A protective layer approach to solvatochromic sensors

Abstract

As they have been designed to undergo colorimetric changes that are dependent on the polarity of solvents, the majority of conventional solvatochromic molecule based sensor systems inevitably display broad overlaps in their absorption and emission bands. As a result, colorimetric differentiation of solvents of similar polarity has been extremely difficult. Here we present a tailor-made colorimetric and fluorescence turn-on type solvatochromic sensor that enables facile identification of a specific solvent. The sensor system displays a colorimetric transition only when a thin protective layer, which protects the solvatochromic materials, is destroyed or disrupted by a specific solvent. The versatility of the strategy is demonstrated by designing a sensor that differentiates chloroform and dichloromethane colorimetrically and one that performs sequence selective colorimetric sensing. In addition, the approach is employed to construct a solvatochromic molecular AND logic gate. The new strategy could open new avenues for the development of novel solvatochromic sensors.

Mechanically Drawable Thermochromic and Mechanothermochromic Polydiacetylene Sensors

“…Importantly, blue colored PDAs undergo a color change to red when they are exposed to various chemical (e.g., volatile organic solvents, ions, and specifi c molecular recognition events) and physical (e.g., temperature and mechanical strain) stimuli. Stimulus-responsive colorimetric PDAs have been prepared in a variety of forms including aqueous suspensions, [24][25][26]33,43,44 ] fi lms, [13][14][15][16][17]31 ] nanowires/nanofi bers, [ 19,45,46 ] microarrays, [ 28,29,47 ] and microfl uidic chips. [ 48 ] In the investigation described below, we prepared a new crayon-like PDA-wax composite by using a mixing-molding technique.…”

Photocatalytic colour switching of redox dyes for ink-free light-printable rewritable paper

“…Rewritable paper that can be used multiple times and does not require additional inks for printing is therefore an attractive alternative that can have enormous economical and environmental merits to modern society [5][6][7][8][9][10][11] . Conventionally, organic dyes capable of undergoing reversible colour switching based on the photoisomerization of constitute chromophores were proposed for potential use as the imaging layer in rewritable printing media [12][13][14][15][16][17][18][19] . However, only limited progresses have been made in this area because of some major challenges [20][21][22] : (i) colour switching often becomes much slower when dyes are present in solid media instead of solution, as their molecular mobility is markedly restricted 23 , (ii) many switchable dyes retain their colour for only several hours under ambient conditions, which is too short for reading, (iii) the toxicity of switchable dyes is often an issue for daily use and (iv) most switchable dyes involve complex synthesis and are therefore expensive.…”

A Tetrahydrofuran‐selective Optical Solvent Sensor Based on Solvatochromic Polydiacetylene

“…The solovatochromic property of PDA is very interesting not only for fundamental understanding of the phenomenon, but also for its practical applications to VOC sensors. 7,8 The majority of PDAs show a blue-to-red (or purple) color transition upon exposure to a solvent that can disturb the ordered structure of PDA. In rare cases, a blue-to-yellow color change occurs when the organic solvent can significantly disrupt the PDA side chains and backbones.…”

“…To avoid the non-specificity, we recently reported the PDA-based solvatochromic sensor system based on a protective layer approach. 8 The sensor system displayed a colorimetric transition only to a specific solvent since only the solvent that can destroy the protective layer is possible to penetrate to the lower solvatochromic layer. The protective layer approach, however, requires proper protective polymer layers for colorimetric differentiation.…”