{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T11:57:28Z","timestamp":1791460648003,"version":"4.3.4"},"reference-count":107,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T00:00:00Z","timestamp":1791417600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T00:00:00Z","timestamp":1791417600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the Ministry of Science and Higher Edu cation of the Russian Federation"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Pyrazine (1,4-diazine) and its annulated derivatives are promising platforms for colorimetric and fluorescent chemosensors of biologically and environmentally relevant metal cations, including Hg2+, Cu2+, Zn2+, Pb2+, Fe3+, Al3+, Co2+, Ni2+, Ag+ and Cr3+. Their sensing potential arises from the strongly electron-deficient pyrazine ring, low-lying unoccupied molecular orbitals, and considerable synthetic versatility. This review systematically summarizes the structural diversity, metal-ion recognition strategies, photophysical response mechanisms, and practical applications of pyrazine-derived small-molecule chemosensors, with emphasis on studies published between 2015 and 2026. Reported architectures include pyrazinamide, pyrazinehydrazide, 2-acetylpyrazine, aminopyrazine, hydrazinopyrazine, aryl(hetaryl)pyrazine derivatives, pyrazines fused with five-membered carbo\/heterocycles, quinoxalines, and pyrido [2,3-b]pyrazines. The analysis shows that N,N,O-tridentate chelation, CHEF\/CHEQ, PET, ICT, ESIPT, FRET and AIE mechanisms govern the sensing behavior, providing detection limits from nanomolar to micromolar levels and enabling naked-eye, test-strip, and live-cell imaging applications. It is concluded that sensing performance is primarily determined by the chelating motif and the substitution pattern, while selectivity towards Cu2+ and Fe3+ remains the main limitation. Promising directions include AIE-active long-wavelength emitters, portable smartphone-assisted platforms, MOF-based architectures, and DFT-guided rational design of next-generation pyrazine chemosensors.<\/jats:p>","DOI":"10.3390\/molecules31193573","type":"journal-article","created":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T11:26:53Z","timestamp":1791458813000},"page":"3573","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Pyrazine-Based Chemosensors for Cation Detection"],"prefix":"10.3390","volume":"31","author":[{"given":"Tatyana N.","family":"Moshkina","sequence":"first","affiliation":[{"name":"Department of Organic and Biomolecular Chemistry, Ural Federal University, Mira St. 19, 620002 Ekaterinburg, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0177-1582","authenticated-orcid":false,"given":"Emiliya V.","family":"Nosova","sequence":"additional","affiliation":[{"name":"Department of Organic and Biomolecular Chemistry, Ural Federal University, Mira St. 19, 620002 Ekaterinburg, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Galina N.","family":"Lipunova","sequence":"additional","affiliation":[{"name":"Department of Organic and Biomolecular Chemistry, Ural Federal University, Mira St. 19, 620002 Ekaterinburg, Russia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,10,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"468","DOI":"10.1016\/j.matchemphys.2012.11.075","article-title":"Quantum Chemical Approach toward the Electronic, Photophysical and Charge Transfer Properties of the Materials Used in Organic Field-Effect Transistors","volume":"138","author":"Chaudhry","year":"2013","journal-title":"Mater. 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