915 resultados para Multienzyme Complexes -- antagonists
Resumo:
La chimie supramolculaire est base sur l'assemblage non covalent de blocs simples, des petites molcules aux polymres, pour synthtiser des matriaux fonctionnels ou complexes. La poly(4-vinylpyridine) (P4VP) est l'une des composantes supramolculaires les plus utilises en raison de sa chane latrale compose dune pyridine pouvant interagir avec de nombreuses espces, telles que les petites molcules monofonctionnelles et bifonctionnelles, grce divers types d'interactions. Dans cette thse, des assemblages supramolculaires de P4VP interagissant par liaisons hydrogne avec de petites molcules sont tudis, en ayant comme objectifs de faciliter l'lectrofilage de polymres et de mieux comprendre et d'optimiser la photorponse des matriaux contenant des drivs d'azobenzne. Une nouvelle approche est propose afin d'largir l'applicabilit de l'lectrofilage, une technique courante pour produire des nanofibres. cet effet, un complexe entre la P4VP et un agent de rticulation bifonctionnel capable de former deux liaisons hydrogne, le 4,4'-biphnol (BiOH), a t prpar pour faciliter le processus dlectrofilage des solutions de P4VP. Pour mieux comprendre ce complexe, une nouvelle mthode de spectroscopie infrarouge (IR) a d'abord t dveloppe pour quantifier l'tendue de la complexation. Elle permet de dterminer un paramtre cl, le rapport du coefficient d'absorption d'une paire de bandes attribues aux groupements pyridines libres et lies par liaisons hydrogne, en utilisant la 4-thylpyridine comme compos modle ltat liquide. Cette mthode a t applique de nombreux complexes de P4VP impliquant des liaisons hydrogne et devrait tre gnralement applicable d'autres complexes polymres. La microscopie lectronique balayage (SEM) a rvl l'effet significatif du BiOH sur la facilit du processus dlectrofilage de P4VP de masses molaires leves et faibles. La concentration minimale pour former des fibres prsentant des perles diminue dans le N, N'-dimthylformamide (DMF) et diminue encore plus lorsque le nitromthane, un mauvais solvant pour la P4VP et un non-solvant pour le BiOH, est ajout pour diminuer l'effet de rupture des liaisons hydrogne caus par le DMF. Les liaisons hydrogne dans les solutions et les fibres de P4VP-BiOH ont t quantifies par spectroscopie IR et les rsultats de rhologie ont dmontr la capacit de points de rticulation effectifs, analogues aux enchevtrements physiques, augmenter la viscolasticit de solutions de P4VP pour mieux rsister la formation de gouttelettes. Cette rticulation effective fonctionne en raison d'interactions entre le BiOH bifonctionnel et deux chanes de P4VP, et entre les groupements hydroxyles du BiOH complex de manire monofonctionnelle. Des tudes sur dautres agents de rticulation de faible masse molaire ont montr que la plus forte rticulation effective est introduite par des groupes dacide carboxylique et des ions de zinc (II) qui facilitent le processus dlectrofilage par rapport aux groupements hydroxyles du BiOH. De plus, la sublimation est efficace pour liminer le BiOH contenu dans les fibres sans affecter leur morphologie, fournissant ainsi une mthode lgante pour prparer des fibres de polymres purs dont le processus dlectrofilage est habituellement difficile. Deux complexes entre la P4VP et des azobenznes photoactifs portant le mme groupement tte hydroxyle et diffrents groupes queue, soit cyano (ACN) ou hydrogne (AH), ont t tudis par spectroscopie infrarouge dabsorbance structurale par modulation de la polarisation (PM-IRSAS) pour valuer l'impact des groupements queue sur leur performance lors de l'irradiation avec de la lumire polarise linairement. Nous avons constat que ACN mne la photo-orientation des chanes latrales de la P4VP et des azobenznes, tandis que AH mne seulement une orientation plus faible des chromophores. La photo-orientation des azobenznes diminue pour les complexes avec une teneur croissante en chromophore, mais l'orientation de la P4VP augmente. D'autre part, l'orientation rsiduelle aprs la relaxation thermique augmente avec la teneur en ACN, la fois pour le ACN et la P4VP, mais la tendance oppose est constate pour AH. Ces diffrences suggrent que le moment dipolaire a un impact sur la diffusion rotationnelle des chromophores. Ces rsultats contribueront orienter la conception de matriaux polymres contenant des azobenzne efficaces.
