Synthese und Charakterisierung neuartiger, ambipolarer organischer Halbleiter, basierend auf Perylencarboximid-Systemen kombiniert mit funktionalisierten Spirobifluoreneinheiten

Das Ziel der vorliegenden Arbeit war die Synthese und Charakterisierung von donor-funktionalisierten Spiro-Perylencarboximiden, welche für den Einsatz in optoelektronischen Bauelementen wie z.B. organischen Phototransistoren, Feldeffekttransistoren oder Solarzellen vorgesehen sind. Die donorfunktionalisierten Spiro-Perylencarboximide stellen kovalent gebundene Donor-Akzeptor-Verbindungen dar, die unter geeigneter Belichtung einen ladungsgetrennten Zustand bilden können. Die Verbindungen wurden aus unterschiedlichen Spiroamin- und Perylenanhydrid-Edukten synthetisiert, die im Baukastenprinzip zu den entsprechenden Zielverbindungen umgesetzt wurden. Mittels unterschiedlicher Charakterisierungsmethoden (z.B. DSC, TGA, CV, Absorptions- und Fluoreszenzmessungen) wurden die Eigenschaften der neuartigen Zielverbindungen untersucht. Im Rahmen der Arbeit wurden vier neue Spiroamin-Edukte erstmalig synthetisiert und charakterisiert. Sie wurden durch Reduktion aus den bisher noch nicht beschriebenen Nitroverbindungen bzw. mittels Pd-katalysierter Kreuzkupplung (Hartwig-Buchwald-Reaktion) aus einer halogenierten Spiroverbindung erhalten. Als Perylenanhydrid-Edukt wurde erstmals eine perfluorierte Perylenanhydrid-Imid-Verbindung hergestellt. Aus den Spiroamin- und Perylenanhydrid-Edukten wurden insgesamt neun neue, donorfunktionalisierte Spiro-Perylencarboximide synthetisiert. Zusätzlich wurden sechs neuartige Spiro-Perylencarboximide ohne Diphenylamin-Donor hergestellt, die als Vergleichsverbindungen dienten. Die donorfunktionalisierten Spiro-Perylencarboximide besitzen eine Absorption im UV- und sichtbaren Spektralbereich, wobei hohe Extinktionskoeffizienten erreicht werden. Die Verbindungen zeigen in verdünnter Lösung (sowohl in polaren als auch in unpolaren Lösungsmitteln) eine Fluoreszenzquantenausbeute unter 1 %, was auf einen effizienten Ladungstransfer zurückzuführen ist. Alle donorfunktionalisierten Spiro-Perylencarboximide zeigen in den CV-Messungen reversibles Verhalten. Mittels CV-Messungen und optischer Methode konnten die HOMO- und LUMO-Lagen der jeweiligen Molekülhälften berechnet und das Fluoreszenzverhalten der Verbindungen erklärt werden. Ebenso konnten die Auswirkungen von unterschiedlichen Substituenten auf die jeweiligen HOMO-/LUMO-Lagen näher untersucht werden. Die durchgeführten DSC- und TGA-Untersuchungen zeigen hohe morphologische und thermische Stabilität der Verbindungen, wobei Glasübergangstemperaturen > 211 °C, Schmelztemperaturen > 388 °C und Zersetzungstemperaturen > 453 °C gemessen wurden. Diese Werte sind höher als die bisher in der Literatur für ähnliche spiroverknüpfte Verbindungen berichteten. Als besonders interessant haben sich die unsymmetrischen donorfunktionalisierten Spiro-Perylencarboximide herausgestellt. Sie zeigen hohe Löslichkeit in gängigen Lösungsmitteln, sind bis zu einer Molmasse < 1227 g/mol aufdampfbar und bilden stabile, amorphe Schichten.

Aproximacions a la síntesi estereoselectiva de noves heteroarilglicines

L'objectiu principal de la present tesi doctoral ha consistit fonamentalment en la síntesi de noves heteroarilglicines òpticament pures. Amb aquesta idea s'han desenvolupat dues estratègies diferents: síntesi estereoselectiva utilitzant auxiliars quirals i síntesi estereocontrolada utilitzant aldehids quirals derivats d' L-serina com a "building-blocks". Així doncs, per a la primera estratègia s'han dissenyat i sintetitzat els dos nous auxiliars quirals del tipus imidazolidin-2-ona 111 i 135 utilitzant L-fenilalanina i L-serina respectivament com a materials de partida òpticament purs. Davant els problemes detectats en la síntesi d'a-aminoàdics mitjançant síntesi asimètric, s'ha canviat d'estratègia i s'ha utilitzat una síntesi estereocontrolada utilitzant aldehids quirals obtinguts a partir d'L-serina.

