Persistent room temperature blue phosphorescence from racemic crystals of 1,1-diphenylmethanol derivatives

Effect of π···π Interactions of Donor Rings on Persistent Room-Temperature Phosphorescence in D4–A Conjugates and Data Security Application

“…This observation further suggests that the type of aggregation plays no major role in determining the stabilization of the triplet excited states. Instead, the self-assembly of the molecules with a large number of intramolecular (lp···π) and intermolecular π···π interactions are the determining factors in the enhancement of the phosphorescence lifetimes. ,− Moreover, we conclude that terephthalonitrile-based molecular systems are suitable to harness triplet excitons via face-to-face interaction between the donor phenoxy rings.…”

“…The controlled molecular packing caused by a large number of intermolecular interactions plays an essential role in aggregation. , The aggregation of the molecules with an increased overlap of the π-clouds and a large number of noncovalent interactions can favor PRTP at ambient conditions. − Such intermolecular interactions lead to low Δ E ST and a high rate of ISC, as recently suggested in the literature. ,,, Introduction of H-bonding, C–H···π, N–H···π, C–H···O, and lone pair (lp)···π-cloud interactions in the aggregates complements the π···π interaction. Intra- and/or intermolecular interactions increase the rigidity of the molecular aggregates and stabilize the triplet states, which otherwise are prone to thermal motions like vibrations and rotations. , Therefore, the controlled assembly of the molecules with a large number of noncovalent interactions is a key to harness long persistent luminescence. − However, the molecular design principle that controls the orientation of the donor rings with the overlap of the π-cloud and noncovalent interactions is rare. ,,,, Taking a cue from our previous reports of D 4 –A systems ,, in which the intramolecular interactions between the phenoxy donors have been effectively utilized to harness the triplet state, herein, we report five donor–acceptor (D 4 –A) molecular systems ( TOPh , TOEPh , TOCPh , TOMPh and TOF ) (Figure ) to understand the RTP quantum yield (Φ P ) with the persistent RTP characteristic utilizing intermolecular π···π interactions of the phenoxy donors. The molecules are designed to utilize the controlled arrangement of the substituted donor rings which impose steric and electronic effects to the molecular backbone.…”

“…The molecules are designed to utilize the controlled arrangement of the substituted donor rings which impose steric and electronic effects to the molecular backbone. These molecular systems prefer to pack via intermolecular π···π (face-to-face) − interactions between the donor parts of the molecules, which suppress the nonradiative decay channels and enhance the triplet lifetimes.…”