Hydrothermal synthesis, structures, and catalytic performance of five coordination compounds driven by...

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(μ₃-aipa)(2,2'-H₂biim)] (1), [Ni₂(μ-aipa)₂(2,2'-H₂biim)₂(H₂O)₄]·4H₂O (2), {[Cd(μ₃-aipa)(2,2'-H₂biim)]·H₂O} (3), {[Ni(μ-aipa)(μ-bpb)]·0.5bpb·H₂O} (4), and {[Ni₂(μ-aipa)(μ₃-aipa)(μ-dpea)₂(H₂O)][Ni(μ-aipa)(μ-dpea)(H₂O)]·8H₂O} (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.