Phototunable Full‐Color Emission of Cellulose‐Based Dynamic Fluorescent Materials

Abstract

An iridescent chameleon‐like material that can change its colors under different circumstances is always desired in color‐on‐demand applications. Herein, a strategy based on trichromacy and the dynamically tunable fluorescence resonance energy transfer (FRET) process to design and prepare these chameleon‐like fluorescent materials is proposed. A set of trichromic (red, green, and blue), solid fluorescent materials are synthesized by covalently attaching spiropyran, fluorescein, and pyrene onto cellulose chains independently. After simply mixing them together, a full range of color is realized. The chameleon‐like nature of these materials is based on the dynamic tunable FRET process between donors (green and blue) and acceptors (red) in which the energy transfer efficiency can be finely tuned by irradiation. Ultimately, the reversible and nonlinear regulation of fluorescence properties, including color and intensity, is achieved on a timescale recognizable by the naked eye. Benefited by the excellent processability inherited from the cellulose derivatives, the as‐prepared materials are feasibly transformed into different forms. Particularly, a fluorescent ink with the complicated fluorescent input–output dependence suggests more than a proof‐of‐concept; indeed, it suggests a unique method of information encryption, security printing, and dynamic anticounterfeiting.

No‐Interference Reading for Optical Information Storage and Ultra‐Multiple Anti‐Counterfeiting Applications by Designing Targeted Recombination in Charge Carrier Trapping Phosphors

“…Recently, multi‐anti‐counterfeiting technology based on inorganic phosphors has aroused great interest by researchers. Examples include up‐conversion phosphor, organic‐inorganic combined phosphors, and charge carrier trapping phosphors . The charge carrier trapping phosphors can show the highest anti‐counterfeiting level in theory, because they do not only realize multi‐kinetic anti‐counterfeiting similar to up‐conversion due to the release of different depth traps by different powers, but they also can realize multi‐emission anti‐counterfeiting by compounding organic materials.…”

Stimuli‐Responsive Naphthalene Diimide as Invisible Ink: A Rewritable Fluorescent Platform for Anti‐Counterfeiting

“…Functional materials because of their unique optical properties offer improved security features due to the difficulty related to duplicate of their unique functions especially the colorimetric approach for authentication is of great interest as visible security features on banknotes, documents, etc. A library of materials, including lanthanides, [21][22][23][24][25][26] organic dyes, [27][28][29] conjugated polymer dots, [30] quantum dots, [31][32][33][34][35] carbon dots, [36][37][38][39] metal-organic frameworks (MOFs), [40][41][42][43][44] etc., have been explored with their respective technologies to serve the purpose. All the abovecited categories have some pros and cons [45] such as photo-stability, toxic nature, low emission property, emission at wide wavelength range, etc.…”

Functional Polymers and Polymer–Dye Composites for Food Sensing

“…These polymers offer a feasible route to design innovative fluorometric, colorimetric, and contamination‐free sensory systems. Until now, much effort has been devoted in this direction, such as the emerging ratiometric fluorescent cellulose derivatives, [ 40,41 ] biopolymer‐natural anthocyanins composites, [ 32,42,43 ] π‐conjugated polymers, [ 29,30,44 ] etc.…”