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Additional criterion for the determination of the handedness of 2 1 helices in crystals of bile acids: Crystal structure of a tert ‐butylphenyl derivative of cholic acid
Author(s) -
Meijide Francisco,
Trillo Juan V.,
Soto Victor H.,
Jover Aida,
Tato JosÉ Vázquez
Publication year - 2011
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.21020
Subject(s) - chemistry , chlorobenzene , orthorhombic crystal system , hydrogen bond , molecule , monoclinic crystal system , crystal (programming language) , crystallography , steroid , cholic acid , chirality (physics) , crystal structure , cyclohexane , solvent , stereochemistry , bile acid , organic chemistry , catalysis , physics , biochemistry , nambu–jona lasinio model , chiral symmetry breaking , quantum mechanics , computer science , hormone , programming language , quark
[3β,5β,7α,12α]‐3‐(4‐ t ‐Butylbenzoilamine)‐7,12‐dihydroxycholan‐24‐oic acid was synthesized and recrystallized from chlorobenzene and acetone. Orthorhombic P 2 1 2 1 2 1 and monoclinic P 2 1 crystals were obtained, respectively, and both crystals include solvent and water molecules with a 1:1:1 stoichiometry. In the second case, there are two nonequivalent molecules of the steroid in the unit cell. In both crystals, a crossing structure results for the molecular packing, stabilized by hydrogen bonds between the steroid molecules. In the second crystal, water links steroid molecules of the same type, which are not directly connected through hydrogen bonds. The steroid molecules define helicoidal assemblies along 2 1 screw axes. The handedness in the crystal in chlorobenzene is unambiguously defined by following the criterion proposed by Miyata et al., as the steroids are in a belly‐to‐belly disposition around the axis. This motif does not appear in the crystal in acetone, and other criterion is required. On the basis of the fact that a staircase and its banister have the same handedness and using the crystal in chlorobenzene as reference, the additional criterion has been established. According to it, in the absence of a belly‐to‐belly orientation, the handedness must be defined by keeping the bile acid with its right side oriented toward the axis. Pitch angles of the helices and tilt angles of the molecules are also determined. Chirality, 2011. © 2011 Wiley‐Liss, Inc.