7b00428 (DOI)000395493400021 ()28186736 (PubMedID)
    Funder
    Swedish Research Council
    Available from: 2017-04-19 Created: 2017-04-19 Last updated: 2017-08-21Bibliographically approved
  • 12.
    Esfandiarfard, Keyhan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Ott, Sascha
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Synthesis of 2,6-Dimesitylphenyl-C,C-dibromophosphaalkene2015In: Phosphorus Sulfur and Silicon and the Related Elements, ISSN 1042-6507, E-ISSN 1563-5325, Vol. 190, no 5-6, p. 816-820Article in journal (Refereed)
    Abstract [en]

    A facile one-pot transformation of Dmp-I to Dmp-P=CBr2 (Dmp = 2,6-dimesitylphenyl), a valuable precursor for other unsaturated phosphorus compounds, is described. VT-1H-NMR experiments reveal a hindered rotation of the m-terphenyl structure with a rotational barrier of approx. 14 kcal/mol. Bromination of Dmp-I gives selective substitution of all aromatic protons of the mesityl substituents.

  • 13.
    Fuchs, Michael
    et al.
    Karl-FranzensUniversity Graz.
    Schober, Markus
    Karl-FranzensUniversity Graz.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Faber, Kurt
    Karl-Franzens University Graz.
    Asymmetric Synthesis of β-Substituted α-Methylenebutyro- lactones via TRIP-Catalyzed Allylation: Mechanistic Studies and Application to the Synthesis of (S)-(−)-Hydroxymatairesinol2013In: Advanced Synthesis and Catalysis, ISSN 1615-4150, E-ISSN 1615-4169, Vol. 355, no 13, p. 2499-2505Article in journal (Refereed)
    Abstract [en]

    Asymmetric allylation of (hetero)aromatic aldehydes by a zinc(II)-allylbutyrolactone species catalyzed by a chiral BINOL-type phosphoric acid gave β-substituted α-methylenebutyrolactones in 68 to >99% ee and 52–91% isolated yield. DFT studies on the intermediate Zn2+-complex – crucial for chiral induction – suggest a six-membered ring intermediate, which allows the phosphoric acid moiety to activate the aldehyde. The methodology was applied to the synthesis of the antitumour natural product (S)-(−)-hydroxymatairesinol.

  • 14.
    Jorner, Kjell
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Jahn, Burkhard O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC. SciClus GmbH & Co. KG, Moritz-von-Rohr-Str. 1a, 07745 Jena, Germany .
    Bultinck, Patrick
    SciClus GmbH & Co. KG, Moritz-von-Rohr-Str. 1a, 07745 Jena, Germany.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Triplet state homoaromaticity: concept, computational validation and experimental relevance2018In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 9, no 12, p. 3165-3176Article in journal (Refereed)
    Abstract [en]

    Cyclic conjugation that occurs through-space and leads to aromatic properties is called homoaromaticity. Here we formulate the homoaromaticity concept for the triplet excited state (T1) based on Baird's 4n rule and validate it through extensive quantum-chemical calculations on a range of different species (neutral, cationic and anionic). By comparison to well-known ground state homoaromatic molecules we reveal that five of the investigated compounds show strong T1 homoaromaticity, four show weak homoaromaticity and two are non-aromatic. Two of the compounds have previously been identified as excited state intermediates in photochemical reactions and our calculations indicate that they are also homoaromatic in the first singlet excited state. Homoaromaticity should therefore have broad implications in photochemistry. We further demonstrate this by computational design of a photomechanical “lever” that is powered by relief of homoantiaromatic destabilization in the first singlet excited state.

  • 15.
    Messersmith, Reid E.
    et al.
    Johns Hopkins Univ, Dept Chem, 3400 North Charles St, Baltimore, MD 21218 USA..
    Yadav, Sangeeta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Siegler, Maxime A.
    Johns Hopkins Univ, Dept Chem, 3400 North Charles St, Baltimore, MD 21218 USA..
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Tovar, John D.
    Johns Hopkins Univ, Dept Chem, 3400 North Charles St, Baltimore, MD 21218 USA.;Johns Hopkins Univ, Dept Mat Sci & Engn, 3400 North Charles St, Baltimore, MD 21218 USA..
    Benzo[b]thiophene Fusion Enhances Local Borepin Aromaticity in Polycyclic Heteroaromatic Compounds2017In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 24, p. 13440-13448Article in journal (Refereed)
    Abstract [en]

