Trinuclear Cobalt Based Porous Coordination Polymers Showing Unique Topological and Magnetic Variety upon Different Dicarboxylate-like Ligands

Abstract

One-pot solvothermal self-assembly is employed to prepare a series of Co 3 based porous coordination polymers, viz. 1, [H 2 N(CH 3 ) 2 ] 2 [Co 3 (ip) 4 ]·H 2 O, 2, [H 2 N(CH 3 ) 2 ] 2 [Co 3 (bdc) 4 ]·(DMF) 2, 3, [H 2 N(CH 3 ) 2 ] 2 [Co 3 (bpdc) 4 ]·(CH 3 OH) 2 (DMF) 1.5, where ip, bdc, bpdc, and DMF are 1,3-benzenedicarboxylate, 1,4-benzenedicarboxylate, 4,4′-biphenyldicarboxylate, and N, N ′-dimethylformamide, respectively. Via different organic connectors such as ip, bdc, and bpdc, such Co 3 molecular building blocks (MBB), [Co 3 (CO 2 ) 8 ] 2−, are associated together to give a tunable 8-connected topological framework, viz. 4 24 6 4 for 1, 3 6 4 14 5 7 6 for 2, and 3 6 4 18 5 3 6 for 3 . Upon the geometry and the length of organic connectors, their corresponding porosity occupied by c counterions plus solvent molecules also can be tunable, for example, with the consideration of [H 2 N(CH 3 ) 2 ] + counterions, the solvent-accessible volume is 460.2 Å 3 for 1, equal to 23.9% of the cell volume, 3320.4 Å 3 for 2, equal to 56.3% of the cell volume, 4107.2 Å 3 for 3, equal to 50% of the cell volume. Notably, besides these outstanding features of tunable 8-connected topology and porosity, their magnetic properties such as ferromagnetic behavior without magnetic ordering for 1, spin-canting and metamagnetic behavior with magnetic ordering for 2, as well as spin-canting, metamagnetic, and spin-glass behavior with magnetic ordering for 3 also can be tunable.