Syntheses, structures and properties of two cadmium compounds containing neutral or in situ protonized 1,4-diazabicyclo[2.2.2]octane

Reaction of Cd(Ac)2, 1,4-diazabicyclo[2.2.2]octane (DABCO) and biphenyl-2,2′-dicarboxylic acid or biphenyl-4,4′-dicarboxylic acid, two new cadmium complexes, namely molecular quadrangle [Cd2(2,2′-BPDC)2(Ac)2(DABCOH)2]·2H2O (1) and one dimension (1-D) chain [Cd(Ac)2(DABCO)(H2O)]n·2nH2O (2), have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray crystallography. The solution–gel–solution transformation course to crystallize 2 was captured. Through the alternately hydrogen bonds between coordinated Ac− and lattice H2O, both 1 and 2 give rise to a three-dimensional supramolecular structures. In room temperature, 1 displays intense blue fluorescent emission derived from ligand-to-metal change transfer (LMCT).