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1.
Mahmoud M. Al Omari Musa I. El-Barghouthi Mohammad B. Zughul J. Eric D. Davies Adnan A. Badwan 《Journal of solution chemistry》2008,37(2):249-264
The interaction of two benzocycloheptanes namely, pizotifen (Pizo) and ketotifen (Keto), with cyclodextrins (CDs: α-, β-, γ-, and HP-β-CDs) has been investigated by several techniques including phase solubility, X-ray powder diffractometry, 1H-nuclear magnetic resonance and molecular mechanical modeling. The effects of CD type, pH, ionic strength and temperature
on complex stability were also explored. The complex formation constant (K
11) values for the Pizo/CD system follows the decreasing order β-CD > γ-CD > HP-β-CD > α-CD. However, for the Keto/CD system it follows the decreasing order γ-CD > β-CD > HP-β-CD > α-CD. The tendency of Pizo and Keto to complex with β-CD is driven to the extent of 70% by the hydrophobic effect. Complex formation of Keto and Pizo was substantially driven
by entropy (>100 J⋅mol−1⋅K−1) but slightly retarded by enthalpy (3–8 kJ⋅mol−1). 1H-NMR and MM+ studies indicate multimodal inclusion of the methylpiperadine, thiophene and phenyl moieties into the β-CD cavity. 相似文献
2.
A. A. Abdoh M. B. Zughul J. Eric. D. Davies A. A. Badwan 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):503-510
Guest–host interactions were examined for neutral diclofenac (Diclo) and Diclofenac sodium (Diclo sodium) with each of the
cyclodextrin (CD) derivatives: α-CD, β-CD, γ-CD and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), all in 0.05 M aqueous phosphate
buffer solution adjusted to 0.2 M ionic strength with NaCl at 20 °C, and with β-CD at different pHs and temperatures. The
pH solubility profiles were measured to obtain the acid–base ionization constants (pK
as) for Diclo in the presence and absence of β-CD. Phase solubility diagrams (PSDs) were also measured and analyzed through
rigorous procedures to obtain estimates of the complex formation constants for Diclo/CD and Diclo sodium/CD complexation in
aqueous solutions. The results indicate that both Diclo and Diclo sodium form soluble 1:1 complexes with α-, β-, and HP-β-CD.
In contrast, Diclo forms soluble 1:1 Diclo/γ-CD complexes, while Diclo sodium forms 1:1 and 2:1 Diclo/γ-CD, but the 1:1 complex
saturates at 5.8 mM γ-CD with a solubility product constant (pK
sp = 5.5). Therefore, though overall complex stabilities were found to follow the decreasing order: γ-CD > HP-β-CD > β-CD > α-CD,
some complex precipitation problems may be faced with aqueous formulations of Diclo sodium with γ-CD, where the overall concentration
of the latter exceeds 5.8 mM γ-CD. Both 1H-NMR spectroscopic and molecular mechanical modeling (MM+) studies of Diclo/β-CD indicate the possible formation of soluble isomeric 1:1 complexes in water. 相似文献
3.
The inclusion of vanadocene dichloride (VDC) and 1,1′-dimethyl vanadocene dichloride (MeVDC) into cyclodextrines (α-CD, β-CD
and γ-CD) was studied by EPR spectroscopy. It was found that VDC and MeVDC with β-CD and γ-CD form true inclusion compounds,
but with α-CD, VDC and MeVDC gave only fine dispersion mixtures. The inclusion was validated by anisotropic EPR spectra of
solid samples. In addition, the antimicrobial was validated by anisotropic EPR spectra of solid samples. In addition, the
antimicrobial behavior (against E. coli) of each of the complexes was determined. It was established that not only did VDC and MeVDC cause elongation of E. coli, but also the new vanadocene inclusion complexes were effective in this regard. 相似文献
4.
