Compared with other molecular liquids, water is highly structured because of its ability to form up to four hydrogen bonds, resulting in a tetrahedral network of molecules. However, this underlying intermolecular structure is constantly in motion, exhibiting large fluctuations and reorganizations on time scales from femtoseconds to picoseconds. These motions allow water to play a key role in a ...

We study a series of intermolecular hydrogen-bonded 1 : 1 complexes formed by chloroacetic acid with 19 substituted pyridines and one aliphatic amine dissolved in CD2Cl2 at low temperature by 1H and 13C NMR and FTIR spectroscopy. The hydrogen bond geometries in these complexes vary from molecular (O-HN) to zwitterionic (O-H-N+) ones, while NMR spectra show the formation of short strong hydrogen...

The physical origins of vibrational frequency shifts have been extensively studied in order to understand noncovalent intermolecular interactions in the condensed phase. In the case of carbonyls, vibrational solvatochromism, MD simulations, and vibrational Stark spectroscopy suggest that the frequency shifts observed in simple solvents arise predominately from the environment's electric field d...

The intermolecular bonding between molecules containing urea moieties is of interest due to the possible bidentate nature of the hydrogen bond. Experimentally, the nature of the hydrogen bond can be determined from the infra-red spectrum of thematerial. TheC=Ostretching frequency shows substantial shifts due to the additional constraints of the hydrogen bonding. To ascertain the capability of q...

interesting results because of the regular arrangement of the molecules in the environment.1–3 We previously reported on the photocycloaddition reaction of 4-methoxy-6-methyl-2-pyrone (1a) (Fig. 1) with maleimide (2) in the solid state to give a highly stereoselective [2 + 2] cycloadduct4 owing to the formation of two sets of 1:1 complex crystals between (1a) and (2) (Fig. 1).5 The crystal show...

The hydrophobic e ect of small apolar solutes is studied by molecular dynamic (MD) simulations. Interactions between two solutes can be described by the potential of mean force (PMF). The general feature of the PMF between two solutes in water is a potential barrier separating a stable contact con guration and a meta-stable solventseparated con guration. Interestingly, compared with classical M...

Highly accurate and precise crystal structures of methyl R-D-arabinofuranoside, methyl â-D-ribofuranoside, methyl R-D-lyxofuranoside, and methyl R-D-xylofuranoside have been determined at 100 K by X-ray crystallography. The structures of methyl R-D-arabinofuranoside and methyl â-D-ribofuranoside have also been determined at 15 K by neutron diffraction. Equilibrium (re) geometries of the same co...