Tunable single and dual emission behavior of imidazole fluorophores based on D-π-A architecture

摘要: Abstract A series of three D-π-A molecules containing 4,5-diphenyl-1H-imidazole moiety as the donor (D) with cyanoacetic acid, rhodanine-3-acetic acid and 4-nitrophenyl acetonitrile acceptor (A) connected by a biphenyl bridge have been synthesized characterized. Crystallography BIC shows C4-phenyl group to be twisted nearly perpendicular imidazole unit remaining groups are in plane. The absorption spectra compounds dominated intramolecular charge transitions that arise from core groups. display distinct dual single emission behavior different solvent environments, namely locally excited (LE ∼ 430 nm) transfer (ICT ∼ 550 nm). Lippert–Mataga analysis suggested state dipole moment ICT band is higher than LE band. influence general specific effects on photophysical properties fluorophores was discussed Catalan four parameter Kamlet–Taft scales. These results suggest major dipolarity takes part prominent role changing compounds. quantum yield ranged between 0.07 0.55 solvents it shown depend substitution pattern most notably based All exhibit two lifetimes singlet corresponding (short lived) (long lived). In addition, triplet also investigated transient measurement. geometric structure electronic ground studied DFT methods, whereas energies lowest states calculated employing TD-DFT methods. show bands oscillator strength for BIC, BIN BIR due LE.