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1
Content available remote Spectral properties of coumarin derivatives in various environments
100%
Holubekova A. , Mach P. , Urban J.
Open Chemistry
|
2013
|
tom 11
|
nr 4
492-501
EN
The structural and spectral properties of coumarin derivatives in complex environments were investigated within the time-dependent density functional theory (TD DFT). Absorption spectra calculations were obtained at TD PBE0/6-31+G(d,p) level of theory for coumarin47 in the gas-phase and in various polar and non-polar organic solvents. The geometries of coumarins 6, 30, 47 and 522 in the gas phase and in inclusion complexes with the β-cyclodextrin (βCD) were determined by PM3 and DFT (HCTH/6-31G) calculations. Encapsulation of coumarin in βCD and associated changes in electronic structure produced either a red or blue shift in the absorption spectra of coumarins. A proposed cavity model for βCD-coumarin complex in water solution allowed identification of various contributions to the overall shift in the absorption spectra of coumarin upon complex formation in a solvent environment [...]
2
Content available remote Theoretical studies on the binding affinities of β-cyclodextrin to small molecules and monosaccharides
100%
Chen S. , Teng Q. , Wu S.
Open Chemistry
|
2006
|
tom 4
|
nr 2
223-233
EN
Equilibrium geometries and electronic structures of complexes between β-cyclodextrin (β-CD) and some small molecules as well as monosaccharides were investigated by Austin Model 1 (AM1) to obtain binding energy of the complexes. It was indicated that β-CD could bind the structurally similar solvent molecules and monosaccharides because of the negative binding energy of the complexes, and especially could show the chiral binding ability to monosaccharides with more hydroxyl groups, due to its chiral characteristics. The complexes were stabilized by the hydrogen bonding between β-CD and guests. Based on the AM1 optimized geometries, the IR spectra were calculated by AM1 method. Vibration frequencies of O-H bonds in the guests were red-shifted owing to the weakening of the O-H bonds with the formation of the complexes.
3
Content available remote Resolution of propranolol and atenolol enantiomers on β-cyclodextrin-impregnated silica gel layers
88%
Joshi S. , Sharma A.
Acta Chromatographica
|
2012
|
tom Vol. 24, no. 2
317--322
EN
Enantiomeric resolution of two commonly used β-blockers, namely, (±)-propranolol and (±)-atenolol, has been achieved on silica gel layers which were bulkimpregnated with β-cyclodextrin. Solvent systems DMF-ethyl acetate-butanol (3:2:5, υ/υ) and butanol-acetic acid-ethyl acetate-ammonia (5:2:2:0.5, υ/υ) successfully resolved the enantiomers of (±)-propranolol and (±)-atenolol, respectively. The spots were located with iodine vapor. The effects of concentration of the chiral selector and mobile phase variation were also studied.
4
Content available remote Direct separation of clopidogrel enantiomers by reverse-phase planar chromatography method using β-cyclodextrin as a chiral mobile phase additive
88%
Antic D. , Filipic S. , Ivkovic B. , Nikolic K. , Agbaba D.
Acta Chromatographica
|
2011
|
tom Vol. 23, no. 2
235--245
EN
A simple and rapid TLC method using β-cyclodextrin as a chiral mobile phase additive (CMPA) was developed for direct separation of S-clopidogrel and its impurity R-clopidogrel. The influence of different factors (stationary phases, organic modifiers, chiral selectors and their concentrations in the mobile phase, and optimal saturation time of the chamber) on enantioseparation was studied. The best resolution of clopidogrel enantiomers was achieved on Polygram®cel 300 Ac-10% plates using isopropanol-0.5 mM β-cyclodextrin (6:4, υ/υ) as mobile phase in TLC chamber previously equilibrated with the mobile phase for 20 min. The spots were detected under UV light and using iodine vapours. The method enables rapid separation of clopidogrel enantiomers and can be successfully used in control of stereoselective synthesis of clopidogrel and in control of its purity. Finally, the molecular modelling of the inclusion complexes between the analytes and α-, β-, and γ-cyclodextrin was performed to investigate the mechanism of the enantiorecognition.
