Visualization and Manipulation of Molecular Motion in the Solid State through Photoinduced Clusteroluminescence

Abstract

The development of molecular machines has long been a dream of scientists and is expected to revolutionize many aspects of technology and medicine. As the prerequisite of a practicable molecular machine, studies on the solid-state molecular motion (SSMM) are not only of scientific importance but also practically useful. Herein, two nonconjugated molecules, 1,2-diphenylethane (s-DPE) and 1,2-bis­(2,4,5-trimethylphenyl)­ethane (s-DPE-TM), are synthesized, and their SSMM is investigated. Experimental and calculation results reveal that s-DPE and s-DPE-TM are capable of performing light-driven SSMM to form excited-state through-space complexes (ESTSC). The radiative decay of ESTSC generates an unexpected visible emission termed clusteroluminescence, which serves as a tool to visualize the process of SSMM. Meanwhile, the original packing structure can be recovered from ESTSC after the removal of light irradiation. This work provides a new strategy to manipulate and “see” the SSMM and gains new insights into clusteroluminescence.

Aggregate Science: From Structures to Properties

“…[168,169] In this regard, aggregation could partially slow down the molecular motion and in some ways simplify the visualization of dynamic aggregate structures. [170] Recently, Tang et al investigated the solid-state molecular motion of TPE crystals employing X-ray crystallographic analysis. [171] Previously, it had been assumed that such motions as twisting, stretching, torsion, wagging, and rocking of AIEgens in solution causing nonradiative decay would effectively be shut off or dramatically attenuated in the solid state.…”

Structural and process controls of AIEgens for NIR-II theranostics

“…58,59 On the other hand, AIE features outstanding solid-state photoluminescence. 44,60 These AIEgens naturally own twisted architectures dressed up with several molecular motors, which are valuable for suppressing the robust intermolecular interactions. In general, visible lightemissive AIEgens are relatively easy to achieve through the incorporation of twisted molecular motors.…”

Thermally Activated Delayed Fluorescence: Beyond the Single Molecule

“…The basis of the AIE field is to understand the interaction between the molecules in these systems and establish the causes of enhancements or reductions in emission, shifts in emission color, mechanochromism or thermochromism. Recent publications and reviews in the area include (Hong et al, 2009;Mei et al, 2014;Furue et al, 2016;Gan et al, 2016;Sturala et al, 2017;Zhang et al, 2017Zhang et al, , 2019bZhang et al, , 2020Liu et al, 2018a;Yu et al, 2020), which demonstrate that phenyl rings should not be considered as entirely inert spacer units in the design of organic emitters and that the aggregation effects can be controlled through photoexcitation. These results have farreaching implications for molecular design of organic emitters as researchers now need to take care in their choice of moieties during synthesis.…”