New mono- and dinuclear ruthenium complexes containing the 3,5-bis(2-pyridyl)pyrazole ligand. Synthesis, characterization and applications

Se han sintetizado dos nuevos complejos mononucleares de Ru, con formula [RuCl2(Hbpp)(dmso)2], a partir de la reacción entre [RuCl2(dmso)4] y Hbpp (3,5-bis(2-piridil)pirazola). El hecho que sólo tres de los seis posibles estereoisómeros se obtengan a partir de esta reacción, se ha racionalizado en base a factores estructurales y electrónicos. Estos complejos se han caracterizado de forma estructural, espectroscópica y electroquímica. En acetonitrilo en medio básico, el isómero trans,cis-[RuCl2(Hbpp)(dmso)2] da lugar a procesos de isomerización de enlace de un ligando dmso cuando el Ru(II) se oxida a Ru(III). Las constantes termodinámicas y cinéticas para el proceso se han determinado por voltametria cíclica. La irradiación de trans,cis-[RuCl2(Hbpp)(dmso)2] y cis(out),cis-[RuCl2(Hbpp)(dmso)2] con luz UV o solar da lugar a reacciones de fotosustitución de un ligando dmso por una molécula de acetonitrilo para dar un nuevo compuesto el cual ha sido caracterizado en solución por técnicas espectroscópicas y electroquímicas. Ambos complejos resultan catalizadores útiles en la transferencia de hidrógeno de isopropanol a acetofenona, obteniéndose 1-feniletanol como único producto y un 42.1% de conversión (36.1 ciclos metálicos) a 80ºC con el isómero trans,cis-[RuCl2(Hbpp)(dmso)2], que resulta significativamente más eficaz que el complejo cis(out),cis-[RuCl2(Hbpp)(dmso)2]. La reacción de cis(out),cis-[RuCl2(Hbpp)(dmso)2] con trpy (2,2':6',2"-terpiridina) da lugar a los dos isómeros geométricos del complejo [Ru(Hbpp)(trpy)(Cl)]+, el in y el out. Estos complejos se han aislado y caracterizado por técnicas estructurales, espectroscópicas y electroquímicas. Estos cloro complejos han sido utilizados como precursores para la síntesis de los complejos análogos con ligandos aqua (in,out-[Ru(Hbpp)(trpy)(H2O)]2+) y piridina (in,out-[Ru(Hbpp)(trpy)(py)]2+), los cuales también han sido aislados y caracterizados. Las propiedades ácido-base de los aqua complejos, y del complejo out-py se han estudiado detalladamente por voltametria cíclica y mediante valoraciones espectrofotométricas ácido-base. El tratamiento matemático de los datos así obtenidos nos ha permitido determinar los valores de pKa para los distintos equilibrios de protonación de los complejos en los estados de oxidación II y III. El complejo out-aqua ha demostrado ser un buen catalizador para la oxidación electroquímica del alcohol benzílico, presumiblemente a benzaldehido. La constante de velocidad de segundo orden para el proceso ha sido determinada como 17.1 M-1 s-1, por simulación matemática. El dímero con un puente cloro, [Ru2Cl(bpp)(trpy)2]2+ ha sido preparado por dos rutas sintéticas diferentes. El dímero análogo con un puente acetato se ha obtenido por reacción del cloro dímero con un exceso de acetato sódico. El dímero con dos ligandos aqua [Ru2(bpp)(trpy)2(OH2)2]3+ puede obtenerse por hidrólisis ácida del complejo con un acetato puente o por hidrólisis básica del complejo con un puente cloro. Estos complejos han sido caracterizados por técnicas estructurales, espectroscópicas y electroquímicas. Las soluciones del dímero con dos ligandos aqua en medio ácido resultan inestables a la coordinación de aniones de la solución con el tiempo. Las propiedades ácido-base del dímero con dos aguas coordinadas han sido estudiadas por voltametria cíclica y mediante experimentos de electrólisis a potencial controlado. El pKa para la desprotonación de uno de los ligandos aqua ha sido determinado mediante una valoración espectrofotométrica ácido-base como 6.7. Este valor tan bajo de pKa se atribuye a la formación de la entidad {Ru2O2H3}, favorable termodinámicamente. Los espectros UV-vis para los distintos estados de oxidación del aqua dímero, de RuIIRuII a RuIIIRuIV, han sido obtenidos por oxidación química y electroquímica del complejo. Se han llevado a cabo estudios cinéticos de la oxidación, paso a paso, de RuII,II a RuIV,IV , y se han determinado las constantes de oxidación de segundo orden para los distintos procesos de oxidación. La capacidad del aqua dímero en la oxidación del agua a oxígeno molecular ha sido investigada en solución homogénea utilizando CeIV como oxidante. La evolución de oxígeno se ha demostrado por cromatografia de gases. Se ha obtenido una eficiencia del 73% y 18.6 ciclos catalíticos, cuando 1.83 x 10-6 moles de dímero se han mezclado con un exceso de 100 equivalentes de cerio. El dímero con dos aguas cataliza también la oxidación del agua de forma heterogénea, con el complejo adsorbido sobre una membrana de nafion, aunque la eficiencia es menor. Se ha propuesto un mecanismo intramolecular para la reacción de oxidación del agua. Consiste en la oxidación a 4 electrones del dímero, de RuII,II a RuIV,IV, el cual reacciona con el agua para formar oxígeno y revierte nuevamente al estado de oxidación II,II. Este modelo es consistente con estudios catalíticos de la evolución de oxígeno en función de las concentraciones de cerio y catalizador, llevados a cabo en solución ácida homogénea, que demuestran que la oxidación a 4 electrones del agua se encuentra catalizada por una sola molécula de complejo bajo concentraciones elevadas de cerio. La constante de pseudo-primer-orden para la evolución de oxígeno tiene un valor de 1.4 x 10-2 s-1, que es uno de los valores de constante más elevados obtenidos hasta la fecha. Desafortunadamente, el aqua dímero se desactiva durante el proceso de catálisis dando lugar a una especie naranja, la cual estamos actualmente tratando de caracterizar.