    This report documents the synthesis, characterization, and computational evaluation of two isomeric borepin-containing polycyclic aromatics. The syntheses of these two isomers involved symmetrical disubstituted alkynes that were reduced to Z-olefins followed by borepin formation either through an isolable stannocycle intermediate or directly from the alkene via the trapping of a transient dilithio intermediate. Comparisons of their magnetic, crystallographic, and computational characterization to literature compounds gave valuable insights about the aromaticity of these symmetrically fused [b,f]borepins. The fusion of benzo[b]thiophene units to the central borepin cores forced a high degree of local aromaticity within the borepin moieties relative to other known borepin-based polycyclic aromatics. Each isomer had unique electronic responses in the presence of fluoride anions. The experimental data demonstrate that the local borepin rings in these two compounds have a relatively high amount of aromatic character. Results from quantum chemical calculations provide a more comprehensive understanding of local and global aromatic characters of various rings in fused ring systems built upon boron heterocycles.

  • 16.
    Mijangos, Edgar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Roy, Souvik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Pullen, Sonja
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Lomoth, Reiner
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Evaluation of two- and three-dimensional electrode platforms for the electrochemical characterization of organometallic catalysts incorporated in non-conducting metal-organic frameworks2017In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 46, no 15, p. 4907-4911Article in journal (Refereed)
    Abstract [en]

    The development of a reliable platform for the electrochemical characterization of a redox-active molecular diiron complex, [FeFe], immobilized in a non-conducting metal organic framework (MOF), UiO-66, based on glassy-carbon electrodes is reported. Voltammetric data with appreciable current responses can be obtained by the use of multiwalled carbon nanotubes (MWCNT) or mesoporous carbon (CB) additives that function as conductive scaffolds to interface the MOF crystals in "three-dimensional" electrodes. In the investigated UiO-66-[FeFe] sample, the low abundance of [FeFe] in the MOF and the intrinsic insulating properties of UiO-66 prevent charge transport through the framework, and consequently, only [FeFe] units that are in direct physical contact with the electrode material are electrochemically addressable.

  • 17.
    Mirmohades, Mohammad
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Towards a Novel Donor-Sensitizer-Catalyst Triad Entirely Composed of Earth Abundant Elements2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 18.
    Morales Salazar, Daniel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Mijangos, Edgar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Pullen, Sonja
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Gao, Ming
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Functional small-molecules & polymers containing P[double bond, length as m-dash]C and As[double bond, length as m-dash]C bonds as hybrid π-conjugated materials2017In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 6, p. 1120-1123Article in journal (Refereed)
    Abstract [en]

    Stable phospha- and arsaalkenes were used to synthesize polymers containing unsaturated P[double bond, length as m-dash]C and As[double bond, length as m-dash]C moieties. The composition, chemical environment, structure, optical, and electronic properties of the monomers and polymers were elucidated. The incorporation of the heteroatom-carbon double bonded units efficiently perturbs the optoelectronics and solid state features of both monomeric and polymeric scaffolds. Proof-of principle work supports their responsive character through post-functionalisation and electrochromic behaviour. To the best of our knowledge, this is the first example of a polymer containing arsenic-carbon double bonds.

  • 19.
    Orthaber, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Belaj, Ferdinand
    Pietschnig, Rudolf
    Synthesis, structure and π-delocalization of a phosphaalkenyl based neutral PNP-pincer2011In: Inorganica Chimica Acta, ISSN 0020-1693, E-ISSN 1873-3255, Vol. 374, no Copyright (C) 2015 American Chemical Society (ACS). All Rights Reserved., p. 211-215Article in journal (Refereed)
    Abstract [en]

    Prepn., characterization and structural properties of a novel bis-phosphaalkenyl based PNP-pincer (I) are reported. In this pincer the π-system is delocalized over all three donor sites, which was demonstrated with DFT calcns., UV-visible measurements and structural findings. As a consequence of this extended delocalization the π-system reveals near coplanarity which is evident from the 1st crystal structure for an uncomplexed bisphosphaalkenyl PNP-pincer. A Cu(I) complex with I was prepd. [on SciFinder(R)]

  • 20.
    Orthaber, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Herber, Rolfe
    Pietschnig, Rudolf
    Phosphaalkenylidene bridged Ferrocenes2012In: Journal of Organometallic Chemistry, Vol. 719, p. 36-40Article in journal (Refereed)
    Abstract [en]

