In this work, mixed alkoxides of general formula [V(O)Nbx(OR)(3+5x)] (R = n-C3H7 and C2H5, x = 1, 4.5 and 9) are obtained. They are used to prepare complex (V/Nb)-pentoxides. Different spectroscopic methods, for example UV/VIS, resonance raman, infrared, temperature dependant 51V NMR and two dimensional 1H or 13C NMR, are used to elucidate structural details. It can be shown that the alkoxide precursor is a mixture of monomers and dimers which exchange very quickly. 2 % [V(O)Nb(OPr)8] (Pr = propyl) exists in a 0.1 molar solution. This complex is in equilibrium with V(O)(OPr)3 and Nb(OPr)5. Nb(OPr)5 itself exchanges with [Nb(OPr)5]2. For nuclear magnetic resonance experiments the exchange has to be slowed down using low temperatures.Controlled hydrolysis at 5 °C of a mixture of V(O)(OPr)3 and [Nb(OEt)5]2 in propanol leads to a clear transparent gel. The ratio of V : Nb is 1 : 1, 1 : 4.5 or 1 : 9, and oxalic acid is used as a chelating agent. Moreover, a dried product of a frozen solution of ammonium vanadate and ammonium oxyoxalatoniobate in water is found to be an appropriate precursor for the fore-mentioned oxides. Thermal decomposition of the gels and of the freeze dried products is monitored thermoanalytically and mass spectrometrically.The compositions of the resulting phases are examined and compared with the composition obtained via conventional synthesis (sintering of powder mixtures). Phases VNbxO(2.5+2.5x) (x = 1, 4.5 and 9) are obtained through the sol-gel technique and freeze drying at distinctly lower temperatures. VNbO5 crystallizes between 400 and 650 °C and V4Nb18O55 between 550 and 750 °C. A clean, non-reduced phase, VNb9O25, crystallizes above 1100 °C in oxygen. Below this temperature, solid solutions of V2O5 in TT- or M-Nb2O5 exist. Conventionally, pure VNbO5 is not obtainable. Some sol-gel synthesized products have the advantage of a more complete phase formation. In this way, a new phase of composition VNb9O25 can be found. The phase is homöotypic to M-Nb2O5.An additional advantage of the sol-gel synthesis lies in relatively high surface areas. Adversely, carbon remaining from the alcohol groups favours the thermodynamically stable phase VNb9O25 over the phase V4Nb18O55. Consequently, the freeze drying method seems to be the best way to get metastable phases in the system V2O5/x·Nb2O5.The formation of the complex oxides is controlled through the thermodynamics at phase boundaries. Therefore, to get mixed phases, structurally similar starting materials are preferred. In other words, using V2O5 and TT-Nb2O5 as starting materials the mixed phase similar to TT-Nb2O5 can be obtained. B-Nb2O5 as precursor yields another mixed phase similar to B-Nb2O5. In this work, this effect is called the "structure directing effect". It is explained through the consumption of free enthalpy at the phase boundaries.As an additional point, catalytic activities of the complex oxides are examined. Because of a synergism of the known good activity of V2O5 and the good selectivity of Nb2O5, a strongly enhanced activity of the mixed oxides is found. Large surface areas further improve the activity. Connections between oxygen partial pressure, band gap and catalytic activity are found. A dilution of V2O5 in Nb2O5 down to 10 mol-% also causes an enhancement of catalytic activity. / In der Arbeit werden durch die Synthese gemischter Alkoxide der Gesamtzusammensetzung [V(O)Nbx(OR)(3+5x)] (R = n-C3H7 und C2H5, x = 1, 4,5 und 9) sowie gefriergetrockneter Pulver Ausgangssubstanzen für gemischte, komplexe Vanadium- und Nioboxide erhalten. Untersuchungen mittels UV/VIS-, Resonanz-Raman- und IR-Spektroskopie