Boron Cluster Functionalization: From Vertex-Specific Modifications to Boron Cage Extension

Polycyclic molecular systems, which play a crucial role in the fields of materials science and pharmacology, typically consist of 2D extended organic aromatic rings. Extensive research has been conducted on conjugates formed through π-extension, leading to substantial advancements in the field. However, further exploration of novel conjugate systems is essential. This is necessary to enhance structural diversity and facilitate the development of advanced applications. Boron clusters, such as carboranes, are 3D aromatic structures featuring multiple C/B–H bonds. The functionalization of these C/B–H bonds offers a pathway for constructing a diverse array of carborane derivatives. In recent years, the extension of boron cages through the functionalization of boron clusters to generate hybrid polycyclic conjugates has attracted significant attention due to the promising properties and applications of these molecules. This review highlights the progress in boron cage modifications and boron cage extension over the past few years. It focuses on synthetic strategies and structure-property relationships of these hybrid conjugates.