M. I. El-Barghouthi N. A. Masoud J. K. Al-Kafawein M. B. Zughul A. A. Badwan 《Journal of inclusion phenomena and macrocyclic chemistry》2005,53(1-2):15-22
The solubility of risperidone (Risp) in aqueous buffered cyclodextrin (CD) solution was investigated for α-, β-, γ- and HP-β-CD. The effects of pH, ionic strength and temperature on complex stability were also explored. Neutral Risp tends to form
higher order complexes (1:2) with both β- and HP-β-CD, but only 1:1 type complexes with α-, and γ-CD. The tendency of Risp to complex with cyclodextrins is in the order β-CD > HP-β-CD > γ-CD > α-CD. The 1:1 complex formation constant of Risp/HP-β-CD increases with increasing ionic strength in an opposite trend to the inherent solubility (S
0) of Risp, thus indicating significant hydrophobic effect. The hydrophobic effect contributes to the extent of 72% towards
neutral Risp/HP-β-CD complex stability, while specific interactions contribute only 4.7 kJ/mol. Thermodynamic studies showed that 1:1 Risp/HP-β-CD complex formation is driven by a favorable enthalpy change (ΔH
0=−31.2 kJ/mol, ΔS
0=−7 J/mol.K) while the 1:2 complex is largely driven by entropy changes (ΔH
0=−5.0 kJ/mol, ΔS
0=42 J/mol.K). Complex stability was found to vary with pH, with a higher formation constant for neutral Risp. Molecular mechanical
computations using MM (atomic charges and bond dipole algorithms) and Amber force fields, which were carried out to explore
possible sites of interactions between Risp and CDs and to rationalize complex stoichiometry, produced similar results concerning
optimal inclusion complex geometries and stoichiometries. 相似文献
5.
L. Omar M. I. El-Barghouthi N. A. Masoud A. A. Abdoh M. M. Al Omari M. B. Zughul A. A. Badwan 《Journal of solution chemistry》2007,36(5):605-616
The extent and mode of solubility enhancement exerted by the cyclodextrins (α-, β-, γ-, and HP-β-CDs) on loratadine (Lort) have been experimentally measured under controlled conditions in buffered aqueous solutions. Rigorous
nonlinear regression analysis of the phase solubility diagrams obtained in 0.1 mol⋅L−1 phosphate buffer at pH=7.0 and 25 °C revealed the following: neutral Lort (pK
a
=4.6) tends to form soluble 1:1 and 1:2 Lort/CD complexes with all four of the examined CDs, where complex stability follows
the decreasing order β-CD>HP-β-CD>γ-CD>α-CD. The hydrophobic character of Lort constitutes about 66% of the driving force for complex formation whereas specific interactions
contribute 11.2 kJ⋅mol−1 towards the stability of the complexes. Thermodynamic studies showed that Lort/CD complex formation was favored by large
enthalpic contributions but was impeded by negative entropic changes. Dissolution studies indicate that the dissolution rate
of Lort from the freeze-dried Lort/β-CD complex is significantly higher than that of the corresponding physical mixture. Both DSC studies and molecular mechanical
modeling of Lort/β-CD interactions were carried out to explore the possible formation of inclusion complexes. 相似文献
6.
Subramanian Annalakshmi Kasi Pitchumani 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):403-408
The effect of cyclodextrin inclusion complex formation on the intramolecular charge transfer (ICT) of the included 4-N,N-dimethylamino-2-strylquinoline (2-StQ-NMe2) has been studied in detail. 2-StQ-NMe2 in presence of α-, β-, γ- and HP-α- and Hp-β-CDs predominantly exhibits ICT fluorescence predominantly than the emission
from locally excited state, whereas in presence of HP-γ-CD the later is observed. In presence of α-CD, 2:1 complexation of
the 2-StQ-NMe2 is observed in addition to 1:1 complexation. The observed results are explained by the CD cavity size and an active role
for the secondary hydroxyl groups present in the wider rim of the CD cavity and also which finds support from absorption,
emission, lifetime and molecular modeling studies.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. 相似文献
7.
J. Báscuas L. García-Río J. R. Leis M. Méndez-Pérez 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):603-606
A kinetic study was carried out on the solvolysis of ortho benzoyl chlorides in the presence of α-, β- and γ-Cyclodextrin (CD). The solvolysis mechanism of benzoyl chlorides is sensitive
to the substituents, and to the solvent in which the reaction takes place. In water, the behaviour exhibited by benzoyl chlorides
which have electron-attracting groups, is consistent with an associative mechanism whilst electron-donating substituents induce
a dissociative mechanism. The results obtained in the presence of CD show a decrease in the observed rate constant, k
obs, as the CD concentration increases. This behaviour can be explained if these substrates undergo solvolysis through a dissociative
path in the presence of α-, β- and γ-CD. 相似文献
8.