sowie temperaturabhängiger 51V- und zweidimensionaler 1H-/13C NMR-Spektroskopie zeigen, dass es sich bei der Alkoxid-Vorstufe um ein Gemisch aus monomeren und dimeren Einheiten handelt, die in schnellem Gleichgewicht miteinander stehen. So liegt [V(O)Nb(OPr)8] als Donorkomplex vor, der im Gleichgewicht mit VO(OPr)3 und Nb(OPr)5 steht. Nb(OPr)5 steht wiederum im Gleichgewicht mit [Nb(OPr)5]2. Die Bildung und der Zerfall des Donorkomplexes erfolgen bei Raumtemperatur so schnell, dass er nur durch UV/VIS- und Resonanz-Raman-Spektroskopie sichtbar wird; bei der Kernresonanzspektroskopie muss der Austausch durch tiefe Temperaturen verlangsamt werden.Mittels kontrollierter Hydrolyse einer Mischung aus VO(OPr)3 und [Nb(OEt)5]2 in Propanol mit Oxalsäure als Chelatbildner und der Verlangsamung der Kondensation über die Erniedrigung der Temperatur wird ein homogenes, transparentes Gel aus V2O5 und Nb2O5 hergestellt. Daneben wird durch eine Lösung aus Ammoniumvanadat und Ammoniumoxyoxalatoniobat ein für die Gefriertrocknung geeigneter Precursor zur Synthese der Oxidphasen gefunden. Die Zersetzung des Gels und der gefriergetrockneten Pulver werden mittels DTA, TG und Massenspektrometrie untersucht und die Phasenausbildung mit der Reaktion von konventionellen Festkörpergemengen verglichen.Die dabei entstehenden metastabilen und thermodynamisch stabilen Phasen VNbxO(2,5+2,5x) (x = 1, 4,5 und 9) sind durch das Sol-Gel-Verfahren sowie durch die Gefriertrocknung bei deutlich niedrigeren Temperaturen und mit geringerem Fremdphasenanteil als bei der konventionellen Synthese erhältlich. VNbO5 existiert bis 650 °C, V4Nb18O55 bis 750 °C, darüber wandelt sich jede Zusammensetzung in VNb9O25 bzw. in verschiedene Nb2O5-Modifikationen und V2O5 um. Die Sol-Gel-Methode liefert im Vergleich zur Gefriertrocknung bei 900-1100 °C den Vorteil der schnelleren Phasenausbildung durch die größere Homogenität der Vorstufe. So erhält man Zwischenstufen, die sonst nur mit Beimengungen zu synthetisieren sind. In diesem Zusammenhang kann erstmalig eine zu M-Nb2O5 homöotype Verbindung der Zusammensetzung VNb9O25 erhalten werden. Ein weiterer Vorteil der Sol-Gel-Synthese ist der Erhalt größerer Oberflächen nach der Zersetzung. Nachteilig erscheinen jedoch bei einer Synthese bei tiefen Temperaturen (500-800 °C) die Alkoholatreste. So entstehen wesentlich eher die thermodynamisch begünstigten Phasen, z. B. VNb9O25 vor V4Nb18O55 und V4Nb18O55 vor VNbO5. Weiterhin macht sich die komplizierte Präparation der Gele bemerkbar; daher stellt im Allgemeinen die Gefriertrockung die Methode der Wahl dar.Die Ausbildung der komplexen Oxide erfolgt stark geprägt durch die Thermodynamik an den Phasengrenzen. Daher erfolgt eine bevorzugte Ausbildung strukturähnlicher Mischphasen. Diese erstmalig in diesem Ausmaß festgestellte Tatsache wird in der Arbeit der Strukturdirigierende Effekt genannt. Eine Erklärung dieses Effektes erfolgt anhand des Verbrauchs der Freien Enthalpie an den Phasengrenzen.Aufgrund eines Synergismus der Eigenschaften von V2O5 und Nb2O5 bei der oxidativen Dehydrierung von Propan zu Propen (relativ hohe katalytische Aktivität von V2O5 und hohe Selektivität von Nb2O5) wird eine überproportional hohe katalytische Aktivität bei den Mischoxiden erhalten. Die durch die unkonventionellen Methoden erhaltenen großen Oberflächen verbessern die Aktivität weiter. Es können Zusammenhänge festgestellt werden zwischen der Sauerstoffabgabetendenz, der Redoxkraft, der Bandlücke der Mischoxide und der katalytischen Aktivität. Die Einzigartigkeit des Nb2O5-Wirtsgitters bewirkt bei der Verdünnung von V2O5 darin eine hohe katalytische Leistungssteigerung.

