Hetero-trinuclear Zn(II)-M(II) (M = Sr, Ba) complexes based on a mononuclear Zn(II) complex metallohost: syntheses, structures and fluorescence properties

A new mononuclear Zn(II) complex, [ZnL(HOAc)] (1) (H2L = 6,6'-diethoxy-2,2'-[1,2-ethylenedioxybis(nitrilomethylidyne)] diphenol), was synthesized by reaction of H2L and Zn(II) acetate under solvothermal conditions. Complex 1 acts as a metallohost possessing a pentadentate O-5 donor. Complex 1 molecules bonded to one Sr(II) or Ba(II) form two new hetero-trinuclear complexes, [(ZnL)(2)M(OAc)(2)] (M = Sr (2), Ba (3)). In 2 and 3, Zn(II) ions are 5-coordinate, but the Sr(II) or Ba(II) ion is 10-coordinate by four mu-phenolic oxygens from two L2- units, four oxygens from four ethoxy groups and two oxygens from two mu-acetato ligands. Furthermore, 1-3 exhibit blue emissions with the maximum emission wavelengths lambda(max) = 477, 500, and 471 nm when excited at 360 nm. [GRAPHICS] .