Study on molecular recognition of para-aminobenzoic acid species by α-, β- and hydroxypropyl-β-cyclodextrin

Time-programmable pH: decarboxylation of nitroacetic acid allows the time-controlled rising of pH to a definite value

“…As a proof of concept, the nitroacetic acid driven pH 1(high) –pH 2(low) –pH 3(high) time-programmed sequence has been applied to the well-known host–guest pH dependent interaction between alpha-cyclodextrin 6 and p -aminobenzoic acid 7 , which can be conveniently monitored using a spectrofluorometer. 19 The charge state of 7 can be easily controlled by adjusting the solution pH. Amino acid 7 is partially positively charged at pH 3.0, neutral (zwitterionic) at intermediate pH and negatively charged at pH 11.0.…”

Phosphorescence Properties of p-Aminobenzoic Acid Immobilized on a Nylon Membrane

“…Recently, the interactions of ␣-, ␤-, and hydroxypropyl-␤-cyclodextrins with PABA were studied in aqueous solution. 10 Among the examined CDs, ␣-CD was the most suitable for the inclusion of the compound (preferably in its neutral form) because of its size. In previous experiments with both ␣and ␤-CD, we also verified that ␣-CD produces better signal from the nylon support and therefore it was selected for subsequent studies.…”

“…8,9 It is often used as a sulfonamide antagonist and as a sunscreen agent, and also in cutaneous alterations such as alopecia. [10][11][12] PABA is administered as N-benzoyl-L-tyrosyl-p-aminobenzoic acid (bentiromide) for a screening test for pancreatic function. The recovery of urinary PABA is proportional to the pancreatic endopeptidase chymotrypsin activity and a low activity is indicative of pancreatic deficiency.…”

Inclusion Complexes of ß-Cyclodextrin and Its Silyl Derivative with Some Pharmacologically Important Aromatic Monocarboxylic Acids

“…Previous studies on inclusion complexes of β-cyclodextrin (I) with acids III [2,4,5], IV [5,6], V [7], VI [8][9][10][11], and VII [12][13][14][15] involved mainly determination of the structure of labile complexes in solution (which occurred in equilibrium with the initial compounds) by different DOI: 10 [4][5][6][8][9][10]. In some cases, crystalline inclusion complexes of β-cyclodextrin (I) with benzoic [2], acetylsalicylic [7], p-aminobenzoic [11], and nicotinic acids [15] were isolated, and their structure was studied by X-ray analysis.…”

“…Fairly severe drying conditions (1 mm, 50°C, 4 h) indicated stability of the isolated compounds. According to the data of [2,[4][5][6][7][8][9][10][11][12][13][14][15] cyclodextrin-acid complexes with the following stoichiometric compositions were detected: I-III: 1 : 1 in solution [4], 2 : 2 in crystal [2]; I-IV: 1 : 1 in solution [5,6]; I-V: 2 : 3 in crystal (2 molecules of acetylsalicylic acid and one molecule of salicylic acid) [7]; I-VI: 1 : 1 in solution [8][9][10], 1 : 1 in crystal [11]; I-VII: 1 : 1 in solution [12][13][14], 1 : 1 in crystal [15]. We can state that under the above conditions β-cyclodextrin with acids III-V and VII forms stable complexes with a different stoichiometry and that no stable complexes are formed with acid VI.…”