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Sensors 2018, 18(10), 3433;

Proton Triggered Colorimetric and Fluorescence Response of a Novel Quinoxaline Compromising a Donor-Acceptor System

Polymers and Functional Material Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India
Department of Chemistry, Indrashil University, Kadi, Mehsana 382740, India
Department of Chemistry, Deogiri College, Aurangabad 431005, India
School of Chemical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 436106, India
Department of Chemistry, Goa University, Taleigao Plateau Goa 403206, India
Authors to whom correspondence should be addressed.
Received: 14 August 2018 / Revised: 24 September 2018 / Accepted: 8 October 2018 / Published: 12 October 2018
(This article belongs to the Special Issue Focused on Organic Luminescent Materials and Molecular Recognition)
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Quinoxaline-based novel acid-responsive probe Q1 was designed on the basis of a conjugated donor-acceptor (D-A) subunit. Q1 shows colorimetric and fluorometric changes through protonation and deprotonation in dichloromethane. With the addition of the trifluoroacetic acid (TFA), UV-vis absorption spectral changes in peak intensity of Q1 was observed. Moreover, the appearance of a new peaks at 284 nm 434 nm in absorption spectra with the addition of TFA indicating protonation of quinoxaline nitrogen and form Q1.H+ and Q1.2H+. The emission spectra display appearance of new emission peak at 515 nm. The optical property variations were supported by time resolved fluorescence studies. The energy band gap was calculated by employing cyclic voltammetry and density functional calculations. Upon addition of triethylamine (TEA) the fluorescence emission spectral changes of Q1 are found to be reversible. Q1 shows color changes from blue to green in basic and acidic medium, respectively. The paper strip test was developed for making Q1 a colorimetric and fluorometric indicator. View Full-Text
Keywords: colorimetric; fluorescent; proton sensor; quinoxaline; reversible sensor colorimetric; fluorescent; proton sensor; quinoxaline; reversible sensor

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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    Description: Additional Supporting Information may be found in the online version of this article. Data SI detail synthesis on intermediate as well as Q1 and FT-IR, 1H NMR, 13C NMR and mass spectra can be found in ESI.

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More, Y.W.; Padghan, S.D.; Bhosale, R.S.; Pawar, R.P.; Puyad, A.L.; Bhosale, S.V.; Bhosale, S.V. Proton Triggered Colorimetric and Fluorescence Response of a Novel Quinoxaline Compromising a Donor-Acceptor System. Sensors 2018, 18, 3433.

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