B3lyp/6-311++G** study of monohydrates of α- and β-D-glucopyranose: hydrogen bonding, stress energies, and effect of hydration on internal coordinates

Abstract Twenty-six monohydrates of α- and β- d -glucopyranose were studied using gradient methods at the B3LYP/6-311++G** level of theory. Geometry optimization was carried out with the water molecules at different configurations around the glucose molecule. A new nomenclature for hydrated carbohydrates was developed to describe the water configurations. Zero-point vibrational energy, enthalpy, entropy, and relative free energy were obtained using the harmonic approximation. Hydrogen-bond energies for the monohydrates range from ∼−5 to −12 kcal/mol, and the average relative free energy is ∼5 kcal/mol. The 1-hydroxy position is the most energetically favored site for hydration, and the region between the two and three positions is the next-most favored site. A water molecule approaching α- d -glucose between the 1- and 2-hydroxy positions pulls the 2-hydroxyl hydrogen atom away from the 1-hydroxy oxygen atom, thus increasing the hydrogen-bond length and also increasing the α- d -glucose energy. The increase in energy that occurs with a similar interaction on the β-anomer is much less effective since the hydrogen bond is much longer. Using the calculated free energies of all 26 configurations, the anomer population (α/β) increases in the β-anomer population relative to the in vacuo case by ∼10% at the expense of the α-anomer, giving an (α/β) ratio of ∼50/50. This result arises from entropy contributions favoring the β-anomer more than the α-anomer. From analysis of donor and acceptor hydrogen-bond lengths, excellent correlation is found between the DFT calculated distances and those taken from carbohydrate structures in the Cambridge Crystallographic Data Bank.

[1]  H. Høiland,et al.  STEREOCHEMICAL ASPECTS OF HYDRATION OF CARBOHYDRATES IN AQUEOUS-SOLUTIONS .3. DENSITY AND ULTRASOUND MEASUREMENTS , 1991 .

[2]  Willis B. Person,et al.  Properties of Hydrogen-Bonded Complexes Obtained from the B3LYP Functional with 6-31G(d,p) and 6-31+G(d,p) Basis Sets: Comparison with MP2/6-31+G(d,p) Results and Experimental Data , 1995 .

[3]  Donald G. Truhlar,et al.  MODEL FOR AQUEOUS SOLVATION BASED ON CLASS IV ATOMIC CHARGES AND FIRST SOLVATION SHELL EFFECTS , 1996 .

[4]  Peter A. Kollman,et al.  Use of Locally Enhanced Sampling in Free Energy Calculations: Testing and Application to the α → β Anomerization of Glucose , 1998 .

[5]  T. Zwier,et al.  Density Functional Theory Calculations of the Structures, Binding Energies, and Infrared Spectra of Methanol Clusters , 1998 .

[6]  Dennis R. Salahub,et al.  Hydrogen-bonding in glycine and malonaldehyde: Performance of the Lap1 correlation functional , 1997 .

[7]  J. L. Willett,et al.  Ab initio computational study of β-cellobiose conformers using B3lYP/6-311++G** , 2002 .

[8]  S. Angyal.  Conformational analysis in carbohydrate chemistry. I. Conformational free energies. The conformations and α : β ratios of aldopyranoses in aqueous solution , 1968 .

[9]  Frank A. Momany,et al.  Computational studies on carbohydrates: I. Density functional ab initio geometry optimization on maltose conformations , 2000 .

[10]  J. Praly,et al.  Influence of solvent on the magnitude of the anomeric effect , 1987 .

[11]  J. L. Willett,et al.  Computational studies on carbohydrates: solvation studies on maltose and cyclomaltooligosaccharides (cyclodextrins) using a DFT/ab initio-derived empirical force field, AMB99C. , 2000, Carbohydrate research.

[12]  G. A. Jeffrey,et al.  A survey of O-H⋯O hydrogen bond geometries determined by neutron diffraction , 1981 .

[13]  T. Bruce Grindley,et al.  Effect of Solvation on the Rotation of Hydroxymethyl Groups in Carbohydrates , 1998 .

[14]  M. Karplus,et al.  The Anomeric Equilibrium in d-Xylose: Free Energy and the Role of Solvent Structuring , 1996 .

[15]  William L. Jorgensen,et al.  Ab Initio Study Of Hydrogen-Bonded Complexes Of Small Organic Molecules With Water , 1998 .

[16]  Hanoch Senderowitz,et al.  Carbohydrates: United Atom AMBER* Parameterization of Pyranoses and Simulations Yielding Anomeric Free Energies , 1996 .

[17]  Juan J. Novoa,et al.  Evaluation of the Density Functional Approximation on the Computation of Hydrogen Bond Interactions , 1995 .

[18]  R. Hooft,et al.  Molecular dynamics study of conformational and anomeric equilibria in aqueous D-glucose , 1993 .

[19]  J. T. Edward.  THE INTRINSIC VISCOSITIES OF AQUEOUS SOLUTIONS OF SMALL MOLECULES , 1957 .

[20]  P. Mark Rodger,et al.  Lifetime of a Hydrogen Bond in Aqueous Solutions of Carbohydrates , 1999 .

[21]  J. L. Willett,et al.  Computational studies on carbohydrates: in vacuo studies using a revised AMBER force field, AMB99C, designed for alpha-(1-->4) linkages. , 2000, Carbohydrate research.

[22]  Michele Parrinello,et al.  Glucose in Aqueous Solution by First Principles Molecular Dynamics , 1998 .

[23]  J. L. Willett,et al.  A DFT/ab initio study of hydrogen bonding and conformational preference in model cellobiose analogs using B3LYP/6-311++G**. , 2002, Carbohydrate Research.

[24]  Sándor Suhai,et al.  Comparative study of BSSE correction methods at DFT and MP2 levels of theory , 1998 .

[25]  J. Engberts,et al.  STEREOCHEMICAL ASPECTS OF HYDRATION OF CARBOHYDRATES IN AQUEOUS-SOLUTIONS .2. KINETIC MEDIUM EFFECTS , 1992 .

[26]  N. Cheetham,et al.  Molecular dynamics simulations of glycosides in aqueous solution , 1996 .