A ciprofloxacin based 1D Cd(II) coordination polymer with highly efficient humidity sensing performance

Coordination polymers (CPs) have recently be considered as promising candidates for electrical sensors, especially impedimetric ones, yet still limited by low sensitivity, slow response, and large humidity hysteresis. In this contribution, {[Cd0.5(cfH)(4, 4′-bpy)0.5](NO3)·H2O}n (named as CdL, cfH = ciprofloxacin, 4,4′-bpy = 4,4′-bipyridine) has been synthesized via a facile solvent evaporation method at room temperature. The CdL CP possesses a one dimensional (1D) structure that is further connected by hydrogen bonds forming a three dimensional (3D) supramolecular network. Taking into account of rich hydrogen bonds and uncoordinated atoms (N, O, and F), the CdL CP was assembled into an impedimetric sensor and thus the humidity sensing performance was investigated systemically. The CdL based sensor exhibited good humidity sensing performance in a wide humidity range, including high sensitivity, small hysteresis, and relatively rapid response–recovery. Moreover, the sensing mechanism was discussed by complex impedance analysis in detail, so as to confirm the charge carrier contribution at different relative humidity (RH) range. These results indicate the potential application of CdL in humidity sensors, and further reveal the promising prospects for construction of CP-based electrical sensory devices.