Symmetric anionic polymethine dyes derived from bis(2,2,3,3,4,4,5,5-octafluoropentyl) 4,5-dinitro-9H-fluorene-2,7-disulfonate: synthesis and spectral properties

Abstract

Anionic polymethine dyes were obtained from fluorene equipped with electron withdraw ing groups (SO 2 OCH 2 (CF 2 ) 3 CHF 2 in positions 2 and 7 and NO 2 in positions 4 and 5). Their electronic absorption spectra in various solvents were examined and compared with the spectra of related dyes derived from tetranitrofluorene and bis(2,2,3,3,4,4,5,5 octafluoropentyl) 9H fluorene 2,7 disulfonate. The ab initio quantum chemical calculations (DFT and TDDFT at the B3LYP/6 31G(d,p) level of theory) were used to analyze the nature of electron transi tions and the orbitals involved as well as the electron density redistribution in the excited state.