O-type Hydrogen Bonds Research Articles

Exploring the non-covalent interactions, vibrational and electronic properties of 2-methyl-4-hydro-1,3,4-triazol-thione-5 in different solutions

In this study, the optimal geometry and vibrational assignments of 2-methyl-4-hydro-1,3,4-triazol-thione-5, one of the triazole derivatives, were analysed by the DFT approach and vibrational spectroscopy. PED values were calculated, and vibrational assignments were determined. Experimental results showed that interactions between 2-methyl-4-hydro-1,3,4-triazol-thione-5 and solvent (acetone, acetonitrile, dioxane, and DMF) molecules lead to a red shift of the N-H stretching vibrational band. The computations were performed at the B3LYP/6-311++G(d,p) functional set. The molecular electrostatic potential surface was used to distinguish between electrophilic and nucleophilic regions. The reactivity of the molecular complexes was determined by examining their frontier molecular orbitals. Topological investigations revealed the existence of N-H…N and N-H…O-type hydrogen bonds between 2-methyl-4-hydro-1,3,4-triazole-thiol-5 and solvent molecules. The red-shift of the N-H stretching band and H-bond strength between solute–solvent molecules are in the order of acetonitrile, acetone, dioxane, and DMF.

Hydrogen-bonded and π-stacked nickel(II) thiosemicarbazone complexes: Synthesis, spectral and structural studies

Mixed ligand Ni(II) complexes were synthesized from triphenylphosphine and S-methyl- or S-ethyl-isothiosemicarbazone ligands derived from 3-bromo-5-chloro-2-hydroxy-benzaldehyde. The complexes were characterized by physicochemical and spectroscopic methods. In addition, their molecular structures were determined by single-crystal X-ray diffraction. In both complexes, the Ni atom has a near square-planar geometry, being coordinated by the phenolato oxygen, azomethine nitrogen and amine nitrogen atoms of the thiosemicarbazone ligands, together with the phosphorus atom of the triphenylphosphine. The S-methyl complex includes an additional free thiosemicarbazone ligand in the asymmetric unit. X-ray analysis shows that O–H···N, N–H···N, C–H···N and C–H···O-type hydrogen bonds and π–π stacking interactions are responsible for stabilizing the crystal structures.

Adsorption of Chlorinated Methane Derivatives at the Ice Surface: A Grand Canonical Monte Carlo Simulation Study

The adsorption behavior of three chlorinated methane derivative molecules, CH3Cl, CHCl3, and CCl4, is investigated at the (0001) surface of Ih ice at the tropospheric temperature of 200 K by means of grand canonical Monte Carlo simulations. This study completes our earlier investigations concerning the adsorption of CH4, CH2Cl2, and fluorinated methane derivatives. Our results show that neither CHCl3 nor CCl4 exhibits any adsorption. This complete lack of adsorption is attributed to the interplay of the very strong cohesion acting between the adsorbate molecules, and their relatively weak interaction with the ice phase. By contrast, CH3Cl does exhibit a noticeable adsorption on ice, and the adsorbed molecules prefer to turn toward the ice surface by their H atoms, forming weak, C–H····O-type hydrogen bonds with surface waters. The lateral (i.e., adsorbate–adsorbate) contribution to the total interaction energy of the adsorbed molecules is always considerably larger (in magnitude) than in the case of the c...

N-(4-Acetyl-3-methyl-1-phenyl-1H-pyrazol-5-yl)-N-methyl-2-(2-methyl-4-oxo-3,4-dihydroquinazolin-3-yl)benzamide.

In the title compound, C29H25N5O3, the dihedral angle between the benzene ring and the pendant quinazoline ring system (r.m.s. deviation = 0.036Å) is 87.60 (17)°. The equivalent angle between the pyrazole ring and the phenyl group is 70.0 (2)°. The dihedral angle between the benzene and pyrazole rings is 30.7 (2)° and overall, the mol­ecular conformation approximates to a Z shape. A short intra­molecular C—H⋯O contact occurs. In the crystal, the mol­ecules are linked by Cπ—H⋯O-type hydrogen bonds and aromatic π–π stacking inter­actions [centroid–centroid distance = 3.860 (3) Å], generating a three-dimensional network.

Intermolecular CH⋯O hydrogen bonds in formyl-substituted diphenylhexatriene, a [2+2] photoreactive organic solid: Crystal structure and IR, NMR spectroscopic evidence

(E,E,E)-1,6-di(4-formylphenyl)-1,3,5-hexatriene (1) undergoes [2 + 2] photocycloaddition in the solid state, while the unsubstituted parent, (E,E,E)-1,6-diphenyl-1,3,5-hexatriene (DPH), is photochemically inert as we reported previously. Although the steering effect of the formyl group for the photoreaction is very clear, the crystal structure of 1 had been unknown. In this study, single crystals of 1 suitable for X-ray diffraction (XRD) analysis were prepared and the crystal structure was investigated. The molecules in crystal are linked through intermolecular CH⋯O-type hydrogen bonds involving formyl groups to form a 3D structure of π-stacked crystal packing arrangement with intermolecular distance of 3.926 Å (=b), less than the Schmidt’s criteria of 4.2 Å for the [2 + 2] photoreaction. The existence of CH⋯O hydrogen bonds is evidenced by FT-IR, 1H and 13C NMR spectroscopic measurements. For the IR peak assignments, ab initio and DFT calculations were performed. The solid-state 1H and 13C NMR spectra were measured using the CRAMPS and CP/MAS techniques, respectively. Owing to the small CH⋯O angular dependence of the interaction energy (directionality), the CH⋯O hydrogen bonds are formed in a multiple manner. Thus, although being rather weak, these hydrogen bonds play a decisive role in constructing the [2 + 2] photoreactive crystal structure, without any other stronger intermolecular interactions coexisting.

