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Jorner, Kjell
Publications (10 of 18) 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
Jorner, K. (2018). Influence of Aromaticity on Excited State Structure, Reactivity and Properties. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Influence of Aromaticity on Excited State Structure, Reactivity and Properties
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis describes work that could help development of new photochemical reactions and light-absorbing materials. Focus is on the chemical concept "aromaticity" which is a proven conceptual tool in developing thermal chemical reactions. It is here shown that aromaticity is also valuable for photochemistry. The influence of aromaticity is discussed in terms of structure, reactivity and properties. With regard to structure, it is found that photoexcited molecules change their structure to attain aromatic stabilization (planarize, allow through-space conjugation) or avoid antiaromatic destabilization (pucker). As for reactivity, it is found that stabilization/destabilization of reactants decrease/increase photoreactivity, in accordance with the Bell-Evans-Polanyi relationship. Two photoreactions based on excited state antiaromatic destabilization of the substrates are reported. Finally, with respect to properties, it is shown that excited state energies can be tuned by considering aromatic effects of both the electronic ground state and the electronically excited states. The fundamental research presented in this thesis forms a foundation for the development of new photochemical reactions and design of compounds for new organic electronic materials.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 55
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1679
Keywords
photochemistry, aromaticity, computational chemistry
National Category
Organic Chemistry Theoretical Chemistry
Research subject
Chemistry with specialization in Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-349229 (URN)978-91-513-0354-3 (ISBN)
Public defence
2018-06-14, room 80101, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2018-05-22 Created: 2018-04-23 Last updated: 2018-09-27
Dreos, A., Jorner, K., Borjesson, K., Wang, Z., Ottosson, H. & Moth-Poulsen, K. (2018). Norbornadiene-quadricyclane photochromic systems for solar energy storage applications and testing in devices. Paper presented at 255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, USA.. Abstract of Papers of the American Chemical Society, 255
Open this publication in new window or tab >>Norbornadiene-quadricyclane photochromic systems for solar energy storage applications and testing in devices
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2018 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Washington, D.C.: American Chemical Society (ACS), 2018
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-368923 (URN)000435539900027 ()
Conference
255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, USA.
Note

Meeting Abstract: 26

Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11Bibliographically approved
Poon, J.-f., Yan, J., Jorner, K., Ottosson, H., Donau, C., Singh, V. P., . . . Engman, L. (2018). Substituent Effects in Chain-Breaking Aryltellurophenol Antioxidants. Chemistry - A European Journal, 24(14), 3520-3527
Open this publication in new window or tab >>Substituent Effects in Chain-Breaking Aryltellurophenol Antioxidants
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2018 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 14, p. 3520-3527Article in journal (Refereed) Published
Abstract [en]

2-Aryltellurophenols substituted in the aryltelluro or phenolic part of the molecule were prepared by lithiation of the corresponding O-THP-protected 2-bromophenol, followed by reaction with a suitable diaryl ditelluride and deprotection. In a two-phase system containing N-acetylcysteine as a co-antioxidant in the aqueous phase, all compounds quenched lipid peroxyl radicals more efficiently than α-tocopherol with 3 to 5-fold longer inhibition times. Compounds carrying electron donating para-substituents in the phenolic or aryltelluro part of the molecule showed the best results. The mechanism for quenching of peroxyl radicals was discussed in the light of calculated OH bond dissociation energies, deuterium labeling experiments and studies of thiol-consumption in the aqueous phase. 

National Category
Organic Chemistry
Research subject
Chemistry with specialization in Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-329202 (URN)10.1002/chem.201704811 (DOI)000426764400024 ()29266496 (PubMedID)
Funder
Stiftelsen Olle Engkvist Byggmästare, 1016/159ÅForsk (Ångpanneföreningen's Foundation for Research and Development), 16-364
Note

Poon, J. and Yan, J. are equally contributing.

Available from: 2017-09-10 Created: 2017-09-10 Last updated: 2018-05-22Bibliographically approved
Jorner, K., Jahn, B. O., Bultinck, P. & Ottosson, H. (2018). Triplet state homoaromaticity: concept, computational validation and experimental relevance. Chemical Science, 9(12), 3165-3176
Open this publication in new window or tab >>Triplet state homoaromaticity: concept, computational validation and experimental relevance
2018 (English)In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 9, no 12, p. 3165-3176Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2018
National Category
Organic Chemistry Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-349228 (URN)10.1039/C7SC05009G (DOI)000428987200010 ()29732099 (PubMedID)
Funder
Swedish Research Council, 2015-04538Wenner-Gren FoundationsThe Royal Swedish Academy of Sciences
Available from: 2018-04-23 Created: 2018-04-23 Last updated: 2018-06-05Bibliographically approved
Ayub, R., El Bakouri, O., Jorner, K., Sola, M. & Ottosson, H. (2017). 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?. Journal of Organic Chemistry, 82(12), 6327-6340
Open this publication in new window or tab >>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?
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2017 (English)In: Journal of Organic Chemistry, ISSN 0022-3263, E-ISSN 1520-6904, Vol. 82, no 12, p. 6327-6340Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2017
National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-329665 (URN)10.1021/acs.joc.7b00906 (DOI)000403854500031 ()28535673 (PubMedID)
Funder
Swedish Research Council
Available from: 2017-09-20 Created: 2017-09-20 Last updated: 2017-10-27Bibliographically approved
Ayub, R., Papadakis, R., Jorner, K., Zietz, B. & Ottosson, H. (2017). Cyclopropyl Group: An Excited-State Aromaticity Indicator?. Chemistry - A European Journal, 23(55), 13684-13695
Open this publication in new window or tab >>Cyclopropyl Group: An Excited-State Aromaticity Indicator?
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2017 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 23, no 55, p. 13684-13695Article in journal (Refereed) Published
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.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-332141 (URN)10.1002/chem.201701404 (DOI)000412193700021 ()28683165 (PubMedID)
Funder
Wenner-Gren FoundationsSwedish Research Council, 2015-04538
Available from: 2017-10-24 Created: 2017-10-24 Last updated: 2018-04-23Bibliographically approved
Ueda, M., Jorner, K., Sung, Y. M., Mori, T., Xiao, Q., Kim, D., . . . Itoh, Y. (2017). Energetics of Baird aromaticity supported by inversion of photoexcited chiral [4n]annulene derivatives. Nature Communications, 8, Article ID 346.
Open this publication in new window or tab >>Energetics of Baird aromaticity supported by inversion of photoexcited chiral [4n]annulene derivatives
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2017 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, article id 346Article in journal (Refereed) Published
Abstract [en]