Resumo:
Les essais prliminaires pour prparer des alcoolates de fer partir du bichlorure ou bibromure de fer (II), en les combinant avec des ligands de type diimino pyridine, ont engendr la formation de complexes homoleptiques et htroleptiques, dpendant des substituants sur les branches imines du ligand. Ces complexes homoleptiques octadriques et paramagntiques ont t tudis par rapport leurs proprits spectroscopiques et cristallographiques. De plus, la synthse des complexes de fer htroleptique a engendr de bons prcurseurs penta-coordonns pour les ractions de substitution de ligands avec des alcoolates de mtaux alcalins, de manire produire les dialcoolates de fer (II) dsirs. Des techniques danalyse telles que la spectroscopie UV-vis, lanalyse lmentaire, la spectromtrie de masse haute rsolution et la cristallographie aux rayons X ont t utilises pour caractriser ces complexes de fer. Lactivit catalytique de ces complexes de fer (II) a aussi t tudie par rapport la polymrisation du lactide; les dialcoolates convoits ont t gnrs in-situ en raison de la difficult produire et isoler les drivs alcoolates des complexes diimino pyridine de fer. Une tude approfondie a aussi t faite sur les ractions de polymrisation, surtout par rapport aux valeurs de conversion lchelle du temps, ainsi qu la tacticit des chaines de polymres obtenues. Ces analyses ont t effectues par lentremise de la spectroscopie de rsonance magntique nuclaire, de la chromatographie dexclusion strique, et de la spectromtrie de masse MALDI (dsorption-ionisation laser assiste par matrice).
Resumo:
La prsentation antignique par les molcules de classe II du complexe majeur dhistocompatibilit (CMH II) est un mcanisme essentiel au contrle des pathognes par le systme immunitaire. Le CMH II humain existe en trois isotypes, HLA-DP, DQ et DR, tous des htrodimres composs dune chane et dune chane . Le CMH II est entre autres exprim la surface des cellules prsentatrices dantignes (APCs) et des cellules pithliales actives et a pour fonction de prsenter des peptides dorigine exogne aux lymphocytes T CD4+. Loligomrisation et le trafic intracellulaire du CMH II sont largement facilits par une chaperone, la chane invariante (Ii). Il sagit dune protine non-polymorphique de type II. Aprs sa biosynthse dans le rticulum endoplasmique (ER), Ii htro- ou homotrimrise, puis interagit via sa rgion CLIP avec le CMH II pour former un complexe Ii. Le complexe sort du ER pour entamer son chemin vers diffrents compartiments et la surface cellulaire. Chez lhomme, quatre isoformes dIi sont rpertories : p33, p35, p41 et p43. Les deux isoformes exprimes de manire prdominante, Iip33 et p35, diffrent par une extension N-terminale de 16 acides amins porte par Iip35. Cette extension prsente un motif de rtention au rticulum endoplasmique (ERM) compos des rsidus RXR. Ce motif doit tre masqu par la chane du CMH II pour permettre au complexe de quitter le ER. Notre groupe sest intress au mcanisme du masquage et au mode de sortie du ER des complexes Ii. Nous montrons ici que linteraction directe, ou en cis, entre la chane du CMH II et Iip35 dans une structure Ii est essentielle pour sa sortie du ER, promouvant la formation de structures de haut niveau de complexit. Par ailleurs, nous dmontrons que NleA, un facteur de virulence bactrien, permet daltrer le trafic de complexes Ii comportant Iip35. Ce phnotype est mdi par linteraction entre p35 et les sous-units de COPII. Bref, Iip35 joue un rle central dans la formation des complexes Ii et leur transport hors du ER. Ceci fait dIip35 un rgulateur clef de la prsentation antignique par le CMH II.
