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1.
Chemistry ; 2020 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-32520396

RESUMO

Dinuclear metallodrugs offer much potential in the development of novel anticancer chemotherapeutics as a result of the distinct interactions possible with biomacromolecular targets and the unique biological activity that can result. Here, we describe the development of isostructural homodinuclear Os(II)-Os(II) and heterodinuclear Os(II)-Ru(II) organometallic complexes formed from the linking of the arene ligands of [M(η6-arene)(C2O4)(PTA)] (M = Os/Ru; PTA = 1,3,5-triaza-7-phosphaadamantane) units. Together with the known Ru(II)-Ru(II) analogue, a chromatin-modifying agent, we probed the impact of variation of the metal ions on the structure, reactivity and biological activity of these complexes. The complexes have been structurally characterised by X-ray diffraction experiments, their stability and reactivity examined using 1H and 31P NMR spectroscopy and biological activity assessed, alongside mononuclear analogues, through MTT assays and cell cycle analysis (HT-29 cell line). Results revealed high antiproliferative activity in each case with cell cycle profiles of the dinuclear complexes found to be similar to that for untreated cells, and similar but distinct profiles for the mononuclear complexes. These results indicate these complexes impact on cell viability predominantly through a non-DNA damaging mechanism of action. The new Os(II)-Os(II and Os(II)-Ru(II) complexes reported here are further examples of a family of compounds operating via mechanism(s) of action atypical of the majority of metallodrugs, and which have potential as tools in chromatin research.

2.
Chem Commun (Camb) ; 56(54): 7519-7522, 2020 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-32510060

RESUMO

Rigid and topologically constrained ethylene cross-bridged tetraazamacrocycles have been increasingly utilised for thirty years as they form remarkably stable transition metal complexes for catalysis, biomedical imaging, and inorganic drug molecule applications. Extending these benefits to pentaazamacrocycles has been achieved and a first transition metal complex prepared and structurally characterized.

3.
Inorg Chem ; 59(4): 2367-2378, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-31984731

RESUMO

Reaction of [ReOCl3(PPh3)2] or [ReO2I(PPh3)2] with 2,2'-diphenylglycine (dpgH2) in refluxing ethanol afforded the air-stable complex [ReO(dpgH)(dpg)(PPh3)] (1). Treatment of [ReO(OEt)I2(PPh3)2] with 1,2,3-triaza-7-phosphaadamantane (PTA) afforded the complex [ReO(OEt)I2(PTA)2] (2). Reaction of [ReOI2(PTA)3] with dpgH2 led to the isolation of the complex [Re(NCPh2)I2(PTA)3]·0.5EtOH (3·0.5EtOH). A similar reaction but using [ReOX2(PTA)3] (X = Cl, Br) resulted in the analogous halide complexes [Re(NCPh2)Cl2(PTA)3]·2EtOH (4·2EtOH) and [Re(NCPh2)(PTA)3Br2]·1.6EtOH (5·1.6EtOH). Using benzilic acid (2,2'-diphenylglycolic acid, benzH) with 2 afforded the complex [ReO(benz)2(PTA)][PTAH]·EtOH (6·EtOH). The potential for the formation of complexes using radioisotopes with relatively short half-lives suitable for nuclear medicine applications by developing conditions for [Re(NCPh2)(dpg)I(PTA)3] (7)[ReO4]- in a 4 h time scale was investigated. A procedure for the technetium analog of complex [Re(NCPh2)I2(PTA)3] (3) from 99mTc[TcO4]- was then investigated. The molecular structures of 1-7 are reported; complexes 3-7 have been studied using in vitro cell assays (HeLa, HCT116, HT-29, and HEK 293) and were found to have IC50 values in the range of 29-1858 µM.

