Halogen···Halogen and π–Hole Interactions in Supramolecular Aggregates and Electrical Conductivity Properties of Cu(II)-Based 1D Coordination Polymers

Abstract

The two isostructural one-dimensional coordination polymers (1D CPs) [Cu­(5-nip)­(3-Clpy)2] n (1) and [Cu­(5-nip)­(3-Brpy)2] n (2) have been synthesized using a 5-nitroisophthalic acid (H25-nip) linker and the meta-substituted 3-chloropyridine (3-Clpy)/3-bromopyridine (3-Brpy) auxiliary ligands. The structural architectures and supramolecular interactions of the CPs have been investigated by single-crystal X-ray diffraction (SCXRD) and density functional theory (DFT) studies, respectively. The SCXRD study reveals that CPs 1 and 2 form a 1D double-chain structure with carboxylato-bridged cyclic secondary building units (SBUs). Interestingly, both CPs involve type I halogen···halogen (X···X) interactions combined with π···π stacking interactions to generate a three-dimensional (3D) supramolecular network. Moreover, both CPs exhibit interesting X···N π-hole interactions involving a nitro group as the electron acceptor. Both CPs show electrical conductivity in the semiconducting regime and behave as Schottky diodes. However, CP 1 has a higher electrical conductivity in comparison to CP 2.

Cu(II)-Based Molecular Hexagons Forming Honeycomb-like Networks Exhibit High Electrical Conductivity

“…Compound 1 with the shortest π···π distance exhibits the highest electrical conductivity, whereas compound 4 with the largest π···π contact exhibits the lowest conductivity. Schottky diode (SD) production at the MS interface was evidently shown by the typical I–V characteristics of the Al/compound 1–4 interface, which showed a nonlinear rectifying behavior. , The rectification ratio ( I on / I off ) of the SDs at ±1 V was observed as 65.3, 36.7, 34.9, and 26.3 for compounds 1–4 , respectively.…”

“…In this regard, very recently, we have reported two Cu(II)-based 1D coordination polymers using 5-H 2 nip and 3-Xpy (X = Cl and Br) by a reverse layering method, i.e., keeping the mixed ligands at the bottom and Cu(II) salt at the top of the tube, which were believed to be kinetically controlled products. 33 Therefore, to attain thermodynamically favored products, 31 we have performed the reaction by layering H 2 5-nip and 3-Xpy (X = H, Cl, Br, and I) mixed ligands onto the Cu(II) salt, which resulted in the formation of series of metal−organic molecular hexagons with general formula [Cu 6 (5-nip) Research on metal complexes with a macrocyclic ring and cavity structure has received special interest due to their ability to accommodate selective ions and molecules. 34 These ring complexes also play specific roles in chemical transformation processes.…”

“…With this intention, we wanted to replace H 2 ip with H 2 5-nip and investigate the compounds obtained by the reaction with Cu­(II) and 3-Xpy. In this regard, very recently, we have reported two Cu­(II)-based 1D coordination polymers using 5-H 2 nip and 3-Xpy (X = Cl and Br) by a reverse layering method, i.e., keeping the mixed ligands at the bottom and Cu­(II) salt at the top of the tube, which were believed to be kinetically controlled products . Therefore, to attain thermodynamically favored products, we have performed the reaction by layering H 2 5-nip and 3-Xpy (X = H, Cl, Br, and I) mixed ligands onto the Cu­(II) salt, which resulted in the formation of series of metal–organic molecular hexagons with general formula [Cu 6 (5-nip) 6 (3-Xpy) 6 (H 2 O) 12 ] (Scheme ).…”

Halogen···Halogen Interactions in the Context of Coordination Polymers: A Superior Design Element for Potential Applications

“…Recently, we have reported two Cu­(II)-based 1D CPs, [Cu­(5-nip)­(3-Clpy) 2 ] n ( 35 ) and [Cu­(5-nip)­(3-Brpy) 2 ] n ( 36 ), synthesized using 5-nitroisophthalic acid (H 2 5-nip) linker and 3-chloropyridine (3-Clpy)/3-bromopyridine (3-Brpy) auxiliary ligands . Here, both CPs involve type I halogen···halogen and halogen···N π–hole interactions combined with π···π stacking contacts to fabricate a 3D supramolecular assembly (Figure ).…”

“…Crystal structures of compounds 35 and 36 along with their corresponding current–voltage characteristic curves. Modified and reproduced from ref . Copyright 2022 American Chemical Society.…”