2026-10-14T07:46:43Z https://api.figshare.com/v2/oai

oai:figshare.com:article/33993546 2026-09-25T06:07:48Z category_1 category_4 category_8 category_12 category_272 category_873 category_46 category_734 portal_63 item_type_3 month_year_09_2026

Competing Photoprocess-Based Sensor: Excitation-Wavelength-Dependent Turn-On and Turn-Off Signaling Response toward Picric Acid Arup Das Kanungo (25107966) Govindarajan Krishnamoorthy (1855819) Biophysics Biochemistry Microbiology Cell Biology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Immunology Biological Sciences not elsewhere classified solvatochromic studies revealed density functional theory steady state fluorescence resolved fluorescence studies dependent dft studies charge transfer depending competing proton transfer proton transfer charge transfer fluorescence spectra dft ), competing photoprocess tap water picric acid paper strip normal emission nmr experiments h </ c </ c ), >] pyridine >- imidazo 5 -< Based on competing proton transfer and charge transfer, a sensor for picric acid (PA), 2-(4′-dimethylamino-2′-hydroxyphenyl)-1<i>H</i>-imidazo[4,5-<i>c</i>]pyridine (DMAHPIP-c), has been designed and synthesized. It exhibits a limit of detection (LOD) of 0.37 nM toward PA. Apart from absorption and steady state fluorescence, time-resolved fluorescence studies and NMR experiments were performed. Solvatochromic studies revealed that the fluorophore exhibits proton transfer or charge transfer depending on the nature of the environment. PA turns off the normal emission and proton transfer and turns on the intramolecular charge transfer emission. Thereby, the fluorophore can be tuned by excitation wavelength to act as not only a turn-off but also a turn-on sensor for PA. The sensor was tested in tap water and on a paper strip. The mechanism of sensing was established by experimental, density functional theory (DFT), and time-dependent DFT studies. The effect of pH on the absorption and fluorescence spectra was also studied. 2026-09-25T00:00:00Z Dataset Dataset 10.1021/acs.joc.6c01284.s001 https://figshare.com/articles/dataset/Competing_Photoprocess-Based_Sensor_Excitation-Wavelength-Dependent_Turn-On_and_Turn-Off_Signaling_Response_toward_Picric_Acid/33993546 CC BY-NC 4.0