In this work, mixed alkoxides of general formula [V(O)Nbx(OR)(3+5x)] (R = n-C3H7 and C2H5, x = 1, 4.5 and 9) are obtained. They are used to prepare complex (V/Nb)-pentoxides. Different spectroscopic methods, for example UV/VIS, resonance raman, infrared, temperature dependant 51V NMR and two dimensional 1H or 13C NMR, are used to elucidate structural details. It can be shown that the alkoxide precursor is a mixture of monomers and dimers which exchange very quickly. 2 % [V(O)Nb(OPr)8] (Pr = propyl) exists in a 0.1 molar solution. This complex is in equilibrium with V(O)(OPr)3 and Nb(OPr)5. Nb(OPr)5 itself exchanges with [Nb(OPr)5]2. For nuclear magnetic resonance experiments the exchange has to be slowed down using low temperatures.Controlled hydrolysis at 5 °C of a mixture of V(O)(OPr)3 and [Nb(OEt)5]2 in propanol leads to a clear transparent gel. The ratio of V : Nb is 1 : 1, 1 : 4.5 or 1 : 9, and oxalic acid is used as a chelating agent. Moreover, a dried product of a frozen solution of ammonium vanadate and ammonium oxyoxalatoniobate in water is found to be an appropriate precursor for the fore-mentioned oxides. Thermal decomposition of the gels and of the freeze dried products is monitored thermoanalytically and mass spectrometrically.The compositions of the resulting phases are examined and compared with the composition obtained via conventional synthesis (sintering of powder mixtures). Phases VNbxO(2.5+2.5x) (x = 1, 4.5 and 9) are obtained through the sol-gel technique and freeze drying at distinctly lower temperatures. VNbO5 crystallizes between 400 and 650 °C and V4Nb18O55 between 550 and 750 °C. A clean, non-reduced phase, VNb9O25, crystallizes above 1100 °C in oxygen. Below this temperature, solid solutions of V2O5 in TT- or M-Nb2O5 exist. Conventionally, pure VNbO5 is not obtainable. Some sol-gel synthesized products have the advantage of a more complete phase formation. In this way, a new phase of composition VNb9O25 can be found. The phase is homöotypic to M-Nb2O5.An additional advantage of the sol-gel synthesis lies in relatively high surface areas. Adversely, carbon remaining from the alcohol groups favours the thermodynamically stable phase VNb9O25 over the phase V4Nb18O55. Consequently, the freeze drying method seems to be the best way to get metastable phases in the system V2O5/x·Nb2O5.The formation of the complex oxides is controlled through the thermodynamics at phase boundaries. Therefore, to get mixed phases, structurally similar starting materials are preferred. In other words, using V2O5 and TT-Nb2O5 as starting materials the mixed phase similar to TT-Nb2O5 can be obtained. B-Nb2O5 as precursor yields another mixed phase similar to B-Nb2O5. In this work, this effect is called the "structure directing effect". It is explained through the consumption of free enthalpy at the phase boundaries.As an additional point, catalytic activities of the complex oxides are examined. Because of a synergism of the known good activity of V2O5 and the good selectivity of Nb2O5, a strongly enhanced activity of the mixed oxides is found. Large surface areas further improve the activity. Connections between oxygen partial pressure, band gap and catalytic activity are found. A dilution of V2O5 in Nb2O5 down to 10 mol-% also causes an enhancement of catalytic activity. / In der Arbeit werden durch die Synthese gemischter Alkoxide der Gesamtzusammensetzung [V(O)Nbx(OR)(3+5x)] (R = n-C3H7 und C2H5, x = 1, 4,5 und 9) sowie gefriergetrockneter Pulver Ausgangssubstanzen für gemischte, komplexe Vanadium- und Nioboxide erhalten. Untersuchungen mittels UV/VIS-, Resonanz-Raman- und IR-Spektroskopie sowie temperaturabhängiger 51V- und zweidimensionaler 1H-/13C NMR-Spektroskopie zeigen, dass es sich bei der Alkoxid-Vorstufe um ein Gemisch aus monomeren und dimeren Einheiten handelt, die in schnellem Gleichgewicht miteinander stehen. So liegt [V(O)Nb(OPr)8] als Donorkomplex vor, der im Gleichgewicht mit VO(OPr)3 und Nb(OPr)5 steht. Nb(OPr)5 steht wiederum im Gleichgewicht mit [Nb(OPr)5]2. Die Bildung und der Zerfall des Donorkomplexes erfolgen bei Raumtemperatur so schnell, dass er nur durch UV/VIS- und Resonanz-Raman-Spektroskopie sichtbar wird; bei der Kernresonanzspektroskopie muss der Austausch durch tiefe Temperaturen verlangsamt werden.Mittels kontrollierter Hydrolyse einer Mischung aus VO(OPr)3 und [Nb(OEt)5]2 in Propanol mit Oxalsäure als Chelatbildner und der Verlangsamung der Kondensation über die Erniedrigung der Temperatur wird ein homogenes, transparentes Gel aus V2O5 und Nb2O5 hergestellt. Daneben wird durch eine Lösung aus Ammoniumvanadat und Ammoniumoxyoxalatoniobat ein für die Gefriertrocknung geeigneter Precursor zur Synthese der Oxidphasen gefunden. Die Zersetzung des Gels und der gefriergetrockneten Pulver werden mittels DTA, TG und Massenspektrometrie untersucht und die Phasenausbildung mit der Reaktion von konventionellen Festkörpergemengen verglichen.Die dabei entstehenden metastabilen und thermodynamisch stabilen Phasen VNbxO(2,5+2,5x) (x = 1, 4,5 und 9) sind durch das Sol-Gel-Verfahren sowie durch die Gefriertrocknung bei deutlich niedrigeren Temperaturen und mit geringerem Fremdphasenanteil als bei der konventionellen Synthese erhältlich. VNbO5 existiert bis 650 °C, V4Nb18O55 bis 750 °C, darüber wandelt sich jede