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Dahlstrand, ChristianORCID iD iconorcid.org/0000-0003-2485-8661
Publications (10 of 10) Show all publications
Yadav, S., El Bakouri, O., Jorner, K., Tong, H., Dahlstrand, C., Sola, M. & Ottosson, H. (2019). Exploiting the Aromatic Chameleon Character of Fulvenes for Computational Design of Baird-Aromatic Triplet Ground State Compounds. Chemistry - An Asian Journal, 14(10), 1870-1878
Open this publication in new window or tab >>Exploiting the Aromatic Chameleon Character of Fulvenes for Computational Design of Baird-Aromatic Triplet Ground State Compounds
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2019 (English)In: Chemistry - An Asian Journal, ISSN 1861-4728, E-ISSN 1861-471X, Vol. 14, no 10, p. 1870-1878Article in journal (Refereed) Published
Abstract [en]

Due to the reversal in electron counts for aromaticity and antiaromaticity in the closed-shell singlet state (normally ground state, S-0) and lowest * triplet state (T-1 or T-0), as given by Huckel's and Baird's rules, respectively, fulvenes are influenced by their substituents in the opposite manner in the T-1 and S-0 states. This effect is caused by a reversal in the dipole moment when going from S-0 to T-1 as fulvenes adapt to the difference in electron counts for aromaticity in various states; they are aromatic chameleons. Thus, a substituent pattern that enhances (reduces) fulvene aromaticity in S-0 reduces (enhances) aromaticity in T-1, allowing for rationalizations of the triplet state energies (E-T) of substituted fulvenes. Through quantum chemical calculations, we now assess which substituents and which positions on the pentafulvene core are the most powerful for designing compounds with low or inverted E-T. As a means to increase the -electron withdrawing capacity of cyano groups, we found that protonation at the cyano N atoms of 6,6-dicyanopentafulvenes can be a route to on-demand formation of a fulvenium dication with a triplet ground state (T-0). The five-membered ring of this species is markedly Baird-aromatic, although less than the cyclopentadienyl cation known to have a Baird-aromatic T-0 state.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2019
Keywords
Baird's rule, excited state aromaticity, fulvenes, quantum chemistry, triplet state energies
National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-389826 (URN)10.1002/asia.201801821 (DOI)000471307500040 ()30659757 (PubMedID)
Funder
Swedish Research CouncilCarl Tryggers foundation Wenner-Gren Foundations
Available from: 2019-07-29 Created: 2019-07-29 Last updated: 2019-07-29Bibliographically approved
Olsson, S. K., Dahlstrand, C. & Gogoll, A. (2018). Design of oxophilic metalloporphyrins: an experimental and DFT study of methanol binding. Dalton Transactions, 47(33), 11572-11585
Open this publication in new window or tab >>Design of oxophilic metalloporphyrins: an experimental and DFT study of methanol binding
2018 (English)In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 47, no 33, p. 11572-11585Article in journal (Refereed) Published
Abstract [en]

