A pH-Responsive Molecular Switch with Tricolor Luminescence

Abstract

We developed a new ratiometric pH sensor based on poly(N-phenylmaleimide) (PPMI)-containing block copolymer that emits three different fluorescent colors depending on the pH. The strong solvatochromism and tautomerism of the PPMI derivatives enabled precise pH sensing for almost the entire range of the pH scale. Theoretical calculations have predicted largely dissimilar band gaps for the keto, enol, and enolate tautomers of PPMI owing to low-dimensional conjugation effects. The tunable emission wavelength and intensity of our sensors, as well as the reversible color switching with high-luminescent contrast, were achieved using rational molecular design of PPMI analogues as an innovative platform for accurate H(+) detection. The self-assembly of block copolymers on the nanometer length scale was particularly highlighted as a novel prospective means of regulating fluorescence properties while avoiding the self-quenching phenomenon, and this system can be used as a fast responsive pH sensor in versatile device forms.

Luminescent films for chemo- and biosensing

“…Moreover, the microstructure of the matrix can be tailored to completely encapsulate the dye, resulting in high pH sensing performances ( Table 3). 136 Ratiometric tricolor switching behavior was observed for the PPMI polymer in an almost entire pH range. 128 The hybrid xerogel film by dip-coating exhibited a linear response to CO 2 in the range 0-30%, and the limit of detection for CO 2 was calculated to be 0.03%.…”

Sustainable Bioresource‐Derived Components for Molecular Keypad Lock and IMPLICATION Logic Gate Construction

“…Scientists have been exploring various molecular machines over the time ranging from molecular motors, molecular switches, shuttles, sensors and logic gates,,, etc. The main advantage of these molecular systems is controlling and monitoring with the responses to external stimuli such as heat, light, pH, electric field etc. Among the various molecular devices vide supra the keypad locks are least exploited.…”

Synthesis and solid‐state properties of crosslinked alternating copolymers of phenyl vinylethylene carbonate and N‐substituted maleimides

“…Additionally, the copolymers of VEC and NMI also exhibited the reversible color change based on an acid–base switching not only in solution but also in solid‐state . Although the color change and luminescence properties of poly(NMI)s with acid–base response in solution were revealed by several reports, those properties in solid‐state have barely been argued to our knowledge . Such reversible color change in solid‐state is well known as various chromisms, which are thermochromism, photochromism, electrochromism, piezochromism, vapochromism, and so on .…”