Several host–guest inclusion compounds of eugenol as a guest molecule and cyclodextrins (α-,β-,γ-CD) and heptakis (2,6-di-O-methyl)-β-cyclodextrin (DMβ-CD) as hosts were investigated in the solid state and in aqueous solution. The one-to-one solid inclusion compounds of eugenol
and β-CD or γ-CD were prepared, but those of eugenol with α- or DMβ-CD were not obtained under the same condition. However, the UV-visible absorption spectroscopy data indicated that the liquid
guest could form a 1:1 inclusion compound with all four hosts respectively in aqueous solution. The two solid inclusion compounds
were characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TG), differential
scanning calorimetry (DSC) and nuclear magnetic resonance (NMR). The association constants (K), calculated from the modified Benesi–Hidebrand equation, of eugenol with α-, β-, γ- and DMβ-CD is 4.95 × 104, 3.96 × 105, 1.47 × 105 and 9.33 × 104 mol−1 dm3, respectively. 相似文献
9.
Mahmoud M. Al Omari Mohammad B. Zughul J. Eric D. Davies Adnan A. Badwan 《Journal of inclusion phenomena and macrocyclic chemistry》2006,55(3-4):247-254
The interaction of celecoxib (Celox) with cyclodextrins (CDs) has been investigated by phase solubility techniques. In this study, the influences of CD type, pH, buffer type, buffer concentration and temperature on the tendency of Celox to form inclusion complexes with CDs were examined. The tendency of Celox to complex with CDs is in the order HP-β-CD > β-CD > γ-CD > α-CD, where the complex formation constants (K
11) were 1377, 693, 126 and 60 M−1, respectively. Also ionization of the slightly acidic Celox (pK
a=9.7) was found to reduce its tendency to complex (i.e., The K
11 values of Celox/β-CD in 0.05 M phosphate buffer were 976 and 210 M−1 for neutral and ionized Celox, respectively). Increasing citrate and phosphate buffer concentration enhances the tendency of ionized Celox to complex with β-CD as a result of a corresponding decrease in the inherent solubility (S
0) of the Celox anion. On the other hand, these two buffers interact differently with neutral Celox and β-CD, where increasing phosphate buffer concentration at low pH enhances the complexation of neutral Celox by lowering S
0, while increasing citrate buffer concentration at low pH reduces complex formation as citrate buffer species, mainly citric acid, act as a solublizer and a competitor for Celox and β-CD. The contribution of Celox hydrophobicity for complex stability constitutes about 77% of the driving force for complex stability. The complex formation of neutral Celox with β-CD (ΔG
0=−28.6 kJ/mol) is driven by both enthalpy (ΔH
0=−21.7 kJ/mol) and entropy (ΔS
0=23.3 J/mol K) changes. 相似文献
10.
Cs. Novák Zsuzsanna Éhen Marietta Fodor L. Jicsinszky Judit Orgoványi 《Journal of Thermal Analysis and Calorimetry》2006,84(3):693-701
Citronellol
and citronellyl acetate have been entrapped with α-, β- and γ-cyclodextrin
(CD). Evolved gas detection and TG-MS coupling was applied to prove the actual
inclusion complex formation between monoterpens and CDs. The terpene content
was determined by UV-VIS specrophotometry and RP-HPLC and the effect of storage
time on the terpene content was also investigated. The α- and γ-cyclodextrin
inclusion complexes showed higher thermal stabilities vs.
dynamic heating compared to the β-CD complexes. On the contray, the retention
of guest using β-cyclodextrin even after 10 years of storage was much
more pronounced. Experimental data other than 1:1 complex compositions are
assumed. Molecular modeling experiments also suggested multiple complex compositions. 相似文献
11.
Sanyo Hamai 《Journal of inclusion phenomena and macrocyclic chemistry》2007,58(3-4):241-247
In pH 7.3 buffers, the interactions of a cationic porphyrin, tetrakis(4-N-methylpyridyl)porphyrin (TMPyP), with cyclodextrins (CDs) and disodium phthalate (DSP) have been examined by means of absorption,
fluorescence, and induced circular dichroism spectroscopy. α-CD, β-CD, and γ-CD form a 1:1 inclusion complex with a TMPyP
monomer, which dimerizes in solution without CD. TMPyP also forms a 1:1 organic cation–organic anion complex with DSP. The
1:1 TMPyP–DSP complex forms a ternary CD–TMPyP–DSP inclusion complex with α-, β-, and γ-CD, in which a DSP molecule is not
incorporated into the CD cavity. From the fluorescence intensity change, the␣equilibrium constants have been evaluated for
the formation of the inclusion complexes and the organic cation–anion complexes. 相似文献
12.
