Triptycene‐Based Organic Nanosheet Assemblies via Reversible Boronic Ester Formation: Alkyl Chain Length‐Dependent Formation and Aggregation

A bottom‐up strategy for the preparation of triptycene‐based organic nanosheet assemblies through reversible boronic ester formation is presented. The triptycene scaffold enables the orthogonal placement of alkyl substituents and boronic ester‐forming sites, providing a molecular platform to examine how peripheral alkyl chains influence nanosheet formation and aggregation. Time‐dependent microscopy observations revealed alkyl‐chain‐length‐dependent assembly behavior. Hexyl‐substituted precursors afforded sheet‐like domains at an earlier stage, whereas methyl‐ and ethyl‐substituted analogs showed slower formation of less‐defined nanosheet‐like morphologies. These results indicate that longer alkyl chains are associated with earlier formation of sheet‐like domains and stronger aggregation; however, this alkyl‐chain effect is described as an empirical trend rather than a definitively established mechanism. Infrared spectroscopy supported boronic ester formation, and single‐crystal structures of partial molecular analogs confirmed the orthogonal arrangement of the alkyl substituents relative to the framework‐forming units. Absorption measurements showed a slight red‐shift for the nanosheet assemblies relative to the corresponding reference compounds, consistent with modest extension of electronic communication within the boronic ester‐linked framework. This study provides a case study showing that peripheral alkyl substituents can influence the formation and aggregation behavior of triptycene‐based organic nanosheet assemblies, offering useful insight into the development of dispersible 2D organic materials.