CRYSTAL STRUCTURE OF THREE SOLVATES OF 1,1'-BINAPHTHYL-2,2'-BICARBOXYLIC ACID WITH 2-PICOLINE
L. Yu. Izotova1, D. M. Ashurov1, S. A. Talipov1, B. T. Ibragimov1, E. Weber2
1A. S. Sadykov Institute of Bioorganic Chemistry, Uzbekistan Academy of Sciences, Tashkent, Uzbekistan
l_izotova@yahoo.com
2Institute of Organic Chemistry, Freiberg Mining Academy, University of Technology, Freiberg, Germany
Keywords: 1,1'-binaphthyl-2,2'-bicarboxylic acid, solvation polymorphism, 2-picoline, crystal structure
Subsection: SUPRAMOLECULAR AND NANODIMENSIONAL SYSTEMS
Abstract
From solutions in 2-picoline (2-methylpyridine), depending on the temperature of crystallization, the universal clathratogen — 1,1'-binaphthyl-2,2'-bicarboxylic acid (BBA) — precipitates as crystals of three types with different composition and structure. Under normal conditions (room temperature), the precipitate is crystals of BBA disolvate with 2-picoline; a temperature reduction of 20°C results in the crystallization of monosolvate dihydrate; and a temperature increase of the same level results in the precipitation of monosolvate. That is, as the temperature of crystallization rises, the number of included guest molecules gradually decreases and the space where they are located becomes more closed. In 1:1:2 BBA/2-picoline/H2O solvate (space group P21/n, a = 11.991(2) Å, b = 9.317(2) Å, c = 22.283(5) Å, β = 99.77(3)°, V = 2453.3(9) Å3, Z = 4), the carboxyl groups of the BBA molecule at the С21 atom are deprotonated and the released proton goes to the nitrogen atom of 2-picoline. BBA molecules interact with those of 2-picoline and water via H bonds to form infinite chains in direction [111], which, in their turn, join together into infinite two-dimensional sheets parallel to plane (–101). 2-Picoline molecules are located in the channels. In BBA/2-picoline disolvate (space group С2/с, a = 11.7523(11) Å, b = 13.8563(13) Å, c = 17.9615(13) Å, β = 108.044(9)°, V = 2781.1(4) Å3, Z = 4), one BBA molecule and two H bond 2-picoline molecules form a 0-dimensional associate of the type G–H–G. The solvent molecules are also located in the channels. In BBA/2-picoline monosolvate (space group P21/с, a = 9.299(5) Å, b = 12.727(5) Å, c = 19.011(5) Å, β = 95.248(5)°, V = 2240.5(16) Å3, Z = 4), each BBA molecule is H-bonded with a 2-picoline molecule to form a 0-dimensional associate of the type H–G. Guest molecules are located in closed cavities.
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