5
Content available remote Nanosized centers for mercury(II) ions adsorption on a surface of modified silica
88%
Belyakova L. , Shvets O. , Lyashenko D.
Open Chemistry
|
2008
|
tom 6
|
nr 4
581-591
EN
The present work investigates the adsorptive interactions of Hg(II) ions in aqueous medium with hydroxylated silica, aminopropylsilica and silica chemically modified by β-cyclodextrin. Batch adsorption studies were carried out with various agitation times and mercury(II) concentrations. The maximum adsorption was observed within 15–30 min of agitation. The kinetics of the interactions, tested with the model of Lagergren for pseudo-first and pseudo-second order equations, showed better agreement with first order kinetics (k1 = 3.4 ± 0.2 to 5.9 ± 0.3 min−1). The adsorption data gave good fits with Langmuir isotherms. The results have shown that β-cyclodextrin-containing adsorbent has the largest adsorption specificity to Hg(II): K L = 4125 ± 205 mmol−1. “β-cyclodextrin-NO3-” inclusion complexes with ratio 1: 1 and super molecules with composition C42H70O35 ⊎ 3 Hg(NO3)2 are formed on the surface of β-cyclodextrin-containing silica. [...]
6
Content available Pyrolysis characteristics and kinetics of β-cyclodextrin and its two derivatives
88%
Zhu G. , Xiao Z. , Zhou R. , Niu Y.
Polish Journal of Chemical Technology
|
2015
|
tom Vol. 17, nr 4
1--4
EN
β-cyclodextrin (β-CD) and its derivatives have been widely used to prepare inclusion complexes. However, systematic research on their thermal stabilities, pyrolysis characteristics and kinetics has rarely been reported. In this paper, thermogravimetric analysis was employed to investigate β-cyclodextrin and its two derivatives, 2-Hydroxypropyl-β-cyclodextrin (HP-β-CD) and monochlorotriazinyl-β-cyclodextrin (MCT-β-CD). The pyrolysis characteristics and kinetic parameters were obtained. The results show that three stages can be distinguished during the heating process of the above three samples. The temperature of initial decomposition of HP-β-CD (309.5°C is higher than that of β-CD (297.8°C), while the temperature of initial decomposition of MCT-β-CD (231.4°C) is lower than that of β-CD. For the three cyclodextrins, the thermal stability in descending order is HP-β-CD, β-CD and MCT-HP-β-CD. The activation energy values are 350.6, 303.3 and 113.9 KJ/mol, and the pre-exponential factor values are 1.11×1031, 1.37×1026 and 1.39×1010 for β-CD, HP-β-CD and MCT-β-CD respectively.
7
Content available remote The protection of Nifedipin from photodegradation due to complex formation with β-cyclodextrin
88%
Nikolić V. , Ilić D. , Nikolić L. , Stanković M. , Cakić M. , Stanojević L. , Kapor A. , Popsavin M.
Open Chemistry
|
2010
|
tom 8
|
nr 4
744-749
EN
The inclusion complex β-cyclodextrin:nifedipin was prepared in solid state by coprecipitation with 1:1 mol ratio. The structure of the obtained complex and nifedipin was characterized by use of X-ray diffraction (XR), infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC) methods. The photodegradation of nifedipin and the β-cyclodextrin:nifedipin inclusion complex in solid state was monitored under natural daylight by infrared spectroscopy, whereby the free nifedipin degraded four to five times faster than the complexed nifedipin. The photodegradation products of both free and complexed nifedipin, formed during irradiation at 350 nm (with corresponding energy flux of 18 W m−2) were monitored by liquid chromatography during various time intervals. The speed of formation of nitroso- and nitro-phenyl derivatives by nifedipin irradiation was significantly higher than those of complexed nifedipin irradiation, which indicates its increased photostability in the inclusion complex. The effect on this property is significant because it contributes both to the improvement of the therapeutic effect of nifedipin and to the safer application thereof. [...]
