Hydrothermal synthesis, structures, and catalytic performance of five coordination compounds driven by 5-aminoisophthalic acid

An amino-functionalized-dicarboxylic acid, 5-aminoisophthalic acid (H2aipa), was used as a versatile building block to synthesize a series of five novel coordination compounds under hydrothermal conditions and formulated as [Co(mu 3-aipa)(2,2 '-H2biim)]n (1), [Ni2(mu-aipa)2(2,2 '-H2biim)2(H2O)4]<middle dot>4H2O (2), {[Cd(mu 3-aipa)(2,2 '-H2biim)]<middle dot>H2O}n (3), {[Ni(mu-aipa)(mu-bpb)]<middle dot>0.5bpb<middle dot>H2O}n (4), and {[Ni2(mu-aipa)(mu 3-aipa)(mu-dpea)2(H2O)][Ni(mu-aipa)(mu-dpea)(H2O)]<middle dot>8H2O}n (5). Three supporting ligands (2,2 '-biimidazole (H2biim),1,4-bis(pyrid-4-yl)benzene (bpb), and 1,2-di(4-pyridyl)ethane (dpea)) were used in the synthesis. The structures of the studied products 1-5 vary significantly, ranging from a 0D dimer (2), 2D sheets (1, 3 and 4) to 3D + 2D interpenetrated frameworks (5). Furthermore, these compounds were evaluated as heterogeneous catalysts for the Knoevenagel reaction, achieving high product yields under optimized conditions. In addition, we also investigated various reaction parameters, substrate scope, and assessed the feasibility of catalyst recycling. This thorough investigation highlights the versatility of H2aipa as a dicarboxylate building block in the formation of functional coordination polymers. The structural and catalytic properties of five new compounds were investigated.