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Differences between DeltaH and DeltaS Values of the 1:2 Complexes of Camphor Enantiomers with alfa-Cyclodextrin Determined by NMR Titrations and by Other Techniques

Dodziuk H., Kozminski W., Dolgonos G.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 2

251-255

EN

DeltaH12 andDeltaS12 values for the 1:2 complexes of camphor enantiomers with alfa-cyclodextrin by NMR titrations, carried out from 25 to 48 graduateC, yielded -16.0 +-0.2 kcal/mol and 28.3 0.3 e.u. for 1a@2 and -9.8 0.2 kcal/mol and 9.10.2 e.u. for 1b@2. A comparison of the values obtained by other groups, using isothermal titration calorimetry and reversed-phase liquid hromatography, showed considerable differences except the Delta H12 and DeltaS12 for 1a@2, obtained by NMR and ITC methods. The reason of the differences, involving RPLC, are not discussed in view of internal inconsistencies of this method. On the other hand, the disagreement between the ITC andNMRresults seems to be due to the difference in solvents (H2O and D2O, respectively) used in both methods, which causes deuteration of all 36 OH groups of the host cyclodextrins. Interestingly, the deuteration causes a lowering of the absolute values of DeltaH12 and DeltaS12 for 1b@2, while the corresponding values of the complex with the second enantiomer are either unchanged or undergo only small changes upon the complexation.

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1:3 Complex between beta-Cyclodextrin and Dendrimer with Three Branches Involving Four Glycine and One Adamantyl Group

Dodziuk H., Demchuk O., Koźmiński W., Dolgonos G.

Polish Journal of Chemistry

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2003

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Vol. 77 / nr 3

333-340

EN

The first-generation dendrimer, benzene-sym-tris-N,N,N-carbonyltriglycylglycine N_-1-adamantylamide, was synthesized by a modification of a described procedure. Its complexation with alfa-, beta- and gamma-cyclodextrins was studied by NMR. The complexation induced fit and NOESY studies indicate that, in agreement with molecular mechanics calculations, the complex with alfa-cyclodextrin is considerably stronger than those with beta- and gamma-cyclodextrins.

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Modelling of Molecular and Chiral Recognition by Cyclodextrins : Is It Reliable? Part 2. Molecular Dynamics Calculations in Vacuum Pertaining to the Selective Complexation of Decalins by B-Cyclodextrin

Dodziuk H., Lukin O.

Polish Journal of Chemistry

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2000

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Vol. 74, nr 7

997-1001

EN

Molecular modelling is frequently used to rationalize experimental finding concerning molecular and chiral recognition by cyclodextrins, although the reliability of neither molecular mechanics nor molecular dynamics in this domain has been extensively analyzed. We have recently started a program aiming at the evaluation of computational methods applied in cyclodextrin research.

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Topological "in-out" isomerism in perhydrogenated fullerenes revisited : C60H58R1R2 with two R groups "in" (R1, R2=H, Me)

Dodziuk H., Lukin O., Nowiński K.

Polish Journal of Chemistry

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1999

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vol. 73 nr 2

299-306

EN

Molecular mechanics calculation (using MM+, MMX and AMBER force fields) of all constitutional and topological isomers of C60H58R1R2 with R1,R2=H, Me revealed that "in,in" isomers are always the most stable, while the corresponding "out,out" isomers have the biggest energy. Moreover, a substitution of an "in" hydrogen atom by a methyl group in the confined volume of the C60 cage doesn't change, or even lowers, the steric energy. The dependence of steric energy on the distance between the "in" hydrogen atoms (or between the carbon atoms of "in" methyl groups) reveals highly irregular behaviour, for close neighbours, reflecting differences in the energies associated withconsiderable distortions of the fullerane skeleton.