A New Dimension for Coordination Polymers and Metal–Organic Frameworks: Towards Functional Glasses and Liquids

Abstract

There are two categories of coordination polymers (CPs): inorganic CPs (i‐CPs) and organic ligand bridged CPs (o‐CPs). Based on the successful crystal engineering of CPs, we here propose noncrystalline states and functionalities as a new research direction for CPs. Control over the liquid or glassy states in materials is essential to obtain specific properties and functions. Several studies suggest the feasibility of obtaining liquid/glassy states in o‐CPs by design principles. The combination of metal ions and organic bridging ligands, together with the liquid/glass phase transformation, offer the possibility to transform o‐CPs into ionic liquids and other ionic soft materials. Synchrotron measurements and computational approaches contribute to elucidating the structures and dynamics of the liquid/glassy states of o‐CPs. This offers the opportunity to tune the porosity, conductivity, transparency, and other material properties. The unique energy landscape of liquid/glass o‐CPs offers opportunities for properties and functions that are complementary to those of the crystalline state.

Coordination polymer glass from a protic ionic liquid: proton conductivity and mechanical properties as an electrolyte

“…7 More recently, CP/MOFs in liquid and glassy states have received attention as moldable amorphous materials. [8][9][10][11][12][13] The phase transitions of CP/MOFs from crystals to liquids and glasses provide the option of use as a grain boundary-free monolith, which is a promising property for solid electrolytes. 8 In spite of their potential, there are still a limited number of reports on proton-conductive CP/MOFs glass, and there are no reports of CP/MOFs to satisfy the criteria for sufficient proton conductivity (above 10 mS cm À1 ) under anhydrous conditions.…”

Crystal structure of a novel one-dimensional zigzag chain-like cobalt(II) coordination polymer constructed from 4,4′-bipyridine and 2-hydroxybenzoate ligands

“…The design and construction of new coordination polymers (CPs) is of current interest and attracts researchers in the fields of modern structural chemistry and materials science because of their potential applications in areas such as ionexchange, catalysis, sensors, magnetism, and non-linear optics (Dzhardimalieva & Uflyand, 2017;Loukopoulos & Kostakis, 2018;Horike et al, 2020). It is well known that the construction of CPs depends on a variety of factors such as the nature of metal ions and the organic ligands, the molar ratio of the reactants, and the reaction conditions e.g.…”

“…This is because 4,4 0 -bpy is a rigid molecule that can link the metal centers to form a network with well-defined structures and also support the stability of the structures through aromaticand C-HÁ Á Á interactions (Kaes et al, 2000). Furthermore, many researchers incorporate carboxylatebased ligands for the construction of CPs, giving rise to frameworks with a variety of dimensions and topologies (Gu et al, 2019;Horike et al, 2020). Benzoate and its derivatives have been widely used to construct the CPs because of the variety of their coordination modes, resulting in a variety of coordination geometries for the metal centers and interesting properties and applications of their CPs (Tong et al, 2000;Busskamp et al, 2007;Zhang et al, 2007;Song et al, 2009).…”

Thermal Reactivity in Metal Organic Materials (MOMs): From Single-Crystal-to-Single-Crystal Reactions and Beyond

“…However, it is important to note also that certain reactions in MOFs can proceed through melting and formation of glass at high temperatures. Although the importance in the development of MOFs as glasses is increasing, such processes will not be discussed in this article and the reader can find excellent examples in the recent literature [60,61].…”