Bioorganometallic fulvene-derived titanocene anti-cancer drugs

A review. 6-Substituted fulvenes are interesting and easily accessible starting materials for the synthesis of novel substituted titanocenes via reductive dimerization, carbolithiation or hydridolithiation reactions, which are followed by a transmetallation reaction with titanium tetrachloride in the latter two cases. Depending on the substitution pattern, these titanocenes prove to be bioorganometallic anticancer drugs, which have significant potential against advanced or metastatic renal-cell cancer. Patients bearing these stages of kidney cancer have a poor prognosis so far and therefore real progress in the area of metal-based anticancer drugs may come from this simple and effective synthetic approach. This tutorial review provides an insight into the synthesis of fulvene-derived titanocenes and their activity in preclin. expts.

The photodimerisation of the alpha- and beta-forms of trans-cinnamic acid: a study of single crystals by vibrational microspectroscopy

Infrared and Raman microspectroscopy have been used to follow the photodimerisation reactions of single crystals, the alpha- and beta-forms of trans-cinnamic acid. This approach allows the starting materials and products -alpha-truxillic acid that has C-i symmetry and beta-truxinic acid, which has C-s symmetry-to be identified. It also allows the topotactic nature of the reaction to be confirmed. Attempts to produce the poorly-defined unreactive gamma-form of trans-cinnamic acid resulted only in a mixture of the alpha- and beta-forms. The findings suggest a wide role for these spectroscopic methods in monitoring solid-state organic reactions. (C) 2002 Elsevier Science B.V. All rights reserved.

Total synthesis of (+/-) maculalactone A, maculalactone B and maculalactone C and the determination of the absolute configuration of natural (+) maculalactone A by asymmetric synthesis

Maculalactones A, B and C from the marine cyanobacterium Kyrtuthrix maculans are amongst the only compounds based on the tribenzylbutyrolactone skeleton known in nature and (+) maculalactone A from the natural source possesses significant biological activity against various marine herbivores and marine settlers. We now report a concise synthesis of racemic maculalactone A in five steps from inexpensive starting materials. Maculalactones B and C were synthesized by a minor modification to this procedure, and the synthetic design also permitted an asymmetric synthesis of maculalactone A to be achieved in around 85% ee. The (+) and (-) enantiomers of maculalactone A were assigned, respectively, to the S and R configurations on the basis of the chiral selectivity expected for catecholborane reduction of an unsymmetrical ketone in the presence of Corey's oxazoborolidine catalyst. Surprisingly, it appeared that natural (+) maculalactone A was biosynthesized in K. maculans in a partially racemic form, comprising ca. 90-95% of the (S) enantiomer and 5-10% of its (R) enantiomer. Coincidentally therefore, the percentage enantiomeric excess of the product obtained from asymmetric synthesis almost exactly matched that found in nature. (C) 2004 Elsevier Ltd. All rights reserved.

