Redetermination of l-tryptophan hydro-bromide.

ABSTRACT: The redetermined crystal structure of the title compound, C(11)H(13)N(2)O(2) (+)·Br(-), is reported. Data collection at 100?K about three crystallographic axes resulted in a crystal structure with significantly higher precision in comparison to the two-dimensional data collected at 176?K [Takigawa et al. [(1966) Bull. Chem. Soc. Jpn, 39, 2369-2378]. The carboxyl group and indole ring system are planar, with maximum deviations of 0.002?(2) and 0.007?(2)?Å, respectively, and make an angle of 70.17?(1)° with each other. The mol-ecules are arranged in double layers of carboxyl and amino groups parallel to the ab plane, stabilized by an extensive network of N-H?Br and O-H?Br hydrogen bonds. The polar layer is held together by a network of three N-H?Br hydrogen bonds and one O-H?Br hydrogen bond. In the non-polar layer, the indole rings are linked mainly by electrostatic N-H?C inter-actions between the polarized bond N-H (H is ?(+)) of the pyrrole unit and two of the ring C atoms (?(-)) of the benzene rings of adjacent mol-ecules. The distances of these electrostatic inter-actions are 2.57 and 2.68?Å, respectively. C-H?O and C-H?? inter-actions are also present.

SUBMITTER: Stewart K 

PROVIDER: S-EPMC2969532 | biostudies-literature | 2009 May

REPOSITORIES: biostudies-literature