The theoretical study on tautomers of xanthine and interaction of this molecule with water and different metal ions in gas and solvent phases

چکیده مقاله

Cyclic organic compounds are classified into homocylic and heterocyclic compounds. Homocylic rings have only one type of atom, while heterocyclic rings in addition to carbon have one or more non-carbon atoms. Nitrogen, oxygen and sulfur are the most common heteroatoms. Epoxides (three-membered cyclic ethers), lactones (cyclic esters), and pyridine (cyclic base), lactam (cyclic amides) and solvents such as tetrahydrofuran (a cyclic ether) are all heterocyclic compounds. Heterocyclic intermediates in the synthesis as protective groups have increasing use, such groups are easily produced and consequently are easily removed. Crown ethers are also heterocyclic compounds. As one of typical properties of ethers is solvation capability of cations, so these compounds are of particular importance, because their molecules are cyclic and rings with specific sizes which can place cations within their vacancies. Heterocyclic compounds are among organic compounds that have biological properties. For example, penicillin (antibiotic), cimetidine (anti peptic ulcer agent) and saccharin (artificial sweetener used in the production of various foods) are among the heterocyclic compounds. In theoretical studies with examining nine structures of the tautomers existing for xanthine molecule, results suggest that the isomer A is the most stable structure in both DFT and MP2 methods and the stability order of these tautomers is as A> D> H> G> I> F> E> B> C.

دریافت لینک دانلود مقاله