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

Abstract

Four new Cu(II)-based hexagonal complexes with the metallomacrocycle formulae [Cu6(5-nip)6(3-py)6(H2O)12] (1), [Cu6(5-nip)6(3-Clpy)6(H2O)12] (2), [Cu6(5-nip)6(3-Brpy)6(H2O)12] (3), and [Cu6(5-nip)6(3-Ipy)6(H2O)12] (4) have been synthesized using 5-nitroisophthalic acid (H25-nip) and pyridine (py)/3-halopyridine (3-Xpy; X = Cl, Br, and I) ligands. The structural features and supramolecular interactions of compounds 1–4 have been investigated using the single-crystal X-ray diffraction (SCXRD) technique. Interestingly, the hexagonal complexes undergo hydrogen bonding and π···π stacking interactions to form fascinating two-dimensional (2D) honeycomb-like structures. The synthesized complexes exhibit high electrical conductivity, arising from charge transport through space via π···π contacts. However, complexes containing 3-Brpy (3) and 3-Ipy (4) exhibit photosensitivity due to the presence of halogens with a larger size and lower ionization energy. The conductivity results are also in accordance with the theoretical prediction calculated by density functional theory (DFT) study.

Mn(II) 3D Coordination Framework with Mixed 5-Aminoisophthalato and Pyridyl-isonicotinoyl Hydrazone Bridges: Structure, Electrical Conductivity, Anticancer Activity, and Drug Delivery

“…Polymers and hybrid materials have established their multifaceted deliverable outcome-based properties to meet many challenges of the environment and the society − such as clean energy, ensuring health, zero-waste management, supply of hygienic water, and pollution-free air. A number of such materials are employed to fabricate energy-saving electronic devices. − Some of the external factors affect the stability and efficiency of such devices made up of organic polymers. − However, after the historic recognition of the coordination chemistry (Alfred Warner, Nobel prize in 1913), it extends the exploration in different branches of science. − Organic–inorganic hybrid compounds are such materials that show promising applications in diverse fields following SDG protocol. − The coordination polymers (CPs)/metal–organic frameworks (MOFs) are such hybrid materials, and their importance is established for the well-being of civilization …”

“…In the construction of organic–inorganic hybrid systems like CPs/MOFs, carboxylate, and amine/imine-N, bridging ligands play a central role in linking metal centers (M n + ) and creating diverse structural platforms of different dimensionalities (1D/2D/3D). , The presence of additional noncovalent interactions (hydrogen bonding, π···π) makes them durable and strong. Their architectural design is so meticulous that makes the material stable but sensitive to external stimuli (mechanical, optical, thermal, magnetic, field induction) and has ensured the applications in stimuli-responsive activities. − These materials serve as gas storage and separation systems, catalysts, charge transporters and capacitors, drug deliverers, light harvesters, etc. Normally, carboxylate-bridging ligands would not conduct electricity due to the presence of insulating C-centers while the presence of metal (even diamagnetic) knots controls the energy difference between valence and conduction bands and make them helpful for electrical communicators and/or semiconductors. − In the past few years, it has been explored that CPs are working as better electrical conductors and storage systems than conventional electrical devices.…”

“…Their architectural design is so meticulous that makes the material stable but sensitive to external stimuli (mechanical, optical, thermal, magnetic, field induction) and has ensured the applications in stimuli-responsive activities. − These materials serve as gas storage and separation systems, catalysts, charge transporters and capacitors, drug deliverers, light harvesters, etc. Normally, carboxylate-bridging ligands would not conduct electricity due to the presence of insulating C-centers while the presence of metal (even diamagnetic) knots controls the energy difference between valence and conduction bands and make them helpful for electrical communicators and/or semiconductors. − In the past few years, it has been explored that CPs are working as better electrical conductors and storage systems than conventional electrical devices. Some excellent porous conducting polymers (PCPs) of Zn­(II), Cd­(II), and few other transition metal ions are reported recently. − To the best of our knowledge, Mn­(II)-based CPs are still rare in the literature for serving as electrical conductors.…”

A dual-functional 2D coordination polymer exhibiting photomechanical and electrically conductive behaviours

“…[41][42][43] Our group has also been working on CPs for better charge transportation and Schottky diode behaviour by utilizing a mixed ligand system. [44][45][46][47] Studies have revealed that the supramolecular assembly offers a suitable environment for better charge transport through a space or "hopping" mechanism. 48,49 For instance, π⋯π stacking interactions play an important part in 2D CPs for better conjugation pathways for charge transport, and this has been used as a tool to modulate the electrical conductivity in CPs.…”