An organocatalytic strategy for the synthesis of tetrasubstituted pyrrolidines with monoactivated azomethine ylides in high enantiomeric excess and excellent exo/endo selectivity is presented. The key to success is the intramolecular activation via hydrogen bonding through an o-hydroxy group, which allows the dipolar cycloaddition to take place in the presence of azomethine ylides bearing only ...

The concept of covalency is widely used to describe the nature of intermolecular bonds, to explain their spectroscopic features and to rationalize their chemical behaviour. Unfortunately, the degree of covalency of an intermolecular bond cannot be directly measured in an experiment. Here we established a simple quantitative relationship between the calculated covalency of hydrogen bonds in liqu...

In the mol-ecule of the title compound, C(16)H(14)O(5), all non-H atoms are approximately co-planar [maximum atomic deviation = 0.064 (5) Å]. The hy-droxy group is a hydrogen-bond donor to a carbonyl O atom. Weak intermolecular C-H⋯O hydrogen bonding is present in the crystal structure. The crystal structure is 'whole-mol-ecule disordered' about an axis that runs approximately along the length ...

The title compound [alternatively called (2-bromo-phen-yl)-(hydr-oxy)acetonitrile], C(8)H(6)BrNO, is the reaction product of 2-bromo-benzaldehyde and hydrogen cyanide. Bond lengths and angles are normal. In the crystal structure, an intermolecular hydrogen bond between the hydr-oxy group and the nitrile N atom is established. In agreement with bonding considerations, a linear C-N⋯H acceptor geo...

Intermolecular hydrogen bond librational modes in cyclic trimers and tetramers of methanol and t-butyl alcohol isolated at low temperature in pulsed supersonic jet expansions are observed by direct absorption spectroscopy in the far-infrared region. The large amplitude librational modes probe the strength and directionality of the intermolecular hydrogen bonds. In addition, their frequency and ...

The interaction of human serum albumin with Ethyl 2-[2-(dimethylamino)-4-(4-nitrophenyl)- 1,3-thiazole-5-yl]-2-oxoacetate was investigated by using isothermal titration UV-visible spectrophotometry in tris-buffer, pH 7.4. According to these results, it was found that there are a set of 4 binding sites for this ligand on HSA with positive cooperativity in the binding process. This thiazole deriv...

In the crystal structure of the title salt, C7H7Cl2N2O2+.Cl-, the chloride anions participate in extensive hydrogen bonding with the aminium cations and indirectly link the molecules through multiple N+-H...Cl- salt bridges. There are two independent molecules in the asymmetric unit, related by a pseudo-inversion center. The direct intermolecular coupling is established by C-H...O, C-H...Cl and...

To study the early time hydrogen-bonding dynamics of chromophore in hydrogen-donating solvents upon photoexcitation, the infrared spectra of the hydrogen-bonded solute-solvent complexes in electronically excited states have been calculated using the time-dependent density functional theory (TDDFT) method. The hydrogen-bonding dynamics in electronically excited states can be widely monitored by ...

Intermolecular chemical networks defined by the hydrogen bonds formed at the α-quartz|water interface have been data-mined using graph theoretical methods so as to identify and quantify structural patterns and dynamic behavior. Using molecular-dynamics simulations data, the hydrogen bond (H-bond) distributions for the water-water and water-silanol H-bond networks have been determined followed b...

Inter- and intra- molecular hydrogen bonding plays important role in determining molecular structure, physical and chemical properties, which may be easily ignored for molecules with a non-typical hydrogen bonding structure. We demonstrated in this paper that the hydrogen bonding is responsible for the different Raman spectra in solid and solution states of p-Nitrothiophenol (PNTP). The consist...