Superconductivity in a Copper(II)‐Based Coordination Polymer with Perfect Kagome Structure

Abstract

Ahighly crystalline copper(II) benzenehexathiolate coordination polymer (Cu-BHT) has been prepared. The twodimensional kagome structure has been confirmed by powder X-ray diffraction, high-resolution transmission electron microscopy, and high-resolution scanning transmission electron microscopy. The as-prepared sample exhibits bulk superconductivity at about 0.25 K, which is confirmed by the zero resistivity,A Cm agnetic susceptibility,a nd specific heat measurements.Another diamagnetic transition at about 3Ksuggests that there is as econd superconducting phase that may be associated with asingle layer or few layers of Cu-BHT.Itisthe first time that superconductivity has been observed in ac oordination polymer.Superconductivity is au nique quantum phenomenon characterized by zero electrical resistance and the Meissner effect.[1] It is one of the most challenging topics in physics and materials science because of its complex physical mechanism [1a,2] and potential applications such as in power transmission, magnetic resonance imaging,magnetic levitated trains,a nd superconducting quantum interference devices. [3] Superconductivity was originally observed in pure metals and later also in avariety of solid-state materials including metal/ metal alloys,i norganic compounds,a nd also,i mportantly, organic compounds.T he first organic superconductor (TMTSF) 2 PF 6 (TMTSF = tetramethyltetraselenafulvalene) were discovered in 1980s.[4] Since then, three main families of organic superconductor have been developed:o rganic charge-transfer salts similar to (TMTSF) 2 PF 6 , [4,5] carbonbased superconductors, [6] and organic aromatic compounds superconductors (OACs).[7] Historically,the low-dimensional characteristics of organic salts make organic superconductor one of the most important candidates for high-temperature superconductivity.[8] Although high-temperature superconductivity has not been observed in the above materials,t hey show many fascinating phenomena respected to chargedensity waves, [9] spin-density waves, [10] the three-dimensional quantum Hall effect, [5] and ap ossible spin-liquid state.[11]They become prototype systems to explore the physics of low-dimensional conductors.O nt he other hand, carbonbased superconductors and OACshave advantages to achieve ahigh superconducting transition temperature, T c . [7,12] Under ahigh pressure of 15 Kbar, T c for Cs 3 C 60 can be up to 38 K.[12a]Foralong time,i tw as the highest value for organic superconductor and even comparative to most of inorganic superconductors.R ecently,O ACsf urther broaden the research boundary of the organic superconductors;m ost of them show as uperconducting transition at ambient pressure.[7a] Motivated both by pursing high T c superconductors and understanding of fundamental science in superconductivity,c ontinuous efforts will be focused on identifying and developing new organic superconductors.Benefiting from the abundance of building blocks,organic two dimensional(2D) materials,s uch as 2D covalent organic frameworks and 2D...

Synthetic Route to a Triphenylenehexaselenol-Based Metal Organic Framework with Semi-conductive and Glassy Magnetic Properties

“…The in-planer p-d conjunction, in favors of charge carriers' delocalization, leads to exceptional electrical conductivity different from traditional MOFs. Due to their intrinsic electrical conductivity and porosity, conductive MOFs in this class exhibit promising applications in electrocatalysis, transparent electrodes, energy storage, and chemoreceptive sensors (Campbell et al, 2015;Dong et al, 2015;Feng et al, 2018;Huang et al, 2017Huang et al, , 2018Jin et al, 2017;Li et al, 2017;Miner et al, 2016Miner et al, , 2017Miner et al, , 2018Park et al, 2018b;Sheberla et al, 2017;Smith et al, 2016;Wu et al, 2017). As bottom-up fabricated solid materials, MOFs with tunable structures and different properties are mainly defined by the two building blocks: metal centers and organic ligands.…”

Single Crystals of Electrically Conductive 2D MOFs: Structural and Electrical Transport Properties

“…The vast majority of MOFs are insulators and have been used in applications that benefit from high surface areas and a chemical tunability, such as gas capture and catalysis. 15 Conductive MOFs represent a new type of hybrid inorganic/organic conductor in addition to non-porous coordination polymers and hybrid perovskites, which have recently demonstrated high conductivities and superconductivity 17 and promising performances for optoelectronics, 18 respectively. Two-dimensional (2D) layered MOFs where metals and redox-active ligands form extended π-d conjugated sheets (Fig.…”

Conductive Metal–Organic Frameworks: Design, Synthesis, and Applications

“…The typical example is Cu‐BHT (BHT = benzenehexathiol) MOF films, which shows a high conductivity of 1580 S cm −1 originated from its symmetrical 2D π‐d conjugated structure. [ 79,80 ] For semiconductors and insulators, the energy gap between conduction band and valence band is wide, which results in the absence of charge carriers and low conductivity. The reported conductive MOFs exhibit semiconducting properties.…”

“…Also, the conductive HAB‐derived 2D MOFs exhibited high volumetric capacitances and areal capacitances, demonstrating their potential in energy‐storage applications. [ 125 ] After the sulfhydryl group and hydroxy group were substituted by amino group, the 2D layered MOFs Cu‐BHT [ 79,80 ] and Cu‐HHB (HHB = hexahydroxybenzene) [ 58 ] also were fabricated (Figure 5b). The 2D π‐d conjugated structures rendered them with high conductivity, and even superconductivity, showing their application potentials in electronics, sensing, field‐effect transistors, energy‐storage, and conversion, etc.…”