Syntheses, Structures, Photochemical and Magnetic Properties of Novel Divalent Cd/Mn Coordination Polymers Based on a Semirigid Tripodal Carboxylate Ligand

The
reactions of a semirigid tripodal carboxylic ligand, 3,5-bi­(4-carboxy-phenoxy)-benzoic
acid (H3BCPBA) with Cd­(NO3)2/Mn­(NO3)2 afford five novel complexes, {[Cd3(BCPBA)2·(DMA)2­·(H2O)5]·7H2O·2DMA}n (1), {[Cd3(BCPBA)2(L1)­(H2O)6]·(L1)}n (L1 = 4-[(E)-4-pyridinylazo]­pyridine)
(2), {[Cd3(BCPBA)2(L2)­·(H2O)3(DMF)2]·2DMF}n (L2 = 1,3-bis­(4-pyridyl)­propane)
(3), {[Mn3(BCPBA)2(H2O)4]·11H2O}n (4), {[Mn3(BCPBA)2(DMF)2(H2O)2]­·2DMF·9H2O}n (5) in the presence
or absence of an auxiliary ligand. Compound 1 is a three-dimensional
(3D) structure with 3,4-connected net structure. Compound 2 possesses 3D networks with two 3D → 3D interpenetration frameworks.
Compound 3 is a 3D sheet structure with a decorated tfz-d
topology. Compound 4 is a 3D structure which consists
of a two-dimensional (2D) Mn honeycomb net with six infinite Mn rings
and BCPBA3– ligands. Compound 5 is
also a 3D structure, while its 2D Mn honeycomb net with eight infinite
Mn rings is different from that of compound 4. The photochemical
property of 1–3 is performed in the
solid state at room temperature. Magnetic susceptibility measurements
indicate that compounds 4 and 5 exhibit
antiferromagnetic coupling between adjacent Mn­(II) ions.