Počet záznamů: 1
Porphyrin Protonation Studied by Magnetic Circular Dichroism
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SYSNO ASEP 0376366 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Porphyrin Protonation Studied by Magnetic Circular Dichroism Tvůrce(i) Štěpánek, Petr (UOCHB-X) RID
Andrushchenko, Valery (UOCHB-X) RID, ORCID
Ruud, K. (NO)
Bouř, Petr (UOCHB-X) RID, ORCIDCelkový počet autorů 4 Zdroj.dok. Journal of Physical Chemistry A. - : American Chemical Society - ISSN 1089-5639
Roč. 116, č. 1 (2012), s. 778-783Poč.str. 6 s. Jazyk dok. eng - angličtina Země vyd. US - Spojené státy americké Klíč. slova magnetic circular dichroism (MCD) ; TPPS ; spectra simulations ; porphyrin protonation Vědní obor RIV CF - Fyzikální chemie a teoretická chemie CEP GAP208/11/0105 GA ČR - Grantová agentura ČR GA203/09/2037 GA ČR - Grantová agentura ČR GAP208/10/0559 GA ČR - Grantová agentura ČR LH11033 GA MŠMT - Ministerstvo školství, mládeže a tělovýchovy CEZ AV0Z40550506 - UOCHB-X (2005-2011) UT WOS 000298978000083 DOI 10.1021/jp2105192 Anotace Magnetic circular dichroism (MCD) spectroscopy provides valuable information about electronic excited states : in molecules. The interpretation of spectra is however difficult, often requiring additional theoretical calculations to rationalize the observed signal Recent developments in time dependent density functional theory (TDDFT) bring hope that the applicability of MCD spectroscopy for chemical problems may be significantly extended. In this study, two modern analytical TDDFT implementations are compared and used to understand experimental MCD spectra of a model porphyrin system upon protonation. Changes in porphyrin geometry and electronic structure are related to MCD intensities by comparing the spectra of 5,10,15,20-tetraphenyl-21H;23H-porphyrintetrasulfonic acid (TPPS) measured at different pH values with the TDDFT calculations. Although the theoretical results slightly dependent on the chosen exchange-correlation functional, the computations provided MCD,curves that could well rationalize the experimental data The protonation of the porphyrin core causes marked changes in the MCD spectrum, whereas the role of the substituents is limited. Also, different conformations of the porphyrin substituents cause relatively minor changes of the MCD pattern, mostly in : the Soret region, where the porphine and phenyl electronic transitions start to mix. The solvent environment simulated by the dielectric model caused a shift (similar to 20 nm) of the absorption bands but only minor variations in the absorption and MCD spectral shapes. The study thus demonstrates that the recently available first principles interpretations of MCD spectra significantly enhance the applicability of the technique for molecular structural studies Pracoviště Ústav organické chemie a biochemie Kontakt asep@uochb.cas.cz ; Kateřina Šperková, Tel.: 232 002 584 ; Viktorie Chládková, Tel.: 232 002 434 Rok sběru 2013
Počet záznamů: 1