Cocrystallizing agents for amino acids .1. The crystal structure of L-glutamic acid 2-methylimidazole

The L-glutamic acid (2-aminopentanedioic acid, L-Glu) 2-methylimidazole (2MI) 1:1 complex crystallizes in the monoclinic space group C2 with two L-Glu anions and two 2MI cations in the asymmetric unit, together with a solvent water molecule located on the twofold axis. The structure was solved by direct methods and refined to a final wR(F-0(2))=0.124 for 5506 unique reflections and R(F-0)= 0.046 for 4578 observed reflections (I>2.0 sigma I) collected at 120 K. Cell parameters: a=19.487(6), b=7.935C3), c=20.351(5) Angstrom, beta=131.39(2)degrees. The crystals were prepared as part of a program aimed at finding suitable cocrystallization agents for amino acids and peptides. The two L-Glu molecules have different sidechain conformations, but have very similar hydrogen bond arrangements, except that only one molecule has an interaction with the water molecule. The 2MI disordered over two equally populated positions close to the twofold rotation axis.