Benzenehexathiol-Based Conjugated Coordination Polymers: A Decade of Breakthroughs in High Conductivity and Quantum Phenomena

ConspectusCoordination polymers (CPs) and metal-organic frameworks (MOFs) are highly valued for applications in gas storage, separation, and catalysis, but their electronic applications have been limited by low electrical conductivity and charge mobility. The rise of conjugated coordination polymers (c-CPs) has changed this scenario entirely. c-CPs utilize planar, conjugated ligands with ortho-donor coordination groups (-OH, -SH, -NH₂, -SeH) to form extended lattices with transition metals, enabling strong d-π conjugation and exceptional charge transport properties.In this Account, we trace our decade-long efforts to develop a distinctive family of c-CPs: those based on the small yet versatile ligand, benzenehexathiol (BHT). We highlight how the small BHT ligand and its soft -SH donors, compared with hexahydroxytriphenylene (HHTP) and hexaaminotriphenylene (HATP) used in conducting CPs and MOFs, promote stronger metal-ligand coupling, enhanced charge delocalization, and richer coordination chemistry, underpinning the high conductivity and structure diversity of BHT-based c-CPs. We detail the innovative synthetic strategies, such as interfacial synthesis and redox modulation, that enable us to obtain a series of high-crystalline, high-conductivity BHT-based c-CPs. This family of materials has consistently broken records, achieving metallic conductivities exceeding 10³ S·cm^-1 and charge mobilities up to 400 cm²·V^-1·s^-1. Notably, they provide a versatile platform for discovering exotic quantum phenomena that are rare in framework materials. Our exploration led to the first CP-based superconductor, Cu₃BHT, and has revealed candidates for topological phases such as Weyl semimetal in Ag₃BHT and Kondo lattice in CuAg₄BHT.We conclude by emphasizing how the structure diversity of BHT-based c-CPs dictates their exceptional chemical and physical properties. This Account is more than a summary. It is a blueprint for the design of the next generation of electrically conducting CPs, illustrating how rational ligand design and synthetic control are able to not only advance electronic material exploration but also open new frontiers in quantum materials research.