title: On the spectroscopic analyses of thioindigo dye.
abstract: A combined experimental and theoretical study on molecular structure and vibrational frequencies of thioindigo was reported. The FT-IR spectrum of thioindigo is recorded in the solid phase. The equilibrium geometries, harmonic vibrational frequencies, thermo-chemical parameters, total dipole moment and HOMO-LUMO energies are calculated by density functional theory DFT/B3LYP utilizing 6-311G(d,p) basis set. Results showed that cis-isomer is highly recommended to be a promising structure for many applications in optoelectronic devices due to its high calculated dipole moment value (3.44 Debye) which indicates its high reactivity to interact with the surrounding molecules as compared to the trans-isomer which has no dipole moment. Both isomers have a similar HOMO-LUMO energy gap, of 3.02 eV (cis-isomer) and 2.78 eV (trans-isomer).
authors.affiliation: Spectroscopy Department, National Research Centre, Dokki, Cairo, Egypt. medahmed6@yahoo.com
authors.forename: M
authors.initials: M
authors.lastname: Ibrahim
authors.forename: M M
authors.initials: MM
authors.lastname: El-Nahass
authors.forename: M A
authors.initials: MA
authors.lastname: Kamel
authors.forename: A A
authors.initials: AA
authors.lastname: El-Barbary
authors.forename: B D
authors.initials: BD
authors.lastname: Wagner
authors.forename: M A M
authors.initials: MA
authors.lastname: El-Mansy
mesh_terms: D004396:Coloring Agents / Q000737:chemistry*; D007203:Indigo Carmine / Q000031:analogs & derivatives* / Q000737:chemistry; D007536:Isomerism; D008958:Models, Molecular; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014732:Vibration
chemical_list: D004396:Coloring Agents; C009466:thioindigo; D007203:Indigo Carmine
keywords: B3LYP; DFT; Dipole moment; FT-IR; HOMO–LUMO energy gap; Thioindigo