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Turn on Fluorogenic Chemosensor for Fe3+ and Schottky Barrier Diode with Frequency Switching Device Applications


A novel, highly sensitive and selective fluorescent chemosensor L has been synthesized and characterized by various physicochemical techniques. In 3:7 water:MeCN (v/v) at pH 7.2 (10 mM HEPES buffer, µ = 0.05 M LiCl) it selectively recognizes Fe3+ through 1:1 complexation resulting a 106 fold fluorescence enhancement and a binding constant of 8.10 x 104 M-1. The otherwise non-fluorescent spirolactam form of the probe results a dual channels (absorbance and fluorescence) recognition of Fe3+ via CHEF through opening of the spirolactam ring. We have also carried out fluorescence titration and anisotropy (r) studies in pure water in the presence of SDS. Based on the dependence of FI and r on [SDS] it was proposed that the probe is trapped between two SDS monolayer which are again interacted among themselves by π•••π stacking. As a result, there is an increase in FI up to [SDS] ~ 7 mM – a phenomenon reminiscent with aggregation induced enhancement of emission (AIEE). Beyond this concentration of SDS (7 mM) micelle formation takes place and π•••π stacked polymer now becomes monomer and trapped inside the micellar cavity. As a result there is a decrease in FI at [SDS] > 7 mM. But for anisotropy, it increases with [SDS] beyond 7 mM. Ligand, metal and SDS interactions are well established through different optical and morphological studies. [L-Fe(NO3)]2+ thin films on FTO glass substrates have been designed with the help of spin-coating deposition technique. The deposited film of thickness1.6×10-5 cm is well characterized by optical band gap calculation with direct band gap, εg ~ 1.6 eV. FESEM was also performed for [L-Fe(NO3)]2+/FTO film. The Current-Voltage characteristics by two probe technique was measured. Light dependent exciton generation was carried out by taking the top and bottom contacts with graphite paste on FTO and on the [L-Fe(NO3)]2+ films for the measurement of switching behavior. The response ratio curve for the light induced frequency switching phenomena have been noticed. It is the oscillation frequency of the photo-generated electron and the hole in an exciton. Thus, light induced frequency switching behavior and Schottky Barrier Diode characteristics of the material were established.

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Publication details

The article was received on 25 Aug 2017, accepted on 26 Feb 2018 and first published on 05 Mar 2018

Article type: Paper
DOI: 10.1039/C7PP00322F
Citation: Photochem. Photobiol. Sci., 2018, Accepted Manuscript
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    Turn on Fluorogenic Chemosensor for Fe3+ and Schottky Barrier Diode with Frequency Switching Device Applications

    A. Mahammad, H. A. Molla, R. Bhowmick, A. S. M. Islam, B. Show, N. Mukherjee and A. Mondal, Photochem. Photobiol. Sci., 2018, Accepted Manuscript , DOI: 10.1039/C7PP00322F

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