Noncovalent Bridged Bis(Coumarin‐24‐Crown‐8) Phosphorescent Supramolecular Switch

Abstract

A multicolor room temperature phosphorescence (RTP) supramolecular photo‐switch encryption film is constructed by the coassembly of coumarin‐24‐crown‐8 (C24C8), diarylethene dicationic alkylammonium derivative (1), rhodamine B (RhB) and poly(vinyl alcohol) (PVA). Benefiting from the tightly binding of C24C8 and secondary alkylammonium ion, 1 formed noncovalent bridged bis(coumarin‐24‐crown‐8), which displayed photo‐switchable RTP with green afterglow (more than 5 s) after coassembly with PVA. Especially doping with RhB gave a photo‐switchable highly efficient phosphorescence‐harvesting system with multicolor through triplet‐to‐singlet Förster‐resonance energy transfer (TS‐FRET). The energy transfer efficiency and antenna effect of C24C8+RhB@PVA film reached 88.3% and 62.6 when the donor/acceptor ratio is 50:1, respectively. Therefore, diarylethene noncovalent bridged bis(coumarin‐24‐crown‐8) supramolecular assembly not only displays a multicolor photoluminescence‐switch, but also presents a phosphorescent photo‐switch with afterglow, which provides a simple and feasible way to construct smart RTP materials through host‐guest strategy.

Polymer-Based Long-Lived Phosphorescence Materials over a Broad Temperature Based on Coumarin Derivatives as Information Anti-Counterfeiting

“…The main objective of this study was to develop a doping strategy through the judicious selection of polymers to achieve the phosphorescence activation of coumarin derivatives (CMDs), aiming to enrich the molecular design strategies of long-lived polymer-based phosphorescence materials and further broaden the application range of coumarin derivatives. 46 In this work, we developed RTP materials by doping CMDs into polymer matrix, achieving charge-transfer character of transition, the allowed ISC process, and effective switch-on ultralong phosphorescence performance from triplet stabilization (Figure 1). We tuned the substituents on nitrogen and oxygen atoms to study the effects of the number of alkyl substituents on the nitrogen atoms on photophysical properties of the films, the effects of the types of substituents on oxygen atoms on the photophysical properties of the film, and the interaction between the coumarin derivatives and polymer.…”

“…It is expected that these substituted groups can interact with the polymer matrix, thereby promoting the phosphorescence performance of these molecules. The main objective of this study was to develop a doping strategy through the judicious selection of polymers to achieve the phosphorescence activation of coumarin derivatives (CMDs), aiming to enrich the molecular design strategies of long-lived polymer-based phosphorescence materials and further broaden the application range of coumarin derivatives …”

Water/Light Multiregulated Supramolecular Polypseudorotaxane Gel with Switchable Room-Temperature Phosphorescence

“…4−6 The encapsulation of macrocyclic hosts could restrict molecular motion of phosphorescent guests and even promote intersystem crossing (ISC) to enhance RTP emission. 7,8 In addition, the abundant hydrogen bonding interactions and ordered spatial structure of supramolecular assemblies supply a rigid microenvironment, which is able to stabilize the triplet state and inhibit nonradiative transitions to promote RTP. 9,10 For example, Xiao et al constructed a new supramolecular hydrogel using 1,4-diaminobenzene (DB) and hexamethyl cucurbit [5]uril (HmeQ [5]) by the host−guest interaction, and then embedded 6-bromo-2-naphthol (BrNp) exhibited fluorescent−phosphorescence double emissions due to the rigid microstructure.…”

“…Recently, supramolecular systems with room-temperature phosphorescence (RTP) have been considered as more advantageous luminescent materials due to the distinctive properties, such as large Stokes shift and long triplet lifetime. − The macrocyclic confinement effect and the reversibility of supramolecular systems have attracted increasing research efforts to effectively enhance RTP through noncovalent interactions. − The encapsulation of macrocyclic hosts could restrict molecular motion of phosphorescent guests and even promote intersystem crossing (ISC) to enhance RTP emission. , In addition, the abundant hydrogen bonding interactions and ordered spatial structure of supramolecular assemblies supply a rigid microenvironment, which is able to stabilize the triplet state and inhibit nonradiative transitions to promote RTP. , For example, Xiao et al constructed a new supramolecular hydrogel using 1,4-diaminobenzene (DB) and hexamethyl cucurbit[5]­uril (HmeQ[5]) by the host–guest interaction, and then embedded 6-bromo-2-naphthol (BrNp) exhibited fluorescent–phosphorescence double emissions due to the rigid microstructure . Multicolor luminescence, especially multicolor RTP materials, is a hot topic in the field of chemical materials.…”

Red Room-Temperature Phosphorescence Supramolecular Assemblies Based on Cucurbit[7]uril: Reversible Temperature Stimulation Response and Cell-Specific Silver Ion Imaging

“…RTP materials can maintain continuous emission after removing external excitation and have the characteristics of antibackground fluorescence interference. Time-resolved imaging can effectively avoid the generation of biological auto-fluorescence and scattered light, so it has received more and more attention. − However, the phosphorescence of pure organic molecules is quenched in the solution phase, especially in the water phase. This quenching is due to their inefficient spin–orbit coupling, nonradiative relaxation of triplet states, and the presence of molecular oxygen quenchers. − Developing efficient and durable pure organic RTP materials under ambient conditions is still a huge challenge; therefore, people have been committed to developing new methods to achieve efficient RTP, such as by introducing heavy atoms, heteroatoms, and aromatic carbonyl compounds to enhance spin–orbit coupling (SOC) to obtain effective phosphorescence .…”