Four 3D coordination polymers based on layers with single syn–anti carboxylate bridges: synthesis, structures, and magnetic properties

Abstract

Four novel coordination polymers (CPs) based on a new 4-(3,5-dicarboxylphenyl) picolinic acid ligands

One-Dimensional CoII and NiII Helical Coordination Polymers Exhibiting Zero-Field Splitting

“…Theoretically, the zfs tensor is obtained from the phenomenological Hamiltonian H ZFS = S · D · S , where the axial ( D ) and rhombic ( E ) parameters are related to the values of the D tensor through; D = 3 / 2 D zz E = ( 1 / 2 ) | D xx − D yy | The obtained J values show a weak magnetic interaction in both compounds, being antiferromagnetic for 1 and ferromagnetic for 2 . This weak superexchange has been reported for other isostructural 3D coordination polymers based on M = Co II and Ni II , also presenting only syn–anti carboxylate connectivity, such as [M 3 (L) 2 (H 2 O) 6 ]·4H 2 O (H 3 L = 4-(3,5-dicarboxylphenyl)picolinic acid) and {[M(C 4 H 4 O 5 )(H 2 O)]·H 2 O} n (C 4 H 4 O 5 = Hmal 2– , malate dianion). , The spin–orbit coupling and the ligand field splitting that presents 1 and 2 should explain the zfs effect and the elevated g values obtained in both compounds . As was shown in the structural section, the cations in the [M(HL)(EtOH) 2 ] + cationic chains present an octahedral MN 2 O 4 geometry in compounds 1 and 2 .…”

From two-dimensional networks to three-dimensional metal–organic frameworks mediated by solvent ratio: luminescence and gas adsorption properties

“…This picolinic acid derivative possesses a π-conjugated rigid backbone. Some interesting CPs and MOFs based on picolinic acid derivative ligands have been reported by our group 11 c ,13 and other 14 groups; it is necessary to exploit novel CPs or MOFs with various structures and/or properties by using new picolinic acid derivative ligands. Based on this new ligand, and only through changing the solvent ratio, two new two-dimensional (2D) CPs 1 ([Co(L) 2 ] n ) and 2 ({[Co 3 (L) 4 (NO 3 ) 2 (H 2 O) 4 ]·2H 2 O} n ), and two novel isostructural three-dimensional (3D) MOFs 3 ({[Co(L)(NO 3 )(H 2 O)]·0.5H 2 O} n ) and 4 ({[Ni(L)(NO 3 )(H 2 O)]·0.5H 2 O} n ) have been solvothermally synthesized and structurally characterized.…”

New High-Nuclear Coordination Complexes Constructed by 2-Hydroxymethylpyridine: From Antiferromagnetic to Spin Glass and Ferromagnetic Behavior

“…34,35 Moreover, the magnetic properties can be influenced by the bridging conformations of carboxylate groups, which mediate antiferromagnetic interactions through syn−syn or anti−anti conformations and weak ferromagnetic interactions by syn− anti bridging conformation. 36 The mixed N/O chelate ligand 2hydroxymethylpyridine (Hhmp) containing one alcohol group can provide a bridging alkoxide, supporting high-nuclearity products. 37−39 Our group has explored the construction of highnuclear metal coordination complexes using Hhmp as a ligand and reported a group of new complexes exhibiting interesting magnetic regulation behavior.…”

“…Since the coordination process is affected by many factors, the rational design and synthesis of complexes with expected structures and magnetic properties still face enormous challenges . It is worth mentioning that carboxylate is widely employed for the construction of coordination complexes as a bridging ligand, because carboxyl groups can not only enhance metal–cation binding ability and selectivity , but also assemble metal ions into metal clusters, which play a role as the second building unit in the whole structure. , Moreover, the magnetic properties can be influenced by the bridging conformations of carboxylate groups, which mediate antiferromagnetic interactions through syn – syn or anti – anti conformations and weak ferromagnetic interactions by syn – anti bridging conformation . The mixed N/O chelate ligand 2-hydroxymethylpyridine (Hhmp) containing one alcohol group can provide a bridging alkoxide, supporting high-nuclearity products. − Our group has explored the construction of high-nuclear metal coordination complexes using Hhmp as a ligand and reported a group of new complexes exhibiting interesting magnetic regulation behavior …”