The coumarin-thiol-based colorimetric and fluorimetric chemosensor (E)-7-(diethylamino)-3-((2-mercaptophenylimino)­methyl)-2H-chromen-2-one 1a was designed, synthesized, and evaluated for anion detection through the metal displacement mechanism. Chemosensor 1a exhibited a high sensitivity and selectivity to Hg2+ ion detection in HEPES-buffered solution [20 mM, 3:7 CH3CN/H2O (v/v), pH 7.0] with a 1:1 binding stoichiometry and a 5.549 × 105 M–1 binding constant. The fluorescence intensity of chemosensor 1a was selectively quenched by Hg2+, and an obvious color change from yellowish green to orange was observed by the naked eye. Moreover, a solution of the in situ generated 1a + Hg2+ complex displayed a high selectivity to CN– through the Hg2+ displacement approach. The gradual addition of CN– to the resultant solution of the 1a + Hg2+ complex induced its fluorescence recovery with a detection limit of 31 nM. This reversibility in fluorescence suggests the promising applicability of chemosensor 1a as an “on–off–on” naked-eye sensor.

A chalcone-based naked-eye colorimetric chemical sensor, (E)-4-hydroxy-3-(3-(4-methoxyphenyl)acryloyl)-2H-chromen-2-one 1a, was developed for selective and sensitive recognition of Cd2+ in mixed aqueous–organic media.

Exposure to even very low concentrations of Pb is known to cause cardiovascular, neurological, developmental, and reproductive disorders, and affects children in particular more severely. Consequently, much effort has been dedicated to the development of colorimetric and fluorescent sensors that can selectively detect Pb ions. Here, we describe the development of a triazole-based fluorescent sensor L5 for Pb ion detection. The fluorescence intensity of chemosensor L5 was selectively quenched by Pb ions and a clear color change from colorless to yellow could be observed by the naked eye. Chemosensor L5 exhibited high sensitivity and selectivity towards Pb ions in phosphate-buffered solution [20 mM, 1:9 DMSO/H O (v/v), pH 8.0] with a 1:1 binding stoichiometry, a detection limit of 1.9 nM and a 6.76 × 10 M binding constant. Additionally, low-cost and easy-to-prepare test strips impregnated with chemosensor L5 were also produced for efficient of Pb detection and proved the practical use of this test.

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In recent times, mesoporous silica sieves gathered considerable attention from a fundamental as well as an applied perspective. Particularly, MCM‐41 has become increasingly popular among researchers because of its chemical flexibility and application in various fields. In addition, MCM‐41‐based materials are currently being extensively studied for their utility as substrates, adsorbents, catalysts, molecular hosts, and ion exchangers. This review article provides a thoughtful analysis of the developments in these areas, particularly emphasizing the recent advance in the functionalization of MCM‐41 via metal complex and their catalytic applications in a variety of reactions such as coupling reactions and oxidation reactions. This review explores the catalytic properties that led to such widespread use, and why there is now an increasing drive to synthesize such a catalytic system.