Crystal structures of three halide salts of l-asparagine: an isostructural series.

The structures of three monohydrated halide salt forms of l-asparagine are presented, l-asparaginium chloride monohydrate, CHNO ·Cl·HO, (I), l-asparaginium bromide monohydrate, CHNO ·Br·HO, (II), and l-asparaginium iodide monohydrate, CHNO ·I·HO, (III). These form an isomorphous and isostructural series. The C-C-C-C backbone of the amino acid adopts a conformation in each case [torsion angles for (I), (II) and (III) = -55.