S. Parkin, William H. Coldren, Joseph P. Fernandez
Oct 8, 2018
Citations
0
Influential Citations
0
Citations
Journal
Crystal Growth & Design
Abstract
Crystalline 5′-iodo-5′-deoxyguanosine (I) exists as a pair of solvent-free polymorphs (Ia, Ib) and as a mixed water/methanol solvate (Ic). The solvent-free polymorphs are capable of epitaxial intergrowth to give hybrid crystals that by visual inspection appear to be single crystals (Parkin et al. Cryst. Growth Des. 2016, 16, 6343–6352; hereafter PTGB). To investigate the generality and origin of the unusual polymorphism of the solvent-free forms, we have prepared and characterized the 5′-bromo- and 5′-chloro-5′-deoxyguanosine analogues (II and III, respectively), as well as the pseudohalide derivative 5′-azido-5′-deoxyguanosine (IV). Monoclinic and orthorhombic polymorphs of II (IIa and IIb, respectively) and an orthorhombic form of III all grow from water as small nonsolvated, tightly packed needles or laths. Although IIa is isostructural with the dominant polymorph of I (i.e., Ia in PTGB), all of these crystals (IIa, IIb, III) have similar molecular conformations and packing characteristics to Ia, in wh...