By systematic measurements we have evaluated a series of tetraphenyl metalloporphyrins and halogenated tetraphenyl metalloporphyrin derivatives for binding to ligands with oxygen containing functional groups, using methanol, acetic acid and acetone as examples. Experimental binding constants identified three metalloporphyrins with good binding to all three ligands: MgTPFPP, MgTPPBr8 and ZnTPPBr8 as well as a range of porphyrins binding to select ligands. Based on these results the optimal porphyrins can be selected for the desired binding interactions. We also show how to use DFT calculations to evaluate the potential binding between a metalloporphyrin and a ligand, which is deduced from free energies of binding ΔG, charge transfer ΔQ, and change of metal spin state. Computations on unsubstituted porphyrins in lieu of tetraphenyl porphyrin systems yield reliable predictions of binding interactions with good correlation to the corresponding experimental data. The calculations have also yielded interesting insights into the effect of halogenation in the β-position on the binding to ligands with oxygen containing functional groups.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
Keywords
Porphyrins, DFT, host-guest
National Category
Organic Chemistry
Research subject
Chemistry with specialization in Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-359830 (URN)10.1039/c8dt02432d (DOI)000442509700031 ()30087966 (PubMedID)
Funder
Swedish Research Council, 621-2012-3379Carl Tryggers foundation , 16:156Swedish National Infrastructure for Computing (SNIC), 2018/3-240National Supercomputer Centre (NSC), Sweden, SNIC 2018/3-240
Available from: 2018-09-06 Created: 2018-09-06 Last updated: 2019-04-23Bibliographically approved
Bunrit, A., Watile, R., Dahlstrand, C., Olsson, S., Srifa, P., Huang, G., . . . Samec, J. (2017). H3PO2-catalyzed intramolecular stereospecific nucleophilic substitution of the hydroxyl group in stereogenic alcohols. Paper presented at 254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC. Abstract of Papers of the American Chemical Society, 254
Open this publication in new window or tab >>H3PO2-catalyzed intramolecular stereospecific nucleophilic substitution of the hydroxyl group in stereogenic alcohols
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2017 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 254Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-357070 (URN)000429556701849 ()
Conference
254th National Meeting and Exposition of the American-Chemical-Society (ACS) on Chemistry's Impact on the Global Economy, AUG 20-24, 2017, Washington, DC
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-08-13Bibliographically approved
Dahlstrand, C., Rosenberg, M., Kilså, K. & Ottosson, H. (2012). Exploration of the π-Electronic Structure of Singlet, Triplet, and Quintet States of Fulvenes and Fulvalenes Using the Electron Localization Function. Journal of Physical Chemistry A, 116(20), 5008-5017
Open this publication in new window or tab >>Exploration of the π-Electronic Structure of Singlet, Triplet, and Quintet States of Fulvenes and Fulvalenes Using the Electron Localization Function
2012 (English)In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 116, no 20, p. 5008-5017Article in journal (Refereed) Published
Abstract [en]

The singlet ground states and lowest triplet states of penta- and heptafulvene, their benzannulated derivatives, as well as the lowest quintet states of pentaheptafulvalenes, either the parent compound or compounds in which the two rings are intercepted by either an alkynyl or a phenyl segment, were investigated at the (U)OLYP/6-311G(d,p) density functional theory level. The influence of (anti)-aromaticity was analyzed by the structure-based aromaticity index HOMA, the harmonic oscillator model of aromaticity. The extent of (anti)aromatic character was also evaluated in terms of the pi-electron (de)localization as measured by the pi component of the electron localization function (ELF pi). The natural atomic orbital (NAO) occupancies were calculated in order to evaluate the degree of pi-electron shift caused by the opposing electron-counting rules for aromaticity in the electronic ground state (S-0; Hiickel's rule) and the first pi pi* excited triplet state (T-1; Baird's rule). Pentaheptafulvalene (5) shows a shift of 0.5 pi electrons from the 5-ring to the 7-ring when going from the S-0 state to the lowest quintet state (Qu(1)). The pentaheptafulvalene 5 and [5.6.7]quinarene 7 were also investigated in their 90 degrees twisted conformations. From our study it is apparent that excitation localization in fulvalenes, but not in fulvenes, to a substantial degree is determined by aromaticity localization to triplet biradical 4n pi-electron cycles. Isolated benzene rings in these compounds tend to remain as closed-shell 6 pi-electron cycles.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-172377 (URN)10.1021/jp3032397 (DOI)000304338600021 ()
Available from: 2012-04-09 Created: 2012-04-09 Last updated: 2017-12-07Bibliographically approved
Dahlstrand, C. (2012). Ground and Excited State Aromaticity: Design Tools for π-Conjugated Functional Molecules and Materials. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Ground and Excited State Aromaticity: Design Tools for π-Conjugated Functional Molecules and Materials
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The main focus of this thesis is on the aromaticity of the ground state and electronically excited states of π-conjugated molecules and polymers, as well as how aromaticity is connected to their properties.

The electronic structures of polybenzenoid hydrocarbons (PBHs) were explored through density functional theory (DFT) calculations and the π-component of the electron localization function (ELFπ). The study revealed how the π-electronic structure is influenced by the fusion of double bonds or benzene rings to the PBHs. We also demonstrated that the π-electrons of benzene extend to accommodate as much aromaticity as possible when bond length distorted.  