Shengkai Xing Qian Zhang Chong Zhang Qiang Zhao Hongqi Ai Dezhi Sun 《Journal of solution chemistry》2009,38(5):531-543
Thermodynamic parameters for formation of the inclusion complexes of α-, β- and γ-cyclodextrin (α-, β- and γ-CD) with ibuprofen (BF) in Tris-HCl buffer solutions (pH=7.0) have been determined by isothermal titration calorimetry (ITC)
with nanowatt sensitivity, and the inclusion structures have been investigated by using 1H-NMR spectra at 298.15 K. A theoretical study on the inclusion processes between BF and CDs has been performed with the B3LYP/6-31G*//PM3
method in order to investigate the formation mechanism of the inclusion complexes. An analysis of the thermodynamic data indicates
that the stoichiometries of α-, β- and γ-CD with BF are all 1:1 and formation of the inclusion complexes α-CD⋅BF and β-CD⋅BF are driven by enthalpy and entropy, whereas formation of γ-CD⋅BF is an entropy driven process. The 1H-NMR spectra provide clear evidence for the inclusion phenomenon, and show that the isobutyl group and aromatic ring of the
guest molecule are trapped inside the cavity of the CDs. Theoretical calculations suggest that the complex formed by the BF
molecule entering into the cavity of the CD molecule from the wide side is more stable than that from the narrow side. 相似文献
13.
Angela Lopedota Adriana Trapani Annalisa Cutrignelli Valentino Laquintana Nunzio Denora Massimo Franco Giuseppe Trapani Gaetano Liso 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):425-432
The objective of this work was to develop a novel microparticulate system based on the mucoadhesive polymer Eudragit-RS 100
and cyclodextrins (CDs), potentially useful for the oral administration of Glutathione (γ–glutamylcysteinylglycine, GSH).
For this purpose, an oil-in-oil (O/O) emulsion-solvent evaporation method was used for the preparation of microparticles (MPs)
containing GSH alone or together with one of the following CDs: α-, β-, γ-, methyl-β-(Me-β-), hydroxypropyl-β-(HP-β-) or sulfobutylether-β-cyclodextrin
(SBE7m-β-CD). MPs were obtained by emulsifying a mixture of Eudragit RS 100, GSH, CD and magnesium stearate in acetone or acetonitrile
with a mixture of liquid paraffin and Span 80. Size, encapsulation efficiency, and drug release of the prepared MPs were evaluated.
The results clearly indicated that all the examined properties were dependent on the water-miscible solvents and CD used.
In particular, MPs prepared by using acetone or acetonitrile showed different size distributions with mean diameters in the
ranges 82–350 and 15–22 μm, respectively. Moreover, encapsulation efficiency values were found to be high in all cases (71–99%)
and was significantly affected by the CD type. The GSH release rates were evaluated employing dissolution media with different
pH values (1.2, 6.8 and 7.4) and the following rank order was obtained for MPs prepared using acetone: MPs incorporating Me-β-CD > MPs
without CD > MPs incorporating the remaining CDs. On the other hand, MPs prepared using acetonitrile gave the highest GSH
release rate. Finally, stability of GSH encapsulated in MPs containing HP-β-CD to enzymatic attack by pepsin A, α-chymotrypsin,
and γ-glutamyltranspeptidase was also investigated. 相似文献
14.
Ameer Ghuzlaan Mahmoud M. Al Omari Khaldoun A. Al-Sou’od 《Journal of solution chemistry》2009,38(1):83-94
Guest–host interaction of prednisone (PN) with cyclodextrins (CDs) have been investigated using phase solubility diagrams
(PSD), differential scanning calorimetry (DSC), X-ray powder diffractometry (XRPD), scanning electron microscopy (SEM) and
molecular mechanical modeling (MM). Estimates of the complex formation constant (K
11) show that the tendency of PN to complex with CDs follows the order: β-CD>γ-CD>HP-β-CD>α-CD. At the same pH of 7.0, β-CD forms soluble 1:1 and insoluble 1:2 PN/CD complexes (BS-type PSDs). The thermodynamic functions for 1:1 PN/β-CD estimated at pH = 7.0 (ΔG
11o=−20.8 kJ⋅mol−1) show that complexation is driven by enthalpy (−30.7 kJ⋅mol−1) but retarded by entropy (ΔS
11o=−33.1 J⋅mol−1⋅K−1) changes. The MM modeling study indicates the formation of different isomeric 1:1 complexes with CDs. PSD, DSC, XRPD, SEM
and MM studies established the formation of inclusion complexes in solution and the solid state. 相似文献
15.
