Influential Role of Geometrical Disparity of Linker and Metal Ionic Radii in Elucidating the Structural Diversity of Coordination Polymers Based on Angular Dicarboxylate and Bis-pyridyl Ligands

Abstract

As a continuation of our recent investigations on coordination polymer/ metal−organic framework containing compounds, herein, four new coordination polymers, namely, {Co 2 (ADA) 2 (px2ampy)} n (1), {Cd(ADA)(px2ampy) 0.5 } n (2), {Co 2 (IPTA) 2 (px2ampy)} n (3), {Mn(IPTA)(px3ampy)} n (4) have been synthesized, based on the flexible dicarboxylate ligand H 2 ADA and rigid dicarboxylate ligand H 2 IPTA along with long flexible bis-pyridyl linkers as coligand (where H 2 ADA = 1,3adamantanediacetic acid; H 2 IPTA = isopthalic acid; px2ampy = 1,4-bis(2pyridylaminomethyl)benzene; px3ampy = 1,4-bis(3-pyridylaminomethyl)benzene). Compounds 1−4 have been characterized by routine elemental analysis, IR spectroscopy, and thermogravimetric (TG) analysis and unambiguously by single crystal X-ray diffraction analysis. The solid-state luminescent property of compound 2 has been additionally characterized. Compound 1 is a two-dimensional (2D) framework, constructed by the connectivity of Co 2 paddle-wheels as secondary building units (SBUs) and the organic linkers. The 2D sheet of compound 2 consists of Cd-dimers as SBUs and extends to a supramolecular three-dimensional (3D) framework through H-bonding interactions among the sheets. Compound 3 is a 3D coordination polymer, in which an unusual SBU is formed by two Co II centers: one in tetrahedral and the other one in octahedral coordination geometries. In the crystal structure of compound 4, the connectivity of the Mn 2 -dimers with the macrocyclic rings, formed from px3ampy coligands, results in the formation of 2D layer structures. The title compounds 1−4 illustrate an important structural relationship, which can be rationalized by the geometrical diversity of two different dicarboxylate ligands and the nature of different metal ions, employed in this study. The role of the metal ionic radii in assessing the formation of final architectures, thereby, influencing the dimensionality of the compounds has been discussed. The long flexible pyridyl spacers, present in all these compounds as an integral part, modulate themselves in different conformations depending on the requirement of the coordination environment.

A Mononuclear CoII Coordination Complex Locked in a Confined Space and Acting as an Electrochemical Water‐Oxidation Catalyst: A “Ship‐in‐a‐Bottle” Approach

“…Metal–organic frameworks (MOFs) having well‐defined void spaces/cages are generally good hosts, capable of encapsulating an active guest . In the last few years, we have been engaged in understanding the mechanistic aspects for the formation of metal–organic frameworks (MOFs) using flexible organic linkers . In this journey, we have recently synthesized and structurally characterized a Co‐based MOF [{Co 3 (μ 3 ‐OH)(BTB) 2 (dpe) 2 }{Co(H 2 O) 4 (DMF) 2 } 0.5 ] n ⋅ n H 2 O ( Co‐WOC‐1 ) [H 3 BTB=1,3,5‐benzenetribenzoic acid; dpe=1,2‐di(4‐pyridyl)ethylene, see Figure b,c], the crystal structure of which shows a mononuclear cobalt(II) complex cation [Co II (H 2 O) 4 (DMF) 2 ] 2+ , entrapped inside the void space of the framework (the mononuclear complex is not coordinated/attached to the host framework) in compound Co‐WOC‐1 .…”

Crystal structure, infrared spectra and luminescence of a 1D Cd coordination polymer with 4-nitrophthalic acid and 1,10-phenanthroline monohydrate ligands

“…[10][11][12][13][14][15]. Among these factors, the organic ligand plays an important role because changing it can control and adjust the coordination frameworks and topologies [16][17][18][19]. Since a carboxylate group can bridge metal ions and lock their position into M-O-C clusters, which can act as rigid entities and improve the stabilization of the compounds, di and polycarboxylic acids are widely used as bridging ligands to construct coordination frameworks with versatile structures [20][21][22][23][24][25].…”

Poly[(μ-pentafluorobenzoato-κ2O:O′)(pentafluorobenzoato-κO)(μ-pyrazine-κ2N:N′)copper(II)]: a coordination polymer linked into a three-dimensional network by intermolecular C—H...F—C interactions

“…To date, a large number of coordination polymers have been obtained through the assembly of various organic ligands and metal ions. However, the rational design and controllable prediction of prospective networks is still a great challenge, due to complicated factors such as the properties of the organic ligands, metal ions, solvent, temperature and counterions that could influence the ultimate structures (Manna et al, 2014;Lee et al, 2004). Recently, the utilization of mixed-ligand systems based on carboxylates and N-donor ligands has proved to be an effective strategy for constructing more intricate coordination polymers (Zhang et al, 2013;Wang et al, 2013).…”