Molecular Engineering for Metal‐Free Amorphous Materials with Room‐Temperature Phosphorescence

Abstract

Materials displaying room‐temperature phosphorescence (RTP) have been attracting wide attention in recent years due to their distinctive characteristics including long emissive lifetime and large Stokes shift, and their various applications. Most synthesized RTP materials are metal complexes that display enhanced intersystem crossing and crystallization is a common way to restrict nonradiative transition. Amorphous metal‐free RTP materials, which do not rely on expensive and toxic metals and can be prepared in a straightforward fashion, have become an important branch of the field. This Minireview summarizes recent progress in amorphous RTP materials according to the approaches used to immobilize phosphors: host–guest interactions, molecule doping, copolymers, and small‐molecule self‐assembly. Some existing challenges and insightful perspectives are given at the end of the Minireview, which should benefit the future design and development of amorphous metal‐free RTP materials.

Purely organic light-harvesting phosphorescence energy transfer by β-cyclodextrin pseudorotaxane for mitochondria targeted imaging

“…40 In recent years, supramolecular complexation and assembly strategies have been used extensively to construct RTP systems. [42][43][44][45] As the main supramolecular macrocyclic molecules, cyclodextrins (CDs) 46 and cucurbiturils (CBs) 47 with hydrophobic cavities can interact with guest molecules through supramolecular interactions, such as electrostatic interactions, hydrogen bonding, hydrophobic effects and so forth. [48][49][50][51] Moreover, the advantages of using macrocyclic molecules to achieve RTP are as follows: (1) stable host-guest complexation can provide a rigid environment for guest molecules, inhibiting non-radiative transitions caused by molecular rotation; (2) hydrophobic cavities can protect phosphorescence from quenching by water or oxygen from the outside.…”

Highly Efficient Room‐Temperature Phosphorescence Based on Single‐Benzene Structure Molecules and Photoactivated Luminescence with Afterglow

“…be reported due to the small spin-orbit coupling (SOC) of organic compounds and the susceptible nature of excited triplet state, which was easily deactivated by thermal vibration or oxygen in the surrounding. [10,11] To restrict the thermal vibration and isolate the oxygen from the phosphor, embedded into a polymer matrix, [10,12,13] included with macrocyclic molecule, [7,14] or crystallization [15] have been reported to be the most popular strategies. Meanwhile, heavy atoms or heteroatoms like Br, I, N, O, or S, were introduced to the phosphor molecular configuration to enhance the intersystem crossing (ISC) process.…”

“…Meanwhile, heavy atoms or heteroatoms like Br, I, N, O, or S, were introduced to the phosphor molecular configuration to enhance the intersystem crossing (ISC) process. [10,12,[16][17][18] Based on the above strategies, RTP crystal materials with high Ф P and various lifetimes have been reported in recent years. [4,19] However, the poor flexibility and pliability limited the application of these materials because of the high crystal structural dependency of the phosphorescence.…”

Construction and Humidity Response of a Room‐Temperature‐Phosphorescent Hybrid Xerogel Based on a Multicharge Supramolecular Assembly

“…[ 11 ] For example, phosphor crystallization or incorporation into inorganic clay can inhibit nonradiative transitions [ 12 ] and enhance phosphorescence emission. [ 13 ] In addition, materials that exhibit RTP can be incorporated into supramolecular composites in which their phosphorescence is enhanced by host–guest interactions. For example, phosphorescent guest molecules can be encapsulated in cyclodextrins to promote phosphorescence emission.…”