We present two-dimensional (2D) infrared (IR) spectra of isotope diluted ice in its low density amorphous form. Amorphous ice, which is structurally more similar to liquid water than to crystalline ice, provides higher resolution spectra of the hydrogen bond potentials because all motion is frozen. In the case of OD vibration of HOD in H2O, diagonal and off-diagonal (intermode) anharmonicity as...

The structural unit of the title compound, [K(C(6)H(3)N(2)O(4))(C(6)H(4)N(2)O(4))(H(2)O)(2)](n), consists of one potassium cation, one hydrogen pyrazine-2,3-dicarboxyl-ate anion, one pyrazine-2,3-dicarboxylic acid mol-ecule and two water mol-ecules; this is twice the asymmetric unit, since the potassium cation lies on an inversion centre. Each anion or acid mol-ecule is linked to two potassium ...

The asymmetric unit of the title salt, C17H17F6N2O+·C8H7O3-·0.5H2O, comprises a pair of pseudo-enanti-omeric (i.e. related by a non-crystallographic centre of symmetry) piperidin-1-ium cations, two carboxyl-ate anions and a water mol-ecule of crystallization. The cations have similar conformations approximating to a letter, L: one of them shows disorder of its -CF3 group over two sets of sites ...

The mechanism of in-source decay (ISD) in matrix-assisted laser desorption/ionization (MALDI) has been described. The MALDI-ISD with an oxidizing matrix is initiated by hydrogen abstraction from peptides to matrix molecules, leading to hydrogen-deficient peptide radicals. Subsequently, the C(α)-C and C(α)-H bonds are cleaved, forming the a•/x fragment pair and [M-2H], respectively. Those reacti...

We have examined the stereoselectivity of molecular recognition between two molecules of the anesthetic sevoflurane using broadband rotational spectroscopy. The transient axial chirality of sevoflurane is revealed upon the formation of the dimer, as two different diastereoisomers made of either homo- or heterochiral species are detected in a supersonic jet expansion. The conformational assignme...

The photophysics of two dyes from the xanthene family, eosin B (EB), and eosin Y (EY) has been investigated in various solvents by femtosecond transient absorption spectroscopy, first, to clarify the huge disparity of the EB fluorescence lifetimes reported in literature, and, second, to understand the mechanism responsible for the ultrafast excited-state deactivation of EB in water. The excited...

The NMR spectra of azo dyes, 5-arylazobarbituric (5a-g), 5-arylazo-1,3-dimethylbarbituric(6a-g) and 5-arylazothiobarbituric acids (7a-g) were studied in DMSO-d6 in differentconcentrations. An intramolecular hydrogen bond was observed and indicating that thehydrazone forms is mostly predominant. The peak of the hydrazone proton was severelybroadened and its chemical shift appeared at down field ...

Micelles are interesting self-organized structures with multiple applications in chemistry and related with the formation of biological structures. Their final shape depends on a subtle equilibrium between several weak forces: namely, van der Waals and hydrogen bond interactions. In order to address the influence of each type of interaction, the aggregation of cyclohexanol molecules was studied...