ISSN:
1572-8951
Keywords:
Charge transfer
;
substituted fulvalenes
;
linker effects
;
excited state dipole moments
;
oscillator strengths
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Semiempirical MNDO and ZINDO calculations have been performed to investigate the ground states of the neutral molecules and mono- and di-cations of nitrobenzyl-substituted tetramethylfulvalene (TMF), tetramethyl-tetrahydrofulvalene (TMTHF), and tetramethyl-tetrathiafulvalene (TMTTF). In particular, the effects of the linker groups on the direct charge transfer between the fulvalene and the nitrobenzyl groups have been studied. As linkers,-(CH2)2-, -CH2O-,-CH2S-, and -CO- were used. The coefficients of the highest occupied and lowest unoccupied molecular orbitals, the oscillator strengths and excited-state dipole moments for the vertical excitations from the neutral ground states, as obtained with SCI calculations, are reported. Although the dipole moments increase by 40–50 D when exciting from the HOMO localized on the fulvalene fragment to the LUMO localized on the nitrobenzyl part, all four linkers are found to be good insulators and thus, no direct optical donor to acceptor charge transfer can be observed. An alternative route, the photoinduced charge transfer process involving local excitations to form metastable intermediate states, is discussed. Due to the insulating properties of the linkers, these will then efficiently stabilize the charge transfer complex.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00999530
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