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 (L1) and 1,3-bis (4-(pyridin-3-yl) pyrimidin-2-ylthio) propane (L2), 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 L1 and L2 led to conspicuous changes of the fluorescent properties of both ligands and their complexes. Mainly due to the size of metal atoms, structures of [ZnL2I2] (1) and [CdL2I2] (2) are varied from a mononuclear macrocycle to a 1D 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 ([ZnL1I2]n (5), [CdL1I2]n (6), {{[ZnL12(H2O)4](ClO4)2}0.5 · L10.5 · CH3OH} (7), {{[Cd0.5L1(H2O)2](ClO4)}2 · CH3OH · L1} (8)), the self-assemble processes were mainly directed by the organic ligand in the reactions of L1 with metal salts. Complexes 1–4 exhibit blue fluorescence emissions, among which 1 and 2 may be suitable as candidates for blue fluorescent materials.

Two series of complexes were prepared from reactions of two dithioether ligands (1,3-bis (4-(pyridin-3-yl) pyrimidin-2-ylthio) propane and 1,2-bis (4-(pyridin-3-yl) pyrimidin-2-ylthio) ethane) with zinc or cadmium salts, respectively. A small difference of the alkyl length between two ligands led to conspicuous changes of the fluorescent properties of both ligands and their complexes with different structural networks.Figure optionsDownload as PowerPoint slide