A 2D coordination polymer of [Cd(TMA)(4-CNPy)(H2O)]n (H2TMA = 3-thiophenemalonic acid, 4-CNPy = 4-cyanopyridine) with impedimetric humidity sensing performance

Abstract A new coordination polymer with formula of [Cd(TMA)(4-CNPy)(H2O)]n (named as CdL, H2TMA = 3-thiophenemalonic acid, 4-CNPy = 4-cyanopyridine) has been obtained through a facile precipitation method at room temperature. It contains two dimensional (2D) planar grid networks with the Schlafli symbol (44) stacked in a stagger-peaked fashion. This CdL was fabricated into humidity sensor and the corresponding humidity sensing properties have been investigated as well. According to the results, the CdL based sensor enjoys the advantages of high sensitivity, fast response and recovery, as well as narrow hysteresis loop. It is worth mentioning that the response time of the sensor is as short as 7 s. Finally, the humidity sensing mechanism has been discussed through complex impedance analysis, and the interaction between water molecules and the CdL active layer under different relative humidity is further visualized by a schematic diagram.