Zeolite Encapsulated Complexes Of Fe,Co,Ni,Cu And Pd:Synthesis , Characterization And Catalysis-2003
Resumo:
This thesis deals with the synthesis, characterization and catalysis activity studies of some zeolite encapsulated complexes. Encapsulation inside the zeolite cages makes the catalysts more stable. Further, the framework prevents the complexes from dimerising. Catalysis by metal complexes encapsulated in the cavities of zeolites and other molecular sieves has many features of homogeneous, heterogenous and enzymatic catalysis. Serious attempts has been made to gain product selectivity in catalysis .The catalytic activity shown by the encapsulated complexes can be correlated to the structure of the active site inside the zeolite pore. It deals with the studies on the partial oxidation of benzyl alcohol to benzaldehyde. The oxidatio was carried out using hydrogen peroxide as oxidant in presence of PdYDMG and CuYSPP as catalysts. The product (benzaldehyde) was detected using TLC and confirmed using GC.The catalytic activity of the complexes was tested for oxidation under various conditions. The operating conditions like the amount of the catalyst, reaction time, oxidant to substrate ratio, reaction temprature, and solvents have been optimized. No further oxidation products were obtained on continuing the reaction for four hours beyond the optimum time. Maximum conversion was obtained at room temperature and the percentage conversion decreased with increase in temperature. Activity was found to be dependent on the solvent used. With increasing awareness about the dangers of environmental degradation, research in chemistry is getting increasing geared to the development of green chemistry, by designing environmentally friendly products and processes that bring down the generation and use of hazardous substances.
Resumo:
The primary aim of these investigations was to probe the spectroscopic, electrochemical, biological and single crystal X-ray diffraction studies of some selected transition metal complexes of 4N-monosubstituted thiosemicarbazones. Transition metal complexes with thiosemicarbazones exhibit a wide range of stereochemistries and possess potential biological activity. Metal complexes of thiosemicarbazones are proved to have improved pharmacological and therapeutic effects. The studies are conducted to bring about a fair understanding of the structure activity relationship and to develop certain effective and economical metal-based antimicrobial agents. Study showed that the thiosemicarbazones have antibacterial, antiviral and antiproliferative properties and hence used against tuberculosis, leprosy, psoriasis, rheumatism, trypanosomiasis and coccidiosis. Certain thiosemicarbazones showed a selective inhibition of HSV and HIV infections. The insolubility of most thiosemicarbazones in water causes difficulty in the oral administration in clinical practice. Transition metal complexes are found to have more activity than uncombined thiosemicarbazones. They exhibit a variety of denticity and can be varied by proper substitution. The stereochemistry assumed by the thiosemicarbazones during the coordination with transition metal ions depends on the factors such as preparative conditions and availability of additional bonding site in the ligand moiety and charge of the ligand. The resulting complexes exhibited a wide range of stereochemistries and have biomimic activity and potential application as sensors.
Resumo:
Coordination chemistry of schiff bases is of considerable interest due to their various magnetic, catalytic and biological applications. Here it describes the spectral characterization of schiff bases and its Mn (II), Cu (II) and Ni (II) complexes. Then synthesis and spectral characterization of Zn (II), Cd (II) and Co (II) complexes of schiff base derived from 3-Formylsalicilic Acid and 1,3-diaminopropane. Then it discusses the synthesis and spectral studies of Copper (II) complexes of 2-Hydroxyacetophenone N-phenyl semicarbazone. Finally it discusses the synthesis and spectral characterization of Co (III) complexes of salicylaldehyde N-phenyl semicarbazone. The preparation and characterization of Cobalt (III) complexes of salicylaldehyde, N-phenylthiosemicarbazone containing hetrocyclic bases phenalthroline and bipyridine. Thiocyanate, azide and perchlorate ions act as coligands. Elemental analysis suggests +3 state for Cobalt. HNMR, IR and UV-visible spectra characterize the complexes.
Resumo:
This study concentrates the chemical properties of hydrazones due to its chelating capability and their pharmacological applications. Studies cover the preparation of different acid hydrazones and their structural studies and studies on their antimicrobial activity, synthesis and spectral characterization of different complexes of copper oxovanadium, manganese, nickel etc. Effect of incorporation of heterocyclic bases to the coordination sphere, change in the biological activity of acid hydrazones upon coordination, development of X-ray quality single crystals and its X-ray diffraction studies, studies on the redox behavior of the coordinated metal ions and correlation between the stereochemistry and biological activities.
