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DFT/B3LYP Study of Thermochemistry of D-Glucosamine, a Representative Polyfunctional Bioorganic Compound

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D-glucosamine, as a representative polyfunctional compound, is a bioactive amino sugar. In this study, the gas phase thermochemical properties of D-glucosamine, including its Metal Ion Affinity (MIA), metal binding sites, Anion Affinity (AA), acidity and proton affinity, have been explored, using the Density Functional Theory (OFT) and a 6-311++G**basis set. The summary of the MIA and AA results (in kcal/rnolt ") are: Li^+= 67.6, Na^+= 51.1, K^+= 37.3, Mg^2+= 207.9, Ca^2+= 150.4, Zn^2+= 251.2, (CL^--= 27.4, CN^-= 28.0. The acidity values calculated at different sites, including four -OH groups and one -NH z group, range from 344.0 to 373.0 kcal/mol- 1 . These results, surprisingly, indicate how drastically the presence of multiple -OH and -NH z groups may vary the thermochemical properties of a polyfunctional bioorganic compound, such as D-glucosamine

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