Hydrogen bonding-mediated assembly of carbon dot@Zr-based metal organic framework as a multifunctional fluorescence sensor for chlortetracycline, pH and temperature detection

Abstract

Hydrogen-bond driven self-assembly of carbon dot-based luminescent materials has been widely studied in the fields of sensor and optoelectronic devices. However, the uniform confinement of carbon-dots (CDs) into crystalline porous materials through hydrogen bond interactions has rarely been reported. Herein, an O-phenylenediamine (O-PD) mediated Zr-based MOF material denoted as CDs@UiO-66(COOH)₂ was successfully synthesized via an efficient solvent-free synthetic method. The O-PD molecules were grafted to the structural pyromellitic acid ligands in the UiO-66(COOH)₂ framework via H-bonding interactions, and during the subsequent thermal treatment process the O-PD molecules were partially decomposed and converted into luminescent CDs. The resultant CDs@UiO-66(COOH)₂ composites retained the crystallinity of UiO-66(COOH)₂, and the confined CDs in UiO-66(COOH)₂ show excitation-independent stable green emitting properties when dispersed in a variety of solvents. The CDs@UiO-66(COOH)₂ composite exhibits excellent chlortetracycline detection performance with high selectivity, anti-interference and low limit of detection (LOD = 0.102 μM) in a wide linear range of 0–100 μM. Also, it shows an excellent stimuli-response in fluorescence intensities toward pH and temperature changes. Acting as an optical thermometer, the maximum relative temperature sensitivity (S_r) is 0.82% °C⁻¹ in the range of 10–80 °C. This work opens a new way for exploring fluorescent CD-integrated MOF composites via a hydrogen-bond driving strategy for multifunctional fluorescent sensing applications.