    The lithi ation of ferrocenylphosphane Fc-PH 2 (Fc = C5 H4 FeC5H 5) has been reinvestiga ted and both Fc- PHLi and Fc-PLi 2 have been identi fi ed by N MR-spectroscopy. The lithia ted phosph anide s have be en conver ted to the corresponding mono and bis(silylated) spec ies the latter of which gave synth etic access to an oligomer in wh ich three ferrocene units are symme trically connec ted by phosph aalke ne unit s. The charge distri bution within this oli gomer and its isomer s has been ana lyzed using DFT calculat ions which indicates that the iron atom of the central metal locene unit is slightly more positive than the terminal ones. The se fi nding s are sup ported exp eriment ally by Mößbauer spectroscopy and cyclic voltammetry.

  • 21. Parada, Giovanny A.
    et al.
    Glover, Starla D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Hydrogen Bonded Phenol-Quinolines with Highly Controlled Proton-Transfer Coordinate2016In: European Journal of Organic Chemistry, ISSN 1434-193X, E-ISSN 1099-0690, no 20, p. 3365-3372Article in journal (Refereed)
    Abstract [en]

    A series of polycyclic phenols with intramolecular hydrogen bonds (IMHB) to quinolines was synthesized by Friedlander annulation of cycloalkanone-functionalized anisoles with 2-aminobenzaldehyde. The prepared compounds represent the first series of IMHB phenols in which the substitution and conjugation patterns between the phenols and the hydrogen bond acceptors are kept constant, and in which comparable electronic interaction between the two subunits is thus ensured. The distance and relative orientation between the phenolic OH and the quinolone nitrogen atom is controlled by 1,3-cycloalkadienes of different ring sizes to which the phenol and quinoline subunits are formally annulated. H-1 delta(OH) chemical shift and Xray crystal structure characterization support the conclusion that the size and conformational preference of the 1,3-cycloalkadiene rings control the H-bond geometry and strength. As a result, the oxygen to nitrogen distances differ by as much as 0.30ss the seri.

  • 22.
    Parada, Giovanny A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Glover, Starla D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Synthesis of Phenol-Quinolines with Intramolecular Hydrogen-Bonds of Different StrengthManuscript (preprint) (Other academic)
  • 23.
    Parada, Giovanny A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Markle, Todd F.
    Department of Chemistry, Yale University.
    Glover, Starla D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hammarström, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Zietz, Burkhard
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Control over Excited State Intramolecular Proton Transfer and Photoinduced Tautomerization: Influence of the Hydrogen-Bond Geometry2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 17, p. 6362-6366Article in journal (Refereed)
    Abstract [en]

    The influence of H-bond geometry on thedynamics of excited state intramolecular proton transfer(ESIPT) and photoinduced tautomerization in a series ofphenol-quinoline compounds is investigated. Control overthe proton donor–acceptor distance (dDA) and dihedralangle between the proton donor–acceptor subunits isachieved by introducing methylene backbone straps ofincreasing lengths to link the phenol and quinoline. Wedemonstrate that a long dDA correlates with a higher barrierfor ESIPT, while a large dihedral angle opens highlyefficient deactivation channels after ESIPT, preventing theformation of the fully relaxed tautomer photoproduct.

  • 24.
    Ren, Yi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Pietschnig, Rudolf
    Baumgartner, Thomas
    Perfluorophenylene-Bridged Bisphospholes: Synthesis and Unexpected Photophysical Properties2013In: Dalton Transactions, Vol. 42, p. 5314-5321Article in journal (Refereed)
  • 25.
    Shameem, Muhammad Anwar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Organophosphorus Compounds in Organic Electronics2016In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 22, no 31, p. 10718-10735Article in journal (Refereed)
    Abstract [en]

    This Minireview describes recent advances of organophosphorus compounds as opto-electronic materials in the field of organic electronics. The progress of (hetero-) phospholes, unsaturated phosphanes, and trivalent and pentavalent phosphanes since 2010 is covered. The described applications of organophosphorus materials range from single molecule sensors, field effect transistors, organic light emitting diodes, to polymeric materials for organic photovoltaic applications.

