Zhi-Gang Yin

Modelling hydrogen bonds in NN-dimethylformamide

N, N-dimethylformamide (DMF) is a ‘universal’ solvent with the simplest amide structure. DMF has different interactions with many polymers and biomolecules. It is therefore necessary to study systematically the interactions in DMF itself first. In this study, both FT-IR and two molecular theoretical methods (MP2 and DFT/B3LYP) were used to study various hydrogen bonding interactions in DMF molecules based on its weak H-bonding donors CH/CH3 and strong H-bonding acceptor C = O. The possible H-bonding donors and acceptors in DMF molecules were first analysed followed by modelling the effect of different structural environments on vC = O bands in infrared spectra. Finally, H-bonding properties including distance, angles and the energy as well as the probability of H-bonding patterns were obtained. The results showed that there exist five possible different weak types of H-bonding dimers; among them, three dimers consist of a pair of weak H-bonds, whereas two other dimers have two pairs of H-bonds, leading to 14 (including eight different) H-bonds. Two types of dimers were dominant, whereas three others can be omitted.

Experimental FTIR and simulation studies on H-bonds of model polyurethane in solutions. I: In dimethylformamide (DMF).

Polyurethane (PU) hard segment is one of the key factors determining the final PU properties whereas dimethylformamide (DMF), with the simplest tertiary amide, is one of the good solvents for PU. In the present paper, both FTIR and molecular simulation (QM/B3LYP) were used to study the hydrogen bonds (H-bonds) of PU model hard segment (PUMHS) in DMF. The FTIR characteristics and the H-bonding interaction between DMF and PUMHS, as well as in DMF and PUMHS themselves have been investigated. The results showed that the H-bonds not only exist in DMF and in PUMHS themselves, but also exist between PUMHS and DMF. Among them, seven H-bonding complexes between DMF and PUMHS were found based on different conformations. The H-bonding properties and the forming probabilities have been obtained and compared. The evolution of H-bonds of PUMHS in DMF with different concentration was qualitatively analyzed.

4-Nitro­aniline: a redetermination

The occurrence of N—H⋯O and C—H⋯O hydrogen bonds in the title compound, C6H6N2O2, results in the formation of two-dimensional sheets parallel to the (101) plane.

Electrochemical Properties and Regioselectivity of Cyclopalladation of Chiral Ferrocenylimines Deriving from (S)-Ferrocenylethylamine

Treatment of a cyclopalladated complex derived from chiral ferrocenylimine (eta(5)-C5H5) Fe(eta(5)-C5H4)-CH(CH3)-N=CH-2-C4H3S, (Sc)-1, with PPh3 produced the heteroannular palladacycle (Sc)-3 in which palladation occurred at the unsubstituted cyclopentadiene ring. While for (eta(5)-C5H5)Fe(eta(5)-C5H4)-CH(CH3)-N=CH-C6H5, (Sc)-4, cyclopalladation took place mainly at the phenyl ring; the heteroannular palladacycle (Sc)-6, as a minor product, was also obtained. Single crystal X-ray analysis, electrochemical, and computational studies have been performed, showing good agreement with experimental results.

Thio-phene-2-carbaldehyde 2,4-dinitro-phenyl-hydrazone.

In the approximately planar molecule of the title compound, C11H8N4O4S, the dihedral angle between the thiophene and benzene rings is 5.73 (10)°. In the crystal structure, bifurcated inter/intramolecular N—H⋯(O,O) hydrogen bonds are present. The intermolecular links lead to inversion dimers containing an R 2 2(12) graph-set motif.

[μ-1,1′-(Butane-1,4-di­yl)di-1H-benz­imidazole-κ2N3:N3′]bis­{[N,N′-bis(car­boxy­meth­yl)ethyl­enediamine-N,N′-di­acetato-κ5O,O′,O′′,N,N′]mercury(II)} methanol disolvate

The binuclear title complex, [Hg2(C10H14N2O8)2(C18H18N4)]·2CH3OH, lies on an inversion center with the unique HgII ion coordinated in a disorted octahedral environment with one Hg—N bond significantly shorter than the other two. In the crystal structure, intermolecular O—H⋯O hydrogen bonds link complex and solvent molecules into a three-dimensional network.

An ortho­rhom­bic polymorph of 1-benzyl-1H-benzimidazole

The title compound, C14H12N2, in contrast to the previously reported monoclinic polymorph [Lei et al. (2009 ▶). Acta Cryst. E65, o2613], crystallizes in the orthorhombic crystal system. The dihedral angle between the imidazole ring system and the phenyl ring is 76.78 (16)°. Weak C—H⋯N and C—H⋯π interactions are observed in the crystal structure.

Diiodido{4-nitro-2-[2-(piperidin-1-yl)ethyl-imino-meth-yl]phenolato}zinc(II).

In the title complex, [ZnI2(C14H19N3O3)], the ZnII atom is four-coordinated by the imine N and phenolate O atoms of the Schiff base ligand, and by two iodide ions in a distorted tetrahedral coordination. In the crystal structure, molecules are linked through intermolecular N—H⋯O hydrogen bonds, forming dimers.

3-(1,3-Benzodioxol-5-yl)-1-phenyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazine

In the title compound, C25H19NO3, the oxazine ring displays a half-chair conformation. The fused benzene ring is nearly parallel to the naphthyl ring system, the dihedral angle between this benzene ring and the naphthyl system being 8.52 (11)°. The imino group is not involved in hydrogen bonding in the crystal structure.

Transition metal/Brønsted acid cooperative catalysis enabled facile synthesis of 8-hydroxyquinolines through one-pot reactions of ortho-aminophenol, aldehydes and alkynes

A convenient and straightforward three-component one-pot strategy has been developed for the synthesis of 8-hydroxyquinoline derivatives. Under the cooperative catalysis of silver(I) triflate and trifluoroacetic acid, ortho-aminophenol reacted with a range of aldehydes and alkynes under mild reactions, affording the corresponding 8-hydroxyquinoline derivatives with good to excellent yields. These transformations exhibited exceptional substrate generality and functional group compatibility.