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Intramolecular Electronic Energy Transfer in the Naphthalene—Anthracene Bichromophoric Molecular Complex in a Supersonic Jet Expansion
Author(s) -
Rosenblum Gershon,
Karni Yoram,
Speiser Shammai
Publication year - 1997
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199700050
Subject(s) - chemistry , anthracene , intramolecular force , chromophore , van der waals force , photochemistry , excited state , molecule , fluorescence , naphthalene , atomic physics , stereochemistry , organic chemistry , physics , quantum mechanics
Intramolecular electronic energy transfer (intra‐EET) was investigated in an isolated bichromophoric naphthalene ( N ) and anthracene ( A ) 1:1 molecular cluster. Investigation of the spectroscopic properties of these chromophores, separately and loosely bound in a van der Waals complex, helps to understand the dependence of the EET rate on the initially excited vibronic level and on the cluster's interchromophoric orientation. Measurement of fluorescence excitation spectra of anthracene at different anthracene pressures shows bands that can be assigned to dimers of anthracene. From measurement of the anthracene excitation spectrum at increasing naphthalene pressures one can identify other spectral features, characterized by different spectral shifts from excitations of the bare molecule. Some transitions are probably due to a 13.5‐cnr −1 progression associated with an interchromophore cluster bond. Pressure dependence of fluorescence intensity gives evidence for 1:1 cluster composition, and for a slow intra‐EET rate that is associated with an unfavored orientation of the two chromophores in one of the two possible conformers of the A‐N cluster, as supported by a calculation of the cluster geometry and by comparison with a recent study of intra‐EET in the A–(CH 2 ) n ‐N bichromophoric molecules.