Issue 32, 2026, Issue in Progress

Straightforward synthesis of Solomon-red-BAPTA as NIR fluorescent sensors via metal-free oxidative coupling

Abstract

An effective, near-infrared (NIR) fluorescent Ca2+ sensor, Solomon-red-BAPTA, featuring a dioxothioxanthene moiety was developed for microscopy. A rapid and operationally simple synthetic route is described. The key step involves a room-temperature DDQ-mediated cross-dehydrogenative coupling (CDC) of the fluorescent precursor and BAPTA followed by a one-pot oxidation. The sensor exhibited excellent photophysical characteristics including a 160-fold fluorescence enhancement with excitation and emission maxima at 712 nm and 736 nm, respectively, suggesting high tissue-penetrating capacity. Based on the experimental data, the structure–property relationship was elucidated and further supported by DFT calculations, particularly with respect to the photoinduced electron transfer (PET)-based fluorescence turn-on mechanism.

Graphical abstract: Straightforward synthesis of Solomon-red-BAPTA as NIR fluorescent sensors via metal-free oxidative coupling

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Article information

Article type
Paper
Submitted
23 Feb 2026
Accepted
12 May 2026
First published
01 Jun 2026
This article is Open Access
Creative Commons BY license

RSC Adv., 2026,16, 29450-29457

Straightforward synthesis of Solomon-red-BAPTA as NIR fluorescent sensors via metal-free oxidative coupling

G. Riszter, L. Forgách, Z. Mucsi, L. Molnár, D. Bogdán, F. Heydari, D. Máthé, I. Mándity, Á. Gömöry and Z. Kaleta, RSC Adv., 2026, 16, 29450 DOI: 10.1039/D6RA01589A

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