Cd-Based Coordination Polymer Using a Bioinspired Ligand: Studies Toward Turn-On Luminescence-Based Sensing and Schottky Diode Behavior through Device Fabrication

A new coordination polymer of formula [Cd-(C8N2O3H7)2(H2O)2]n, 1, has been synthesized via the hydro-thermal method using a bioinspired ligand, N-nicotinoylglycinate. The compound was characterized by SCXRD, PXRD, FTIR spectra, and thermogravimetric analysis (TGA). Single-crystal X-ray diffraction reveals the connectivity between Cd2+ ions and N-nicotinoylglycinate layers in nature, and the layers are arranged in an ABAB.... fashion to give a three-dimensional packing arrange-ment stabilized by interlayer N-H center dot center dot center dot O and O-H center dot center dot center dot O hydrogen bonds and pi center dot center dot center dot pi interactions. An aqueous dispersion of compound 1 exhibits strong emission centered at 420 nm after excitation at 280 nm. This emission has been used for the selective sensing of p-xylene over other related electron-rich C8 aromatic isomers based on luminescence turn-on. The calculated value of the limit of detection (LOD) was 84.55 ppb, which is far lower than the safe limit of p-xylene (300 ppb in water). This compound also shows pH-dependent luminescence properties and stability in a wide range of pH (1-14). In both cases (p-xylene detection and pH dependence), time-resolved studies were used to determine the excited-state lifetime and understand the mechanism of luminescence behavior in the presence of analytes. Density functional theory (DFT)-based computational studies were also carried out to understand the selectivity of detection of p-xylene over the other isomers. Schottky diodes fabricated using this material (CP) showed ideal diode-like behavior at a low voltage regime.