For the concept of aromaticity, energetic quantification is crucial. However, this has been elusive for excited-state (Baird) aromaticity. Here we report our serendipitous discovery of two nonplanar thiophene-fused chiral [4n]annulenes Th4COT Saddle and Th6CDH Screw, which by computational analysis turned out to be a pair of molecules suitable for energetic quantification of Baird aromaticity. Their enantiomers were separable chromatographically but racemized thermally, enabling investigation of the ring inversion kinetics. In contrast to Th6CDH Screw, which inverts through a nonplanar transition state, the inversion of Th4COT Saddle, progressing through a planar transition state, was remarkably accelerated upon photoexcitation. As predicted by Baird’s theory, the planar conformation of Th4COT Saddle is stabilized in the photoexcited state, thereby enabling lower activation enthalpy than that in the ground state. The lowering of the activation enthalpy, i.e., the energetic impact of excited-state aromaticity, was quantified experimentally to be as high as 21–22 kcal mol–1.

National Category
Chemical Engineering
Identifiers
urn:nbn:se:uu:diva-333965 (URN)10.1038/s41467-017-00382-1 (DOI)000408375700010 ()
Available from: 2017-12-13 Created: 2017-12-13 Last updated: 2018-04-23Bibliographically approved
Ayub, R., Jorner, K. & Ottosson, H. (2017). The Silacyclobutene Ring: An Indicator of Triplet State Baird-Aromaticity. Inorganics, 5(4), Article ID 91.
Open this publication in new window or tab >>The Silacyclobutene Ring: An Indicator of Triplet State Baird-Aromaticity
2017 (English)In: Inorganics, ISSN 2304-6740, Vol. 5, no 4, article id 91Article in journal (Refereed) Published
Abstract [en]

Baird's rule tells that the electron counts for aromaticity and antiaromaticity in the first pi pi* triplet and singlet excited states (T-1 and S-1) are opposite to those in the ground state (S-0). Our hypothesis is that a silacyclobutene (SCB) ring fused with a [4n]annulene will remain closed in the T-1 state so as to retain T-1 aromaticity of the annulene while it will ring-open when fused to a [4n + 2]annulene in order to alleviate T-1 antiaromaticity. This feature should allow the SCB ring to function as an indicator for triplet state aromaticity. Quantum chemical calculations of energy and (anti)aromaticity changes along the reaction paths in the T-1 state support our hypothesis. The SCB ring should indicate T-1 aromaticity of [4n]annulenes by being photoinert except when fused to cyclobutadiene, where it ring-opens due to ring-strain relief.

Keywords
Baird's rule, computational chemistry, excited state aromaticity, Photostability
National Category
Chemical Sciences
Identifiers
urn:nbn:se:uu:diva-340320 (URN)10.3390/inorganics5040091 (DOI)000419214000030 ()
Available from: 2018-02-08 Created: 2018-02-08 Last updated: 2018-04-23Bibliographically approved
Oh, J., Sung, Y. M., Mori, H., Park, S., Jorner, K., Ottosson, H., . . . Kim, D. (2017). Unraveling Excited-Singlet-State Aromaticity via Vibrational Analysis. Chem, 3(5), 870-880
Open this publication in new window or tab >>Unraveling Excited-Singlet-State Aromaticity via Vibrational Analysis
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2017 (English)In: Chem, ISSN 24519294, Vol. 3, no 5, p. 870-880Article in journal (Refereed) Published
Abstract [en]

Summary

The concept of excited-state aromaticity is receiving much attention in that completely reversed aromaticity in the excited state (so-called aromaticity reversal) provides crucial insight into photostability, photoreactivity, and its application to the photosynthetic mechanism and photoactive materials. Despite this significance, experimental elucidation of excited-state aromaticity is still unsolved, particularly for the excited singlet state. Here, as an unconventional approach, time-resolved IR (TRIR) spectroscopy on aromatic and anti-aromatic hexaphyrin congeners shed light on excited-singlet-state aromaticity. The contrasting spectral features between the Fourier transform IR and TRIR spectra reveal the aromaticity-driven structural changes, corroborating aromaticity reversal in the excited singlet states. Our paradigm for excited-state aromaticity, the correlation of IR spectral features with aromaticity reversal, provides another fundamental key to understanding the role of (anti)aromaticity in the stability, dynamics, and reactivity in the excited singlet state of π-conjugated molecular systems.

National Category
Organic Chemistry
Identifiers
urn:nbn:se:uu:diva-349223 (URN)10.1016/j.chempr.2017.09.005 (DOI)000416368000014 ()
Funder
Swedish Research Council, 2015-04538
Available from: 2018-04-23 Created: 2018-04-23 Last updated: 2018-09-24Bibliographically approved
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