Biomedical subjects
Publications and source records attributed to Ranko M Vrcelj.
Coprecipitation provides a rapid high-yield method for self-assembly of nanoparticles on the surface of flat water-soluble crystalline surfaces and a simple immobilisation technique prior to storage or thermal and chemical modification.
The antibiotic cephalexin [systematic name: D-7-(2-amino-2-phenylacetamido)-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid] forms a range of isomorphic solvates, with the maximum hydration state of two water molecules formed only at high relative humidities. The water content of the structure reported here (C(16)H(17)N(3)O(4)S.1.9H(2)O) falls just short of this configuration, having three independent cephalexin molecules, one of which is disordered, and 5.72 observed water molecules in the asymmetric unit. The facile nature of the cephalexin solvation/desolvation process is found to be facilitated by a complex channel structure, which allows free movement of solvent in the crystallographic a and b directions.
This work reports on the crystal structures of two dioxane solvates of paracetamol that are true polymorphs. The high temperature phase is an orthorhombic form, space group Pbca, Z = 8, a = 12.6078(3) A, b = 12.1129(2) A, c = 13.4138(3) A, V = 2048.52(7) A(3), (at 295 K) and the low temperature form is monoclinic, space group P21/c, Z = 4, a = 12.325(6) A, b = 11.965(4) A, c = 13.384(6) A, beta = 92.01 degrees, V = 1972.6(14)A(3) (at 123 K). The structures of these polymorphs are described as is the interrelationship between the two structures. In addition to the structural interrelationship, it is shown that the two forms undergo a reversible phase transformation. Desolvation of either form generates the stable monoclinic phase of paracetamol.