Organic two-dimensional nanostructures: Harnessing soft matter for multifunctional applications

[Display omitted] Over the past two decades, two-dimensional (2D) materials have garnered substantial interest because of their distinctive atomic-scale layered structures, which are associated with a variety of applications, ranging from materials science to biomedical processes. However, in the case of inorganic 2D materials, challenges related to large-scale production and the toxicity associated with heavy metals greatly restrict their applications. Hence, the development of organic 2D systems has garnered significant interest, offering immense potential, as an almost infinite range of molecules can be designed and synthesized with predictable functionalities. Thus, developing a range of techniques that provide advanced, customizable synthesis methods for producing intrinsically flexible, lightweight, and easily processable 2D nanomaterials is crucial. In this context, various non-covalent interactions, including hydrogen bonding (H-bonding), π-stacking, electrostatic forces, coordination linkages, and van der Waals forces, play a vital role in stabilizing the overall structure, which can be tuned to manipulate the structure–property relationship. The high surface area and active site exposure of these 2D systems are key to their advancement in applications in materials science, nanodevices, optoelectronics, energy and environmental science, and biomedical fields. This review discusses the development of non-covalently and covalently linked organic 2D nano assemblies, highlighting various synthetic approaches and their potential applications in the current context. Beginning with the increasing dimensionality of small molecular self-assembled nanostructures, the discussion progresses to various interfacial synthetic approaches for creating covalently linked systems with precise control over their dimensionality and crystallinity. Specifically, we presented an overview of supramolecular 2D assemblies of small organic molecules, peptide self-assembly, covalent organic frameworks (COFs), and coordination polymers (CPs), offering insights into potential future research directions.