Rapid naked-eye colorimetric detection of gaseous alkaline analytes using rhodamine B hydrazone-coated silica strips

Abstract

Development of rhodamine B hydrazone-coated silica strips for rapid detection of alkaline vapors by the naked-eye or using a smartphone camera.

Ratiometric fluorescent chemosensor based on the block copolymer of poly(N‐isopropylacrylamide)‐b‐poly(N‐vinylcarbazole) containing rhodamine 6G and 1,8‐naphthalimide moieties

“…Since there are many possible reactive sites in the skeleton of rhodamine for organic modification, numerous derivatives of rhodamine dyes have been reported in recent years to satisfy various practical demands, especially for designing chemosensors 10,11 . As an important form of rhodamine derivatives, spirocyclic rhodamine derivatives can undergo great fluorescence enhancements via a structural change from the spirocyclic state (non‐fluorescent) to the ring‐open state (fluorescent) induced by metal ions and inorganic anions, which have been widely used as colorimetric and fluorometric chemosensors 12–14 . The selectivities of rhodamine‐based sensors depend on the nature of the functional groups affixed to the xanthene rings 15 .…”

A Brief Review on Advances in Rhodamine B Based Chromic Materials and Their Prospects

“…In 2020, Nour and El Malah from Cairo, Egypt, developed a novel halochromic system based on RhB hydrazone-3 through a popular Schiffbase reaction (Figure 44). 81 Critical Understanding. In halochromism, the reversible color changes in the visible region arise mainly due to the pHtriggered different states of electronic conjugation.…”

“…1−4 The proposed mechanism of halochromism of the material is shown in Figure 45, which involves a structural change in terms of ring-opening and iclosing in the presence of (I) acid (protonation) and (II) base (deprotonation), respectively. 81 Applications. The halochromic material (Figure 44) finds application for the quick recognition of various bases with the help of chromatographic paper.…”

“…A smartphone-aided, modern digital image-based colorimetric technique (DIBCT) uses the concept of halochromism. 81 ■ IONOCHROMISM Advances. Ionochromic substances change their color in the visible region in the presence of an externally added ion (cation/anion) and return back to their initial state when the same ion is removed.…”

“…In halochromism, the reversible color changes in the visible region arise mainly due to the pH-triggered different states of electronic conjugation. − The proposed mechanism of halochromism of the material is shown in Figure , which involves a structural change in terms of ring-opening and iclosing in the presence of (I) acid (protonation) and (II) base (deprotonation), respectively …”