Resumo:
The thesis deals with the synthesis, characterization and catalytic activity studies of supported cobalt(ii), nickel(II) and copper(II) complexes of O-phenylenediamine and Schiff bases derived from 3-hydroxyquinoxaline -2-carboxaldehyde. Zeolite encapsulation and polymer anchoring was employed for supporting the complexes. The characterization techniques proved that the encapsulation as well as polymer supporting has been successfully achieved. The catalytic activity studies revealed that the activities of the simple complexes are improved upon encapsulation. Various characterization techniques are used such as, chemical analysis, EPR, magnetic measurements, FTIR studies, thermal analysis, electronic spectra, XRD, SEM, surface area, and GC.The present study indicated that the that the mechanism of oxidation of catechol and DTBC by hydrogen peroxide is not altered by the change in the coordination sphere around the metal ion due to encapsulation. This fact suggests outer sphere mechanism for the reactions. The catalytic activity by zeolite encapsulated complex was found to be slower than that by the neat complex. The slowing down of the reaction in the zeolite case is probably due to the constraint imposed by the zeolite framework. The rate of DTBC ( 3,5-di-tert-butylchatechol)oxidation was found to be greater than the rate of catechol oxidation. This is obviously due to the presence of electron donating tertiary butyl groups.
Resumo:
The thesis deals with the synthesis, characterization and catalytic activity studies of some new Fe (III), Co (II), Ni (II) and Cu (II) complexes of hydrazones and their zeolite encapsulated analogues. Hydrazones have diverse applications in biological, non-biological and biochemical front. During the present study three hydrazone types of ligands namely, acetylacetone- 2-hydroxyphenylhydrazone (APAcAc), acetoacetanilide- 2-hydroxyphenylhydrazone (APAcAcA) and acetoacetanilide-3,5-dihydro-2,4-dione pyrimidylhydrazone (AUAcAcA) were synthesized by diazotization of primary amine and coupling with compounds containing active methylene group. First part of the thesis deals with the synthesis of Fe, Co, Ni and Cu complexes using three hydrazone types of ligands are given. Details regarding the characterization of these complexes with a view to establishing the molecular structures are presented in this part. The other part contains the method of encapsulation of these complexes in zeolite cavities and their characterizations of the encapsulated metal species are described. A comparitive account of the catalytic activities of the pure and encapsulated complexes for cyclohexanol oxidation was also carried out.
Resumo:
The study deals with the diversity in structural and spectural characteristics of some transition metal complexes derived from aldehyde based thiosemicarbazone ligands thiosemicarbazones are a family of compounds with beneficial biological activity viz., anticancer,antitumour, antifungal, antibacterial, antimalarial, antifilarial, antiviral and anti-HIV activities. Many thiosemicarbazone ligands and their complexes have been prepared and screened for their antimicrobial activity against various types of fungi and bacteria. The results prove that the compounds exhibit antimicrobial properties and it is important to note that in some cases metal chelates show more inhibitory effects than the parent ligands. The increased lipophilicity of these complexes seems to be responsible for their enhanced biological potency. Adverse biological activities of thiosemicarbazones have been widely studied in rats and in other species. The parameters measured show that copper complexes caused considerable oxidative stress and zinc zinc complexes behaved as antioxidants. It has applications on analytical field also. Some thiosemicarbazones produce highly colored complexes with metal ions. This thesis aims to synthesis some novel thiosemicarbazone ligands and their transition metal complexes together with their physico-chemical characterization.
Resumo:
The study deals with structural and spectral investigations of transition metal complexes of di-2-pyridyl ketone N(4),N(4)-disubstituted thiosemicarbazones. The main objective and scope of the work deals with di-2-pyridyl ketone N(4),N(4)-disubstituted thiosemicarbazones are quardridentate NNNS donor ligands. To chosen this ligand for study because, the ligands are prepared and characterized for the first time, since there are two pyridyl nitorgens, dimmers and polymers of complexes may result leading to interesting structural aspects. The work includes the preparation of the thiosemicarbzones and their structural and spectral studies, synthesis and spectral characterization of complexes of copper(II),,nickel(II),manganese(II), dioxovanadium(V),cobalt(III),zinc(II),cadmium(II) of the ligand HL, synthesis and spectral characterization of complexes of copper(II),manganese(II), of the ligand HL and the development of X-ray quality crystals and its X-ray diffraction studies. The structural characterization techniques are elemental analysis, conductivity measurements, magnetic measurements, electronic spectroscopy, H NMR spectroscopy, Infrared spectroscopy and X-ray crystallography.
