UNASSIGNED: In this paper three different "push-pull" @entity68994 dyes have been synthesized in order to characterize their photochromic behavior in different solvents. The molecular geometry was optimized by DFT/B3LYP functional combined with the standard 6-31+G(d,p) basis set for trans (E) and cis (Z) isomers and the energy levels of HOMO and LUMO frontier orbitals were computed using IEFPCM solvation in @entity39320 and @entity9104 . The calculated results were compared to the experimental optical band gap and HOMO values of cyclic voltammetry. The intramolecular six-membered @entity3884 bond was formed in both isomers of the synthesized dyes. The thermodynamic parameters such as total electronic energy E (RB3LYP), enthalpy H298 (sum of electronic and thermal enthalpies), free Gibbs energy G298 (sum of electronic and thermal free Gibbs energies) and dipole moment   were computed for trans (E) and cis (Z) isomers in order to estimate the   Etrans > cis,    trans > cis,   Htrans > cis,   Gtrans > cis and   Strans > cis values. The NBO analysis was performed in order to understand the intramolecular charge transfer and energy of resonance stabilization. The solvatochromic shift was evaluated by UV-VIS spectroscopy in @entity39320 (nonpolar), @entity167 (polar protic) and @entity9104 (polar aprotic) solvents to determine the electron withdrawing and donating properties of the substituents on electron transitions energy. Through the increasing solvent polarity a strong bathochromic shift is observed. The photoisomerization experiments have been performed in two solvents @entity39320 (nonpolar) and @entity9104 (polar aprotic) by UV light irradiation with   =365nm at equal concentrations and time of illuminations. The electronic spectra were computed by TD-DFT after geometry optimization using IEFPCM solvation in @entity39320 and @entity9104 . The degree of photoisomerization was calculated for the three azo chromophores in both solvents. By using first derivative of the UV-VIS spectra it was possible to resolve the overlapped electron transitions absorption bands. The existing intramolecular @entity3884 bond in the azo chromophores was discussed in relation to the isomerization mechanisms and relative stability of the cis (Z) isomers.

Synthesis, structure, spectral properties and DFT quantum chemical calculations of XXXX dyes. Effect of intramolecular @entity3884 bonding on photoisomerization.

@entity3884 :: ('MESH:D006859', 'Chemical') :: ['hydrogen'] @entity167 :: ('CHEBI:16236', 'Chemical') :: ['EtOH'] @entity9104 :: ('CHEBI:17741', 'Chemical') :: ['DMF'] @entity68994 :: ('CHEBI:233869', 'Chemical') :: ['4-aminoazobenzene'] @entity39320 :: ('CHEBI:35255', 'Chemical') :: ['CHCl3']
@entity68994 :: (CHEBI:233869,Chemical) :: ['4-aminoazobenzene']
