Cluster-based Cd(II) coordination polymers: Step-wise synthesis, structure, and luminescence.

Two new Cd(II) coordination polymers based on a flexible ligand 5-(bis(4- carboxybenzyl)amino)isophthalic acid (H 4 L) namely {[Cd 2 (L)(NMP) 2 (H 2 O) 2 ]·H 2 O} n (1) and{[Cd 4 (L) 2 (NMP) 2 (H 2 O)]∙2NMP} n (2) (NMP=N-methyl-2-pyrrolidone) have been prepared under hydrothermal conditions. Structural analyses revealed that 1 and 2 all exhibit three-dimensional network structures. Compound 1 shows 4-connect crb topology with [Cd 2 (CO 2) 4 ] as secondary building unit, while compound 2 can be regarded as a new 4,4,8-connect with a {411.615.82}{45.6}{46} topology with tetranuclear [Cd 4 (CO 2) 8 ]. By step-wise synthesis, tetranuclear cluster-based {[Cd 4 (L) 2 (NMP) 2 (H 2 O)]∙2NMP} n (2) can be synthesized successfully by using compound 1. The powder X-ray diffraction, the thermal stabilities, and solid-state luminescence properties of compounds 1 – 2 have also been investigated. Two 3D Cd coordination polymers with different topology were synthesized successfully. By step-wise synthesis, binuclear-cluster units can be transferred to tetranuclear cluster. Image 1 • Achieving the structure transformation from binuclear units to tetranuclear units by employing a step-wise synthesis method. • Two cadmium coordination polymers have been synthesized by using flexibly carboxylic ligand. • A new topology with 4,4,8-connected 3-nodal net. [ABSTRACT FROM AUTHOR]