Document Detail

Potentiometric study of molecular complexes of weak acids and bases applied to complexes of alpha-cyclodextrin with para-substituted benzoic acids.
MedLine Citation:
PMID:  7062249     Owner:  NLM     Status:  MEDLINE    
The theory of the potentiometric methods of studying complexes of ionizable substrates was developed, nd 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 1:1 (SL) and 1:2 (SL2) complexes with the ligand (L). It was applied to complexes of alpha-cyclodextrin (cyclohexaamylose) with 10 para-substituted benzoic acid derivatives. Letting K11a and K12a be stability constants for the conjugate acid forms of the substrates, and K11b, K12b for the conjugate base forms, it was found that K12b is zero for all substrates, K12a is zero for seven of the substrates, and K11a greater than K11b in every case. Hammett plots yielded p11a and p11b values of -0.31 and 0.77, respectively, which was interpreted to mean that K11a mainly represents binding at the carboxylic acid site, and K11b describes binding at the site of the para-substituent. This model of the complexing suggests that K12a represents binding at the para-substituent, and therefore K12a should vary roughly with substituent as K11b does; this trend was observed.
K A Connors; S F Lin; A B Wong
Related Documents :
23747099 - The antibacterial activity and stability of acetic acid.
24124979 - A zwitterionic carbanion frustrated by boranes - dihydrogen cleavage with weak lewis ac...
18819519 - Enhanced oral bioavailability of salvianolic acid b by phospholipid complex loaded nano...
24116229 - ω3-pufas exert anti-inflammatory activity in visceral adipocytes from colorectal cance...
23094139 - Artificial specific binders directly recovered from chemically modified nucleic acid li...
23973629 - A direct and continuous assay for the determination of thioredoxin reductase activity i...
24797379 - Use of a caspase multiplexing assay to determine apoptosis in a hypothalamic cell model.
1623959 - Phospholipid composition of myeloid bodies from chick retinal pigment epithelium.
1938199 - Proximal gastric vagotomy. a comparative study between the standard technique and the e...
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of pharmaceutical sciences     Volume:  71     ISSN:  0022-3549     ISO Abbreviation:  J Pharm Sci     Publication Date:  1982 Feb 
Date Detail:
Created Date:  1982-05-12     Completed Date:  1982-05-12     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  2985195R     Medline TA:  J Pharm Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  217-22     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Chemical Phenomena
Hydrogen-Ion Concentration
Models, Chemical
Reg. No./Substance:
0/Acids; 0/Benzoates; 0/Cyclodextrins; 0/Dextrins; 0/Ligands; 0/alpha-Cyclodextrins; 10016-20-3/alpha-cyclodextrin; 9005-25-8/Starch

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Investigation of digoxin, quinidine, and disopyramide interactions in rats utilizing parotid saliva,...
Next Document:  Reversed-phase ion-pair chromatography of tetracycline, tetracycline analogs, and their potential im...