The aromatic chameleon property displayed by fulvenes, isobenzofulvenes, fulvalenes, bis(fulvene)s, and polyfulvenes were investigated using DFT calculations. The tria-, penta-, and heptafulvenes were shown to possess ionization energies and electron affinities which can be tuned extensively by substitution, some of which even outperform TTF and TCNQ, the prototypical electron donor and acceptor, respectively. The singlet-triplet energy gap of pentafulvenes can be tuned extensively by substitution to the point that the triplet state is lower than the singlet state and thus becomes the ground state. The ELFπ of isobenzofulvene shows that the benzene ring in an electronically excited state can be more aromatic than the corresponding ring in the ground state. We have shown that the 6-ring of [5.6.7]quinarene is influenced by a Hückel aromatic resonance structure with 4n+2 π-electrons in the excited quintet state. The bis(fulvene)s which are composed of a donor type heptafulvene and an acceptor type pentafulvene, retain the basic donor-acceptor properties of the two fragments and could function as compact donor-acceptor dyads. A few of the designed polyfulvenes were found to have band gaps below 1 eV at the PBC-B3LYP/6-31G(d) level.

Various 2,7-disubstituted fluorenones and dibenzofulvenes were synthesized and their excited state properties were investigated by absorption spectroscopy and time-dependent DFT calculations. It was found that the 1A1B transition of ππ* character can be tuned by substitution in the 2,7-positions. The 2,7-bis(N,N-dimethyl) derivatives of fluorenone and dibenzofulvene displayed low energy transitions at 2.18 and 1.61 eV, respectively, in toluene.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. p. 84
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 929
Keywords
fulvene, fulvalene, polyfulvene, aromaticity, triplet state, excited state, Clar structure, polybenzenoid hydrocarbons (PBH), conjugated polymers, computational chemistry, optical spectroscopy
National Category
Organic Chemistry
Research subject
Chemistry with specialization in Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-173115 (URN)978-91-554-8362-3 (ISBN)
Public defence
2012-06-05, B42, BMC, Husargatan 3, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2012-05-14 Created: 2012-04-18 Last updated: 2012-08-01Bibliographically approved
Zhu, J., Dahlstrand, C., Smith, J. R., Villaume, S. & Ottosson, H. (2010). On the Importance of Clar Structures of Polybenzenoid Hydrocarbons as Revealed by the n-Contribution to the Electron Localization Function. Symmetry, 2(3), 1653-1682
Open this publication in new window or tab >>On the Importance of Clar Structures of Polybenzenoid Hydrocarbons as Revealed by the n-Contribution to the Electron Localization Function
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2010 (English)In: Symmetry, ISSN 2073-8994, E-ISSN 2073-8994, Vol. 2, no 3, p. 1653-1682Article in journal (Refereed) Published
Abstract [en]

The degree of p-electron (de)localization and aromaticity of a series of polybenzenoid hydrocarbons (PBHs) has been analyzed through the π-contribution to the electron localization function (ELFπ), calculated at the B3LYP/6-311G(d,p) hybrid density functional theory level. The extent of p-electron delocalization in the various hexagons of a PBH was determined through analysis of the bifurcation values of the ELFp basins (BV(ELFp)), the spans in the bifurcation values in each hexagon (ΔBV(ELFπ)), and the ring-closure bifurcation values of the ELFπ (RCBV(ELFπ)). These computed results were compared to the qualitative description of local aromaticities of the different hexagons in terms of Clar structures with p-sextets. Benzene, [18]annulene, and thirty two PBHs were analyzed at their equilibrium geometries, and benzene and triphenylene were also analyzed at bond length distorted structures. In general, the description of PBHs in terms of Clar valence structures is supported by the ELFp properties, although there are exceptions. For PBHs at their equilibrium geometries there is a clear sigmoidal relationship between the CC bond lengths and the amount of p-electron (de)localization at these bonds, however, this relationship is lost for bond distorted geometries. In the latter cases, we specifically examined benzene in D3h symmetric “1,3,5-cyclohexatriene” structures and triphenylene in eight different structures. From the distorted benzenes and triphenylenes it becomes clear that there is a distinct tendency for the p-electron network to retain delocalization (aromaticity). The ELFp analysis thus reveals an antidistortive rather than a distortive behavior of the p-electrons in these investigated compounds.

