Modulation of the luminescence quantum efficiency for blue luminophor {Al(salophen)}(+) by ester-substituents.

A series of Al(III) complexes of a salophen (N,N'-bis(salicylidene)-o-phenylenediamine) derivative with an ester substituent at the C5 position of the salicylidene rings have been prepared and their luminescence properties investigated. All exhibit a bright blue emission (lambda(em) = 478 nm) that is observed neither for other metal ions nor with the non-functionalized ligand. Moreover, the ester-R group (Me, (t)Bu, Ph) was found to significantly affect the quantum yields (varphi = 12 to 20%) of the luminophor. DFT calculations have been undertaken to reveal the influence of the ester and its R-group on the frontier molecular orbitals. Preparation and photoluminescence properties in solution and solid state are reported. The crystal structure of a pyridine oxide adduct [L(tBu)Al(PyO)(2)].NO(3), where L(tBu) stands for the tButyl-ester functionalized Schiff base, has been solved.