Zusammensetzung in VNb9O25 bzw. in verschiedene Nb2O5-Modifikationen und V2O5 um. Die Sol-Gel-Methode liefert im Vergleich zur Gefriertrocknung bei 900-1100 °C den Vorteil der schnelleren Phasenausbildung durch die größere Homogenität der Vorstufe. So erhält man Zwischenstufen, die sonst nur mit Beimengungen zu synthetisieren sind. In diesem Zusammenhang kann erstmalig eine zu M-Nb2O5 homöotype Verbindung der Zusammensetzung VNb9O25 erhalten werden. Ein weiterer Vorteil der Sol-Gel-Synthese ist der Erhalt größerer Oberflächen nach der Zersetzung. Nachteilig erscheinen jedoch bei einer Synthese bei tiefen Temperaturen (500-800 °C) die Alkoholatreste. So entstehen wesentlich eher die thermodynamisch begünstigten Phasen, z. B. VNb9O25 vor V4Nb18O55 und V4Nb18O55 vor VNbO5. Weiterhin macht sich die komplizierte Präparation der Gele bemerkbar; daher stellt im Allgemeinen die Gefriertrockung die Methode der Wahl dar.Die Ausbildung der komplexen Oxide erfolgt stark geprägt durch die Thermodynamik an den Phasengrenzen. Daher erfolgt eine bevorzugte Ausbildung strukturähnlicher Mischphasen. Diese erstmalig in diesem Ausmaß festgestellte Tatsache wird in der Arbeit der Strukturdirigierende Effekt genannt. Eine Erklärung dieses Effektes erfolgt anhand des Verbrauchs der Freien Enthalpie an den Phasengrenzen.Aufgrund eines Synergismus der Eigenschaften von V2O5 und Nb2O5 bei der oxidativen Dehydrierung von Propan zu Propen (relativ hohe katalytische Aktivität von V2O5 und hohe Selektivität von Nb2O5) wird eine überproportional hohe katalytische Aktivität bei den Mischoxiden erhalten. Die durch die unkonventionellen Methoden erhaltenen großen Oberflächen verbessern die Aktivität weiter. Es können Zusammenhänge festgestellt werden zwischen der Sauerstoffabgabetendenz, der Redoxkraft, der Bandlücke der Mischoxide und der katalytischen Aktivität. Die Einzigartigkeit des Nb2O5-Wirtsgitters bewirkt bei der Verdünnung von V2O5 darin eine hohe katalytische Leistungssteigerung.

The research work reported in this thesis is focused on the chiral analysis, quantification of enantiomeric composition, assignment of absolute configuration of molecules with chosen functional groups. The weak intra-molecular hydrogen bonding interactions are detected by exploiting several multinuclear and multi-dimensional techniques. Pulse sequences have been designed to manipulate the spin dynamics to derive specific information from the complex NMR spectra encountered in diverse situations. Broadly, the thesis can be classified in to three sections. The section I containing two chapters reports the introduction of new chiral auxiliaries and protocols developed for enantiomeric discrimination, measurement of enantiomeric contents, assignment of absolute configuration for molecules possessing specific functional groups using chiral solvating and derivatizing agents. The section II, reports NMR experimental evidence for the observation of the rare type of intramolecular hydrogen bonds involving organic fluorine in biologically important organic molecules, that are corroborated by extensive DFT based theoretical calculations. The section II also discusses the H/D exchange mechanism as a tool for quantification of HB strengths in organic building blocks. The section III reports the two different novel NMR methodologies designed for deriving information on the scalar interaction strengths in an orchestrated manner. The designed sequences are able to completely eradicate the axial peaks, prevents the evolution of unwanted couplings and also yields ultrahigh resolution in the direct dimension, permitting the accurate measurement of scalar couplings for a particular spin. The brief summary about each chapter is given below. Chapter 1 provides a general introduction to one and two dimensional NMR spectroscopy. The pedagogical approach has been followed to discuss the conceptual understanding of spin physics and the NMR spectral parameters. The basic introduction to chirality, existing approaches in the literature for discrimination of enantiomers and the assignment of absolute configuration of molecules with chosen functional groups and their limitations are briefly discussed. The brief introduction to hydrogen bond, experimental methods to obtain the qualitative information about the strengths of hydrogen bonds, and the theoretical approaches employed in the thesis to corroborate the NMR experimental findings have been provided. The mechanism of H/D exchange, the utilization of exchange rates to derive strengths of intra-molecular hydrogen bond in small molecules have also been discussed. This chapter builds the bridge for the rest of the chapters. Each of these topics are discussed at length in the corresponding chapters. Part I: NMR Chiral Analysis: Novel Protocols Chapter 2 discusses a simple mix and shake method for testing the enantiopurity of primary, secondary and tertiary chiral amines and their derivatives, amino alcohols. The protocol involves the in-situ formation of chiral ammonium borate salt from a mixture of C2 symmetric chiral BINOL, trialkoxyborane and chiral amines. The proposed concept has been convincingly demonstrated for the visualization of enantiomers of a large number of chiral and pro-chiral amines and amino alcohols. The protocol also permits the