Nh. Hu et Sl. Zhang, HOST-GUEST INTERACTIONS OF THIAMINE WITH ANIONS - CRYSTAL-STRUCTURE OF THIAMINE IODIDE SESQUIHYDRATE, Journal of inclusion phenomena and molecular recognition in chemistry, 16(3), 1993, pp. 273-281
The crystal structure of thiamine iodide sesquihydrate has been determ
ined by X-ray diffraction methods as a host-guest model for coenzyme-s
ubstrate interactions. The asymmetric unit contains two chemical units
. Both the thiamine molecules A and B, which are crystallographically
independent, assume the usual F conformation and have a disordered hyd
roxyethyl side chain. An iodide anion (or a water molecule) bridges th
e pyrimidine and thiazolium rings of molecule A (or B) by forming a hy
drogen bond with the amino group and an electrostatic contact with the
thiazolium ring to stabilize the molecular conformation. In the cryst
al the thiamine molecules self-associate to form a pipe-like polymeric
structure, in which four thiamine hosts surround an iodide guest and
hold it through C(2)-H...I hydrogen bonds and thiazolium...I electrost
atic interactions. Crystal data: C12H17N4OS+.I- . 1.5 H2O, monoclinic,
P2(1)/c, a = 12.585(2), b = 25.303(5), c = 12.030(2) angstrom, beta =
115.15(1)degrees, V = 3468(1) angtrom3, Z = 8, D(c) = 1.606 g cm-3, R
= 0.045 for 3328 observed reflections.