Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
A highly selective colorimetric and fluorescent chemosensor for Al(III) based-on simple naphthol in aqueous solution
Graphical abstract
A new chemosensor for Al(III) showed effective colorimetric/fluorescent single selectivity and high sensitivity for Al3 + in aqueous solution. The binding ratio of L–Al3 + complexes was determined from the Job plot (absorption and fluorescence spectra) and MALDI-TOF MS data to be 1:1. Moreover, the binding site of L with Al3 + is determined by 1H NMR titration experiment.
Introduction
Aluminum is the most prevalent (8.3% by weight) metallic element and the third most abundant of all elements (after oxygen and silicon) in the earth's crust [1]. It is well known that aluminum has widespread prevalence in food additives, aluminum-based pharmaceuticals, and storage/cooking utensils. This would inevitably lead to environmental pollution and accumulation in human body [2], [3]. Especially, excess accumulation of Al3 + would cause human illnesses in virtue of its toxicological effects on the central nervous system, such as dementia and encephalopathy, Parkinson's disease, and Alzheimer's disease [4], [5], [6], [7]. In plants, higher concentration of aluminum affects the growth of root and seed [8], [9]. Thus, the monitoring of aluminum is essential in environment, medicine, foodstuff, etc.
Recently, the fluorescent method has become popular as compared to the other traditional detection methods viz., AMS, AAS, GFAAS, ICP–AAS, and IC–AES, due to its operational simplicity, high selectivity and sensitivity, real-time response and naked eye detection [10], [11], [12], [13]. However, it has always been troublesome to detect Al3 + due to its poor coordination ability, strong hydration ability, and the lack of spectroscopic characteristics, and only a few fluorescent sensors have been reported [14], [15], [16], [17], [18], [19], on the other hand, most of the Al3 + sensors are difficult to synthesize and insoluble in aqueous solvents. Therefore, there is a great demand for developing low cost and real-time monitoring systems that can effectively determine Al3 + ion in natural environment and living organisms.
Naphthalene ring has been proved as an ideal fluorophore due to its characteristic photophysical properties and the competitive stability in the environment, and its correlative derivates have been synthesized as effective fluorescent probes in determination of some metal ions [20], [21], [22], [23], [24]. Especially, some highly selective fluorescent probes for Al3 + using naphthalene derivates have been reported in recent years, they exhibited high signal response toward Al3 + and showed good application prospect [25], [26], [27], [28], [29], [30], [31]. Herein, a simple and highly selective colorimetric/fluorescent sensor, (E)-N′-((2-hydroxynaphthalen-1-yl)methylene)benzohydrazide (L), was synthesized and fully characterized. The chemosensor showed effective colorimetric/fluorescent single selectivity and high sensitivity for Al3 + in CH3CN–H2O solution, which will enhance the application prospect of the chemosensor for Al3 + in environment monitoring and biological analysis.
Section snippets
General information
Absorbance spectra measurements were measured on a Purkinje general UV-1901 spectrophotometer. Fluorescence spectra measurements were performed on a Cary Eclipse fluorescence spectrophotometer. 1H NMR spectra were recorded on a Varian INOVA-400 MHz spectrometer with tetramethylsilane (TMS) as internal standard.
All reagents were of analytic grade and used without further purification. The solutions of cations were prepared from their chloride salts. Double distilled water was used throughout the
Absorption spectra studies
UV–vis experiments were carried out to obtain the detailed absorption properties. The UV–vis titration of the Al3 + was conducted by using 50 μM of L in CH3CN–H2O (1:1, v/v) solution, as shown in Fig. 1. Upon binding with Al3 +, a new absorption peak appears at 402 nm and its absorption intensity gradually increases with the addition of Al3 + ion with the color changing from colorless to blue, while the absorbance of L at 359 nm gradually decreases. At the same time, an isosbestic point appears at 377
Acknowledgments
This project is supported by the National Natural Science Foundation of China (21171040), the International Sea Area Resources Survey and Development of the 12th Five-year Plan of China (DY125-15-E-01), the Educational Commission of Anhui Province of China (2014KJ016, 2014KJ024, 2015KJ002), and the Natural Science Foundation of Fuyang Normal College (2015FSKJ02ZD, 2014FSKJ06, FS201402001B).
References (33)
- et al.
Sensors Actuators B Chem.
(2006) Coord. Chem. Rev.
(1996)Environ. Res.
(2002)- et al.
Dyes Pigments
(2013) - et al.
Inorg. Chem. Commun.
(2014) - et al.
Sensors Actuators B Chem.
(2015) - et al.
Sensors Actuators B Chem.
(2015) - et al.
Dyes Pigments
(2013) - et al.
Sensors Actuators B Chem.
(2015) - et al.
Spectrochim. Acta A
(2014)