precise measurement of enantiomeric composition. The significant advantage of the protocol is that it can be performed directly in the NMR tube, without any physical purification. The structure of the borate complex responsible for the enantiodifferentiation of amines has also been established by employing multinuclear NMR techniques and DFT calculations. From DOSY and 11B NMR experiments it has been ascertained that there are only two possible complexes or entities which are responsible for differentiating enantiomers. From the combined utility of DFT calculations and the 11B NMR chemical shifts, the structure of the borate complex has been determined to be an amine-coordinated complex with the N atom of the amine. Chapter 3 discusses a simple chiral derivatizing protocol involving the coupling of 2-formylphenylboronic acid and an optically pure [1,1-binaphthalene]-2,2-diamine for the rapid and accurate determination of the enantiopurity of hydroxy acids and their derivatives, possessing one or two optically active centres. It is established that this protocol is not only rapid method for discrimination of enantiomers but also highly effective for assigning the absolute configuration of various chiral hydroxy acids and their derivatives. The developed protocol involves the coupling of 2-formylphenylboronic acid with (R)-[1,1-binaphthalene]-2,2-diamine, and 2-formylphenylboronic acid with (S)-[1,1-binaphthalene]-2,2-diamine as chiral derivatizing agents. The absence of aliphatic peaks from the derivatizing agent, large chemical shift separation between the discriminated peaks of diastereomers, and the systematic change in the direction of displacement of peaks for an enantiomer in a particular diastereomeric complex, permitted the unambiguous assignment of absolute configuration. Part II : Rare Type of Intramolecular Hydrogen Bonding In chapter 4 The rare occurrence of intramolecular hydrogen bonds of the type N–H˖˖˖F–C, in the derivatives of imides and hydrazides in a low polarity solvent, is convincingly established by employing multi-dimensional and multinuclear solution state NMR experiments. The observation of 1hJFH, 2hJFN, and 2hJFF of significant strengths, where the spin polarization is transmitted through space among the interacting NMR active nuclei, provided strong and conclusive evidence for the existence of intra-molecular hydrogen bonds. Solvent induced perturbations and the variable temperature NMR experiments unambiguously supported the presence of intramolecular hydrogen bond. The two dimensional HOESY and 15N–1H HSQC experiments reveals the existence of multiple conformers in some of the investigated molecules. The 1H DOSY experimental results discarded any possibility of self or cross-dimerization of the molecules. The results of DFT based calculations, viz., Quantum Theory of Atoms In Molecules (QTAIM) and Non Covalent Interaction (NCI), are in close agreement with the NMR experimental findings. In chapter 5 the rates of hydrogen/deuterium (H/D) exchange determined by 1H NMR spectra have been utilized to derive the strength of hydrogen bonds and to monitor the electronic effects in the site-specific halogen substituted Benz amides and anilines. The theoretical fitting of the time dependent variation in the integral areas of 1H NMR resonances to the first order decay function permitted the determination of H/D exchange rate constants (k) and their precise half-lives (t1/2) with high degree of reproducibility. The comparative study also permitted the determination of relative strengths of hydrogen bonds and the contribution from electronic effects on the H/D exchange rates. Part III: Novel NMR Methodologies for the Precise Measurement of 1H-1H Couplings Chapter 6 describes two novel NMR methodologies developed for the precise measurement of 1H-1H couplings. Poor chemical shift dispersion and the pairwise interaction among the entire coupled network of protons results in the severely complex and overcrowded one dimensional 1H NMR spectra, hampering both the resonance assignments and the accurate determination of nJHH. The available two-dimensional selective refocusing (SERF) based experiments suffer from the evolution of magnetization from uncoupled protons as intense uninformative axial peaks. This creates ambiguity in the identification of peaks belonging to the coupled partners of a selectively excited proton, hindering the extraction of their interaction strengths. This challenge has been circumvented by designing two novel experimental technique, cited as “Clean-G-SERF” and “PS-Clean-G-SERF”. The Clean-G-SERF technique completely eradicates the axial peaks and suppresses the evolution of unwanted couplings while retaining only the couplings to the selectively excited proton. The method permits the accurate determination of spin-spin couplings even from a complex proton NMR spectrum in an orchestrated manner. The PS-Clean-G-SERF technique has been designed for the complete elimination of axial peaks and undesired couplings, with a blend of ultra-high resolution achieved by real time broad band mononuclear decoupling has been discussed in this chapter. The spin dynamics involved in both these pulse sequences have been discussed. The diverse applications of both these novel experiments have been demonstrated.