4.
Molecules ; 25(2)2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31936104

RESUMO

Metallation of biomacromolecular species forms the basis for the anticancer activity of many metallodrugs. A major limitation of these compounds is that their reactivity is indiscriminate and can, in principle, occur in healthy tissue as well as cancerous tissue, potentially leading to side effects in vivo. Here we present pH-dependent intramolecular coordination of an arene-tethered sulfonamide functionality in organometallic ruthenium(II) ethylenediamine complexes as a route to controlling the coordination environment about the central metal atom. Through variation of the sulfonamide R group and the length of the tether linking it to the arene ligand the acidity of the sulfonamide NH group, and hence the pH-region over which regulation of metal coordination occurs, can be modulated. Intramolecular sulfonamide ligation controlled the reactivity of complex 4 within the physiologically relevant pH-region, rendering it more reactive towards 5'-GMP in mildly acidic pH-conditions typical of tumour tissue compared to the mildly alkaline pH-conditions typical of healthy tissue. However, the activation of 4 by ring-opening of the chelate was found to be a slow process relative to the timescale of typical cell culture assays and members of this series of complexes were found not to be cytotoxic towards the HT-29 cell line. These complexes provide the basis for the development of analogues of increased potency where intramolecular sulfonamide ligation regulates reactivity and therefore cytotoxicity in a pH-dependent, and potentially, tissue-dependent manner.


Assuntos
Antineoplásicos/química , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Diaminas/química , Compostos Organometálicos/farmacologia , Rutênio/química , Sulfonamidas/química , Antineoplásicos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Quelantes/química , Complexos de Coordenação/síntese química , Complexos de Coordenação/toxicidade , Cristalografia por Raios X , Diaminas/farmacologia , Etilenodiaminas/química , Etilenodiaminas/farmacologia , Guanosina Monofosfato/metabolismo , Células HT29 , Humanos , Concentração de Íons de Hidrogênio , Cinética , Ligantes , Modelos Moleculares , Compostos Organometálicos/química , Rutênio/farmacologia , Sulfonamidas/farmacologia
5.
Chem Commun (Camb) ; 55(75): 11279-11282, 2019 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-31475709

RESUMO

Homo-dinuclear Co and Zn complexes derived from the macrocycle LH2, {[2-(OH)-5-(R)-C6H2-1,3-(CH)2][CH2CH2(2-C6H4N)2]}2 (R = Me, tBu), revealed near inactivity for the ring opening polymerization (ROP) of the cyclic esters δ-valerolactone (δ-VL) and ε-caprolactone (ε-CL). By contrast, the hetero-bimetallic complexes [LCo(NCMe)(µ-Br)ZnBr]·nMeCN (n = 3 or 3.25) were found to be efficient catalysts for the ROP of ε-CL and δ-VL.

6.
Polyhedron ; 163: 42-53, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30976133

RESUMO

A total of 44 bis-aryl-monocyclic polyamines, monoaryl-monocyclic polyamines and their transition metal complexes were prepared, chemically characterized, and screened in vitro against the Leishmania donovani promastigotes, axenic amastigotes and intracellular amastigotes in THP1 cells. The IC50 and/or IC90 values showed that 10 compounds were similarly active at about 2-fold less potent than known drug pentamidine against promastigotes. The most potent compound had an IC50 of 2.82 µM (compared to 2.93 µM for pentamidine). Nine compounds were 1.1-13.6-fold more potent than pentamidine against axenic amastigotes, the most potent one being about 2-fold less potent than amphotericin B. Fourteen compounds were about 2-10 fold more potent than pentamidine, the most potent one is about 2-fold less potent than amphotericin B against intracellular amastigotes in THP1 cells. The 2 most promising compounds (FeL7Cl2 and MnL7Cl2), with strong activity against both promastigotes and amastigotes and no observable toxicity against the THP1 cells are the Fe2+- and Mn2+- complexes of a dibenzyl cyclen derivative. Only 2 of the 44 compounds showed observable cytotoxicity against THP1 cells. Tetraazamacrocyclic monocyclic polyamines represent a new class of antileishmanial lead structures that warrant follow up studies.

