title: Synthesis, structures and electrochemical and photophysical properties of anilido-benzoxazole boron difluoride (ABB) complexes.
abstract: A new series of four-ring-fused π-conjugated anilido-benzoxazole boron difluoride (ABB) dyes were synthesized by employing an unsymmetrical bidentate ligand under a mild reaction condition. X-ray structural analysis demonstrated that the four-ring-fused π-conjugated skeleton is nearly coplanar, and almost orthogonal to the side anilido phenyl group with dihedral angles of 74-86°. The synthesized complexes exhibit very bright luminescence in solution (Φf = 0.45-0.96 in CH2Cl2) and in the solid-state (Φf = 0.07-0.37). These complexes show a larger Stokes shift (56-128 nm) than the well-known boron dipyrromethene dyes (8-12 nm, in most cases). The role of molecular packing patterns elucidated by the assistance of their X-ray crystal structures rationalizes the solid-state fluorescence. One of the tested compounds displayed aggregation induced emission (AIE). First-principle-based quantum-chemical studies were carried out on complexes . Time-dependent DFT (TD-DFT) calculations support the experimental results. The participation of the anilido phenyl moiety and the fluorine atoms was found to be negligible in the LUMO orbitals.
authors.affiliation: Department of Chemistry, National Taiwan Normal University, Taipei, 11677, Taiwan (R.O.C.). wzlee@ntnu.edu.tw.
authors.forename: Yedukondalu
authors.initials: Y
authors.lastname: Meesala
authors.forename: Veerababurao
authors.initials: V
authors.lastname: Kavala
authors.forename: Hao-Ching
authors.initials: HC
authors.lastname: Chang
authors.forename: Ting-Shen
authors.initials: TS
authors.lastname: Kuo
authors.forename: Ching-Fa
authors.initials: CF
authors.lastname: Yao
authors.forename: Way-Zen
authors.initials: WZ
authors.lastname: Lee
mesh_terms: D001583:Benzoxazoles / Q000737:chemistry*; D001896:Boron Compounds / Q000737:chemistry*; D018360:Crystallography, X-Ray; D055664:Electrochemical Techniques; D005456:Fluorescent Dyes / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D011789:Quantum Theory
chemical_list: D001583:Benzoxazoles; D001896:Boron Compounds; D005456:Fluorescent Dyes; C579460:boron difluoride