In Situ Assembled Polynuclear Zinc Oxo Clusters Using Modified Schiff Bases as Ligands.

A series of different cores and nuclearity zinc metal clusters 1 - 5 have been synthesized using Zn(ClO 4 ) 2 ·6H 2 O, Schiff-base primary ligands, and dibenzoyl methane (DBM) or monoethanolamine (MEA) as co-ligand in a room-temperature reaction. The structure of the complexes is characterized using single-crystal X-ray diffraction. Among them, ( 1 ) [Zn(L1)(DBM)] is mononuclear; ( 2 ) [Zn 4 (L2) 2 (DBM) 4 ], ( 3 ) [Zn 4 (L2) 4 (H 2 O) 2 (ClO 4 ) 2 ]·2CH 2 Cl 2 , and ( 4 ) [Zn 4 (L3) 2 (DBM) 4 ] have a cubane core; and ( 5 ) [Zn 4 (L4) 4 (MEA) 2 (ClO 4 ) 2 ] has a ladderlike core structure. Compounds 1 - 5 have also been characterized using UV-vis absorption and emission spectroscopies. For an in-depth understanding of the absorption spectra of 1 and 3 , density functional theory (DFT) calculations have been performed, which suggest that the transitions correspond to the π → π * intraligand charge transfer (ILCT) transitions.