7.
Dalton Trans ; 48(8): 2785-2801, 2019 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-30729243

RESUMO

A number of disease states including WHIM syndrome, HIV infection and cancer have been linked to the chemokine receptor CXCR4. High-affinity CXCR4 antagonist transition metal complexes of configurationally restricted bis-tetraazamacrocyclic ligands have been identified in previous studies. Recently synthesised and structurally characterised Co2+/Co3+ and Ni2+ acetate complexes of mono-macrocycle cross-bridged ligands have been used to mimic their known coordination interaction with the aspartate side chains on binding to CXCR4. Here, X-ray crystal structures for three Co2+/Co3+ acetate complexes and five Ni2+ acetate complexes are presented and demonstrate flexibility in the mode of binding to the acetate ligand concomitantly with the requisite cis-V-configured cross-bridged tetraazamacrocyle. Complexes of the smaller Co3+ metal ion exclusively bind acetate by chelating both oxygens of acetate. Larger Co2+ and Ni2+ metal ions in cross-bridged tetraazamacrocycles show a clear tendency to coordinate acetate in a monodentate fashion with a coordinated water molecule completing the octahedral coordination sphere. However, in unbridged tetraazamacrocycle acetate structures reported in the literature, the coordination preference is to chelate both acetate oxygens. We conclude that the short ethylene cross-bridge restricts the equatorial bulk of the macrocycle, prompting the metal ion to fill the equator with the larger monodentate acetate plus water ligand set. In unbridged ligand examples, the flexible macrocycle expands equatorially and generally only allows chelation of the sterically smaller acetate alone. These results provide insight for generation of optimised bis-macrocyclic CXCR4 antagonists utilising cobalt and nickel ions.

8.
Acta Crystallogr E Crystallogr Commun ; 75(Pt 2): 185-188, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30800448

RESUMO

The linear two-coordinate silver (I) complex [Ag(C4H2NO2S)(C4H3NO2S)] or [Ag(2-Htza)(2-tza)] is reported (2-Htza = 1,3-thia-zole-2-carb-oxy-lic acid). The AgI ion is coordinated by two heterocyclic N atoms from two ligands in a linear configuration, forming a discrete coordination complex. There is an O-H⋯O hydrogen bond between 2-tza- and 2tzaH of adjacent complexes. The hydrogen atom is shared between the two oxygen atoms. This inter-action produces a hydrogen-bonded tape parallel to the [110] direction, which is augmented through inter-molecular C-H⋯O hydrogen-bonding inter-actions between the bound thia-zole groups. There is a further rather long Ag⋯O inter-action [2.8401 (13) Å, compared with a mean of 2.54 (11) Šfor 23 structures in the CSD] that assembles these tapes into columns, between which there are C-H⋯π inter-actions, leading to the formation of a three-dimensional supra-molecular architecture.

9.
Dalton Trans ; 48(4): 1454-1466, 2019 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-30629056

RESUMO

The mono-oxo aryloxide complexes [M(O)(L1)2] (M = Mo (1·hexane), W(2·2MeCN)) have been prepared from [Mo(O)(Cl)4] or [W(O)(Ot-Bu)4] and two equivalents of the di-phenol 2,2'-ethylidenebis(4,6-di-tert-butylphenol) L1H2, respectively. Use of in situ generated [Mo(O)(Ot-Bu)4] with two equivalents of L1H2 also led to the isolation of 1·2MeCN. In the presence of adventitious oxygen, attempts to generate in situ [Mo(O)(Ot-Bu)4] and reaction with one equivalent of L1H2 afforded the bi-metallic complex [Mo(O)(L1)(µ-O)Li(THF)(MeCN)]2·2MeCN (3·2MeCN). Use of the tetra-phenol α,α,α',α'-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl)-p-xyleneH4 (L2H4) with [Mo(O)(Oi-Pr)4] led to the isolation of {[Mo(O)]L2}2 (4), whilst the analogous tungsten complex {[W(O)]L2}2 (5) was isolated from the reaction of L2H4 with [W(O)(Ot-Bu)4]. Similar reaction of p-tert-butylcalix[4]areneH4 (L3H4) with [Mo(O)(Oi-Pr)4] afforded ([Mo(O)L3(NCMe)]·3MeCN (6). Modifications of known routes were employed to access complexes [W(Cl)2L3]·3.5MeCN (7·3.5MeCN) and [W(O)L3(NCMe)] (8), whilst use of [WO(Ot-Bu)4] with L3H4 unexpectedly afforded [W(Ot-Bu)2L3]·MeCN (9·MeCN). The molecular crystal structures for 1-9 are reported, and the ability of these complexes to act as catalysts for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL), δ-valerolactone (δ-VL) and ω-pentadecalactone (ω-PDL) has been investigated. The molybdenum complexes 1 and 4 were the best performers for ε-Cl and δ-VL, but all complexes exhibited poor control and were also inactive toward the ROP of PDL.

