Fluorescent organic nanoparticles (FONPs) have attracted much attention as a practicable and effective platform for detection applications. The present article describes the preparation of FONPs derived from the quinazolinone-based 2-(furan-2-yl)-2,3-dihydroquinazolin-4(1H)-one derivative FHDQ. Self-assembly of FHDQ in an aqueous medium resulted in the formation of FONPs through H-type aggregation and showed excellent uorescence properties. The presence of other coexisting species solutions had no effect on the selective uorescence quenching observed with the addition of 4-nitrophenol. The photophysical properties, i.e., UV absorbance, uorescence emission, and lifetime measurements together with zeta particle sizer, support excited-state complex formation followed by a dynamic uorescence quenching phenomenon in the emission of FDHQNPs. In the concentration range of 0 to 36 μg.mL 1 , the detection limit of this turn-off sensor FDHQNPs against 4-NP was determined to be 0.01611 μM. Finally, the practicability of the FDHQNPs for the analysis of 4-NP in environmental samples was demonstrated.
Fluorescence resonance energy transfer (FRET) between tryptophan (Trp) and quinine sulphate (QS) has been investigated in aqueous medium at room temperature by absorption, emission, and time resolved fluorescence spectroscopy. Absorbance spectral characteristics rule out the possibility of ground state complex formation between them. Time resolved decay indicates dynamic type of quenching. Saturation of efficiency of energy transfer reveals the existence of FRET. Efficiency of energy transfer and distance between donor and acceptor pair were determined according to Förster's non radiative energy transfer theory.
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