Place, publisher, year, edition, pages
Basel: MDPI, 2010
Keywords
Clar structures, electron localization function, polybenzenoid hydrocarbons
National Category
Other Basic Medicine
Research subject
Chemistry with specialization in Organic Chemistry; Chemistry with specialization in Quantum Chemistry
Identifiers
urn:nbn:se:uu:diva-140983 (URN)10.3390/sym2031653 (DOI)000208831900018 ()
Available from: 2011-01-10 Created: 2011-01-10 Last updated: 2018-01-12Bibliographically approved
Dahlstrand, C., Yamazaki, K., Kilså, K. & Ottosson, H. (2010). Substituent Effects on the Electron Affinities and Ionization Energies of Tria-, Penta-, and Heptafulvenes: A Computational Investigation. Journal of Organic Chemistry, 75(23), 8060-8068
Open this publication in new window or tab >>Substituent Effects on the Electron Affinities and Ionization Energies of Tria-, Penta-, and Heptafulvenes: A Computational Investigation
2010 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 75, no 23, p. 8060-8068Article in journal (Refereed) Published
Abstract [en]

The extent of substituent influence on the vertical electron affinities (EAs) and ionization energies (IEs) of 43 substituted tria-, penta-, and heptafulvenes was examined computationally at the OVGF/6-311G(d)//B3LYP/6-311G(d) level of theory and compared with those of tetracyanoquinodimethane (TCNQ) and tetrathiafulvalene (TTF) as representing strong electron-acceptor and -donor compounds, respectively. The substituents X at the exocyclic positions of the fulvenes were either NH2, H, or CN, while the substituents Y at the ring positions were H, CI, F, CN, or NH2. The variations of the EAs and lEs were rationalized by qualitative arguments based on frontier orbital symmetries for the different fulvene classes with either X or Y being constant. The minimum and maximum values found for the calculated EAs of the tria-, penta-, and heptafulvenes were 0.51-2.05, 0.24-3.63, and 0.53-3.14 eV, respectively, and for the IEs 5.27-9.96, 7.07-10.31, and 6.35-10.59 eV, respectively. Two of the investigated fulvenes outperform TCNQ (calcd EA = 2.63 eV) and one outperforms TTF (calcd IE = 6.25 eV) with regard to acceptor and donor abilities, respectively. We also evaluated the properties of bis(fulvene)s, i.e., compounds composed of a donor-type heptafulvene fused with an acceptor-type pentafulvene, and it was revealed that these bis(fulvene)s can be designed so that the IE and EA of the two separate fulvene segments are retained, potentially allowing for the design of compact donor-acceptor dyads.

National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-140156 (URN)10.1021/jo101634v (DOI)000284519900008 ()21067236 (PubMedID)
Available from: 2011-01-04 Created: 2011-01-04 Last updated: 2017-12-11Bibliographically approved
Tong, H., Dahlstrand, C., Villaume, S., Jun, Z., Piqueras, M. C., Crespo, R. & Ottosson, H.Fulvenes: Compounds for which the Singlet-Triplet Energy Gaps are Closely Linked to Aromaticity and  Aromaticity Differences.
Open this publication in new window or tab >>Fulvenes: Compounds for which the Singlet-Triplet Energy Gaps are Closely Linked to Aromaticity and  Aromaticity Differences
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(English)Manuscript (preprint) (Other academic)
National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-172869 (URN)
Available from: 2012-04-16 Created: 2012-04-16 Last updated: 2012-08-01
Rosenberg, M., Dahlstrand, C., Ottosson, H. & Kilså, K.Manipulation of Excited State Energies in Fulvenic Molecules.
Open this publication in new window or tab >>Manipulation of Excited State Energies in Fulvenic Molecules
(English)Manuscript (preprint) (Other academic)
National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-172871 (URN)
Available from: 2012-04-16 Created: 2012-04-16 Last updated: 2012-08-01
Dahlstrand, C., Jahn, B., Grigoriev, A., Villaume, S., Ahuja, R. & Ottosson, H.Tuning the Band Gap of Polyfulvenes by Use of “Handles”: On the Effects of Exocyclic Substitution, Benzannulation, and Ring Methylation..
Open this publication in new window or tab >>Tuning the Band Gap of Polyfulvenes by Use of “Handles”: On the Effects of Exocyclic Substitution, Benzannulation, and Ring Methylation.
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(English)Manuscript (preprint) (Other academic)
National Category
Polymer Chemistry Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-172872 (URN)
Available from: 2012-04-16 Created: 2012-04-16 Last updated: 2012-08-01
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2485-8661

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