𝔖 Bobbio Scriptorium
✦   LIBER   ✦

Potentiometric study of molecular complexes of weak acids and bases applied to complexes of α-Cyclodextrin with para-Substituted Benzoic Acids

✍ Scribed by Kenneth A. Connors; Shu-Fen Lin; Albert B. Wong

Publisher
John Wiley and Sons
Year
1982
Tongue
English
Weight
628 KB
Volume
71
Category
Article
ISSN
0022-3549

No coin nor oath required. For personal study only.

✦ Synopsis

The theory of the potentiometric method for studying complexes of ionizable substrates was developed, and graphical techniques are described for obtaining stability constant estimations from the data. The method described is for a system in which the conjugate acid and base forms of the substrate (S) are capable of forming 1:l (SL) and 1:2 (SL:!) complexes with the ligand (L). It was applied to complexes of a-cyclodextrin (cyclohexaamylose) with 10 para-substituted benzoic acid derivatives. Letting Klla and K1za be stability constants for the conjugate acid forms of the substrates, and Kllb, Kl2b for the conjugate base forms, it was found that K12b is zero for all substrates, K1za is zero for seven of the substrates, and Klla > Kllb in every case. Hammett plots yielded p l l a and P l l b values of -0.31 and 0.77, respectively, which was interpreted to mean that Klla mainly represents binding at the carboxylic acid site, and Kllb describes binding at the site of the para-substituent. This model of the complexing suggests that K1za represents binding at the para-substituent, and therefore K1za should vary roughly with substituent as Kllb does; this trend was observed.

Keyphrases Complexation-potentiometric study, a-cyclodextrins with para-substituted benzoic acids 0 Stability constants-a-cyclodextrins with para-substituted benzoic acids, potentiometric studies a-Cyclodextrins-complexes with para -substituted benzoic acids, potentiometric study having 1:l and 1 2 stoichkmetry,-respectively.

📜 SIMILAR VOLUMES

Theoretical studies of inclusion complex
Theoretical studies of inclusion complexes of α- and β-cyclodextrin with benzoic acid and phenol
✍ Ming-Ju Huang; John D. Watts; Nicholas Bodor 📂 Article 📅 1997 🏛 John Wiley and Sons 🌐 English ⚖ 257 KB 👁 1 views

A series of semiempirical molecular orbital calculations using the AM1 method were performed on the inclusion complexes of ␣and ␤-cyclodextrin with benzoic acid and phenol in the ''head-first'' and ''tail-first'' positions. The AM1 results show that ␣-cyclodextrin complexes with both guest compounds

H5dotasa (=(αRS)-α-(Carboxymethyl)-1,4,7
H5dotasa (=(αRS)-α-(Carboxymethyl)-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic Acid), an Asymmetrical Derivative of H4dota (=1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetraacetic Acid) Substituted at One Acetate Pendant Arm: 1H-NMR and Potentiometric Studies of the Ligand and Its Lanthanide(III) Complexes
✍ João P. André; Ernö Brücher; Robert Kiraly; Rui A. Carvalho; Helmut Mäcke; Carlo 📂 Article 📅 2005 🏛 John Wiley and Sons 🌐 German ⚖ 192 KB 👁 1 views

## Abstract The ligand H~5~dotasa (=(__αRS__)‐__α__‐(carboxymethyl)‐1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid) is a H~4~dota‐like macrocyclic ligand with a carboxymethyl CH~2~COOH substituent at the C(__α__) atom of one of the four acetate pendant arms of H~4~dota (=1,4,7,10‐tetraaza