Green and Scalable Preparation of Highly Conductive Alkali Metal-dhta Coordination Polymers

2,5-Dihydroxyterephthalic acid (H₄dhta) is well-known for its use in the construction of functional metal-organic frameworks (MOFs). Among them, simple coordination polymers (CPs), such as lithium and sodium coordination polymers with H₄dhta, have been used successfully to synthesize electrically conductive MOFs and have also demonstrated great potential as positive or negative electrode materials on their own. However, there has been little exploration of the structure and physicochemical properties of these and other alkali complexes of H₄dhta. To address this gap, a series of 1:1 alkali metal-dhta coordination polymers (Li-, Na-, K-, Rb-, Cs-), showing high conductivity with a nonmonotone trend inside the series, were synthesized using green mechanochemical processing. The crystal structures of these metal-organic conductors reveal the rich coordination chemistry of the alkali cations ranging from four to ten. Their electric conductivity was influenced by cation type, coordination environment, the water present in the structure, atmosphere, and temperature. Overall, this study not only sheds light on the fascinating behavior and efficiency of monoalkali metal-dhta CPs and paves the way for the development of more efficient coordination materials for energy storage and conversion applications but also proves that sometimes the smallest changes in materials' structure and composition can make a significant difference in conductivity.