Pekka Mattssoin Tlmo Korpela Sari Paavilainen Mauri Mäkelä 《Applied biochemistry and biotechnology》1991,30(1):17-28
Improved formation of cyclodextrins (CDs) from starch in ethanolic solutions byBacillus circulans var alkalophilus cyclomaltodextrin glucanotransferase was studied. The β- and γ-CD yields increased and α-CD yield gradually decreased as
the ethanol concentration was raised. The ethanol concentration required for maximal CD yield depended essentially on starch
concentration. The ethanol's effect was pronounced at high starch concentrations. For example, with 30% (w/v) starch, the
CD yield was 2.4-fold (146.5 g/L) in the presence of 15% (v/v) ethanol. The effect of dimethylsulfoxide on the formation of
CDs was similar to that of ethanol. The disintegration of β- and γ-CDs were narrowly interdependent on the formation of a
α-CD and malto-sugars. The amount of reducing sugars decreased from a dextrose equivalent value of roughly 7.5 to 4.5 in the
presence of ethanol at starch concentrations 1-30% (w/v). The effect of ethanol on starchy materials from various sources
was similar. It was concluded that ethanol retards the decomposition of β-CD by a general mechanism involving a decreased
activity of water. 相似文献
16.
Kim Lambertsen Larsen Stig Bruse Andersen Anne Louise Mørkbak Reinhard Wimmer 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):185-190
The inclusion complexes between fusidate, 3-keto fusidate, 11-keto fusidate and 11-deoxy fusidate and α-, β-, and γ-cyclodextrin
(CD) were studied using capillary electrophoresis. By monitoring the changes in mobility of the negatively charged compounds
in the presence of varying amount of CD the stability constants of the complexes formed could be obtained. In the case of
α- and β-CD the obtained results could be modelled to a simple model assuming 1:1 stoichiometry, revealing, not surprisingly,
that β-CD formed a stronger complex compared to α-CD. A model assuming 1:2 (fusidate:CD) stoichiometry could be fitted to
the data obtained with γ-CD. The results showed that the different fusidanes formed very strong 1:1 complexes with γ-CD as
well as a quite weak 1:2 complex. 3-keto-, 11-keto- and 11-deoxy-fusidate formed stronger complexes compared to fusidate,
probably due to an decrease in hydrophilicity caused by the reduced number of hydroxyl groups. The complex between γ-CD and
fusidate was studied by use of 2D-NMR spectroscopy. The results showed that most of the hydrogen atoms of fusidate show interactions
with the hydrogen atoms in the cavity of γ-CD. The interaction pattern suggests that fusidate may be fully embedded in the
cavity of γ-CD. No interactions between fusidate and the hydrogen atoms situated at the outside of the CD were found. 相似文献
17.
Arpansiree Wongmekiat Satoko Yoshimatsu Yuichi Tozuka Kunikazu Moribe Keiji Yamamoto 《Journal of inclusion phenomena and macrocyclic chemistry》2006,56(1-2):29-32
Drugs with poor water solubility were co-ground with cyclodextrins (CDs) to create nanoparticles with improved solubility characteristics. Indomethacin (IDM), furosemide (FRM) and naproxen (NAP) were co-ground with β-CD at the molar ratio of 2:1 (CD:drug). Co-grinding of a drug with CD resulted in not only the formation of drug nanoparticles but also the solubilization of the drug by inclusion complex formation with CD in aqueous media. The nanoparticle fraction of IDM, and FRM from ground mixtures prepared with β-CD was as high as 60–70% while the solubilization fraction was less than 10%. In contrast, β-CD–NAP ground mixture showed a large fraction, 48%, for drug solubilization and only 4% for nanoparticle formation. Furosemide ground mixtures prepared with α-CD, β-CD and γ-CD showed comparatively high nanoparticle fraction while the solubilization fraction was around 10%. Both the nanoparticle fraction and the solubilization fraction were greater in the IDM–β-CD system than those in γ-CD and α-CD systems. The nanoparticle formation of NAP depended on the types of CD used as a co-grinding additive. Naproxen nanoparticles could be prepared by co-grinding NAP and α-CD, while the solubilization of NAP tended to improve when β-CD or γ-CD was used. 相似文献
18.
