Calix[4]arene Derivative Capped Quantum Dots for Fluorogenic Sensing of Aromatic Analytes

Abstract

Quantum dots (CdSe and CdS) were synthesized and capped with Calix[4]arene derivative (2-12). Method for green route of synthesis of CdS QD in [BMIM]Cl was established in our lab. Quantum dots (CdSe and CdS) were characterized by the TEM, DLS, UV-Vis, and Fluorescence. Calix[4]arene derivatives (1-12) were synthesized and characterized by FTIR and 1H NMR spectroscopy. Calix[4]arene derivatives adsorption on CdSe QD1-4 was characterized by fluorescence quenching and the binding characteristics were studied by applying Stern-Volmer plot to Langmuir adsorption. A non-covalent interaction between 2-12 and TOPO capped CdSe QD1-4 was observed. CdSe QD and Calix[4]arene derivative capped CdS QDs were evaluated for fluorescence sensing behavior towards sixteen polynuclear aromatic hydrocarbons (PAHs) and aromatic analytes, respectively. 2@QD2, 4@QD2, 7@QD2 and 9@QD2 showed selective and sensitive fluorescence enhancement in upto presence of fluorine (8 nM), acenaphthelene (30 nM), acenaphthene (135 nM) and benzo[b]fluorenthene (15 nM), respectively. However, 2@CdS QDs Showed selective and sensitive fluorescence enhancement in benzene. The limit of detection for benzene using 2@CdS QDs was found to be upto 30 nM. The proposed method was demonstrated for its use in determination of fluorene, acenaphthelene, acenaphthene and benzo[b]fluorenthene in spiked respirable dust (PM10) in ambient air samples collected during the open biomass (stubble) burning event in Bathinda, Punjab, ground water, milli Q water and canal water from CUP, Bathinda.