Fluorescence Spectroscopic Properties of Nitro-Substituted Diphenylpolyenes: Effects of Intramolecular Planarization and Intermolecular Interactions in Crystals

The steady-state absorption and fluorescence properties of (E,E,E)-1,6-diaryl-1,3,5-hexatrienes (2, aryl = 2-nitrophenyl; 3, aryl = 3-nitrophenyl; 4, aryl = 4-nitrophenyl) have been investigated in solution and in the crystalline state. The solid-state absorption spectra of 2-4 shifted to longer wavelengths than those in solution. A combination of theoretical calculations and single-crystal X-ray structure analyses shows considerable planarization of molecules in the solid state, which is mainly responsible for the spectral red shifts. The effects of intermolecular interactions on the absorption spectra appeared to be relatively small in these crystals. This is consistent with the monomeric origin of the solid-state emission. Molecule 2 was nonfluorescent in all solvents studied, probably due to the efficient nonradiative deactivation from ionic species produced by excited-state intramolecular proton transfer (ESIPT) along the C-H...O-type hydrogen bonds. The fluorescence of 3, observed only in medium polar solvents, originated from an intramolecular charge transfer (ICT*) state, while that of 4 derived from locally excited (LE*) and/or ICT* states depending on the solvent polarity. All three molecules exhibited LE* fluorescence in the solid state. No observation of ICT* emission in crystals strongly suggests the twisted geometries for ICT* (TICT) of 3 and 4 in solution. The measurable fluorescence from crystal 2 can be attributed to the restricted torsional motions in the solid excited state.

Dimethyl 1-(3-chloro-4-methylphenyl)pyrazole-3,4-dicarboxylate

The dihedral angle between the phenyl and pyrazole moieties of the title compound, C14H13ClN2O4, is 8.66 (8)°. In the solid state, the symmetry-related mol­ecules are linked by intermolecular C—H⋯O-type hydrogen bonds to form a continuous chain, which runs parallel to the c axis.

Racemic dipeptide glycyl-DL-leucine at 120 K.

The structure of glycyl-DL-leucine, C(8)H(16)N(2)O(3), has been determined at 120 K by single-crystal X-ray diffraction. In addition to three N-H.O-type hydrogen bonds of the positively charged RNH(3)(+) group of the zwitterionic molecule, an intermolecular N-H. O contact exists between the peptide bond and the carboxylate group. Four hydrogen-bond cycles were identified, giving a complex pattern.

Topography of the 1:1 α-cyclodextrin–nitromethane inclusion complex

Dissolution of α-cyclodextrin (α-CD) in 9:1 water–nitromethane smoothly generates the title compound, which crystallizes as the pentahydrate in the orthorhombic space group P2 12 12 1 with a=9.452(4), b=14.299(3), c=37.380(10) Å, and Z=4. Its crystal structure analysis revealed the α-CD macrocycle in an unstrained conformation stabilized through a ring of O-2⋯O-3′ hydrogen bonds between five of the six adjacent glucose residues. The nitromethane is located in the α-CD cavity in an orientation parallel to the plane of the macrocycle, and assumes two sites of equal population with the nitro group in excessive thermal motion; the guest is held by van der Waals contacts and C-H⋯O-type hydrogen bonds to the pyranose H-3 and H-5 protons. The packing of the macrocycles in the crystal lattice is of cage herringbone-type with an extensive intra- and intermolecular hydrogen bonding network. The ready formation of a nitromethane inclusion complex in aqueous nitromethane, and the subtleties of its molecular structure amply demonstrate the ease with which water is expelled from the α-CD cavity by a more hydrophobic co-solvent.

5,6,8-Trichloro-4-phenyl-3,4-dihydroquinolin-2(1H)-one

In the quinolone ring system of the title compound, C15H10Cl3NO, the pyridone moiety assumes a slightly twisted boat conformation. The plane of the benzene ring is twisted at an angle of 11.9 (1)° to the pyridone ring, indicating the slight non-planarity of the system. The molecules are stabilized by N—H⋯O-type hydrogen bonds in addition to van der Waals interactions.

Bis(propane-1,3-diammonium) Diphosphate Tetrahydrate

A new organic diphosphate compound, 2C3H12N22+.P2O74−.4H2O, has a non-acidic anion and a mineral-like layered structure similar to the monophosphate, which has an acidic anion. Layers are formed through hydrogen bonding between the water molecules and cohesion between the layers is the result of a hydrogen-bonding network involving NH3 groups and three aggregated water molecules. The XXX from OW—H⋯O-type hydrogen bonds are somewhat stonger than the N—H⋯O type.

2-(3,4-Methylenedioxyphenyl)-1-(phenylsulfonyl)vinyl]-3-(phenylthio)indole

The dioxole ring of the title compound, C 29 H 21 NO 4 S 2 , is inclined at an angle of 67.9 (2) o to the indole ring system. The phenyl rings of the phenylsulfonyl and phenylthio substituents are almost perpendicular to each other [73.3 (2) o ], while the phenylthio and the phenyl ring of the methylenedioxyphenyl ring system are almost parallel to each other [8.2 (2) o ]. The indole ring system is slightly folded along the central C-C bond (2.1 o ). All the rings are quite planar. The molecules are linked by N-H...O-type hydrogen bonds