Achieving the blue-light-emitting materials for benzothiazolate Zn(II) complexes by introducing different functional groups

A series of blue-light-emitting bis(2-(4-R-2-hydroxyphenyl)benzothiazolate)zinc [Zn(4-RBTZ)2] [R = OCH3, 4a; CH3, 4b; CF3, 4c; F, 4d] complexes were synthesized and investigated by optical spectroscopy, electrochemistry as well as density functional theory (DFT). On this basis, the influences of substituents at the same position on molecular structures and optical properties were discussed. The X-ray single-crystal diffractions reveal that complexes of 4a and 4b exhibit monomer structures with a distorted tetrahedral; while complex 4c with trigonal bipyramidal geometry has the special dimeric structure. A gradual increasing red-shift order in emission peak is 4a < 4d < 4b < 4c = [Zn(BTZ)2]2. The substituents change the distributions of HOMO and LUMO and resulting complexes have the distinct blue-shift relative to [Zn(BTZ)2]2. These complexes were shown to be the potential blue-emitting materials.