2‐Hydro­xy‐3‐(4,5,6,7‐tetra­hydro‐1H‐imidazo­[4,5‐c]­pyridin‐5‐ium‐4‐yl)­benzoate monohydrate

The title mol­ecule, C₁₃H₁₃N₃O₃·H₂O, is in the form of a mono­hydrated zwitterion. The tetra­hydro­pyridinium ring adopts an envelope conformation and is nearly coplanar with the plane of the imidazoline ring. The water solvate mol­ecule plays an important role as a bridge between zwitterions, forming molecular chains running along the c direction, which are interconnected by N—H?O hydrogen bonds into molecular ribbons. The crystal packing is further stabilized by another N—H?O and one O—H?N hydrogen bond, which interconnect the molecular ribbons.     

Electron-impact studies—XVIII. Fragmentation of some epimeric 7-substituted norbornenes

The fragmentation modes of some epimeric 7-substituted norbornenes have been established from deuteration and high resolution studies. Stereochemical differences were found to have very little influence in directing the fragmentation modes of these epimers. Formation of common intermediates or transition states by ring opening process has been proposed to rationalise the mass spectral behaviour of these compounds.     

Vibrational spectra of mono, di and trimethyl ammonium double sulphates of rare earths Pr, Nd, Ho and Eu

Infrared and Raman spectra of four rare earth (Ho, Eu, Nd and Pr) double sulphates have been recorded and analysed based on the vibrations of methyl ammonium cations, sulphate anions and water molecules. Formation of hydrogen bonds of the type N-H...O and O-H...O are identified in all the compounds. Bifurcated hydrogen bonds are present in the compounds with dimethyl ammonium cations. The sulphate anions are distorted and occupy a lower site symmetry in the compounds. The bands obtained for (CH(3))(2)NH(2) and SO(4)(2-) ions indicate that the structural bonding of (CH(3))(2)NH(2)Eu(SO(4))(2).H(2)O and (CH(3))(2)NH(2)Ho(SO(4))(2).4H(2)O is identical. Electronic transition bands of Eu(3+) and Nd(3+) observed in the Raman spectra of these two compounds have been identified and discussed.     

Hydroxyapatite coating on stainless steel pre-coated with bovine serum albumin at ambient conditions

A biomimetic process for coating of nanosized hydroxyapatite on stainless steel, which capitalises the dual nature of the protein bovine serum albumin in both metal binding and a strong affinity for calcium ions, has been developed. The novelty of the process lies in pre-conditioning the metallic surface using the above protein prior to its mineralization with hydroxyapatite at ambient conditions. The microporous morphology of these coatings may provide favourable solubility and resorbability as desired by many orthopaedic and orthodontic applications.     

Mass spectra of partially n-acetylated derivatives of kanamycin a

As part of a program concerned with the chemistry and biochemistry of aminocyclitol antibiotics, a number of selectively N-acetylated kanamycins have been prepared from kanamycin monosulfate and characterized by a study of the electron impact induced fragmentation of two types of derivatives. In one of these, the remaining free amino groups were N-trideuteroacetylated and the N-acylated kanamycins thus obtained, were N.O-methylated. The spectra of these derivatives were useful for the location of the N-acetyl and N-trideu-teroacetyl groups, except in the 2-deoxystreptamine unit. In a second type of derivative, the partially N-acetylated kanamycins were N.O-permethylated converting the free amino groups into dimethylamino groups. In this form, it was possible to locate the site of N-aeelylation on the 2-deoxystreptamine ring. The partially N-acetylated kanamycins have been identified as 1,3,6'-tri-N-acetyl, 3,6',3'-tri-N-acetyl, 3,6'-di-N-acetyl, 1,6'-di-N-acetyl and 6'-N-acetyl kanamycin, from a study of the mass spectra of these two types of derivatives.