FEATURES OF COORDINATION OF o-IODOBENZOIC ACID IN SUPRAMOLECULAR COMPLEXES WITH
β-GLYCYRRHIZIC ACID ACCORDING
 TO SPECTROSCOPIC DATA 
I.G Konkina.1, O.V.Shitikova 2, S.P.Ivanov 1, N.G Yarkieva.2,
O.V.Zakiryanova 1, Yu.I.Murinov 1
1Ufa Institute of Chemistry RAS, Ufa
irkonk@anrb.ru
2Ufa State University of Economics and Service, Ufa,
ovs11@mail.ru

     Supramolecular complexes with iodine-containing compounds are of interest as demanded by the biologically active substances. In this paper the study of coordination of o-iodobenzoic acid (o-BAI) with natural podand  β-glycyrrhizic acid (GA) was continued [1]. The stoichiometry composition of the complex was determined by spectrophotometry. It corresponds to the interaction of one molecule of o-BAI with two molecules of GA.
     Тhe compound of the following composition (o-BAI:GA = 1:2) was isolated  preparatively and was characterized by elemental analysis and IR spectroscopy. 
     The method described previously was used to study the structure of this  complex  [2]. Full assignment of signals in the 1H and 13C NMR spectra of o-BAI  and GA in MeOD-d4 for individual components  and for  different ratios o-BAI : GA  was conducted. DEPT methods were used to establish the multiplicity of signals in the NMR spectra of 13C, a two-dimensional techniques of homo (1H-1H COSY) and hetero (1H-13C HSQC, HMBC) nuclear correlations - for the complete classification of the signals in the spectra. According to the  results it was revealed that the "guest" molecule in contact with GA, –"host" molecule, -  in the solution mixture of components by ratio o-BAI:GA  2:1, 1:1, 1:2 and 1:4 interacts through conjugated bonds C=C-C=O of GA triterpene fragment and  through all three carboxyl groups of GA molecule.  In isolated product [o-BAI∙(GA)2] o-BAI molecule interacts  with GA through the glucuronic acids residues in carbohydrate part  of GA.
     Based on the 1H and 13C NMR spectra analysis, as well as the temperature dependence of the configuration  signals, it was concluded that the  o-BAI molecules in isolated product may be oriented differently relative GA functional groups. Since it is known that GA exists in the solution preferably in the form of dimers [3,4], the proposed structures can be represented as follows.  
                       
    This variants are in agreement with the  results obtained.

     IR, UV  and NMR spectra were recorded on equipment at the Center for the Сollective Use “Chemistry” of the Ufa Institute of Chemistry of the Russian Academy of Sciences.

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