H-bonding interactions enable a 3D pillared cobalt(Ⅱ) coordination polymer for touchless finger moisture detection

Coordination polymers(CPs) are emerging as the next generation of macromolecule materials in many industrial and technological applications,e.g.gas/humidity sensing.The design of CP-based sensors with high performance and low cost is of significance,but this work is still in the infancy stage.In this contribution,a new one dimensional(1D) CP has been successfully synthesized by a simple solvent evaporation method at room temperature,namely [Co(DPP)(H_(2)O)_(2)]n·(TCA)2(H_(2)O)_(4)(named as Co-1,HTCA=3-thiophenezoic acid,DPP=1,3-di(4-pyridyl)propane).The Co-1 structure contains abundant H-bonding interactions,weaving it from 1D chain structure into three dimensional(3D) pillared-layer structure.As an impedimetric humidity sensing material,this CP exhibits short response time,small hysteresis,excellent repeatability,and good stability in the working range of 11%-97% relative humidity(RH).Furthermore,it also shows excellent performance in monitoring the moisture content of human finger skin.By analyzing the complex impedance spectra,the humidity sensing mechanism of Co-1 sensor was expounded at different RH ranges.