Citrate-capped quantum dots of CdSe for the selective photometric detection of silver ions in aqueous solutions

摘要

A simple strategy for the synthesis of water soluble, luminescent, citrate-capped CdSe quantum dots (Q-CdSe) and their applications to selective detection of silver ions are described. The steady state pho-toluminescence (PL) spectra show single, narrow emission band at ca. 554 nm without any contribution from the trap states. The effect of various ions including physiologically important metal ions (viz. K~+, Ca~(2+), Fe~(3+), ZN~(2+), Mg~(2+), MN~(2+), Cu~(2+), Ag*, Pb~(2+) and Cd~(2+)), on the PL intensity of citrate-capped Q-CdSe has been studied. Among these, selective luminescence quenching with Ag* ion was found to be predominant. Under the optimum conditions, the response was linear between 1.7 and 18 μM. The quenching constant Ksv was found to be ca. 3.4 × 10~5 M~(-1). The mechanism of photoluminescence quenching of Q-CdSe by metal ions (Ag~+) is also discussed. Based on these studies, the potential use of Q-CdSe as a luminescent probe for the selective detection of silver ion has been proposed.