Abstract
A rhodamine organosilane derivative (Rh-UTES) has been obtained by one-pot synthesis. The chemical structure of Rh-UTES was confirmed by nuclear magnetic resonance (NMR) and infrared (FTIR) techniques. To obtain an inorganic-organic hybrid sensor, Rh-UTES was covalently immobilized on a porous silicon microcavity (PSiMc) via triethoxysilane groups. The attachment of the organic derivative into PSiMc was confirmed by FTIR, specular reflectance, and scanning electron microscopy (SEM). The optical performance of Rh-UTES receptor for Hg2+ detection was investigated by fluorescent spectroscopy and microscopy. Upon the addition of increasing amounts of Hg2+ ions, a remarkable enhancement in emission intensity was produced in both systems. In the solid phase, an increase of integrated fluorescent emission of 0.12- and 0.15-fold after Hg2+ receptor coordination was observed. The light harvesting capability of PSiMc devices allowed obtaining an enhanced fluorescent emission after Rh-UTES immobilization (277-fold). The fluorescence microscopy of hybrid PSiMc sensor provided an optical qualitative test for Hg2+ detection.
Highlights
The toxicity of mercury (Hg) and its complex forms on ecosystems and human health is well known
It is observed that rhodamine organosilane derivative (Rh-UTES) derivative binding produces a red shift (12 nm) in the porous silicon microcavity (PSiMc) reflectance spectrum; we found that this process is repeatable showing a standard deviation (SD) of ±2.12 nm
In this work we have proposed a novel method for detection of Hg2+ ions using rhodamine fluorescent derivative as the recognizing element
Summary
The toxicity of mercury (Hg) and its complex forms on ecosystems and human health is well known. Emphasis has been placed on compound development that selectively responds to the presence of specific metal ions through a change in one or more properties of the system, such as redox potentials [7], absorption [8], or fluorescence spectra [9]. Such sensors based on ion-induced changes in fluorescence appear to be designed a new functional rhodamine derivative (RhUTES) that acts as a receptor of heavy metal ions. The variation of this method was used here to produce detection of low concentrations of heavy metals by forming metallic complexes within the pores that turn on the luminescence emission
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