trans-Cinnamic acid--alpha-cyclodextrin system as studied by solubility, spectral, and potentiometric techniques.

Complex formation in aqueous solutions of trans-cinnamic acid or trans-cinnamate ion (the substrate, S) and alpha-cyclodextrin (the ligand, L) can be described quantiatively as the 1:1 and 1:2 complexes, SL and SL2. The solubility, spectral, and potentiometric data over a wide range of ligand concentrations yielded consistent estimates of the complex association constants. For cinnamic acid at 25 degrees K11 = 2260 M-1, delta H degree 11 = 9.3 kcal/mole, and delta S degree 11 = -8 e.u.; and K12 = 60 M-1, delta H degree 12 = -12 kcal/mole, and delta S degree 12 = -26 e.u. For cinnamate ion at 25 degrees, K11 = 110 M-1, delta H degree 11 = -1.9 kcal/mole, and delta S degree 11 = +11 e.u.; and K12 = 15 M-1, delta H degree 12 = 9 kcal/mole, and delta S degree 12 = -15 e.u. (all entrophy changes are unitary quantities). Thermodynamic cycles for the complexes, using solubility data, reveal that complex formation in the solid phase is thermodynamically spontaneous but that complex stability is greater in ageous solution than in the solid phase.

[1]  Charles Tanford,et al.  The hydrophobic effect , 1980 .

[2]  L. M. Schwartz,et al.  The complexation chemistry of cyclohexaamyloses. 3. Per-O-methylcyclohexaamylose adducts with 4-biphenylcarboxylate and p-methylcinnamate anions , 1979 .

[3]  L. M. Schwartz,et al.  THE COMPLEXATION CHEMISTRY OF CYCLOHEXAAMYLOSES. 4. REACTIONS OF CYCLOHEXAAMYLOSE WITH FORMIC, ACETIC, AND BENZOIC ACIDS AND THEIR CONJUGATE BASES , 1979 .

[4]  L. M. Schwartz,et al.  Complexation chemistry of cyclohexaamyloses. 2. p-Methylcinnamate anion , 1978 .

[5]  L. M. Schwartz,et al.  Complexation of 4-biphenylcarboxylate by cyclohexaamylose. A conductometric and carbon-13 nuclear magnetic resonance spectrometric analysis , 1978 .

[6]  Makoto Komiyama,et al.  Importance of apolar binding in complex formation of cyclodextrins with adamantanecarboxylate , 1978 .

[7]  K. A. Connors,et al.  Effect of cycloamyloses on apparent dissociation constants of carboxylic acids and phenols: equilibrium analytical selectivity induced by complex formation. , 1976, Journal of pharmaceutical sciences.

[8]  K. Uekama,et al.  Inclusion complexes of cinnamic acids with cyclodextrins. Mode of inclusion in aqueous solution. , 1975 .

[9]  K. A. Connors.  Reaction mechanisms in organic analytical chemistry , 1973 .

[10]  K. A. Connors,et al.  Stability of some molecular complexes in aqueous mixed solvents. Correlation with solvent surface tension , 1971 .

[11]  K. A. Connors,et al.  Stability and structure of some organic molecular complexes in aqueous solution. , 1970, Journal of pharmaceutical sciences.

[12]  K. A. Connors,et al.  Modification of reaction rates by complex formation. V. Alkaline hydrolysis of some xanthine complexes of acetoxycinnamic acids and related compounds , 1970 .

[13]  K. A. Connors,et al.  Interactant structure and complex stability for complexes of theophylline with cinnamate esters and related compounds in aqueous solution. , 1969, Journal of the American Chemical Society.

[14]  K. A. Connors,et al.  Modification of the reactivity of some carboxylic acid derivatives by complexation. Effects on some intermolecular and intramolecular reactions. , 1969, Journal of the American Chemical Society.

[15]  W. Jencks.  Catalysis in chemistry and enzymology , 1969 .

[16]  M. L. Bender,et al.  Acceleration of phenyl ester cleavage by cycloamyloses. A model for enzymic specificity , 1967 .

[17]  K. A. Connors,et al.  Modification of reaction rates by complex formation. II. Inhibition of the rate of alkaline hydrolysis of methyl trans-cinnamate by some heterocyclic compounds. , 1967, Journal of the American Chemical Society.

[18]  W. Saenger,et al.  Inclusion Compounds. XIX.1a The Formation of Inclusion Compounds of α-Cyclodextrin in Aqueous Solutions. Thermodynamics and Kinetics , 1967 .

[19]  K. A. Connors,et al.  Theoretical analysis of comparative studies of complex formation. , 1966, Journal of pharmaceutical sciences.

[20]  J. Lach,et al.  Interaction of pharmaceuticals with schardinger dextrins V. Interaction with a series of phenyl‐substituted carboxylic acids , 1965 .

[21]  G. Johnson,et al.  Computation of Association Constants from Spectrophotometric Data. II. Multiple Equilibria , 1965 .

[22]  K. A. Connors,et al.  Inhibition of an Ester Hydrolysis by Imidazole , 1965 .

[23]  J. Cohen,et al.  Interaction of pharmaceuticals with Schardinger dextrins. I. Interaction with hydroxybenzoic acids and p-hydroxybenzoates. , 1963, Journal of pharmaceutical sciences.

[24]  M. L. Bender,et al.  Spectrophotometric Investigations of the Mechanism of α-Chymotrypsin-catalyzed Hydrolyses. Detection of the Acyl-enzyme Intermediate1-3 , 1962 .

[25]  H. Schlenk,et al.  The Association of α- and β-Cyclodextrins with Organic Acids1 , 1961 .

[26]  C. A. Streuli.  Relative Acidities of Substituted Phenols in Pyridine and Water , 1960 .

[27]  J. Fritz,et al.  Differentiating Titration of Acid Mixtures in Acetone , 1957 .

[28]  R. Gurney.  Ionic processes in solution , 1953 .

[29]  J. Hildebrand,et al.  ULTRAVIOLET ABSORPTION BANDS OF IODINE IN AROMATIC HYDROCARBONS , 1948 .