8
Content available Thermo-, magneto- and photo- dependent electrical properties of hierarchical InSe<β-CD> supramolecular compound
88%
Popławski T. , Bordun I. , Pidluzhna A.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2020
|
tom Vol. 68, nr 2
361--366
EN
The hierarchical structure of InSe<β-CD> composition with 4-fold grade expansion was synthesized with the intercalation-deintercalation technique. Electrical properties of the structure obtained were examined using impedance and thermostimulated current spectroscopy methods. Influence of temperature, static magnetic field and illumination on electrical properties of the synthesized compound was investigated. Changes in the impurity spectrum of the expanded hierarchical structure were analyzed and extraordinary magneto- and photoimpedance behavior of InSe<β-CD> at room temperature was explained.
9
Content available Theoretical studies of interactions in cyprodinil-α-cyclodextrin and cyprodinil-β-cyclodextrin systems
75%
Hołaj-Krzak J. T.
Journal of Water and Land Development
|
2023
|
tom no. 57
9--20
EN
The paper presents the results of theoretical calculations in terms of the G4MP2 composite method for cyprodinil-α-cyclodextrin (C0@α-CD) and cyprodinil-β-cyclodextrin (C0@β-CD) systems. Studies also covered analogous systems consisting of the anion (C-) and the cation (C+) of cyprodinil. The geometries of the cyprodinil molecule and ions were optimized on the basis of the DFT theory, using hybrid (B3LYP, PBE0), pure (B97-D) and “meta” (M06-2X) GGA functionals for selected Pople basis sets [6-311++G(d,p), 6-311++G(2d,p), 6-311++G(2d,2p)] and Dunning basis set (aug-cc-pVDZ). The research results suggest that the affinity of “guest” molecules for “hosts” is relatively low. Theoretical studies of the “guest-host” systems allow to predict the properties of the designed preparations.
10
Content available remote Applications of β-cyclodextrins in textiles
63%
Bhaskara-Amrit U. R. , Agrawal P. B. , Warmoeskerken M. M. C. G.
Autex Research Journal
|
2011
|
tom Vol. 11, no. 4
94--101
EN
In this paper, the general features of β-cyclodextrin and their applications in the textile industry have been reviewed. The use of β-cyclodextrin in the textile industry is of great significance due to its wide range of application. One of the key aspects is the attachment technique of β-cyclodextrin to the textile's surface. This review deals with this in depth. Some quantification and characterization methods of Textile-β-cyclodextrin are discussed. In the last few years, the new direction in textile research is the functionalisation of textile systems. It is believed that β-cyclodextrin will play a very important role in these new developments. β-cyclodextrin can act as a host for various guest molecules. This enables the development of fabrics that release chemical compounds such as fragrances and antimicrobial agents. It is concluded that there are many possibilities for the development of new textile products with advanced properties based on β-cyclodextrin.
11
Content available remote Dyeing Kinetics of Vinylon Modified with β-Cyclodextrin
63%
Lu M. , Liu Y. P.
Fibres & Textiles in Eastern Europe
|
2011
|
tom Vol. 19, no. 5 (88)
133--135
EN
In this paper, dyeing experiments were performed on vinylon modified with β-cyclodextrin using a reactive dye. The kinetics of the dyeing process for vinylon modified with β-cyclodextrin was researched by measuring the dye uptake, time of half dyeing, dyeing rate constant and the diffusion coefficient. The results show that grafting β-cyclodextrin onto vinylon enables to increase the diffusion and uptake of reactive dyestuffs from a bath, and that the degree of grafting is closely related to the improvement of diffusion and uptake of dyestuffs.
PL
Przeprowadzono próby barwienia barwnikami reaktywnymi włókien winylowych modyfikowanych β–cyklodekstrynami. Kinetykę procesu określano mierząc zużycie barwnika, połowiczny czas barwienia, stała prędkość barwienia oraz współczynnik dyfuzji. Wyniki wykazały, że pokrycie włókien ß–cyklodekstrynami pozwoliło na zwiększenie dyfuzji barwnika i zuzycie stosowanych barwnikow reaktywnych oraz, że stopień pokrycia jest skorelowany z poprawa dyfuzji i zużycia barwników.
