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Triplet excited states of nitronaphthalenes. II. b ‐Nitronaphthalene
Author(s) -
Capellos C.,
Suryanarayanan K.
Publication year - 1976
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550080407
Subject(s) - chemistry , flash photolysis , excited state , triplet state , photochemistry , intramolecular force , ultrafast laser spectroscopy , absorption (acoustics) , solvent , dipole , polar , reaction rate constant , analytical chemistry (journal) , atomic physics , stereochemistry , kinetics , molecule , spectroscopy , organic chemistry , physics , quantum mechanics , astronomy , acoustics
Nanosecond flash photolysis of b ‐nitronaphthalene ( b ‐NO 2 C 10 H 7 ) in nonpolar and polar solvents shows a transient species with maximum absorption and lifetime dependent on solvent polarity. In deaerated n ‐hexane the absorption maximum and lifetime (1/ k ) are 425 nm and 530 nsec, while in deaerated ethanol the corresponding values are 470 nm and 1.7 ·sec. This transient absorption is attributed to the triplet excited state of b ‐NO 2 C 10 H 7 , and the observed red shift as well as its longer lifetime in polar solvents are indicative of the intramolecular charge transfer character of this state. The change of dipole moment accompanying the transition T 1 → T n , as well as rate constants for electron and proton transfer reactions involving the T 1 state of b ‐NO 2 C 10 H 7 , were determined. The spectroscopic and kinetic data obtained in this work indicate that the triplet state of b ‐NO 2 C 10 H 7 behaves like a n ‐π* state in nonpolar media, while in polar solvents the n ‐π* character of the state is reduced with a simultaneous increase in the charge transfer character.