International Journal of Research and Scientific Innovation (IJRSI) | Volume IV Issue XI, November 2017 | ISSN 2321–2705

Coumarin Derived Efficient Fluorescent Probe for Trace Level Determination of Hg(II) and Pb(II) in Environmental Samples: Experimental and Computational Studies

Dr. Subarna Guha
Faculty of Chemistry, Central Institute of Plastic Engineering and Technology, Haldia, West Bengal, India

Abstract : A coumarin based efficient fluorescent probe selective for Hg2+ and Pb2+ ions was synthesized by coupling 6-aminocoumarin with 2-hydroxy naphthaldehyde. The probe and its metal complexes were well characterized by different spectroscopic techniques. The probe could detect up to 1µM Hg2+ and Pb2+ in aqueous methanol solution. The method showed linearity up to 10 μM for both Hg2+ and Pb2+ . Interference from other common cations is almost negligible. The probe showed a strong binding to Hg2+ and Pb2+ ions as evident from their binding constant values (2.2×104 and 1.4×104 respectively) estimated by Benesi-Hildebrand method. Computational studies (Ab-initio, Hartree Fock) indicated a molecular level interaction between the probe and Hg2+ and Pb2+ ions.

Keywords: Fluorescence, coumarin- naphthalene hybrid, Hg2+ , Pb2+, environmental samples.

I. INTRODUCTION

Hg 2+ and Pb2+ ions are the most hazardous toxic heavy metal ions. Even the low dose exposure of mercury may lead to digestive, heart, stomach, kidney and especially neurological diseases [1-2]. Several analytical techniques for the determination of mercury ions in various real samples have been reported which include spectrophotometry [3-4], neutron activation analysis [5], anodic stripping voltammetry [6], X-ray fluorescence spectrometry [7], inductively coupled plasma mass spectrometry [8-11], electrothermal atomic absorption spectrometry [12-13] atomic fluorescence spectrometry [14] and cold vapor atomic absorption spectrometry [15]. Fluorescent chemosensors using chromoionophores [16] or polymers [17] have also been reported for Hg2+ detection. On the other hand, the fluorescence sensing method is nowadays a very efficient and popular method for low level monitoring of Hg2+ [18 – 25] due to its operational simplicity, high selectivity, sensitivity, rapidity, nondestructive methodology and direct visual perception [26-31]. The cumulative poisoning effect of lead causes hematological damage, anemia, kidney malfunctioning, brain damage, sore muscles, fatigue, irritation, and disturbances in the central nervous system [32]. The organic derivatives of lead are highly toxic because of the ease of their absorption by the body through skin and mucus membranes [33].

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