Bis(dithioline)-Based Metal-Organic Frameworks with Superior Electronic and Magnetic Properties: Spin Frustration to Spintronics and Gas Sensing

摘要

Inspired by recent experimental synthesis of two-dimensional cobalt bis(dithioline) (CoBHT) metal-organic surface (J. Am. Chem. Soc., 2015, 137, 118-121), herein, using first principle calculations, we have investigated the electronic and magnetic properties of two-dimensional BHT-based metal (M = Co, Fe, Mn, Cr)-organic frameworks (MBHT). Our detailed theoretical calculations predict that CoBHT, FeBHT, and MnBHT are planar ferromagnetic.(FM) half-metals, whereas CrBHT is planar spin frustrated kagome lattice antiferromagnetic (AFM) semimetal, a new state of matter referred as spin-liquid. These planar ferromagnetic half-metal materials are promising candidates for spintronic devices. Further, polluting gas such as CO can be detected by these MOFs as there is remarkable variation of electronic and magnetic properties after gas adsorption. Interestingly, these properties have been found to be a function of coordination environment of central metal atom, which is actually a coordinatively unsaturated (CUS) center. Square planar central metal atom changes its coordination geometry to distorted square pyramidal geometry (as metal atom protrude out of the square plane) to octahedral, after single and both side full coveraged gas adsorption, respectively. Especially, for their practical purposes in gas sensing, we have calculated the transport properties, taking the cobalt bis(dithioline) (Cobdt) molecule as an example. Unadsorbed (Cobdt) and coordinatively saturated bis-CO [Cobdt(CO)(2)] adsorbed molecule provide remarkably distinct I-V responses, which becomes a signal for detection of CO gas. Moreover, Cobdt molecule shows the spin-filtering effect as it is half-metallic, thus Cobdt can be used as novel material for spintronic device fabrication. Therefore, the MOFs we have studied and Cobdt molecule can be used as potential materials for spintronic devices and for polluting gas sensing.