H. Krajian N. Mofaddel D. Villemin P. L. Desbène 《Analytical and bioanalytical chemistry》2009,394(8):2193-2201
Enantioseparation of 6,6′-dibromo-1,1′-binaphthyl-2,2′-diol (DBBD) by cyclodextrin-modified capillary zone electrophoresis
(CD-CZE) was studied using the three native α, β, and γ cyclodextrins, the three hydroxypropylated cyclodextrins (2-hydroxypropyl-α,
β, and γ), heptakis-2,6-di-O-methyl-β-CD (DM-β-CD), and heptakis-2,3,6-tri-O-methyl-β-cyclodextrin (TM-β-CD). First, the acidity constants of DBBD were determined using capillary electrophoresis, before
performing enantioseparation. The influence of the concentrations of the studied cyclodextrins on the enantioseparation was
explored and the experimental optimal concentrations were determined and compared to the theoretical optimal concentrations.
Moreover, the apparent complexation constants between each studied cyclodextrin and the two DBBD enantiomers were evaluated
using a non-linear curve fitting method and three linear plotting methods (x-reciprocal, y-reciprocal and double reciprocal). For TM-β-CD, the order of migration of the enantiomers of DBBD reversed as a function
of TM-β-CD concentration. The influence of the nature of methylated cyclodextrin derivatives (methyl-β-CD (M-β-CD) and DM-β-CD)
was then studied. Inversion of the order of migration of the enantiomers of DBBD was observed for DM-β-CD, whereas the S enantiomer of DBBD always migrated first for M-β-CD. 相似文献
19.
Alexis Morales Jochem Struppe Enrique Meléndez 《Journal of inclusion phenomena and macrocyclic chemistry》2008,60(3-4):263-270
The possible inclusion complexes of Cp2NbCl2 into α-, β-, and γ-CD hosts have been investigated. The existence of a true inclusion complex in the solid state was confirmed
by a combination of thermogravimetric analysis, FTIR, PXRD, and 13C CP-MAS NMR spectroscopies. The solid-state results demonstrated that α-cyclodextrin does not form inclusion complexes with
Cp2NbCl2 whereas β- and γ-cyclodextrins do form such complexes. PXRD, NMR, and thermal analysis showed that the organometallic molecules
of Cp2NbCl2OH are included in the cavities of β- and γ-cyclodextrins, possibly adopting a symmetrical conformation in the complex, with
each glucose unit in a similar environment. In solution, 1H NMR experiments suggest that niobocene has a shallow penetration on the β-CD leading to upfield shift on H-3 signal with
a minor perturbation on the H-5 proton while for γ-CD, both H-3 and H-5 are shifted upfield substantially. This suggests that
niobocene penetrates deeper into the γ-CD cavity than in the β-CD cavity, as a result of the cavity size.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
Pontes F. M. L. Oliveira S. F. Espínola J. G. P. Arakaki L. N. H. Fonseca M. G. Airoldi C. 《Journal of Thermal Analysis and Calorimetry》2004,75(3):975-988
Solid adducts SbX3·L-pic (X=Cl, I and L=α-, β- and γ-picolines) were synthesized and characterized by elemental analysis, 1H and 13C NMR, IR spectroscopy and thermal analysis. The infrared spectroscopy and the magnetic resonance for 1H and 13C nuclei of these compounds suggest that the ligands coordinate through nitrogen atom. Kinetic studies were accomplished by
means of thermogravimetric data, through isothermal and non-isothermal techniques. The best adjusting models for adducts thermal
decomposition were R1 for isothermal and R1 and R2 for the non-isothermal methods. The energy of activation values obtained by isothermal method indicate the following orders
of thermal stability for adducts: i) SbCl3·α-pic>SbCl3·β-pic>SbCl3·γ-pic and ii) SbI3·β-pic>SbI3·γ-pic>SbI3·α-pic. The activation energy values obtained by non-isothermal were higher than those from isothermal methods, showing the
order of stability:iii) SbCl3·α-pic<SbCl3·β-pic<SbCl3·γ-pic and iv) SbI3·β-pic>SbI3·α-pic=SbI3··γ-pic. These obtained data through R1 model presented the kinetic compensation effect for trichloride adducts, which could be associated to both isothermal and
non-isothermal processes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献