Vibrational dynamics as an essential determinant of the thermal stability of zinc zeolitic imidazolate lattices.

Thermal stability and kinetics of zeolitic imidazolate frameworks (ZIFs) are crucial for their applications as energetic materials. Here, the effect of microscopic vibrational dynamics on the thermal stability of ZIFs is demonstrated by using simple tools. Specifically, we explored the thermal kinetics based on Flynn-Wall-Ozawa and Kissinger's methods.

Infrared spectroscopic monitoring of solid-state processes.

Infrared spectroscopy, ubiquitous in contemporary chemical laboratories, is frequently underutilised for just the basic characterisation of products. However, its unique ability to provide rich molecular-level information, its simplicity and flexibility for various applications, and its ability to be combined with a variety of techniques, make it one of the most useful techniques for a deep understanding of the microscopic background of chemical and physical phenomena, especially those of relevance for materials applications. This tutorial review puts a spotlight on IR spectroscopic investigations in materials science by providing a critical insight into the state of the art, covering both fundamental aspects and illustrative examples of its utilisation, as well as current challenges and perspectives focusing on physical and chemical transformations in the solid state.

Mechanochemical Metathesis between AgNO and NaX (X = Cl, Br, I) and AgXNO Double-Salt Formation.

Here we describe real-time, monitoring of mechanochemical solid-state metathesis between silver nitrate and the entire series of sodium halides, on the basis of tandem powder X-ray diffraction and Raman spectroscopy monitoring. The mechanistic monitoring reveals that reactions of AgNO with NaX (X = Cl, Br, I) differ in reaction paths, with only the reaction with NaBr providing the NaNO and AgX products directly. The reaction with NaI revealed the presence of a novel, short-lived intermediate phase, while the reaction with NaCl progressed the slowest through the well-defined AgClNO intermediate double salt.

In-Situ and Real-time Monitoring of Mechanochemical Preparation of Li Mg(NH BH ) and Na Mg(NH BH ) and Their Thermal Dehydrogenation.

For the first time, in situ monitoring of uninterrupted mechanochemical synthesis of two bimetallic amidoboranes, M Mg(NH BH ) (M=Li, Na), by means of Raman spectroscopy, has been applied. This approach allowed real-time observation of key intermediate phases, and a straightforward follow-up of the reaction course. Detailed analysis of time-dependent spectra revealed a two-step mechanism through MNH BH ⋅NH BH adducts as key intermediate phases which further reacted with MgH , giving M Mg(NH BH ) as final products.

Mechanochemical reactions studied by in situ Raman spectroscopy: base catalysis in liquid-assisted grinding.

In situ Raman spectroscopy was employed to study the course of a mechanochemical nucleophilic substitution on a carbonyl group. We describe evidence of base catalysis, akin to catalysis in solution, achieved by liquid-assisted grinding.

18-crown-6-sodium cholate complex: thermochemistry, structure, and stability.

18-Crown-6, one of the most relevant crown ethers, and sodium cholate, a steroidal surfactant classified as a natural bile salt, are components of a novel, synthesized coordination complex: 18-crown-6-sodium cholate (18C6·NaCh). Like crown ethers, bile salts act as building blocks in supramolecular chemistry to design new functionalized materials with a desired structure and properties. In order to obtain thermal behavior of this 1:1 coordination complex, thermogravimetry and differential thermal analysis were used, as well as microscopic observations and differential scanning calorimetry.

Temperature-dependent IR spectroscopic and structural study of 18-crown-6 chelating ligand in the complexation with sodium surfactant salts and potassium picrate.

18-crown-6 ether (18C6) complexes with the following anionic surfactants: sodium n-dodecylsulfate (18C6-NaDS), sodium 4-(1-pentylheptyl)benzenesulfonate (18C6-NaDBS); and potassium picrate (18C6-KP) were synthesized and studied in terms of their thermal and structural properties. Physico-chemical properties of new solid 1:1 coordination complexes were characterized by infrared (IR) spectroscopy, thermogravimetry and differential thermal analysis, differential scanning calorimetry, X-ray diffraction and microscopic observations. The strength of coordination between Na(+) and oxygen atoms of 18C6 ligand does not depend on anionic part of the surfactant, as established by thermodynamical parameters obtained by temperature-dependent IR spectroscopy.

Characterization of intramolecular hydrogen bonds by atomic charges and charge fluxes.

The electronic charge redistribution and the infrared intensities of the two types of intramolecular hydrogen bonds, O-H···O and O-H···π, of o-hydroxy- and o-ethynylphenol, respectively, together with a set of related intermolecular hydrogen bond complexes are described in terms of atomic charges and charge fluxes derived from atomic polar tensors calculated at the B3LYP/cc-pVTZ level of theory. The polarizable continuum model shows that both the atomic charges and charge fluxes are strongly dependent on solvent. It is shown that their values for the OH bond in an intramolecular hydrogen bond are not much different from those for the "free" OH bond, but the changes are toward the values found for an intermolecular hydrogen bond.

Infrared optical constants, molar absorption coefficients, dielectric constants, molar polarisabilities, transition moments and dipole moment derivatives of liquid N,N-dimethylformamide-carbon tetrachloride mixtures.

Mid-infrared spectra of the N,N-dimethylformamide-carbon tetrachloride system by transmission and single- and multiple-reflection ATR technique in the whole composition range (0 View Article and Find Full Text PDF

Infrared optical constants, molar absorption coefficients, dielectric constants, molar polarisabilities, transition moments and dipole moment derivatives of liquid N,N-dimethylacetamide-carbon tetrachloride mixtures.

Mid-infrared spectra of the DMA-carbon tetrachloride system by transmission and single- and multiple-reflection ATR technique in the whole composition range (0 View Article and Find Full Text PDF

A partial proton transfer in hydrogen bond O-H···O in crystals of anhydrous potassium and rubidium complex chloranilates.

Hydrogen bonding and proton transfer in the solid state are studied on the crystals of isostructural anhydrous potassium and rubidium complex chloranilates by variable-temperature single crystal X-ray diffraction, solid state (1)H NMR and IR spectroscopies, and periodic DFT calculations of equilibrium geometries, proton potentials, and NMR chemical shifts. Their crystal structures reveal neutral molecules of chloranilic acid and its dianions connected into a chain by O-H···O hydrogen bond. A strong hydrogen bond with a large-amplitude movement of the proton with NMR shift of 13-17 ppm and a broad continuum in IR spectra between 1000 and 500 cm(-1) were observed.

Hydrogen bonding in 1,1'-Bi-2-naphthol within the polarizable continuum model.

Intra- and intermolecular hydrogen bonding of 1,1'-bi-2-naphthol in a series of solvents and in solid phase has been investigated by means of mid-IR spectroscopy and DFT reaction field calculations. The polarizable continuum model has been used to estimate the relative stability of isomers differing in the positions of the hydroxyl groups. The height of the potential barriers between them was also calculated and the corresponding transition states characterized.