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Indexed by:期刊论文

Date of Publication:2008-10-30

Journal:JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM

Included Journals:SCIE、Scopus

Volume:867

Issue:1-3

Page Number:10-16

ISSN No.:0166-1280

Key Words:Dye molecules; Excited state; Transition dipole moment; Intramolecular charge transfer

Abstract:Two novel metal-free organic dyes (JK-1, JK-2), composed of bis-dimethylfluoreneaniline moiety as the electron donor and cyanoacrylic acid moiety as the electron acceptor, are theoretically investigated with quantum chemical methods. The energies and densities of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), as well as the binding energies, are compared between the two dyes. The HOMO -> LUMO electronic transition describes their lowest singlet excited states. The orientation and strength of transition dipole moment are revealed visually with transition density. We also show the orientation and results of the intramolecular charge transfer with charge difference density. Transition density matrices provide information about the electron-hole coherence and excitation delocalization. Theoretical results reveal that exciton size and transition dipole moment increase with the expansion of the pi conjugation and the charge transfer occurs from donor unit across the it bridge to the acceptor unit. (c) 2008 Elsevier BY. All rights reserved.