Coordination Polymers from an Amino-Functionalized Terphenyl-Tetracarboxylate Linker: Structural Multiplicity and Catalytic Properties.

An amino-functionalized terphenyl-tetracarboxylic acid, 2'-amino-[1,1':4',1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid (H 4 tpta), was used as an adaptable linker to synthesize, under hydrothermal conditions, eight coordination polymers (CPs). The obtained products were formulated as [Co(μ 6 -H 2 tpta)] n ( 1 ), [Co(μ 3 -H 2 tpta)(2,2'-bipy)] n ( 2 ), [M 3 (μ 6 -Htpta) 2 (2,2'-bipy) 2 ] n (M = Mn ( 3 ), Cd ( 4 )), [Ni 2 (μ 4 -tpta)(phen) 2 (H 2 O) 4 ] n ( 5 ), [Zn 2 (μ 6 -tpta)(phen) 2 ] n ( 6 ), {[Zn 2 (μ 6 -tpta)(μ-4,4'-bipy)]·H 2 O} n ( 7 ), and [Zn 2 (μ 6 -tpta)(μ-H 2 biim)(H 2 O) 2 ] n ( 8 ), wherein 2,2'-bipyridine (2,2'-bipy), 4,4'-bipyridine (4,4'-bipy), 1,10-phenanthroline (phen), or 2,2'-biimidazole (H 2 biim) are present as additional stabilizing ligands. The structural types of 1 - 8 vary from one-dimensional (1D) ( 2 , 5 ) and two-dimensional (2D) ( 3 , 4 , 6 ) CPs to three-dimensional (3D) metal-organic frameworks (MOFs) ( 1 , 7 , and 8 ) with a diversity of topologies. The products 1 - 8 were investigated as catalysts in the Knoevenagel condensation involving aldehydes and active methylene derivatives (malononitrile, ethyl cyanoacetate, or tert -butyl cyanoacetate), leading to high condensation product yields (up to 99%) under optimized conditions. Various reaction conditions, substrate scope, and catalyst recycling were investigated. This work broadens the application of H 4 tpta as a versatile tetracarboxylate linker for the generation of diverse CPs/MOFs.