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VG_chemrxiv_fluoride sensing.pdf (13.35 MB)

A Subtle Change in Substituent Enabled Multi-Ways Fluoride Signals Including Paper-Strip Colorimetric Detection Using Urea Receptor Functionalized 1,1,4,4-Tetracyanobuta-1,3-Diene-Based Push-Pull Chromophore

submitted on 28.07.2020, 06:02 and posted on 28.07.2020, 13:24 by Vijayendran Gowri, Sachin Jalwal, Arif Hassan Dar, Arya Gopal, Azhagumuthu Muthukrishnan, Ashima Bajaj, Md. Ehesan Ali, Govindasamy Jayamurugan
A simple color change detection by the naked-eye using untreated paper for a biologically relevant fluoride (F) anion in water is a challenge. New non-planar push-pull chromophore involving intramolecular charge-transfer (ICT) from urea donor in 2,3-disubstituted-1,1,4,4-tetracyanobuta-1,3-diene (TCBD) turns out to be an efficient system for detecting Fion giving various output signals. But, replacing phenyl (Ph) at C3-position with 4-(dimethylamino)phenyl (DMA) led to the absence of colorimetric and fluorometric detections due to the masking and quenching, nature of strong ICT by the DMA. NMR and electrochemical studies revealed that the sensing mechanism is governed by H-bonding as well as the deprotonation of N–H attached with TCBD moiety which reduces the HOMO–LUMO gap and causes the dramatic color change. Coupled with excellent sensitivity (3 ppm) and specificity towards F, a successful demonstration of cheap tissue paper-based visual strip-detection in aqueous is presented.


SERB, Department of Science and Technology (DST), grant no. ECR/2016/000441

SERB, Department of Science and Technology (DST), grant no. SB/S2/RJN-047/2015


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Institute of Nano Science and Technology



ORCID For Submitting Author


Declaration of Conflict of Interest

The authors declare no competing financial interest.