Different crystal structures and luminescent properties of zinc and cadmium coordination polymers constructed from two flexible thioether ligands with different alkyl chains

Treatments of nitrogen-containing heterocyclic dithioether ligands, 1,2-bis(4-(pyridin-3-yl) pyrimidin-2-ylthio) ethane (L-1) and 1,3-bis (4-(pyridin-3-yl) pyrimidin-2-ylthio) propane (L 2). with zinc or cadmium salts have resulted in the interesting frameworks with structural motifs from a mononuclear macrocycle or a dinuclear macrocycle to an one-dimensional structure. A small difference of the alkyl length between L-1 and L 2 led to conspicuous changes of the fluorescent properties of both ligands and their complexes. Mainly due to the size of metal atoms, structures of [(ZnLI2)-I-2] (1) and [(CdLI2)-I-2] (2) are varied from a mononuclear macrocycle to a I D framework, while {[ZnL2(H2O)(4)](ClO4)(2))(2) (3) and {[CdL2(H2O)(4)](ClO4)(2)}(2) (4) are dinuclear macrocycles in which perchlorate anions may play an important template role. As for complexes 5-8 ([(ZnLI2)-I-1](n) (5), [(CdLI2)-I-1](n) (6). {{[ZnL21(H2O)(4)](ClO4)(2)}(0.5)center dot L-0.5(1)center dot CH3OH) (7), {{[Cd0.5L1(H2O)(2)] (ClO4)}(2) center dot CH3OH center dot L-1] (8)), the self-assemble processes were mainly directed by the organic ligand in the reactions of Ll with metal salts. Complexes 1-4 exhibit blue fluorescence emissions, among which I and 2 may be suitable as candidates for blue fluorescent materials. (C) 2009 Elsevier Ltd. All rights reserved.