nÃo hà / Este trabalho descreve o estudo fitoquÃmico das cascas e do lenho de Andira surinamensis (Leguminosae), bem como a composiÃÃo quÃmica volÃtil dos Ãleos essenciais das folhas e frutos de Piper divaricatum G. Mey (Piperaceae). O estudo fitoquÃmico dos extratos de A. surinamensis, utilizando tÃcnicas clÃssicas de cromatografia em gel de sÃlica, resultou no isolamento de um dÃmero isoflavona inÃdito na literatura, 4â-metoxiisoflavona-(7-O-7ââ)-3âââ,4âââ- metilenodioxiisoflavona (Surinamensina), um triterpeno pentacÃclico comumente conhecido como Lupeol e mais quatro isoflavonas: 5,7-dihidroxi-4â-metoxiisoflavona (biochanina A), 5,4â- dihidroxi-7-metoxiisoflavona (prunetina), 7,3â-dihidroxi-4â-metoxiisoflavona (calicosina) e 5,7,3â-trihidroxi-4â-metoxiisoflavona (pratenseÃna). A determinaÃÃo estrutural dos compostos isolados foram elucidadas por tÃcnicas espectroscÃpicas tais como: espectro de massa, espectro de infravermelho e RessonÃncia MagnÃtica Nuclear de 1H, 13C uni e bidimensionais. A composiÃÃo quÃmica dos Ãleos essenciais das folhas e frutos de Piper divaricatum G. Mey., foram analisadas por CG / EM e CG / DIC. Um total de 24 compostos, representando mais do que 94% da composiÃÃo quÃmica dos Ãleos, foram identificados. Ambos os Ãleos mostraram grande concentraÃÃes de monoterpenos, em especial, o Ãleo das folhas que apresentou 81,1%. Os Ãleos mostraram composiÃÃo quÃmica similares, mas o Ãleo dos frutos pode ser facilmente distinguido do Ãleo das folhas pela exclusiva presenÃa do a-felandrene (4,60%), (E)-muurola- 4(14),5-dieno (9,0%) e do (E)-cariofileno (11,4%). Os maiores constituintes do Ãleo das folhas foram: linalool (23,4%), b-pineno (25,3%) e a-pineno (18,8%), enquanto que os Ãleo frutos apresentaram b-pineno (18.0%), a-pineno (17.6%) e (E)-cariofileno (11.4%), como compostos majoritÃrios. / This work describes the phytochemical investigation of extracts from the branch wood and branch barks of Andira surinamensis (Leguminosae), as well as, the volatile chemical composition of essential oil from leaves and fruits of Piper divaricatum G. Mey (Piperaceae). The phytochemical investigation of A. surinamensis extracts, using classic methods of chromatography on silica gel, yielded a novel isoflavone dimer, 4â-methoxyisoflavone-(7-O- 7ââ)-3âââ,4âââ-methylenedioxyisoflavone (surinamensin), along with the triterpene lupeol and the known isoflavones 5,7-dihydroxy-4\\\'-methoxyisoflavone (biochanin A), 5,4\\\'-dihydroxy-7- methoxyisoflavone (prunetin), 7,3â-dihydroxy-4â-methoxyisoflavone (calycosin) and 5,7,3â- trihydroxy-4â-methoxyisoflavone (pratensein). The structures of all isolated compounds were elucidated by spectroscopic methods, such as MS, IR and particularly 1D and 2D homonuclear and heteronuclear NMR spectroscopy and, comparison with published data for closely related compounds. The chemical composition of the essential oils from leaves and fruits of Piper divaricatum G. Mey., was analyzed by GC/MS and GC-FID. Twenty-four components, representing more than 94.0% of the chemical compositions of the oils, were identified. Both oils showed higher concentrations of monoterpenoids, particularly the oils from leaves (81.1%). The oils showed some compositional similarities but the fruit oil could be easily distinguished from the leaf oil by the exclusive presence of a-phellandrene (4.60%), (E)-muurola-4(14),5-diene (9,0%) and significant content of (E)-caryophyllene (11.4%). The major constituents of the leaf oils were linalool (23.4%), b-pinene (25.3%) and a-pinene (18.8%), while the fruit oils of the fruits contained b-pinene (18.0%) and a-pinene (17.6%) and (E)-caryophyllene (11.4%) as prevalent compounds.

No description available.