10.
11.
Chem Asian J ; 14(1): 235-242, 2019 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-30462888

RESUMO

The interaction between cucuribit[8]uril (Q[8]) and a series of 4-pyrrolidinopyridinium salts bearing aliphatic substituents at the pyridinium nitrogen, namely 4-(C4 H8 N)C5 H5 NRBr, where R=Et (g1), n-butyl (g2), n-pentyl (g3), n-hexyl (g4), n-octyl (g5), n-dodecyl (g6), has been studied in aqueous solution by 1 H NMR spectroscopy, electronic absorption spectroscopy, isothermal titration calorimetry and mass spectrometry. Single crystal X-ray diffraction revealed the structure of the host-guest complexes for g1, g2, g3, and g5. In each case, the Q[8] contains two guest molecules in a centrosymmetric dimer. The orientation of the guest molecule changes as the alkyl chain increases in length. Interestingly, in the solid state, the inclusion complexes identified are different from those observed in solution, and furthermore, in the case of g3, Q[8] exhibits two different interactions with the guest. In solution, the length of the alkyl chain plays a significant role in determining the type of host-guest interaction present.

12.
Dalton Trans ; 47(44): 15983-15993, 2018 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-30378621

RESUMO

Reaction of differing amounts of vanadyl sulfate with p-tert-butylthiacalix[4]areneH4 and base allows access to the vanadyl-sulfate species [NEt4]4[(VO)4(µ3-OH)4(SO4)4]·½H2O (1), [HNEt3]5[(VO)5(µ3-O)4(SO4)4]·4MeCN (2·4MeCN) and [NEt4]2[(VO)6(O)2(SO4)4(OMe)(OH2)]·MeCN (3·MeCN). Similar use of p-tert-butylsulfonylcalix[4]areneH4, p-tert-butylcalix[8]areneH8 or p-tert-butylhexahomotrioxacalix[3]areneH3 led to the isolation of [HNEt3]2[H2NEt2]2{[VO(OMe)]2p-tert-butylcalix[8-SO2]areneH2} (4), [HNEt3]2[V(O)2p-tert-butylcalix[8]areneH5] (5) and [HNEt3]2[VIV2VV4O11(OMe)8] (6), respectively. Dc magnetic susceptibility measurements were performed on powdered microcrystalline samples of 1-3 in the T = 300-2 K temperature range. Preliminary screening for electrochemical water oxidation revealed some activity for 2 with turnover frequency (TOF) and number (TON) of 2.2 × 10-4 s-1 and 6.44 × 10-6 (mmol O2/mmol cat.), respectively. The compound 3 showed an improved electrochemical activity in the presence of water. This is related to the increased number and the rate of electrons exchanged during oxidation of V4+ species, facilitated by protons generated in the water discharge process.

