The host–guest inclusion driven by host-stabilized charge transfer for construction of sequentially red-shifted mechanochromic system

Abstract

Developing more extensive methods to understand the underlying structure-property relationship of mechanochromic luminescent molecules is demanding but remains challenging. Herein, the effect of host-guest interaction on the mechanochromic properties of organic molecules is illustrated. A series of pyridinium-functionalized triphenylamine derivatives show bathochromic-shifted emission upon mechanical stimulation. These derivatives bind to cucurbit[8]uril to form homoternary host-guest inclusion complexes through host-stabilized intermolecular charge transfer interactions. Remarkably, the homoternary complexes exhibit longer emission than that of free guests in the solid state (even longer than ground guests), and a further bathochromic-shifted emission is observed upon grinding. Additionally, a heteroternary complex constructed through the encapsulation of pyrene (donor) and pyridinium (acceptor) guest pair in cucurbit[8]uril also displays the mechanochromic luminescent property. This work not only discloses the effect of host-guest inclusion on the mechanochromic property of organic molecules, but also provides a principle and a facile way to design the sequentially red-shifted mechanochromic materials.

Donor-acceptor bulk-heterojunction sensitizer for efficient solid-state infrared-to-visible photon up-conversion

“…In detail, it undergoes a rapid solvent evaporation stage from 0 to 3.4 s, then enters the nucleation stage (3.4-4.5 s), followed by crystal growth (4.5–5.3 s), and finally reaches the dried film stage at 5.3 s. However, in comparison, PYIT1 in the PYIT1:PBQx-TCl:rubrene system exhibits a relatively short crystallization process, including the solvent evaporation stage (0–2.9 s), the nucleation stage (2.9–3.5 s), rapid crystal growth (3.5-3.9 s), and the dried film stage (after 3.9 s), resulting in smaller crystal sizes. Additionally, in the solid state, the absorption peak of PYIT1 shows an obvious blue-shift after introducing rubrene, indicating that the molecular packing order between PYIT1 molecules in the PYIT1:PBQx-TCl system is stronger than that in the PYIT1:PBQx-TCl:rubrene system 52 . For PBQx-TCl, due to its strong solution aggregation effect, it is difficult to investigate its phase transition process by tracing its peak position changes.…”

Revisiting organic charge-transfer cocrystals for wide-range tunable, ambient phosphorescence

“…Our study opens up a plethora of new possibilities for utilizing organic charge-transfer cocrystals in ambient triplet harvesting and designing organic phosphors, extending beyond their well-explored applications in organic electronics and ferroelectrics. 9…”

Grinding-induced supramolecular charge-transfer assemblies with switchable vapochromism toward haloalkane isomers

“…In supramolecular chemistry, macrocyclic receptors have been the primary tools for molecular recognition and assembly by right of their inherent cavity features and multiple noncovalent binding sites 23 – 32 . Taking advantage of the synergy from host−guest complexation, CT properties in macrocycles-based D−A assemblies could be robust and highly exploitable 33 – 54 . Pillararenes, as a relatively young generation of representative macrocyclic hosts, have promoted a phenomenal research field in modern supramolecular chemistry over the past decade and are also considered the ideal molecular entities in constructing organic CT co-crystals by virtue of their remarkable host–guest properties, highly symmetric molecular structure, facile functionalization, and good crystallization and solubility in commonly used organic solvents 43 – 52 .…”