Distinguishment of Weak Interactions of Hydrogen Atoms Bound to Carbon Atoms: X-Ray Crystal Structural and Hirshfeld Surface Analyses of 2-Hydroxy-7-methoxy-3-(2,4,6-trimethylbenzoyl)naphthalene with the 2-Methoxylated Homologue

X-ray crystal and Hirshfeld surface analyses of 2-hydroxy-7-methoxy-3-(2,4,6-trimethylbenzoyl)naphthalene and its 2-methoxylated homologue show quantitatively and visually distinct molecular contacts in crystals and minute differences in the weak intermolecular interactions. The title compound has a helical tubular packing, where molecules are piled in a two-folded head-to-tail fashion. The homologue has a tight zigzag molecular string lined up behind each other via nonclassical intermolecular hydrogen bonds between the carbonyl oxygen atom and the hydrogen atom of the naphthalene ring. The dnorm index obtained from the Hirshfeld surface analysis quantitatively demonstrates stronger molecular contacts in the homologue, an ethereal compound, than in the title compound, an alcohol, which is consistent with the higher melting temperature of the former than the latter. Stabilization through the significantly weak intermolecular nonclassical hydrogen bonding interactions in the homologue surpasses the stability imparted by the intramolecular C=O…H–O classical hydrogen bonds in the title compound. The classical hydrogen bond places the six-membered ring in the concave of the title molecule. The hydroxy group opposingly disturbs the molecular aggregation of the title compound, as demonstrated by the distorted H…H interactions covering the molecular surface, owing to the rigid molecular conformation. The position of effective interactions predominate over the strength of the classical/nonclassical hydrogen bonds in the two compounds.

Dual XH–π Interaction of Hexafluoroisopropanol with Arenes

The dual XH (OH and CH) hydrogen-bond-donating property of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and the strong dual XH–π interaction with arenes were firstly disclosed by theoretical studies. Here, the high accuracy post-Hartree–Fock methods, CCSD(T)/CBS, reveal the interaction energy of HFIP/benzene complex (−7.22 kcal/mol) and the contribution of the electronic correlation energy in the total interaction energy. Strong orbital interaction between HFIP and benzene was found by using the DFT method in this work to disclose the dual XH–π intermolecular orbital interaction of HFIP with benzene-forming bonding and antibonding orbitals resulting from the orbital symmetry of HFIP. The density of states and charge decomposition analyses were used to investigate the orbital interactions. Isopropanol (IP), an analogue of HFIP, and chloroform (CHCl3) were studied to compare them with the classical OH–π, and non-classical CH–π interactions. In addition, the influence of the aggregating effect of HFIP, and the numbers of substituted methyl groups in benzene rings were also studied. The interaction energies of HFIP with the selected 24 common organic compounds were calculated to understand the role of HFIP as solvent or additive in organic transformation in a more detailed manner. A single-crystal X-ray diffraction study of hexafluoroisopropyl benzoate further disclosed and confirmed that the CH of HFIP shows the non-classical hydrogen-bond-donating behavior.

FTIR Spectroscopic Studies on the Binary Solutions of 1 – Propanol with Xylene Isomers

FTIR spectroscopic study is performed in 4000 – 400cm−1wavenumber rangeon pure Propanol(PRO), pure o-xylene (OXY), pure m-xylene(MXY), pure p-xylene(PXY) and their binary solutions (SS1 = 0.2 PRO + 0.8 OXY/MXY/PXY, SS2 =0.4+0.6 , SS3 = 0.6 + 0.4 and SS4 = 0.8 + 0.2)at various mole fractions. It was observed that neat propanol liquid appearsto be multimer especially as cyclic tetramer and involve in classical and non-classical hydrogen bond interactions with the three xylene isomers in all the binary solutions.

QTAIM-Based Local Potential Energy Model: Applications and Limitations to Quantify the Binding Energy of Intra/intermolecular Interactions

<p>In previous work, we developed the local potential energy model, LPE, based on the electrostatic force and QTAIM topological data to quantify classical hydrogen bond energies. In this work, we extended the investigation to other inter/intramolecular interactions (non-conventional hydrogen bonds and others). The LPE presented high precision and linearity with supramolecular binding energy, when excluding interactions of an ion with π-bonded groups or polar molecule. The energy decomposition analysis from SAPT-DFT and LMOEDA showed that dispersion and electrostatic components are important to LPE, while polarization component impairs it. The LPE cannot be used for complexes with predominant polarization component. </p>

QTAIM-Based Local Potential Energy Model: Applications and Limitations to Quantify the Binding Energy of Intra/intermolecular Interactions

