1. On the phosphate linkages and the structure of a disaccharide unit of the type-specific polysaccharide of Pneumococcus type XIX
T Yadomae, N Ohno, T Miyazaki Carbohydr Res. 1979 Oct;75:191-8. doi: 10.1016/s0008-6215(00)84638-8.
The structure of the capsular polysaccharide (S-XIX) of Pneumococcus Type XIX, which contains residues of D-glucose, L-rhamnose, 2-acetamido-2-deoxy-D-mannose, and phosphate, has been investigated by acid hydrolysis, treatment with acid phosphatase, mass spectrometry, and 13C-n.m.r. spectroscopy. Phosphoric esters in S-XIX were largely resistant to hydrolysis (4M HCl, 100 degrees, 3 h). With M or 2M HCl at 100 degrees for 3 h, 4-O-(2-amino-2-deoxy-beta-D-mannopyranosyl)-D-glucose 4'-phosphate was liberated. More-drastic hydrolysis of S-XIX gave 2-amino-2-deoxy-D-mannose 3-, 4-, and 6-phosphates, and 4-O-(2-amino-2-deoxy-D-mannopyranosyl)-D-glucose and its 4'-phosphate.
2. 4-Amino-2-chloro-benzoic acid
Muneeb Hayat Khan, Islam Ullah Khan, Mehmet Akkurt Acta Crystallogr Sect E Struct Rep Online. 2011 Sep 1;67(Pt 9):o2247. doi: 10.1107/S1600536811030728. Epub 2011 Aug 6.
The title compound, C(7)H(6)ClNO(2), crystallizes with two roughly planar mol-ecules in the asymmetric unit (r.m.s. deviations = 0.073 and 0.074 Å). The amine H atoms of the two mol-ecules have opposite orientations. In the crystal, mol-ecules are linked into dimers by pairs of O-H⋯O hydrogen bonds, generating R(2) (2)(8) loops. N-H⋯N and N-H⋯Cl hydrogen bonds link the dimers into a three-dimensional network. The crystal studied was found to be a racemic twin.
3. Crystal structure and Hirshfeld surface analysis of ethyl 6'-amino-2'-(chloro-meth-yl)-5'-cyano-2-oxo-1,2-di-hydro-spiro-[indoline-3,4'-pyran]-3'-carboxyl-ate
Farid N Naghiyev, Maria M Grishina, Victor N Khrustalev, Mehmet Akkurt, Afet T Huseynova, Anzurat A Akobirshoeva, İbrahim G Mamedov Acta Crystallogr E Crystallogr Commun. 2021 Jun 25;77(Pt 7):739-743. doi: 10.1107/S2056989021006459. eCollection 2021 Jul 1.
The mol-ecular conformation of the title compound, C17H14ClN3O4, is stabilized by an intra-molecular C-H⋯O contact, forming an S(6) ring motif. In the crystal, the mol-ecules are connected by N-H⋯O hydrogen-bond pairs along the b-axis direction as dimers with R 2 2(8) and R 2 2(14) ring motifs and as ribbons formed by inter-molecular C-H⋯N hydrogen bonds. There are weak van der Waals inter-actions between the ribbons. The most important contributions to the surface contacts are from H⋯H (34.9%), O⋯H/H⋯O (19.2%), C⋯H/H⋯C (11.9%), Cl⋯H/H⋯Cl (10.7%) and N⋯H/H⋯N (10.4%) inter-actions, as concluded from a Hirshfeld surface analysis.
