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Hydrogen-bonded organic frameworks (HOFs) are a promising class of porous crystalline materials for gas sorption and gas separation technologies that can be constructed under mild synthetic conditions. In forming three-dimensional networks of flexible hydrogen bonds between donor/acceptor subunits, these materials have displayed high stability at elevated temperature and under vacuum. Although the structural properties of HOFs are commonly characterized by diffraction techniques, new complimentary methods to elucidate phase behaviour and host-guest interactions at the molecular level are sought, particularly those that can be applied under changing physical conditions or solvent environment. To this end, this study has applied synchrotron far-IR and mid-IR spectroscopy to probe the properties of two known and one new HOF system assembled from tetrahedral amidinium and carboxylate building blocks. All three frameworks produce feature-rich and resolved infrared profiles from 30 to 4000 cm

As hydrogen bonded frameworks are held together by relatively weak interactions, they often form several different frameworks under slightly different synthesis conditions and respond dynamically to stimuli such as heat and vacuum. However, these dynamic restructuring processes are often poorly understood. In this work, three isoreticular hydrogen bonded organic frameworks assembled through charge-assisted amidinium⋅⋅⋅carboxylate hydrogen bonds (1

The melting behaviour of metal-organic frameworks (MOFs) has aroused significant research interest in the areas of materials science, condensed matter physics and chemical engineering. This work first introduces a novel method to fabricate a bimetallic MOF glass, through melt-quenching of the cobalt-based zeolitic imidazolate framework (ZIF) [ZIF-62(Co)] with an adsorbed ferric coordination complex. The high-temperature chemically reactive ZIF-62(Co) liquid facilitates the formation of coordinative bonds between Fe and imidazolate ligands, incorporating Fe nodes into the framework after quenching. The resultant Co-Fe bimetallic MOF glass therefore shows a significantly enhanced oxygen evolution reaction performance. The novel bimetallic MOF glass, when combined with the facile and scalable mechanochemical synthesis technique for both discrete powders and surface coatings on flexible substrates, enables significant opportunities for catalytic device assembly.

A combined Fourier transform infrared (FTIR) spectra of ferrocene (Fc) and density functional theory (DFT) based quantum mechanical calculations confirmed the dominance of the eclipsed Fc conformer in the fingerprint region of 400–500 cm−1 in solutions. Solution IR spectra of Fc measured in acetonitrile (ACN, e = 35.69), dichloromethane (DCM, e = 8.93), tetrahydrofuran (THF, e = 7.43) and dioxane (DOX, e = 2.21) show two well-defined bands in the 480-500 cm−1 region with the higher-wavenumber band higher in intensity. The band profile agrees well with the earlier IR spectra of Lippincott and Nelson (1958) in tetrachloromethane solution as well as more recent measurement in dichloromethane solution of Duhovic and Diaconescu (2013). DFT based quantum mechanical calculations predict that the eclipsed (D5h) Fc conformer is lower in energy than the staggered (D5d) conformer and that the room-temperature solution spectrum of Fc is dominated by that of the D5h form (Best et al., 2016). The present study confirms that solvent effects enhanced the dominance of the D5h Fc conformer which resulted in switch of the IR profile patterns in 400–500 cm−1, from low-wavenumber band higher in intensity pattern in gas phase to higher-wavenumber band higher in intensity in solutions. It further suggests that the effects of solvents on the IR spectra of Fc in this region are small and the solvent model effects are also small for the IR spectrum in the region of 400–500 cm−1 of Fc.