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M. K. Rotich – One of the best experts on this subject based on the ideXlab platform.
Modelling the thermal behaviour of carboxylic Acid derivatives with cylcodextrins in the solid-stateJournal of Thermal Analysis and Calorimetry, 2004Co-Authors: S. Agotonovic-kustrin, M. E. Brown, B. D. Glass, M. K. RotichAbstract:
The application of classical QSAR and molecular modelling to the inclusion complexation of natural and modified cyclodextrins (CDs) with carboxylic Acid derivatives as guest molecules was examined. Information was available on the thermal behaviour, in the solid-state of benzoic Acid (BA), salicylic Acid (SA), and various substituted aminosalicylic Acids (3-aminosalicylic Acid, 3-ASA, 4-Aminosalicylic Acid, 4-ASA and 5-aminosalicylic Acid, 5-ASA), as well as on the thermal behaviour of 1:1 molar ratio physical and kneaded mixtures of these Acids with each of three different cyclodextrins, β-, (BCD) 2-hydroxypropyl-β-, (HPBCD) and γ-cyclodextrin (GCD). The thermal behaviour of the binary (1:1 stoichiometry) mixtures was modelled using stepwise multiple regression (SMR). Two models for the prediction of the percentage mass loss and enthalpy of dehydration of the physical mixtures were established with correlation coefficients ( r ) of 0.79 and 0.92, respectively. Decreased correlation in the thermal behaviour of kneaded mixtures indicated significant interaction and possible formation of inclusion complexes.
Thermal studies on the sodium salts of aminosalicylic AcidsJournal of Thermal Analysis and Calorimetry, 2003Co-Authors: M. K. Rotich, M. E. Brown, B. D. GlassAbstract:
The effect on the stability of the isomers of aminosalicylic Acid of formation of their sodium salts has been studied by use of differential scanning calorimetry and thermogravimetry, coupled with evolved gas analysis by Fourier transform infrared spectroscopy. X-ray powder diffraction and infrared spectroscopy provided complementary information. The DSC curves for the sodium salts of all of the isomers showed complex dehydration/decomposition endotherms. From the initial mass losses of the TG curves, the amounts of water per mole of salt were estimated as 0.5, 2.4 and 1.4 moles for the sodium salts of 3-aminosalicylic Acid, 4-Aminosalicylic Acid and 5-aminosalicylic Acid, respectively. TG-FTIR results for the sodium salt of 3-aminosalicylic Acid showed the evolution of carbon dioxide in three stages: below 150°C, between 200 and 300°C and continuous formation up to 500°C. This behaviour differs from that of 3-aminosalicylic Acid itself, which forms CO_2 between 225 and 290°C. For the sodium salt of 4-Aminosalicylic Acid, the formation of carbon dioxide starts from 250°C and is still being formed at about 650°C. 4-Aminosalicylic Acid decarboxylates above 150°C. 5-aminosalicylic Acid and its sodium salt showed no evolution of carbon dioxide below 600°C.
Thermal studies on mixtures of aminosalicylic Acids with cyclodextrinsJournal of Thermal Analysis and Calorimetry, 2003Co-Authors: M. K. Rotich, Michael E. Brown, Beverley D. GlassAbstract:
The thermal behaviour of the aminosalicylic Acids is compared with the behaviour of their 1:1 molar ratio physical and kneaded mixtures with each of three different cyclodextrins (b-, hydroxypropyl-b-, and g-cyclodextrin), using differential scanning calorimetry and thermogravimetry coupled with evolved gas analysis by Fourier transform infrared spectroscopy. X-ray powder diffraction and infrared spectroscopy provided complementary information. Comparison of the effects of the different cyclodextrins on the behaviour of the individual aminosalicylic Acid isomers shows that hydroxypropyl-b-cyclodextrin has the greatest interaction with 3-aminosalicylic Acid and 5-aminosalicylic Acid, followed by g-cyclodextrin, while b-cyclodextrin generally shows the least interaction. For 4-Aminosalicylic Acid, the effect of g-cyclodextrin seems to be more marked than for 3-aminosalicylic Acid and 5-aminosalicylic Acid.
