title: Synthesis, characterization and density functional theory investigations of the electronic, photophysical and charge transfer properties of donor-bridge-acceptor triaminopyrazolo[1,5-a]pyrimidine dyes.
abstract: We have synthesized multifunctional dyes 3-(4-methyl-phenylazo)-6-(4-nitro-phenylazo)-2,5,7-triaminopyrazolo[1,5-a]pyrimidine (4a) and 3-(4-methyl-phenylazo)-6-(4-acetyl-phenylazo)-2,5,7-triaminopyrazolo[1,5-a]pyrimidine (4b), then characterized by IR, (1)H NMR and (13)C NMR techniques. The ground state geometries have been computed by using density functional theory at B3LYP/6-31G(*) level of theory. The absorption spectra have been calculated by using time dependent density functional theory with and without solvent. The highest occupied molecular orbitals (HOMOs) and lowest unoccupied molecular orbitals (LUMOs) are delocalized and localized on throughout the backbone, respectively. Solvent also play important role towards elevating the dipole moment. Significant red shift in absorption wavelengths have been observed in methanol compared to without solvent. We discussed the electron injection, electronic coupling constant and light harvesting efficiency.
authors: Department of Chemistry, Faculty of Science, King Khalid University, P.O. Box 9004, Abha 61413, Saudi Arabia. agmasq@gmail.com
authors: Abdullah G
authors: AG
authors: Al-Sehemi
authors: Ahmad
authors: A
authors: Irfan
authors: Ahmed M
authors: AM
authors: Fouda
mesh_terms: D000042:Absorption; D004396:Coloring Agents / Q000138:chemical synthesis* / Q000737:chemistry*; D004583:Electrons; D008027:Light; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry; D011743:Pyrimidines / Q000138:chemical synthesis* / Q000737:chemistry; D011789:Quantum Theory; D013816:Thermodynamics
chemical_list: D004396:Coloring Agents; D011720:Pyrazoles; D011743:Pyrimidines; C030986:pyrimidine