Syntheses, structures and properties of four Cd(II) coordination polymers induced by the pH regulator.

Four new coordination polymers [Cd 2 (CHDC) 2 (APYZ)(H 2 O) 2 ](H 2 O) ( 1 ), [Cd(HCHDC) 2 (APYZ) (H 2 O)] ( 2 ), [Cd 2 (CHDC) 2 (PYZ)(H 2 O) 2 ](H 2 O) ( 3 ), and [Cd(HCHDC) 2 (PYZ)(H 2 O)] ( 4 ) (H 2 CHDC = 1,4-cyclohexanedicarboxylic acid, APYZ = 2-aminopyrazine, PYZ = pyrazine) have been synthesized under the hydrothermal conditions by changing the pH regulator and the N-containing ligands. The pH regulator impacted on the degree of deprotonation of the 1,4-cyclohexanedicarboxylic acid ligand and resulted in the formation of the two pairs of different networks. Polymers 1 and 3 crystallize in monoclinic, space group P 2 1 / c , exhibit two dimensional 6 3 net, which further formed three-dimensional supramolecular structure by the C H⋯O hydrogen bond interactions. While polymers 2 and 4 possess one dimensional chain structures and further link into two dimensional layered supramolecular structures by intermolecular hydrogen bonding interactions. From all three conformers of H 2 CHDC, e , a - cis is consistently present in the Cd coordination polymers. Furthermore, photoluminescence properties of four polymers are also investigated, the luminescent intensity of polymer 1 (or 2 ) with amino group in pyrazine is dramatically stronger than that of the similar structure of polymer 3 (or 4 ) without amino group in pyrazine, the results shown that the presence of the amino group from 2-aminopyrazine play a key role in increasing the luminescence properties. [ABSTRACT FROM AUTHOR]