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Tailored fluoropolymers remain the leading choice for a wide variety of advanced high-performance applications, including electronic/optical and energy conversion, owing to their unique blend of complementary high-performance properties. Amorphous semi-fluorinated polymers exhibit improved solubility and melt processability when compared to traditional perfluoropolymers. A leading class of semi-fluorinated aryl ether polymers includes perfluorocyclobutyl (PFCB), perfluorocycloalkenyl (PFCA), and fluoroarylene vinylene ether (FAVE) polymers. Monomers containing aromatic trifluorovinyl ethers (TFVE) are used to synthesize PFCB polymers via radical-mediated [2+2] cyclodimerization. On the other hand, FAVE and PFCA polymers are polymerized via base-mediated nucleophilic addition/elimination of bisphenols with TFVE monomers and decafluorocyclohexene respectively. The use of different monomer cores (aromatic, aliphatic, contorted, and renewable) should help to develop general structure/property relationships for this versatile and expanding approach to semi-fluorinated aryl ether polymers. The enchainment of polycyclic aromatic hydrocarbon (PAH) cores with functional fluorocarbon groups (or segments) recently afforded a new class of semi- fluorinated polymers in the continuing quest for novel organic materials for potential applications in optoelectronic, gas-separation, and advanced composites. Chapter 2 details the incorporation of commercially available acenaphthenequinone was achieved to afford PFCB aryl ether polymers with excellent solubility, high thermal stability, and film-forming capability. Chapter 3 represents base-promoted nucleophilic addition/elimination of commercial bisphenols with TFVE-triphenylene monomers affording FAVE aryl ether polymers possessing excellent solution processability, high thermal stability and photostability. In addition, triphenylene-enchained FAVE polymers exhibit extreme thermal-oxidative photostability and emit blue light after heating in air at 250 °C for 24 h. Further, time-dependent density functional theory (TD-DFT) computations were performed to understand electronic polymer structures. In one case, post-polymerization Scholl coupling converted the central triphenylene core to afford a hexabenzocoronene containing semi-fluorinated polymer with new optoelectronic properties. Chapter 4 demonstrates synthesis and characterization of renewable semi-fluorinated polymers obtained using aliphatic diol isosorbide. This renewable diol readily polymerizes with bis-TFVE derivatives of bisphenol A and 6F to provide high molecular weight thermoplastics exhibiting excellent solubility and tough, transparent film-forming capability. Finally, Chapter 5 presents synthesis of TFVE enchained corannulene which gave blue-light emission and outstanding processability. Synthesis and characterization, including the new materials' optical, thermal, and electronic properties, is presented.

L’apparition de plusieurs maladies, telles que le cancer, le diabète, l'hypertension artérielle et la propagation d'infections de type virus mutagènes peuvent être liées à la qualité et au mode de vie que nous menons aujourd’hui. En effet, plusieurs études sur les facteurs déclenchant ces maladies dites "morbides" à long ou à court terme, sont liées au stress et à la qualité des aliments consommés, qu'ils soient d'origine végétale ou animale. Ces maladies deviennent un phénomène courant, elles touchent différentes races et toutes les catégories de la société. D'après les recherches ethnobotaniques, les substances d’origine naturelle, ont permis à des civilisations de survivre à des maladies mortelles. A titre d'exemple, on retrouve ainsi des références à des périodes de fièvre paludique en Chine et à des symptômes de cette maladie dans le «Huangdi Neijiang» Le Canon de Médecine datant des environs du premier siècle avant notre ère, plus de 2000 ans, qui relate de l'emploi de plantes médicinales, pour soulager les fièvres (Desgrouas et al., 2014).Vers 186 avant J.-C. apparaît, dans certaines régions de Chine, l'utilisation en tisane, du Qing hao su, appelé plus tard artémisinine en Occident et extrait d'une plante médicinale utilisée comme antipyrétique appelée "Qing hao", Artemisia annua ou Armoise annuelle. L'artemisinine bloque une enzyme qui permet au parasite de pomper le calcium et l'empêche ainsi de se développer. Au jour d'aujourd'hui l’Artemisinin-based combination therapy, en français Thérapie combinée à base d'artémisinine et en sigle ACT, est une thérapie et une prévention tertiaire dans les cas de paludisme simple.Dans cette optique notre étude vient s'ajouter à une longue série d'études menées sur les plantes médicinales et les substances naturelles extraites. Elle a pour objectif de révéler de nouvelles biomolécules, de mettre en évidence leurs activités biologiques grâce à des techniques de biotechnologies d'une part. D'autre part ces investigations permettront de valoriser les ressources naturelles qui se distinguent par leur endémicité.Pour se faire, notre choix s'est porté sur deux plantes médicinales endémiques à l'Algérie Cyclamen africanum Boiss. & Reuter et Zygophyllum cornutum Coss. , après une recherche ethnobotanique sur la