No abstract

Conductive coordination polymers are hybrid materials with the potential to be implemented in the next generation of electronic devices, owing to several desirable properties. A decade ago, only a few scattered examples exhibiting conductivity existed within this class of materials, yet today groups of coordination polymers possess electrical conductivities and mobilities that rival those of inorganic semiconductors. Many currently emerging energy harvesting and storage technologies are limited by the use of inefficient, unstable, and unsustainable charge transport materials with little tunability. Coordination polymers, on the other hand, offer great electrical properties and fine-tunability through their assembly from molecular building blocks. Herein, the structure–function relationship of these building blocks and how to characterize the resulting materials are examined. Solution processability allows devices to step away drastically from conventional fabrication methods and enables cheap production from earth abundant materials. The ability to tune the electrical and structural properties through modifications at the molecular level during the material synthesis stages allows for a large design space, opening the door to a wide spectrum of applications in environmentally friendly technologies, such as molecular wires, photovoltaics, batteries, and sensors. Sustainable, high-performing charge transport materials are crucial for the continued advance of emerging molecular technologies. This review aims to provide examples of how the promising properties of coordination polymers have been exploited to accelerate the development of molecular devices.

Two coordination complexes have been made by combining the dithiolene complexes [M(mnt)2]2– (mnt = maleonitriledithiolate; M = Ni2+ or Cu2+) as anion, with the copper(II) coordination complex [Cu(Stetra)] (Stetra = 6,6′-bis(4,5-dihydrothiazol-2-yl)-2,2′-bipyri-dine) as cation. The variation of the metal centers leads to a dramatic change in the conductivity of the materials, with the M = Cu2+ variant (Cu–Cu) displaying semiconductor behavior with a conductivity of approximately 2.5 × 10–8 S cm–1, while the M = Ni2+ variant (Ni–Cu) displayed no observable conductivity. Computational studies found Cu–Cu enables a minimization of reorganization energy losses and, as a result, a lower barrier to the charge transfer process, resulting in the reported higher conductivity.