Molecular Motion in the Solid State

Abstract

All matter is in motion, and such behavior has been well studied in the gas and liquid states. However, the study of solid-state molecular motion is still in its infancy, mainly, because of the absence of valid characterization methods. Aggregation-induced emission (AIE) is a cutting-edge fluorescence technology related to aggregate-state luminescence. Thus, it holds great potential to address this issue. AIE luminogens (AIEgens) are often propeller-like in shape and are, therefore, born with molecular mobility. The emission of AIEgens is determined by molecular motion, and thus, the motion in the solid state can be visualized by fluorescence variation. The active molecular motion of AIEgens promotes nonradiative decay of excitons to release heat in the nanoparticles. This makes AIEgens find application in photothermal therapy and photoacoustic imaging. In this Viewpoint, we briefly introduce a newly emerging frontier derived from AIE: molecular motion in the solid state with the hope to stimulate new ideas and inspire new endeavors in this area.

Dual Enhancement of Gold Nanocluster Electrochemiluminescence: Electrocatalytic Excitation and Aggregation‐Induced Emission

“…When we soaked the dried ATT‐AuNC film in acidic buffers, the film can be dissolved. Inspired by the above results, it seems plausible that the aggregation events can also induce AIECL of the ATT‐AuNCs owing to the intimate relevance between ECL and photoluminescence . We reason that the AIE effect to be responsible for the rest enhancement.…”

Aggregate Science: From Structures to Properties

“…However, the studies of dynamic structures are more significant as motion (vibration and rotation) is innate to substances at both microscopic and macroscopic scales. [164][165][166][167] Unfortunately, structural dynamics can prove difficult to elucidate and visualize at the molecular state due to the ultrashort timescales of molecular motion. [168,169] In this regard, aggregation could partially slow down the molecular motion and in some ways simplify the visualization of dynamic aggregate structures.…”

Aggregation‐Induced Emission: New Vistas at the Aggregate Level

“…In particular, we present the new properties that molecular ensembles bring to molecules and highlight the role of molecular aggregates in improving the performance of organic functional materials. The branches of AIE include crystallization‐induced emission (CIE), room‐temperature phosphorescence (RTP), aggregation‐induced delayed fluorescence (AIDF), anti‐Kasha transition (AKT), clusterization‐triggered emission (CTE), through‐space interaction (TSI), mechanoluminescence (ML), circularly polarized luminescence (CPL), aggregation‐induced generation of reactive oxygen species (AIG‐ROS), photothermal/photoacoustic (PT/PA), and solid‐state molecular motion (SSMM) . In addition, some of the latest advancements of AIE research will also be introduced in the Supporting Information.…”