In this study, chemical transformations of benzyl ester of О-(phenyl-2-acetamido-2,3-dideoxy-1-thio-β-d-glucopyranoside-3-yl)-d-lactoyl-l-alanyl-d-isoglutamine (SPhMDPOBn) on the fumed silica surface were examined, and the surface complex structure was characterized by temperature-programmed desorption mass spectrometry (TPD-MS), infrared spectroscopy (FTIR) and electrospray ion trap mass spect...

THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND (SYSTEMATIC NAME: methyl 3,4,5-trihydroxy-benzoate), C(8)H(8)O(5), is composed of essentially planar mol-ecules [maximum departures from the mean carbon and oxygen skeleton plane of 0.0348 (10) Å]. The H atoms of the three hydroxyl groups, which function as hydrogen-bond donors and acceptors simultaneously, are oriented in the same direction around th...

The title compound, C(19)H(14)ClNO(3)·0.2H(2)O, crystallizes with five mol-ecules and a disordered water mol-ecule in the asymmetric unit. Four of the five mol-ecules form hydrogen-bonded dimers via N-H⋯O hydrogen bonds towards another symmetry-independent mol-ecule, whereas the fifth mol-ecule forms a hydrogen-bonded dimer with its symmetry equivalent, also via N-H⋯O hydrogen bonds. The dihedr...

In the title compound, C(10)H(12)N(2)O(5)S, one of the sulfonyl O atoms is hydrogen bonded to the amido N atom of an adjacent mol-ecule. There is also a weak hydrogen-bonding inter-action between the other sulfonyl O atom and the secondary amino N atom. In addition, the amido O atom is also hydrogen bonded to a carboxyl O atom. These hydrogen-bonding inter-actions give rise to a layer structure...

The title compound, [PdCl(2)(C(6)H(16)N(3))](C(7)H(7)SO(3)), consists of a Pd(II) atom bonded to two N atoms of the 1,4,7-triaza-cyclo-nonane (TACN) ligand and two chloride ions, which define a distorted square-planar geometry. The third N atom of the TACN ligand is protonated and hydrogen bonds to the p-toluene-sulfonate anion. The Cl-Pd-Cl angle is larger than the N-Pd-N angle. The packing is...

In the title complex, (C(5)H(6)ClN(2))(C(7)H(8)NO)[CoCl(4)], the Co(II) ions are tetra-hedrally coordinated. The crystal structure is built from hydrogen-bonded centrosymmetric tetra-mers of tetra-chloridocobaltate(II) dianions and 3-amino-2-chloro-pyridinium cations, additionally strengthened by significant π-π stacking of pyridinium rings [interplanar distance 3.389 (3) Å]. The tetra-mers are...

The conduction of protons in the hydrogen-bonded chain of water molecules (or "proton wire") embedded in the lumen of gramicidin A is studied with molecular dynamics free energy simulations. The process may be described as a "hop-and-turn" or Grotthuss mechanism involving the chemical exchange (hop) of hydrogen nuclei between hydrogen-bonded water molecules arranged in single file in the lumen ...

Solvent-free spin crossover (SCO) iron(III) complex, [FeIII(Him)2(hapen)]SbF6 (Him = imidazole, H2hapen = N,N′-bis(2-hydroxyacetophenylidene)ethylenediamine), is synthesized. The FeIII ion has an octahedral coordination geometry, with N2O2 donor atoms of hapen and N2 atoms of two imidazoles at the axial positions. The saturated five-membered chelate ring of hapen moiety assumes a gauche-type δo...

We previously suggested that proteins gain more stability from the burial and hydrogen bonding of polar groups than from the burial of nonpolar groups (Pace, C. N. (2001) Biochemistry 40, 310-313). To study this further, we prepared eight Thr-to-Val mutants of RNase Sa, four in which the Thr side chain is hydrogen-bonded and four in which it is not. We measured the stability of these mutants by...

Mol-ecules of the title compound, C7H10N2O4, systematic name 5-hy-droxy-5-propyl-pyrimidine-2,4,6(1H,3H,5H)-trione, form a hydrogen-bonded framework which is based on three independent hydrogen bonds, N-H⋯O(carbon-yl), N-H⋯O(hy-droxy) and O-H⋯O(carbon-yl). This framework has the topology of the 5-connected nov net. Each mol-ecule is linked to five other mol-ecules via six hydrogen bonds, and th...