  • 26.
    Sollert, Carina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Pilarski, Lukasz T.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC.
    Crystal structure of acetonitrile[eta(6)-1-methyl-4-(1-methylethyl)benzene][1-(pyrimidin-2-yl )-3H-indol-1-ium-2-yl-kappa N-2,C]ruthenium(II) bis-(hexafluoridoantimonate)2015In: ACTA CRYSTALLOGRAPHICA SECTION E-CRYSTALLOGRAPHIC COMMUNICATIONS, ISSN 2056-9890, Vol. 71, p. 1190-+Article in journal (Refereed)
    Abstract [en]

    In the title compound, [Ru(C10H14)(C12H9N3)(CH3CN)][SbF6](2), the ruthenium(II) cation is eta(6)-coordinated by the para-cymene ligand with a Ru-centroid(eta(6)-benzene) distance of 1.746 (2) angstrom. Furthermore, ruthenium coordinations to the C and N atoms of the pyrimidyl indole ligand are found to be 1.986 (4) and 2.082 (3) angstrom, respectively. The typical piano-stool coordination environment is saturated with an acetonitrile solvent molecule with a Ru-N distance of 2.044 (3) angstrom. The indolyl ligand is protonated at the C3 position with the N=C imine bond length appropriate to that of related 3H-indole-based complexes. In the crystal, the complex cation is linked to the SbF6- ions through weak C-H center dot center dot center dot F hydrogen bonds.

  • 27.
    Wang, Lei
    et al.
    KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden..
    Duan, Lele
    KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden..
    Ambre, Ram B.
    KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden..
    Daniel, Quentin
    KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden..
    Chen, Hong
    Stockholm Univ, Berzelii Ctr EXSELENT Porous Mat, SE-10691 Stockholm, Sweden.;Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Sun, Junliang
    Stockholm Univ, Berzelii Ctr EXSELENT Porous Mat, SE-10691 Stockholm, Sweden.;Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Das, Biswanath
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Thapper, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Uhlig, Jens
    Lund Univ, Dept Chem Phys, S-22100 Lund, Sweden..
    Diner, Peter
    KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden..
    Sun, Licheng
    KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden.;Dalian Univ Technol DUT, DUT KTH Joint Educ & Res Ctr Mol Devices, State Key Lab Fine Chem, Dalian 116024, Peoples R China..
    A nickel (II) PY5 complex as an electrocatalyst for water oxidation2016In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 335, p. 72-78Article in journal (Refereed)
    Abstract [en]

    A Ni-PY5 [PY5 = 2,6-bis(1,1-bis(2-pyridyl)ethyl)pyridine)] complex has been found to act as an electrocatalyst for oxidizing water to dioxygen in aqueous phosphate buffer solutions. The rate of water oxidation catalyzed by the Ni-PY5 is remarkably enhanced by the proton acceptor base HPO42-, with rate constant of 1820 M-1 s(-1). Controlled potential bulk electrolysis with Ni-PY5 at pH 10.8 under an applied potential of 1.5 V vs. normal hydrogen electrode (NHE) resulted in dioxygen formation with a high faradaic efficiency over 90%. A detailed mechanistic study identifies the water nucleophilic attack pathway for water oxidation catalysis.

  • 28.
    Xiong, Ruisheng
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Bornhof, Anna-Bea
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Arkhypchuk, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Orthaber, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Borbas, Eszter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Furan- and Thiophene-Based Auxochromes Red-shift Chlorin Absorptions and Enable Oxidative Chlorin Polymerizations2017In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 17, p. 4089-4095Article in journal (Refereed)
    Abstract [en]

    The de novo syntheses of chemically stable chlorins with five-membered heterocyclic (furane, thiophene, formylfurane and formylthiophene) substituents in selected meso- and beta-positions are reported. Heterocycle incorporation in the 3- and 13-positions shifted the chlorin absorption and emission to the red (up to lambdaem =680 nm), thus these readily incorporated substituents function analogously to auxochromes present in chlorophylls, for example, formyl and vinyl groups. Photophysical, theoretical and X-ray crystallographic experiments revealed small but significant differences between the behavior of the furan- and the thiophene-based auxochromes. Four regioisomeric bis-thienylchlorins (3,10; 3,13, 3,15 and 10,15) were oxidatively electropolymerized; the chlorin monomer geometry had a profound impact on the polymerization efficiency and the electrochemical properties of the resulting material. Chemical co-polymerization of 3,13-bis-thienylchlorin with 3-hexylthiophene yielded an organic-soluble red-emitting polymer.

1 - 28 of 28
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