A modular approach for molecular recognition by zinc dipicolinate complexes

Abstract

A series of zinc dipicolinate (2,6-pyridinedicarboxylate; pdc) complexes [H2tmbpy][Zn(pdc)2]·5H2O () {H2tmbpy = 1,3-bis(4-pyridinium)propane(2+)}, [H2bpy][Zn(pdc)2]·6H2O () {H2bpy = 4,4'-bipyridinium(2+)}, [H2bpy][Zn(pdc)2]·3.5(4np)·2H2O () {4np = 4-nitrophenol}, [H2tmbpy][Zn(pdc)2]·4(2,7dhn)·3H2O () {2,7dhn = 2,7-dihydroxynaphthalene}, [H2bpy][Zn(pdc)2]·2(2,7dhn)·5H2O (), [H2bpy][Zn(pdc)2]·2(pyrogl)·6H2O () {pyrogl = pyrogallol}, and [H2tmbpy][Zn(pdc)2]·2(2,6dhn)·8H2O () {2,6dhn = 2,6-dihydroxynaphthalene} were synthesized and characterised. Different packing patterns in these complexes arise from differences in the abilities of cations to π-stack with zinc dipicolinate units. In , the planar [H2bpy](2+) moieties are π-stacked with adjacent 4,4'-bipyridinium cations and [Zn(pdc)2](2-) anions, whereas in , π-stacks are formed exclusively between [Zn(pdc)2](2-) moieties. 4-Nitrophenol can selectively replace the [H2bpy](2+) cations to form adduct , thus representing a novel host-guest system for molecular recognition of 4-nitrophenol. This recognition does not occur upon treatment of 4-nitrophenol with which bears a nonplanar [H2tmbpy](2+) cation. Host-guest interactions of pyrogallol, 2,6-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene with the parent complexes and were studied, resulting in the crystallization of . The crystal structures of show that guest organic molecules are accommodated in the layers of zinc dipicolinate anions. The formation of different water clusters is also discussed. In addition, topological analysis and classification of the H-bonded patterns driven by strong hydrogen bonds between the [H2bpy](2+) or [H2tmbpy](2+) cations and the [Zn(pdc)2](2-) anions, and organic guest molecules were carried out. This analysis revealed: (i) discrete 0D dimeric (in and ) or tetrameric (in ) motifs with 1M2-1 or 1,3M4-1 topology, respectively, (ii) infinite 1D zigzag chains with 2C1 topology in , and (iii) infinite 2D layers with the hcb [Shubnikov hexagonal plane net/(6,3)] topology in .

Tetranuclear Cobalt Complexes as Nano-Dimensional Template for Inclusion of Nitrophenols

“…The cyclic assemblies were held to ethylhydroxy groups by hydrogen bond. On the other hand complex 2 had an additional [Co(H 2 O) 6 ]Cl 2 molecule (Figure 2d). Tetranuclear cations in these two complexes had comparable end to end distances, which were~1.69 nm and~1.62 nm respectively.…”

“…[2] Nitroaromatic compounds are generally detected by nano-dimensional [3] and polymeric receptors. [4] Factors relating to sizes of receptors such as medium size [5] and small size [6] inorganic complexes with p-stacking ligands have attracted attention in devicing sensors for nitroaromatics. Fluorescent ligand such as 1,10-phenanthroline forms p-stacks [7] and interacts with nitrophenols.…”

Changes in the proportions of an active pharmaceutical through cocrystals

“…Complex 2 was dihydrate; where the water of crystallization molecules formed hydrogen bonds with cations and anions. It may be mentioned that the pyridinedicarboxylate complexes had been well known to form layer-like structures through stacking interactions (Shankar et al, 2015). To accomodate two relatively large-sized cations per anion in a self-assembly higher space would be required.…”

“…2,6-Pyridinedicarboxylic acid (abreviated as H 2 pdc) is a biocompatible compound (Powell, 1953) whose neutral form F and two different anionic forms G and H are shown in Figure 2. It is a good coformer for API cocrystals (Bankiewicz & Wojtulewski, 2019;Steed, 2013), and it also forms various metal complexes (Das & Baruah, 2012;Shankar, Kirillov, & Baruah, 2015;Yang et al, 2002). Due to biocompatibility and medicinal values of the metal-pdc complexes have prospects (Yang et al, 2002).…”

Cocrystals of Naphthalenediols with Aliphatic Amines and Their Photoluminescence Properties

“…We chose to study hmta , dabco and piperazine cocrystals with dihydroxynaphthalenes [Figure (c)] to look for inherent structural features of their self‐assemblies contributing to fluorescence emission properties in solid state. Generally, dihydroxynaphthalene molecules interact with different fluorophores to change emission properties . There are also studies relating effect of aromatic π‐π and C−H⋅⋅⋅π interactions influencing fluorescence emission of cocrystals of dihydroxynaphthalenes and nitrogen‐based heterocycles .…”