scholarly journals Environmental Effects on the Absorption and Fluorescence Spectral Characteristics of Benzimidazole-2-carboxylic Acid and Its Ester

1989 ◽  
Vol 62 (8) ◽  
pp. 2668-2675 ◽  
Author(s):  
Hemant K. Sinha ◽  
Sneh K. Dogra
Keyword(s):  
Carboxylic Acid ◽  
Environmental Effects ◽  
Spectral Characteristics

Spectral characteristics of the ? (OH) infrared bands and enthalpy of carboxylic acid-base H-complexes

1974 ◽  
Vol 20 (5) ◽  
pp. 645-648
Author(s):  
A. A. Mashkovskii ◽  
V. P. Glazunov ◽  
S. E. Odinokov
Keyword(s):  
Carboxylic Acid ◽  
Spectral Characteristics ◽  
Acid Base

scholarly journals Encapsulation of benzene carboxylic acids using cyclodextrins

2021 ◽  
Vol 12 (1) ◽  
pp. 40-51
Author(s):  
L. A. Belyakova ◽  
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Spectral Characteristics ◽  
Complexing Agents ◽  
X Ray ◽  
Medicinal Substances ◽  
Nonspecific Interactions ◽  
The Stability ◽  
Formation Of Complexes

The encapsulation of medicinal substances in various polymers is a common way to increase their thermal, hydrolytic, and chemical stability. However, the bioavailability of the encapsulated drugs decreases. The solution to this important problem can be the preparation of nanocapsules of medicinal substances using complexing agents, for example, cyclodextrins. The purpose of this work is to study the possibility of encapsulation of benzoic, salicylic, and β-resorcylic acids using α- and β-cyclodextrins. The interaction of benzene carboxylic acids with cyclodextrins in aqueous solutions at 20–30 оС has been studied by spectrophotometry. The formation of complexes with a composition of 1:1 in the cyclodextrin – benzene carboxylic acid systems has been proven. The stability constants of the complexes and the main thermodynamic parameters of complex formation have been calculated. It has been shown that the nature of changes in the spectral characteristics of benzene carboxylic acids in the presence of cyclodextrins can be used to predict the possibility of aromatic organic compounds encapsulation. The determining role of the complementarity of geometric parameters of cyclodextrins and benzene carboxylic acids in the preparation of inclusion complexes with features of nanocapsules has been found. The prospects of using β-cyclodextrin for encapsulation of benzene carboxylic acids have been demonstrated. The complexes of β-cyclodextrin with benzene carboxylic acids were synthesized and studied by IR spectroscopy, X-ray analysis and derivatography. The formation of two types of complexes in the β-cyclodextrin – benzene carboxylic acid system was established. The first type of complexes is formed due to nonspecific interactions between the hydrophobic cavity of β-cyclodextrin and the benzene carboxylic acid molecule, the second type is due to specific interactions between the functional groups of molecules. Benzoic and salicylic acids form nanocapsules with β-cyclodextrin, and their hydrolytic and thermal stability increases. Complexes of the second type acquire the properties of a new compound: β-resorcylic acid loses its individuality, forming strong supramolecular structures with β-cyclodextrin.

Imaging molecules adsorbed onto electrodes under potential control by scanning probe microscopy

1991 ◽  
Vol 49 ◽  
pp. 376-377 ◽  
Author(s):  
N.J. Tao ◽  
J.A. DeRose ◽  
P.I. Oden ◽  
S.M. Lindsay
Keyword(s):  
Surface Charge ◽  
Environmental Effects ◽  
Scanning Probe Microscopy ◽  
Statistical Significance ◽  
Electrochemical Methods ◽  
Surface Structures ◽  
Scanning Probe ◽  
Potential Control ◽  
Afm Imaging ◽  
Special Circumstances

Clemmer and Beebe have pointed out that surface structures on graphite substrates can be misinterpreted as biopolymer images in STM experiments. We have been using electrochemical methods to react DNA fragments onto gold electrodes for STM and AFM imaging. The adsorbates produced in this way are only homogeneous in special circumstances. Searching an inhomogeneous substrate for ‘desired’ images limits the value of the data. Here, we report on a reversible method for imaging adsorbates. The molecules can be lifted onto and off the substrate during imaging. This leaves no doubt about the validity or statistical significance of the images. Furthermore, environmental effects (such as changes in electrolyte or surface charge) can be investigated easily.

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