12
Content available remote Electrospun Thermoplastic Polyurethane Mats Containing Naproxen– Cyclodextrin Inclusion Complex
51%
Akduman C. , Özgüney I. , Kumbasar E. P. A.
Autex Research Journal
|
2014
|
tom Vol. 14, no. 4
239--246
EN
Incorporation of cyclodextrins (CDs) into electrospun nanofibrous materials can be considered as potential candidates for functional medical textile applications. Naproxen (NAP) is a type of non-steroidal anti-inflammatory drug commonly administered for the treatment of pain, inflammation and fever. Drug-inclusion complex formation with CDs is an approach to improve the aqueous solubility via molecular encapsulation of the drug within the cavity of the more soluble CD molecule. In this study, NAP or different NAP-CD inclusion complexes loaded nanofibres were successfully produced through electrospinning and characterised. The inclusion complex loaded mats exhibited significantly faster release profiles than NAP-loaded thermoplastic polyurethane (TPU) mats. Overall, NAP-inclusion complex loaded TPU electrospun nanofibres could be used as drug delivery systems for acute pain treatments since they possess a highly porous structure that can release the drug immediately.
13
Content available Application of Environment-Friendly Processes Aimed at Bonding β-Cyclodextrine onto Cellulosic Materials
51%
Grgac S. F. , Malinar R.
Fibres & Textiles in Eastern Europe
|
2018
|
tom Vol. 26, no. 5 (131)
63--69
EN
The impact of the pre-treatment of cellulose material in NaOH solution and of microwave radiation on the mechanism of crosslinking β-cyclodextrin with cellulose was investigated in this paper. Citric acid and Na-hypophosphite as catalysts were applied for better crosslinking. Inclusion compounds with tea tree essential oil and cyclodextrines grafted onto cotton fabric were made in order to verify that cavities were available for inclusion compounds. The permanence of β-CD on the cellulose fabrics treated was tested by ISO 6330:2012. The properties and structure of the materials treated were characterised by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The breaking force and mechanical damage of the materials were determined according to EN ISO 13934-1:1999. The results indicated better bonding between cellulose and β-cyclodextrin where microwave treatment was applied, the phenomenon of which is of great importance for long lasting wash durability. In order to quantify the odour releasing behaviour of β-CD treated cellulose fabrics, olfactometric determination of the intensity of odour was undertaken.
PL
Badano wpływ wstępnej obróbki materiału celulozowego w roztworze NaOH i promieniowania mikrofalowego na mechanizm sieciowania β-cyklodekstryny z celulozą. Dla lepszego usieciowania zastosowano kwas cytrynowy i Na-podfosforyn jako katalizator. Zastosowano także olej eteryczny z drzewa herbacianego i cyklodekstryny szczepione na tkaninie bawełnianej. Trwałość β-CD na obrabianych tkaninach celulozowych została przetestowana zgodnie z normą ISO 6330: 2012. Właściwości i strukturę obrabianych materiałów scharakteryzowano za pomocą spektroskopii w podczerwieni z transformatą Fouriera (FTIR) i skaningowej mikroskopii elektronowej (SEM). Siła zrywająca i mechaniczne uszkodzenia materiałów zostały określone zgodnie z normą EN ISO 13934-1: 1999. Wyniki wskazują na lepsze wiązanie pomiędzy celulozą i β-cyklodekstryną, w której zastosowano obróbkę mikrofalową. Zjawisko to ma ogromne znaczenie dla długotrwałej trwałości na pranie. W celu ilościowego określenia uwalniania nieprzyjemnych zapachów tkanin celulozowych poddanych obróbce β-CD, przeprowadzone zostało olfaktometryczne oznaczanie intensywności zapachu.
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