13.
Inorg Chem ; 57(15): 8890-8902, 2018 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-30024738

RESUMO

Macrocyclic ligands have been explored extensively as scaffolds for transition metal catalysts for oxygen and hydrogen atom transfer reactions. C-C reactions facilitated using earth abundant metals bound to macrocyclic ligands have not been well-understood but could be a green alternative to replacing the current expensive and toxic precious metal systems most commonly used for these processes. Therefore, the yields from direct Suzuki-Miyaura C-C coupling of phenylboronic acid and pyrrole to produce 2-phenylpyrrole facilitated by eight high-spin iron complexes ([Fe3+L1(Cl)2]+, [Fe3+L4(Cl)2]+, [Fe2+L5(Cl)]+, [Fe2+L6(Cl)2], [Fe3+L7(Cl)2]+, [Fe3+L8(Cl)2]+, [Fe2+L9(Cl)]+, and [Fe2+L10(Cl)]+) were compared to identify the effect of structural and electronic properties on catalytic efficiency. Specifically, catalyst complexes were compared to evaluate the effect of five properties on catalyst reaction yields: (1) the coordination requirements of the catalyst, (2) redox half-potential of each complex, (3) topological constraint/rigidity, (4) N atom modification(s) increasing oxidative stability of the complex, and (5) geometric parameters. The need for two labile cis-coordination sites was confirmed based on a 42% decrease in catalytic reaction yield observed when complexes containing pentadentate ligands were used in place of complexes with tetradentate ligands. A strong correlation between iron(III/II) redox potential and catalytic reaction yields was also observed, with [Fe2+L6(Cl)2] providing the highest yield (81%, -405 mV). A Lorentzian fitting of redox potential versus yields predicts that these catalysts can undergo more fine-tuning to further increase yields. Interestingly, the remaining properties explored did not show a direct, strong relationship to catalytic reaction yields. Altogether, these results show that modifications to the ligand scaffold using fundamental concepts of inorganic coordination chemistry can be used to control the catalytic activity of macrocyclic iron complexes by controlling redox chemistry of the iron center. Furthermore, the data provide direction for the design of improved catalysts for this reaction and strategies to understand the impact of a ligand scaffold on catalytic activity of other reactions.

14.
J Environ Manage ; 222: 30-36, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29800862

RESUMO

Steel slag is a major by-product of the steel industry and a potential resource of technology critical elements. For this study, a basic oxygen furnace (BOF) steel slag was tested for bacterial leaching and recovery of aluminium (Al), chromium (Cr), and vanadium (V). Mixed acidophilic bacteria were adapted to the steel slag up to 5% (w/v). In the batch tests, Al, Cr, and V were bioleached significantly more from steel slag than in control treatments. No statistical difference was observed arising from the duration of the leaching (3 vs 6 d) in the batch tests. Al and Cr concentrations in the leachate were higher for the smaller particle size of the steel slag (<75 µm), but no difference was observed for V. In the column tests, no statistical difference was found for pH, Al, Cr and V between the live culture (one-step bioleaching) and the supernatant (two-step bioleaching). The results show that the culture supernatant can be effectively used in an upscaled industrial application for metal recovery. If bioleaching is used in the 170-250 million tonnes of steel slag produced per year globally, significant recoveries of metals (100% of Al, 84% of Cr and 8% of V) can be achieved, depending on the slag composition. The removal and recovery percentages of metals from the leachate with Amberlite®IRA-400 are relatively modest (<67% and <5%, respectively), due to the high concentration of competing ions (SO42-, PO43-) in the culture medium. Other ion exchange resins can be better suited for the leachate or methods such as selective precipitation could improve the performance of the resin. Further research is needed to minimise interference and maximise metal recovery.


Assuntos
Alumínio/isolamento & purificação , Cromo/isolamento & purificação , Aço , Vanádio/isolamento & purificação , Resíduos Industriais , Reciclagem
15.
Molecules ; 23(1)2018 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-29342978

RESUMO

The host-guest interaction of a series of cyclohexyl-appended guests with cucurbit[8]uril (Q[8]) was studied by ¹H NMR spectroscopy, isothermal titration calorimetry (ITC), and X-ray crystallography. The X-ray structure revealed that two cycloalkane moieties can be simultaneously encapsulated in the hydrophobic cavity of the Q[8] host to form a ternary complex for the first time.


Assuntos
Hidrocarbonetos Aromáticos com Pontes/química , Cicloexilaminas/química , Imidazóis/química , Calorimetria , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estrutura Molecular , Termodinâmica
16.
Dalton Trans ; 46(48): 16973-16982, 2017 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-29177295