M. Teresa Duarte – One of the best experts on this subject based on the ideXlab platform.
Expanding the Pool of Multicomponent Crystal Forms of the Antibiotic 4-Aminosalicylic Acid: The Influence of Crystallization ConditionsCrystal Growth & Design, 2017Co-Authors: Vânia André, Fabrizia Grepioni, Dario Braga, Oleksii Shemchuk, M. Teresa DuarteAbstract:
Finding new multicomponent crystal forms of commercially available pharmaceuticals is important, as they represent a straightforward way to drastically influence the solid-state properties of a drug. The antibiotic 4-Aminosalicylic Acid (ASA) is known to exist in several multicomponent crystal forms, and in this work we expand the world of ASA cocrystals and salts by reporting new crystalline forms comprising diazabicyclo[2.2.2]octane (DABCO), and caffeine. All species were characterized by X-ray single crystal, powder diffraction, and thermal behavior. This study contributes to the rationalization of preferred functional groups for the synthesis of 4-Aminosalicylic Acid new multicomponent crystal forms and highlights the relevance of the reaction conditions in the achievement of those forms.
Mechanochemistry – A green synthetic methodology leading to metallodrugs, metallopharmaceuticals and bio-inspired metal-organic frameworksInorganica Chimica Acta, 2017Co-Authors: Sílvia Quaresma, Vânia André, Auguste Fernandes, M. Teresa DuarteAbstract:
Abstract Mechanochemistry an environment-friendly synthetic technique has been successfully used in the search for new metallopharmaceuticals, metallodrugs and bio-inspired metal-organic frameworks. These materials recently became highly promising on the pharmaceutical and medical field due to their ability to function as drug carriers, allowing a controlled drug delivery and release in addition to potential applications in imaging and magnetic resonance imaging for diagnostic and therapy. Here we refer to some of our previous results on Ag and Ni with piracetam and 4-Aminosalicylic Acid complexes as well as on the bismuth salicylates metallodrugs. Our results on bioinspired gabapentin networks are also discussed. Furthermore we disclose herein novel metallopharmaceuticals with flufenamic Acid and a bio-inspired framework with muconic Acid. The synthesis and structural characterization of these materials is described and their thermal and on-shelf stability was assessed, showing that they are stable under the relevant temperature range for pharmaceutical applications.
Polymorphic Ammonium Salts of the Antibiotic 4-Aminosalicylic AcidCrystal Growth & Design, 2012Co-Authors: Vânia André, M. Teresa Duarte, Dario Braga, Fabrizia GrepioniAbstract:
Reaction of the antibiotic 4-Aminosalicylic Acid with ammonia yields three polymorphic forms of the ammonium 4-aminosalicylate salt [NH4][C6H3NH2OH(COO)]. When the reaction is conducted in solution, the three polymorphs are obtained concomitantly, while liquid-assisted grinding and solid–gas reaction result in the formation of pure Form II. The three polymorphs are characterized by different patterns of hydrogen bonding interactions between the structurally rigid anions and the ammonium cations. Solid products were characterized by single-crystal and powder X-ray diffraction, variable temperature powder diffraction, calorimetric techniques (DSC and TGA), and hot-stage microscopy (HSM).
P. D. Patel – One of the best experts on this subject based on the ideXlab platform.
Metal Complexation Studies, Characterization and Biological Activities of 1-(4-Carboxy-3-Hydroxy-N- Sec.Butyl Phenyl Amino Methyl) BenzotriazoleAsian Journal of Research in Chemistry, 2017Co-Authors: P. D. PatelAbstract:
Aminomethylation of benzotriazole was carried out by treating benzotriazole with formaldehyde and N-sec.butyl 4-Aminosalicylic Acid. The resultant compound was designated as 1-(4-caroxy-3-hydroxy-N-sec.butyl phenyl amino methyl) benzotriazole (CSPB). The transition metal complexes of Cu 2+ , Co 2+ , Ni 2+ , Mn 2+ and Zn 2+ of CSPB have been prepared and characterized by elemental analysis, spectral studies, magnetic moment, molar conductivity and antimicrobial activity.
Synthesis, Characterization and Biological Activities of 1-(4-Carboxy-3-Hydroxy-N- N-Butyl Phenyl Amino Methyl) BenzotriazoleInternational journal of scientific research, 2016Co-Authors: P. D. PatelAbstract:
Aminomethylation of benzotriazole was carried out by treating benzotriazole with formaldehyde and N-n-butyl 4-Aminosalicylic Acid. The resultant compound was designated as 1-(4-caroxy-3-hydroxy-N-n-butyl phenyl amino methyl) benzotriazole (CBPB). The transition metal complexes of Cu 2+ , Co 2+ , Ni 2+ , Mn 2+ and Zn 2+ of CBPB have been prepared and characterized by elemental analysis, spectral studies, magnetic moment, molar conductivity and antimicrobial activity. Summary: The metal complexes of derivatives of benzotriazole were synthesized and characterized with various analytical techniques. The biological activities of those complexes were carried out and reported here.