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

Abstract

4,4′-(Pyridine-3,5-diyl)dibenzoic acid (H2pdba) 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(μ4-pdba)(H2O)] n (1), {[M(μ3-pdba)(phen)]·2H2O} n (M = Co (2), Ni (3)), {[Cu2(μ3-pdba)2(bipy)]·2H2O} n (4), {[Co(μ3-pdba)(bipy)]·2H2O} n (5), [Co2(μ3-pdba)(μ-Hbiim)2(Hbiim)] n (6), and [M(μ4-pdba)(py)] n (M = Co (7), Ni (8)). The CPs were hydrothermally synthesized using metal(II) chloride precursors, H2pdba, and different coligands functioning as crystallization mediators (phen: 1,10-phenanthroline; bipy: 2,2′-bipyridine, H2biim: 2,2′-biimidazole; py: pyridine). Structural networks of 1–8 range from two-dimensional (2D) metal–organic layers (1–3, 5–8) to three-dimensional (3D) metal–organic framework (MOF) (4) and disclose several types of topologies: sql (in 1), hcb (in 2, 3, 5), tfk (in 4), 3,5L66 (in 6), and SP 2-periodic net (6,3)Ia (in 7, 8). 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 4. This catalyst is recyclable and can lead to substituted dinitrile products in up to 99% product yields. The present study widens the use of H2pdba as a still poorly studied linker toward designing novel functional coordination polymers.

Metal–organic frameworks constructed using acid–base mixed ligands, carboxylic acids and N-containing chalcone, and their catalytic performance for Knoevenagel condensation

“…The methyl group belonged to the electron-donating group, but the conversion of methyl benzaldehyde still could reach 99% (Table 2, entry 5). 36 In contrast, electron-donating groups (–OCH 3 ) dramatically decreased the efficiency of aldehyde conversion (Table 2, entry 6), implying that the enhancement of electron-donating ability would be more detrimental to the Knoevenagel condensation reaction. In terms of the observed activity, 1 appears to be superior to some reported coordination polymer catalysts in Knoevenagel condensation of aldehydes (Table S2, ESI†).…”

Hydrothermal Assembly, Structural Multiplicity, and Catalytic Knoevenagel Condensation Reaction of a Series of Coordination Polymers Based on a Pyridine-Tricarboxylic Acid

“…(b) H 3 dpna bears some sites for coordination (six carboxyl O sites and one pyridine N site). (c) The presence of a free N pyridine atom can provide a base site for catalysis, including Knoevenagel condensation [33,34]. (d) In 2017-2021, several Mn(II)-, Ni(II)-, Co(II)-, Zn(II)-, and Cd(II)dpna coordination polymers were synthesized [35][36][37][38].…”

“…Recently, our group used a pyridine-dicarboxylic acid, 4,4 -(pyridine-3,5-diyl)dibenzoic acid (H 2 pdba), to synthesize a series of transition metal coordination polymers. The catalytic performance of these polymers was evaluated [34]. As a continuation of that As a linker, H3dpna has a lot of interesting characteristics that favor its exploration.…”

Functionalized Metal–Organic Framework for Selective Fluorometric Detection of Sodium Dodecyl Sulfate and Vitamin B12 Using MOF@Cotton Composites and Lewis Base-Catalyzed Condensation Reaction

“…Previous literature reports suggested that the amine functional groups can act as Lewis base and catalyze many organic reactions. − Keeping this feature in mind, the catalytic performance of this MOF with diamino functionality was examined in Knoevenagel condensation between aldehyde and active methylene compounds. Although this reaction has been reported with MOFs as heterogeneous catalysts with different active sites, − this study explores the activity of easily available MOF-based solid for this reaction with a comparable yield of the products as that of the previous reports, even in milder reaction conditions and in lower times with a wide substrate scope.…”