Nature of the N‐Substituted Alkyl Chain Influencing Emission Properties of Naphthalene Diimide (NDI) Via Excimer, and Exciplex Formation

Tuning Optical Properties of Organic Thin Films through Intermolecular Interactions - Fundamentals, Advances and Strategies

In applications ranging from photon-energy conversion into electrical or chemical forms (such as photovoltaics or photocatalysis) to numerous sensor technologies based on organic solids, the role of supramolecular structures and chromophore interactions is crucial. This review comprehensively examines the critical intermolecular interactions between organic dyes and their impact on optical properties. We explore the range of changes in absorption or emission properties observed in molecular aggregates compared to single molecules. Each effect is dissected to reveal its physicochemical foundations, relevance to different application domains, and documented examples from the literature that illustrate the potential modulation of absorption or emission properties by molecular and supramolecular structural adjustments. This work aims to serve as a concise guide for exploiting supramolecular phenomena in the innovation of novel optical and optoelectronic organic materials, with emphasis on strategic application and exploitation.

Aggregation-Induced Emission of Naphthalene Diimides: Effect of Chain Length on Liquid and Solid-Phase Emissive Properties

The aggregation-induced emission (AIE) properties of a systematic series of naphthalene diimides (NDIs) varying the chain length at the imide positions have been studied. A solvophobic collapse of NDI units through the flash injection of THF NDI solutions in sonicating water triggers the formation of stable suspensions with enhanced fluorescence emissions. Shorter chains favor the π-π stacking of NDI units through H-aggregation producing a strong AIE effect showing remarkably high quantum yields that have not been observed for non core-substitued NDIs previously. On the other hand, NDIs functionalized with longer chains lead to more disordered domains where π-π stacking between NDI units is mainly given by J-aggregation unfavoring the AIE effect.