Two Metal Complexes Based on the Ligand 3, 4‐Pyrazoledi­carboxylic Acid: Synthesis, Structures, and Luminescent ­Properties

Abstract

Two new metal complexes, {[Cd2(μ2‐H2pdc)2(H2O)8]·[Cd2(H2pdc)4(H2O)2(μ2‐Cl)2]}·2H2O (1), and [Ba2(H2pdc)4(H2O)8]·2H2O (2) (H3pdc = 3, 4‐pyrazoledicarboxylic acid), were synthesized and characterized by elemental analysis, IR spectroscopy, and single‐crystal X‐ray diffraction. The crystal structures show that compound 1 is an independent unit consisting of two discrete dinuclear complex ions [Cd2(μ2‐H2pdc)2(H2O)8]2+ cation and [Cd2(H2pdc)4(H2O)2(μ2‐Cl)2]2– anion, and the two kinds of ions are linked by hydrogen bonds and electrostatic interactions to generate a 3D supramolecular network. Complex 2 is a common dinuclear structure, which is further assembled to a 3D supramolecular network through intermolecular hydrogen bonds and π–π stacks. The hydrogen bonding interactions involving lattice water or coordinated water molecules all exist in complexes 1 and 2. Notably, three coordination modes of 3, 4‐pyrazoledicarboxylic acid were observed. The thermal and photoluminescent properties of complexes 1 and 2 in the solid state were also investigated.

Synthesis and Structural Diversity of Main Group Metal Coordination Complexes Constructed from V‐Shape Bis(3‐methyl‐1H‐pyrazole‐4‐carboxylic acid)alkane Ligands

“…In the past decades, pyrazolecarboxylic acid as a rigid and multifunctional bridge has been extensively used to construct complexes . In the resulting complexes, they coordinated to metal ions not only in a N,O‐chelating fashion but also in bridging mode acting as μ 2 ‐, μ 3 ‐, μ 4 ‐, μ 5 ‐ and so on connectors.…”

“…In the resulting complexes, they coordinated to metal ions not only in a N,O‐chelating fashion but also in bridging mode acting as μ 2 ‐, μ 3 ‐, μ 4 ‐, μ 5 ‐ and so on connectors. Hence, our group is actively involved in the construction and systematic investigation of pyrazolecarboxylic acids CPs and their applications . In addition, we have paid more attention to functionalize 3‐methyl‐1H‐pyrazole‐4‐carboxylic acid, and synthesized three isomeric bis(3‐methyl‐1H‐pyrazole‐4‐carboxylic acid)methane ligands, namely, (1,1'‐methylenebis(5‐methyl‐pyrazole‐4‐carboxylic acid (H 2 L 1 ), 1, 2'‐methylenebis(3‐methyl‐pyrazole‐4‐carboxylic acid (H 2 L 2 ) and 1,1'‐methylenebis(3‐methyl‐pyrazole‐4‐carboxylic acid (H 2 L 3 )), which have been successfully used to construct CPs with d 10 metal ions .…”

A Three-Dimensional Copper Coordination Polymer Constructed by 3-Methyl-1H-pyrazole-4-carboxylic Acid with Higher Capacitance for Supercapacitors

“…Many CPs with functional properties based on 3,4-pyrazoledicarboxylic acid, 3,5-dimethyl-1 H -pyrazole-4-carboxylic acid, 1 H -pyrazole-4-carboxylic acid, 5-methyl-1 H -pyrazole-3-carboxylic acid, 1-carboxymethyl-3,5-dimethyl-1 H -pyrazole-4-carboxylic acid, etc. have been synthesized by us and other research groups. − However, to the best of our knowledge, only a few CPs derived from 3-methyl-1 H -pyrazole-4-carboxylic acid (H 2 mpca) have been reported by us so far. , Tetrafluoroterephthalic acid (H 2 tfbdc), as a versatile linker similar to 1,4-benzenedicarboxylic acid, has been used in synthesizing CPs with interesting structures and properties. − For instance, two-dimensional (2D) CPs Ln­(tfbdc) 1.5 ­·DMF·H 2 O (Ln = Pr 3+ ( 1 ), Nd 3+ ( 2 )) present antiferromagnetic property; [Mn­(tfbdc)­(4,4′-bpy)­(H 2 O) 2 ], a 2D CP, serves as an anode material for Li-ion batteries, displaying a reversible specific capacity of 390 mA h g –1 . However, three-dimensional (3D) CPs based on H 2 tfbdc and H 2 mpca ligands have not been reported so far.…”

Four Complexes with the Rigid Ligand 1,4‐Bis(1H‐imidazol‐4‐yl)benzene and Varied Carboxylate Ligands

“…In addition, the typical non‐covalent interactions (such as H‐bonding and π/π stacking)6 and reaction conditions such as temperature, pH, solvent also play a important role in metallosupramolecular assemblies 7,8. Generally, the multi‐nitrogen donor ligands and polyfunctional carboxylates are most effective building units not only because of their strong coordination ability,9,10 and the NH or N atom of multiple N‐containing groups as well as the OH or O atom of carboxylate groups can act as a hydrogen bonding donor or acceptor and benefit the construction of supramolecular structures 11. As a result, prototypical organic‐inorganic hybrids have been successfully constructed from metal or metal cluster nodes liked through the polyfunctional multi‐N donor ligands or carboxylates 12,13.…”