<p>In previous work, we developed the local potential energy model, LPE, based on the electrostatic force and QTAIM topological data to quantify classical hydrogen bond energies. In this work, we extended the investigation to other inter/intramolecular interactions (non-conventional hydrogen bonds and others). The LPE presented high precision and linearity with supramolecular binding energy, when excluding interactions of an ion with π-bonded groups or polar molecule. The energy decomposition analysis from SAPT-DFT and LMOEDA showed that dispersion and electrostatic components are important to LPE, while polarization component impairs it. The LPE cannot be used for complexes with predominant polarization component. </p>

Crystal structure of bis{(3,5-dimethylpyrazol-1-yl)dihydro[3-(pyridin-2-yl)pyrazol-1-yl]borato}iron(II)

The structure determination of [Fe(C13H15BN5)2] was undertaken as part of a project on the modification of the recently published spin-crossover (SCO) complex [Fe{H2B(pz)(pypz)}2] (pz = pyrazole, pypz = pyridylpyrazole). To this end, a new ligand was synthesized in which two additional methyl groups are present. Its reaction with iron trifluoromethanesulfonate led to a pure sample of the title compound, as proven by X-ray powder diffraction. The asymmetric unit consists of one complex molecule in a general position. The FeII atom is coordinated by two tridentate N-binding {H2B(3,5-(CH3)2-pz)(pypz)}− ligands. The Fe—N bond lengths range between 2.1222 (13) and 2.3255 (15) Å, compatible with FeII in the high-spin state, which was also confirmed by magnetic measurements. Other than a very weak C—H...N non-classical hydrogen bond linking individual molecules into rows extending parallel to [010], there are no remarkable intermolecular interactions.

Crystal structure of atazanavir, C38H52N6O7

The crystal structure of atazanavir has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Atazanavir crystallizes in space group P21 (#4) with a = 15.33545(7), b = 5.90396(3), c = 21.56949(13) Å, β = 96.2923(4)°, V = 1941.134(11) Å3, and Z = 2. Despite being labeled as “atazanavir sulfate”, the commercial reagent sample consisted of atazanavir free base. The structure consists of an array of extended-conformation molecules parallel to the ac-plane. Although the atazanavir molecule contains only four classical hydrogen bond donors, hydrogen bonding is, surprisingly, important to the crystal energy. Both intra- and intermolecular hydrogen bonds are significant. The hydroxyl group forms bifurcated intramolecular hydrogen bonds to a carbonyl oxygen atom and an amide nitrogen. Several amide nitrogens act as donors to the hydroxyl group and carbonyl oxygen atoms. An amide nitrogen acts as a donor to another amide nitrogen. Several methyl, methylene, methyne, and phenyl hydrogens participate in hydrogen bonds to carbonyl oxygens, an amide nitrogen, and the pyridine nitrogen. The powder pattern is included in the Powder Diffraction File™ as entry 00-065-1426.

Synthesis and crystal structure of 7-bromo-3,3-dibutyl-8-methoxy-5-phenyl-2,3-dihydrobenzo[b][1,4]thiazepin-4(5H)-one

7-Bromo-3,3-dibutyl-8-methoxy-5-phenyl-2,3-dihydrobenzo[ b][1,4]thiazepin-4(5 H)-one is prepared from 6-methoxybenzo[ d]thiazol-2-amine and 2-(bromomethyl)-2-butylhexanoic acid as the key starting materials via five simple steps including hydrolysis, substitution, condensation, bromination, and aromatic amidation under microwave conditions. This new route has reduced the reaction time and increased the overall yield to 43%. Moreover, the structure of the target product is also confirmed by X-ray crystal analysis, and further studies indicate that the existence of an intramolecular C–H···C g1 non-classical hydrogen bond is effective in stabilization of the crystal structure.

Structure–property relationship studies of 3-acyl-substituted furans: the serendipitous identification and characterization of a new non-classical hydrogen bond donor moiety

A serendipitous identification and characterization of a new non-classical hydrogen bond donor moiety found in N-acylhydrazones containing 3-acyl-substituted furan subunit is presented.

Heterogenization of manganese porphyrin via hydrogen bond in zeolite imidazolate framework-8 matrix, a host–guest interaction, as catalytic system for olefin epoxidation

A heterogenized meso-tetrakis(2,3-dihydroxyphenyl)porphyrinatomanganese(III) acetate at zeolite imidazolate framework-8 (T(2,3-OHP)PorMn@ZIF-8) is investigated for the catalytic olefin epoxidation reactions at room temperature. Heterogenization is accomplished through a non-classical hydrogen bond proposed between T(2,3-OHP)PorMn bearing O–H groups and C–H of the 2-methylimidazolate linkers in the ZIF-8 structure. The aforementioned compound is characterized by X-ray powder diffraction (XRD), atomic absorption spectroscopy (AAS), nitrogen adsorption−desorption, FT-IR spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The catalytic system with rather high potential of reusability is proposed as a fairly efficient epoxidation catalyst compared to reports in homogeneous media.