Coordination Polymers Constructed from an Adaptable Pyridine-Dicarboxylic Acid Linker: Assembly, Diversity of Structures, and Catalysis.

4,4'-(Pyridine-3,5-diyl)dibenzoic acid (Hpdba) was explored as an adaptable linker for assembling a diversity of new manganese(II), cobalt(II/III), nickel(II), and copper(II) coordination polymers (CPs): [Mn(μ-pdba)(HO)] (), {[M(μ-pdba)(phen)]·2HO} (M = Co (), Ni ()), {[Cu(μ-pdba)(bipy)]·2HO} (), {[Co(μ-pdba)(bipy)]·2HO} (), [Co(μ-pdba)(μ-Hbiim)(Hbiim)] (), and [M(μ-pdba)(py)] (M = Co (), Ni ()). The CPs were hydrothermally synthesized using metal(II) chloride precursors, Hpdba, and different coligands functioning as crystallization mediators (phen: 1,10-phenanthroline; bipy: 2,2'-bipyridine, Hbiim: 2,2'-biimidazole; py: pyridine). Structural networks of - range from two-dimensional (2D) metal-organic layers (-, -) to three-dimensional (3D) metal-organic framework (MOF) () and disclose several types of topologies: (in ), (in , , ), (in ), 3,5L66 (in ), and SP 2-periodic net (6,3)Ia (in , ). Apart from the characterization by standard methods, catalytic potential of the obtained CPs was also screened in the Knoevenagel condensation of benzaldehyde with propanedinitrile to give 2-benzylidenemalononitrile (model reaction). Several reaction parameters were optimized, and the substrate scope was explored, revealing the best catalytic performance for a 3D MOF . This catalyst is recyclable and can lead to substituted dinitrile products in up to 99% product yields. The present study widens the use of Hpdba as a still poorly studied linker toward designing novel functional coordination polymers.