Aggregate Science: From Structures to Properties

Abstract

Molecular science entails the study of structures and properties of materials at the level of single molecules or small interacting complexes of molecules. Moving beyond single molecules and well‐defined complexes, aggregates (i.e., irregular clusters of many molecules) serve as a particularly useful form of materials that often display modified or wholly new properties compared to their molecular components. Some unique structures and phenomena such as polymorphic aggregates, aggregation‐induced symmetry breaking, and cluster excitons are only identified in aggregates, as a few examples of their exotic features. Here, by virtue of the flourishing research on aggregation‐induced emission, the concept of “aggregate science” is put forward to fill the gaps between molecules and aggregates. Structures and properties on the aggregate scale are also systematically summarized. The structure–property relationships established for aggregates are expected to contribute to new materials and technological development. Ultimately, aggregate science may become an interdisciplinary research field and serves as a general platform for academic research.

Ligand-controlled and nanoconfinement-boosted luminescence employing Pt(ii) and Pd(ii) complexes: from color-tunable aggregation-enhanced dual emitters towards self-referenced oxygen reporters

“…This kind of aggregation-enhanced dual emission is different from the well-documented aggregation induced emission (AIE) concept, where luminescence occurs upon aggregation. 58,59 The corresponding Φ L data is provided in the SI (Table S19). The bathochromic emission shift and the appearance of the long-wavelength absorption tail ( Figure S99a) confirmed the presence of the lowest excited state and ground state with MMLCT character, respectively.…”

Organic supramolecular aggregates based on water‐soluble cyclodextrins and calixarenes

“…AIE of solid‐state fluorescent materials has been extensively investigated, and numerous functional luminescent materials have been developed for diverse applications. [ 66 ] However, because the aggregation states of AIE‐active molecules strongly affect their emission patterns, control of the assembly and morphology of such aggregates is of great importance, and the necessary control has been achieved by incorporation of macrocyclic elements into AIE systems. [ 67 ] For example, in 2014, Tang and coworkers reported an excellent demonstration of the use of host–guest interactions between β‐CD and an AIE molecule (tetraphenylethene) to restrict the intramolecular motion of the latter.…”

Aggregation‐enhanced theranostics: AIE sparkles in biomedical field

“…Aggregate science that spotlights meso territory is captivating increasing research interests nowadays as it builds a significant bridge between the micro‐ and macrofields [1] . Although the concept of aggregate science is newly put forward, the issues about aggregates based on various elements in terms of phenomenon, mechanism, and applications have actually long been studied [2] . As a cutting‐edge scientific research area, aggregation‐induced emission (AIE) is the springboard of aggregate science and serves as a guiding light in the progression of aggregate science.…”