pharmacopée traditionnelle du Nord de l'Afrique, et qui a révélé l’efficacité de ces plantes dans les problèmes inflammatoires minimes chez les autochtones, nous avons entrepris des investigations pharmaco- biochimiques.Ces dernières nous ont permis d'isoler : cinq composés à partir de l'extrait méthanolique des racines de l'espèce Cyclamen africanum Boiss. & Reuter, deux nouvelles saponines triterpéniques de type Oleanane, Afrocyclamin A et B (1, 2), ainsi que trois saponines triterpénoïdes connus sous le nom de lysikokianoside (3), deglucocyclamin I (4) et de son dérivé d'acide dicrotalique (5); et Sept saponosides connus à partir de l'extrait méthanolique de la plante entière de Zygophyllum cornutum Coss., ces saponosides sont de type ursane, ce type de triterpène est rapporté dans cette espèce pour la première fois et peuvent être considérés comme un marqueur chimio-taxonomique (chemotype) du genre Zygophyllum. Les structures ont été élucidées, sur la base de l'analyse des spectres de l'expérience RMN-1D et RMN- 2D (COSY, TOCSY, NOESY, HMBC et HSQC) et spectrométrie de masse en source FAB mode ion négatif. Des activités biologiques, des fractions saponosidiques Fr.1 et Fr.2, ont été testées sur des lignées de Rats mâles et femelles, de la race Winstar pour évaluer l'activité anti inflammatoire.La fraction saponosidique Fr.1 de Cyclamen africanum à la dose 5 mg, a montré un effet significatif sur l'inflammation causé par la carragénine, en réduisant l'oedème et la réponse immunitaire, qui s'est traduite par la concentration des protéines de la réponse inflammatoire (PRI) à travers leurs action sur les pro-médiateurs de l'inflammation (COX-2, PGE2, TNF -α, iNOS). / The appearance of several diseases, such as cancer, diabetes, high blood pressure and spread of infections mutagenic virus type can be linked to the quality and lifestyle that we lead today. Indeed, several studies on the factors triggering these so-called "morbid" long-or short-term illnesses are related to stress and quality of food consumed, whether of plant and animal origin. These diseases are becoming a common occurrence, they affect different races and all classes of society. According ethnobotanical research, naturally occurring substances, allowed civilizations to survive deadly diseases. For example, we thus find references to periods of malarial fever in China and one of the symptoms of this disease in the "Huangdi Neijiang" The Canon of Medicine dating from around the first century BC, more than 2000 years, which relates to the use of herbal medicines to relieve fevers (Desgrouas et al., 2014).Around 186 BC appears, in some parts of China, the use in herbal tea, Qing hao su, later known as artemisinin in the West and extracted from a medicinal plant used as antipyretic called "Qing hao" Artemisia annua or annual wormwood. Artemisinin blocks an enzyme which enables the parasite to pump calcium and prevents it from developing. As of today the Artemisinin-based combination therapy in French Combination therapy of artemisinin and ACT acronym, is a therapy and tertiary prevention in cases of uncomplicated malaria.From this perspective our study adds to a long series of studies on medicinal plants and natural substances extracted. It aims to reveal new biomolecules, highlighting their biological activities through techniques of biotechnology on the one hand. Moreover, these investigations will develop natural resources that are characterized by endemic.To do this, our choice is focused on two endemic medicinal plants in Algeria Cyclamen africanum Boiss. & Reuter and Zygophyllum cornutum Coss. After an ethnobotanical research on traditional medicine in Northern Africa, which showed the effectiveness of these plants in minimal inflammatory problems among Aboriginal, we undertook biochemical pharmacological investigations.The latter allowed us to isolate, five compounds from the methanol extract of the roots of the species Cyclamen africanum Boiss. Reuter & two new oleanane triterpene saponins type, Afrocyclamin A and B (1, 2) and three triterpenoid saponins known lysikokianoside of (3), deglucocyclamin I (4) and its derivative dicrotalique acid (5) September and known from the methanol extract saponins from the whole plant of Zygophyllum cornutum Coss. these saponins are ursane type, type triterpenes are reported in this species for the first time and can be considered a chemotherapy marker Taxonomic (chemotype) of Zygophyllum kind. The structures were elucidated on the basis of the analysis of NMR spectra of the experience-1D and 2D-NMR (COSY, TOCSY, NOESY, HSQC and HMBC) and mass spectrometry method negative ion FAB source. The biological activities of saponosidiques FR.1 and Fr.2 fractions were tested on lines of male and female rats of the Winstar rats to evaluate the anti-inflammatory activity. The saponosidique fraction FR.1 Cyclamen africanum the 5 mg dose, showed a significant effect on inflammation caused by carrageenan, reducing edema and immune response, which resulted in the concentration of protein the inflammatory response (PRI) through their action on the pro-inflammatory mediators (COX-2, PGE2, TNF -α, iNOS). The fraction of Fr.2 saponosidique Zygophyllum dose 20 mg did not show a significant effect on inflammation in general.