ISSN:
1432-2234
Keywords:
p-nitroaniline
;
Nitrobenzene
;
Triplet state
;
Photo reductions
;
Quantum Yield
;
Solvent shifts
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The nature of the lowest energy triplet state (T 1) ofp-nitroaniline (PNA), N,N-dimethyl-p-nitroaniline (DMPNA) and nitrobenzene (NB) is reexamined using the semiempirical CNDO/S-CI method with selected parameter options. The present results indicate that in the case of theunperturbed molecules the short-axis polarized π* ←n(π) triplet largely localized at the acceptor end of the molecule may lie lower in energy than the triplet manifold counterpart of the intense intramolecular charge-transferD + →A −singlet excitation. Computations suggest, however, that polar solvents strongly stabilize the PNA and DMPNA π* ← π charge-transfer triplet relative to other excitations, whereas specific solvent hydrogen-bonded interactions stabilize the π* ←n(σ) triplet of NB below those of π* ← π character. These assignments allow a rationalization of phosphorescence lifetime data,T n ←T 1 absorption measurements and relative photochemical behavior.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00569244
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