Intramolecular photoassociation and photoinduced charge transfer in bridged diaryl compounds. 7. A semiempirical MO study of intramolecular charge transfer in the excited singlet states of dinaphthylamines

Journal Article · Thu Feb 24 04:00:00 EST 1994 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100059a007· OSTI ID:7274824

Chen, D; Sadygov, R; Lim, E C ^[1]

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1. Univ. of Akron, OH (United States)

A semiempirical MO study of the intramolecular charge transfer (CT) in the excited singlet states of dinaphthylamines has been carried out with the program systems MOPAC and ARGUS. The excited-state energies for various conformations of the molecules were obtained, in both the absence and the presence of a polarizable medium, by adding the transition energies calculated with the INDO I/S method to the ground-state energies calculated by means of the AM1 method. The CT state corresponds to a twisted geometry in which one naphthalene moiety is conjugated with the amino bridge, while the other moiety is perpendicular to the first. The gas-phase energy of this twisted intramolecular CT (TICT) state is only slightly greater than that of the lowest excited singlet (S[sub 1]) state of smaller dipole moment. In solvent of large dielectric constant, the TICT state is therefore predicted to be the lowest excited singlet state of the module. The computed oscillator strength of the absorption to the TICT state is much smaller than that to the lowest-energy excited state of an isolated molecule, so that the increase CT character of the S[sub 1] state in polar solvents is expected to lead to a decrease in the radiative decay rate of the state. These results are consistent with the experimental observation of a large fluorescence Stokes shift, and a reduction in the S[sub 1] radiative decay rate, of the compounds in polar solvents relative to nonpolar solvents. 14 refs., 9 figs., 4 tabs.

• DOE Contract Number: FG02-89ER14024
• OSTI ID: 7274824
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 98:8; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
400500* -- Photochemistry
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
ACETONITRILE
AMINES
AROMATICS
CHARGE TRANSPORT
CHEMICAL BONDS
CHEMICAL REACTIONS
COMPUTER CALCULATIONS
DATA
DNA
ENERGY LEVELS
EXCITED STATES
FLUORESCENCE
INFORMATION
LUMINESCENCE
NITRILES
NUCLEIC ACIDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
SOLVENTS
THEORETICAL DATA