Hydrogen‐Bonding‐Assisted Intermolecular Charge Transfer: A New Strategy to Design Single‐Component White‐Light‐Emitting Materials

Abstract

This study reveals the mechanism of the dual-emission properties for asymmetrical diphenylsulfone and diphenylketone derivatives. A series of asymmetrical diphenylketone and diphenylsulfone derivatives with dualemission properties are designed and synthesized. By single crystal structure analyses, various photophysical studies, and 2D 1 H-1 H NOSEY NMR studies, the lower energy emission bands in the dual-emission spectra are successfully assigned to hydrogen-bonding-assisted intermolecular charge transfer emission. The emission properties of these compounds can easily be tuned in both solid state and solution state by destroying or strengthening the intermolecular hydrogen bonding. In addition, thermally activated delayed fluorescence characteristics for the intermolecular charge transfer emissions are also observed. The control of the intermolecular and intramolecular charge transfers serves as the basis for the generation of the white-light emission. For compound CPzPO, nearly pure white-light emission with CIE coordinates of (0.31, 0.32) is easily achieved by precipitation from dichloromethane and hexane mixed solvent system. These results clearly give an insight into the dual-emission properties and provide a rational strategy for the design and synthesis of single-component white-light-emitting materials and mechanoresponsive light-emitting materials.

Achieving Dual‐Emissive and Time‐Dependent Evolutive Organic Afterglow by Bridging Molecules with Weak Intermolecular Hydrogen Bonding

“…As mentioned previously, the structured emission band (at ≈476 nm) of SOBF‐OMe might be due to intermolecular charge transfer. The dual‐emissive mechanism has been well established in our previous work with similar molecular structures . To confirm the origin of the emission band at ≈476 nm, concentration‐dependent emission studies of SOBF‐OMe were carried out in toluene solutions (Figure S11, Supporting Information).…”

“…In recent years, afterglow emission has been successfully promoted by the formation of organic frameworks through intermolecular hydrogen bonding . With the assistance of intermolecular hydrogen bonding, our group has breached Kasha's rule and realized single‐component dual‐emissive properties . Therefore, the dual‐emissive afterglow is quite possible to accomplish by adding weak intermolecular hydrogen bonds to traditional pRTP materials.…”

Molecular Engineering Approaches Towards All‐Organic White Light Emitting Materials

“…The fluoride‐substituted compound was found to be a solid‐state white light emitter with an exceptionally high quantum efficiency of 67 % . Aldred and co‐workers developed a phosphine oxide and phenothiazine containing asymmetrical diphenylketone (CPzPO)‐based white light emitter (Figure g) . Dual emission bands were obtained by controlling the intra‐ and intermolecular charge transfer.…”

“…On the other hand, the lower energy emission band (568 nm) originated owing to the intermolecular charge transfer from the phenothiazine moiety of one molecule to the ketone moiety of the adjacent molecule in the aggregated state. Therefore, a multicolor emission including white light was obtained through tuning the intermolecular charge transfer upon aggregation in the form of nanoparticles …”

Intramolecular Charge Transfer Controls Switching Between Room Temperature Phosphorescence and Thermally Activated Delayed Fluorescence

“…The spectra had the profile and dynamic behavior of a CT band undergoing a transient Stokes shift . Since dual emission is very common in the PICT model, α‐OP emits blue at ≈450 nm and yellow at ≈540 nm, which provides a design for white light emission from a single organic molecule . The white emission from OPM crystals (Figure S2) demonstrates this application of the PICT model.…”