RESUMO

Gallium-68 (68Ga) has been the subject of increasing interest for its potential in the production of radiotracers for diagnosis of diseases. In this work we report the complexation of 68Ga by the amino acid based tripodal chelate H3Dpaa, and two bifunctional derivatives, H3Dpaa.dab and H4Dpaa.ga, under a range of conditions with particular emphasis on the rapid complexation of 68Ga at pH 7.4. 100 µM H3Dpaa achieved a radiochemical yield of 95% at pH 7.4 in 5 minutes at 37 °C. The bifunctional derivatives H4Dpaa.ga and H3Dpaa.dab achieved 94% and 84% radiochemical yields, respectively, under the same conditions. The resulting Ga(iii) complexes show thermodynamic stabilities of log KGaDpaa = 18.53, log KGaDpaa.dab = 22.08, log KGaDpaa.ga = 18.36. Unfortunately, the resulting radiolabelled species do not present sufficient serum stability for in vivo application. Herein we show a flexible synthesis for bifunctional chelators based on amino acids that rapidly complex 68Ga under physiological conditions.

17.
Molecules ; 22(7)2017 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-28698496

RESUMO

Heating a mixture of Nd(NO3)3·6H2O, KCl, Q[10] and Q[5] in HCl for 10 min affords the inclusion complex {NdQ[5]K@Q[10](H2O)4}·4NO3·20H2O. The structure of the inclusion complex has been investigated by single crystal X-ray diffraction and by X-ray Photoelectron spectroscopy (XPS).


Assuntos
Amantadina/análogos & derivados , Amantadina/química , Complexos de Coordenação/química , Neodímio/química , Amantadina/síntese química , Cristalografia por Raios X/métodos , Estrutura Molecular , Espectroscopia Fotoeletrônica/métodos , Difração de Raios X/métodos
18.
Bioorg Med Chem Lett ; 27(16): 3878-3882, 2017 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-28669445

RESUMO

Two new tricyclic ß-aminoacrylate derivatives (2e and 3e) have been found to be inhibitors of Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) with Ki 0.037 and 0.15µM respectively. 1H and 13C NMR spectroscopic data show that these compounds undergo ready cis-trans isomerisation at room temperature in polar solvents. In silico docking studies indicate that for both molecules there is neither conformation nor double bond configuration which bind preferentially to PfDHODH. This flexibility is favourable for inhibitors of this channel that require extensive positioning to reach their binding site.


Assuntos
Acrilatos/farmacologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Plasmodium falciparum/enzimologia , Acrilatos/síntese química , Acrilatos/química , Relação Dose-Resposta a Droga , Simulação de Acoplamento Molecular , Estrutura Molecular , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Relação Estrutura-Atividade
19.
Anal Chem ; 88(20): 10111-10117, 2016 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-27642771

RESUMO

We report a powerful new technique: hyphenating synchrotron X-ray powder diffraction (XRD) with differential scanning calorimetry (DSC). This is achieved with a simple modification to a standard laboratory DSC instrument, in contrast to previous reports which have involved extensive and complex modifications to a DSC to mount it in the synchrotron beam. The high-energy X-rays of the synchrotron permit the recording of powder diffraction patterns in as little as 2 s, meaning that thermally induced phase changes can be accurately quantified and additional insight on the nature of phase transitions obtained. Such detailed knowledge cannot be gained from existing laboratory XRD instruments, since much longer collection times are required. We demonstrate the power of our approach with two model systems, glutaric acid and sulfathiazole, both of which show enantiotropic polymorphism. The phase transformations between the low and high temperature polymorphs are revealed to be direct solid-solid processes, and sequential refinement against the diffraction patterns obtained permits phase fractions at each temperature to be calculated and unit cell parameters to be accurately quantified as a function of temperature. The combination of XRD and DSC has further allowed us to identify mixtures of phases which appeared phase-pure by DSC.


Assuntos
Varredura Diferencial de Calorimetria/métodos , Glutaratos/química , Difração de Pó/métodos , Sulfatiazóis/química , Difração de Raios X/métodos , Transição de Fase , Estereoisomerismo , Sulfatiazol , Temperatura
20.
Chem Commun (Camb) ; 52(81): 12028-12031, 2016 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-27510730

RESUMO

The design of a melt synthesis of the first air-stable formulation of the metastable form III of paracetamol is derived from thermo-spectroscopic and thermo-diffraction experiments. Melt crystallisation in the presence of ß-1,4-saccharides produces form III selectively and the excipients appear to act as stabilising 'active' templates of the metastable polymorph.

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