Resumo:
The primary aim of these investigations was to probe the spectroscopic, electrochemical, biological and single crystal X-ray diffraction studies of some selected transition metal complexes of 4N-monosubstituted thiosemicarbazones. Transition metal complexes with thiosemicarbazones exhibit a wide range of stereochemistries and possess potential biological activity. Metal complexes of thiosemicarbazones are proved to have improved pharmacological and therapeutic effects. The studies are conducted to bring about a fair understanding of the structure activity relationship and to develop certain effective and economical metal-based antimicrobial agents. Study showed that the thiosemicarbazones have antibacterial, antiviral and antiproliferative properties and hence used against tuberculosis, leprosy, psoriasis, rheumatism, trypanosomiasis and coccidiosis. Certain thiosemicarbazones showed a selective inhibition of HSV and HIV infections. The insolubility of most thiosemicarbazones in water causes difficulty in the oral administration in clinical practice. Transition metal complexes are found to have more activity than uncombined thiosemicarbazones. They exhibit a variety of denticity and can be varied by proper substitution. The stereochemistry assumed by the thiosemicarbazones during the coordination with transition metal ions depends on the factors such as preparative conditions and availability of additional bonding site in the ligand moiety and charge of the ligand. The resulting complexes exhibited a wide range of stereochemistries and have biomimic activity and potential application as sensors
Resumo:
In this regard Schiff base complexes have attracted wide attention. Furthermore, such complexes are found to play important role in analytical chemistry, organic synthesis, metallurgy, refining of metals, electroplating and photography. Many Schiff base complexes are reported in literature. Their properties depend on the nature of the metal ion as well as on the nature of the ligand. By altering the ligands it is possible to obtain desired electronic environment around the metal ion. Thus there is a continuing interest in the synthesis of simple and zeolite encapsulated Schiff base complexes of metal ions. Zeolites have a number of striking structural similarities to the protein portion of natural enzymes. Zeolite based catalysts are known for their remarkable ability of mimicking the chemistry of biological systems. In view of the importance of catalysts in all the areas of modern chemical industries, an effort has been made to synthesize some simple Schiff base complexes, heterogenize them by encapsulating within the supercages of zeoliteY cavities and to study their applications. The thesis deals with studies on the synthesis and characterization of some simple and zeoliteY encapsulated Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) complexes and on the catalytic activity of these complexes on some oxidation reactions. Simple complexes were prepared from the Schiff base ligands SBT derived from 2-aminobenzothiazole and salicylaldehyde and the ligand VBT derived from 2-aminobenzothiazole and vanillin (4-hydroxy-3- methoxybenzaldehyde). ZeoliteY encapsulated Mn(II), Fe(III), Co(II), Ni(II) and Cu(II) complexes of Schiff base ligands SBT and VBT and also of 2-aminobenzothiazole were synthesized. All the prepared complexes were characterized using the physico-chemical techniques such as chemical analysis (employing AAS and CHN analyses), magnetic moment studies, conductance measurements and electronic and FTIR spectra. EPR spectra of the Cu(II) complexes were also carried out to know the probable structures and nature of Cu(II) complexes. Thermogravimetric analyses were carried out to obtain the information regarding the thermal stability of various complexes. The successful encapsulations of the complexes within the cavities of zeoliteY were ascertained by XRD, surface area and pore volume analysis. Assignments of geometries of simple and zeoliteY encapsulated complexes are given in all the cases. Both simple and zeoliteY encapsulated complexes were screened for catalytic activity towards oxidation reactions such as decomposition of hydrogen peroxide, oxidation of benzaldehyde, benzyl alcohol, 1-propanol, 2-propanol and cyclohexanol.
