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Titolo:
SOLVENT EFFECTS ON MOLECULAR AND IONIC SPECTRA .6. HYDROGEN-BONDING AND THE DELOCALIZED NATURE OF THE FIRST (1)(N,PI-ASTERISK) EXCITED-STATE OF PYRAZINE
Autore:
ZENG J; WOYWOD C; HUSH NS; REIMERS JR;
Indirizzi:
UNIV SYDNEY,DEPT PHYS & THEORET CHEM SYDNEY NSW 2006 AUSTRALIA UNIV SYDNEY,DEPT PHYS & THEORET CHEM SYDNEY NSW 2006 AUSTRALIA TECH UNIV MUNICH,INST PHYS & THEORET CHEM D-85748 GARCHING GERMANY UNIV SYDNEY,DEPT BIOCHEM SYDNEY NSW 2006 AUSTRALIA
Titolo Testata:
Journal of the American Chemical Society
fascicolo: 33, volume: 117, anno: 1995,
pagine: 8618 - 8626
SICI:
0002-7863(1995)117:33<8618:SEOMAI>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
MONTE-CARLO SIMULATIONS; N-PI TRANSITIONS; ELECTRONIC-SPECTRA; AZABENZENE MOLECULES; POTENTIAL FUNCTIONS; ABSORPTION-SPECTRA; TRIPLET ABSORPTION; DILUTE PYRIMIDINE; REACTION FIELD; NUCLEIC-ACIDS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
89
Recensione:
Indirizzi per estratti:
Citazione:
J. Zeng et al., "SOLVENT EFFECTS ON MOLECULAR AND IONIC SPECTRA .6. HYDROGEN-BONDING AND THE DELOCALIZED NATURE OF THE FIRST (1)(N,PI-ASTERISK) EXCITED-STATE OF PYRAZINE", Journal of the American Chemical Society, 117(33), 1995, pp. 8618-8626

Abstract

Our method (Parts 1-5(1-6)) for estimating solvent shifts of species which have strong specific interactions (e.g., hydrogen bonding) with the solvent is applied to calculate the absorption and fluorescence solvatochromic (solvent) shifts of dilute pyrazine in water. On the basis of interpretation of solvent shift data, pyrazine in its S-1 (1)(n,pi) excited state has been thought to display reduced nuclear symmetry, with the excitation localized on just one of the two nitrogen atoms;this view has also been supported by electronic structure calculations. Such localization could occur, despite the presence of significant through-bond interactions between the nitrogen lone pairs, if the reorganization energy associated with symmetry breaking were sufficiently large. Here, the alternate description is developed for the electronicstructure of this excited state of pyrazine based on studies of the free molecule, of pyrazine-water clusters, and of pyrazine in dilute aqueous solution. For the free molecule, extensive ab initio Davidson-corrected CASSCF with MRCI calculations strongly suggest a high-symmetrygeometry, and verify that this is the correct interpretation of the available experiment data. For pyrazine-water clusters, only a high-symmetry model is shown capable of describing the observed high-resolution spectra, and for pyrazine in solution, only a high-symmetry model isshown to be capable of interpreting the observed fluorescence solventshift.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/11/20 alle ore 10:24:16