Cellulose‐Based Solid Fluorescent Materials

Abstract

Organic solid‐state fluorescent materials have exhibited great potential application in optoelectronics, imaging, sensing, and security printing. However, the conventional conjugated luminogens such as perylene and pyrene derivatives are not highly recommended for preparation of the solid fluorescent materials because they always undergo fluorescence self‐quenching in solid state, i.e., aggregation caused quenching (ACQ) phenomenon. Herein, a series of solid materials with excellent fluorescent emission have been realized via covalently bonding the ACQ luminogens onto the cellulose chains and subsequently ionizing process. The synergy between the anchoring and diluting effect on luminogens of cellulose skeleton and the electrostatic repulsion among the ACQ luminogens efficiently inhibits the aggregation and the self‐quenching of luminogens. Such a general strategy is suitable for different ACQ luminogens and various partially substituted cellulose derivatives. Furthermore, the prepared fluorescent solids preserve the excellent properties of original cellulose derivatives such as good solubility and processibility. Therefore, they can be readily processed into materials in different forms, including printing pattern, coating, film, fiber, colloid, etc. This simple and effective strategy gives added impetus to the applications of solid fluorescent materials in practice.

pH and Thermo Dual‐Responsive Fluorescent Hydrogel Actuator

“…First of all, PTCA was grafted onto gelatin according to a reported procedure (Figure S1, Supporting Information) . As shown in Figure a, the aqueous solution of PTCA–gelatin (5 mg mL −1 ) shows no fluorescence in acidic condition (0.1 m HCl).…”

Shape Memory Hydrogels with Simultaneously Switchable Fluorescence Behavior

“…First of all, PTCA was prepared from 3,4,9,10‐perylene tetracarboxylic dianhydride (Figures S1 and S2, Supporting Information), then it was grafted to chitosan following a reported procedure to obtain PTCA modified chitosan (PTCA‐CS) (Figure S3, Supporting Information). The attachment of PTCA onto chitosan chains is confirmed by UV–vis spectra.…”

“…The appearance of the hydrogel under UV irradiation (365 nm) is more prominence, the just prepared hydrogel shows no fluorescence, and a strong cyan fluorescence is observed after it was immersed into alkaline solution, and the pH‐responsive fluorescence of the PAAm/PTCA‐CS hydrogel is fully reversible (Figure S6, Supporting Information). Because PTCA is a typical luminogen, though it is grafted onto chitosan chains with a low grating ratio and introduced into hydrogels, the strong hydrogen bonding and π–π stacking interactions between PTCA groups still make them aggregate together, therefore the fluorescence emission of the just prepared hydrogel is quenched. If the remaining carboxyl groups of PTCA groups are transformed into negatively charged carboxylate ions via NaOH aqueous solution, the hydrogen bonding of carboxyl groups will be destroyed, and the deprotonation of the carboxylic groups will bring electrostatic repulsion between PTCA moieties, which will effectively hinders them from getting together.…”

Design and Synthesis of Fluorescent Nanocelluloses for Sensing and Bioimaging Applications

“…[49] NC film modified with fluorescent dyes has been used to absorb and detect pollutants in wastewater, but most of the dye molecules in high concentration or solid state show undesired aggregation, leading to a quenching effect (ACQ). Inspired by previous studies [81] , Li et al have prepared fluorescent sensing NPs for detecting mercury ions by mixing CNCs and coumarin-based probe molecules (CAM) that are a kind of representative Hg 2 + -responsive molecule. The CNC skeleton can be regarded as a spacer separating CAM and effectively avoiding the ACQ effect caused by CAM agglomeration.…”