Design, synthesis and computational modelling of aromatic tweezer-molecules as models for chain-folding polymer blends

Novel 'tweezer-type' complexes that exploit the interactions between pi-electron-rich pyrenyl groups and pi-electron deficient diimide units have been designed and synthesised. The component molecules leading to complex formation were accessed readily from commercially available starting materials through short and efficient syntheses. Analysis of the resulting complexes, using the visible charge-transfer band, revealed association constants that increased sequentially from 130 to 11,000 M-1 as increasing numbers of pi-pi-stacking interactions were introduced into the systems. Computational modelling was used to analyse the structures of these complexes, revealing low-energy chain-folded conformations for both components, which readily allow close, multiple pi-pi-stacking and hydrogen bonding to be achieved. In this paper, we give details of our initial studies of these complexes and outline how their behaviour could provide a basis for designing self-healing polymer blends for use in adaptive coating systems. (C) 2008 Elsevier Ltd. All rights reserved.

The kinetics of the 2π+2π photodimerisation reactions of single-crystalline derivatives of trans-cinnamic acid: a study by infrared microspectroscopy

The kinetics of the photodimerisation reactions of the 2- and 4-β-halogeno-derivatives of trans-cinnamic acid (where the halogen is fluorine, chlorine or bromine) have been investigated by infrared microspectroscopy. It is found that none of the reactions proceed to 100% yield. This is in line with a reaction mechanism developed by Wernick and his co-workers that postulates the formation of isolated monomers within the solid, which cannot react. β-4-Bromo and β-4-chloro-trans-cinnamic acids show approximately first order kinetics, although in both cases the reaction accelerates somewhat as it proceeds. First order kinetics is explained in terms of a reaction between one excited- and one ground-state monomer molecule, while the acceleration of the reaction implies that it is promoted as defects are formed within the crystal. By contrast β-2-chloro-trans-cinnamic acid shows a strongly accelerating reaction which models closely to the contracting cube equation. β-2-Fluoro- and β-4-fluoro-trans-cinnamic acids show a close match to first order kinetics. The 4-fluoro-derivative, however, shows a reaction that proceeds via a structural intermediate. The difference in behaviour between the 2-fluoro- and 4-fluoro-derivative may be due to different C–HF hydrogen bonds observed within these single-crystalline starting materials.

Application of olefin metathesis for the synthesis of constrained beta-amino esters from norbornenes

Synthesis of a number of novel, conformationally rigid beta-amino esters has been achieved via a tandem olefin metathesis reaction. The starting materials are readily accessible from the Diels-Alder adduct between cyclopentadiene and maleic anhydride.

Facile bisurethane supramolecular polymers containing flexible alicyclic receptor units

This paper details the synthesis, characterisation and physical analyses of a series of hydrogen bonded urethane supramolecular polymer systems that are created by a facile one-step synthesis from inexpensive and commercially available starting materials. We report the synthesis and characterisation of a series of low molecular weight bisurethanes (<650 a.m.u.) that exhibit physical properties in the bulk that are characteristic of polyurethane materials possessing far higher molecular weight. The physical characteristics of these low molecular weight bisurethanes were investigated by using temperature-dependent rheological analysis and viscometry and the nature in which these compounds assembled was assessed using IR and NMR spectroscopies. These studies reveal that these simple bisurethanes self-assemble via hydrogen bonding interactions.

Thermally responsive elastomeric supramolecular polymers featuring flexible aliphatic hydrogen-bonding end-groups

The present paper details the synthesis, characterization, and preliminary physical analyses of a series of polyisobutylene derivatives featuring urethane and urea end-groups that enable supramolecular network formation to occur via hydrogen bonding. These polymers are readily accessible from relatively inexpensive and commercially available starting materials using a simple two-step synthetic approach. In the bulk, these supramolecular networks were found to possess thermoreversible and elastomeric characteristics as determined by temperature-dependent rheological analysis. These thermoreversible and elastomeric properties make these supramolecular materials potentially very useful in applications such as adhesives and healable surface coatings.

Glycol methyl ether and glycol amine substituted titanocenes as antitumor agents

6-[4-(2-Methoxyethoxy)phenyl]fulvene (3a) and 6-(4-[2-(di-methylamino)ethoxy]phenyl)fulvene (3b) were prepared as starting materials for the synthesis of three dofferent classes of titanocenes, which are ansa-titanocenes, diarylmethyl-substituted titanicenes and benzyl-substituted titanocenes and benyzyl-subtituted titanocenes. Because the synthetic possibilities seem to be limited, only ansa-titanocene {1,2-bis(cyclopentadienyl)-1,2-bis[4-(2-methoxyethoxy)phenyl]ethanediyl}titanium dichloride (4a) and benzyl-substituted titanocene bis-{[4-(2-methoxyethoxy)benzyl]cyclopentadienyl}titantium(IV) dichloride (6a) were obtained and characterised. The change in the substitution pattern f the phenyl moiety from an oxygen atom to a nitrogen atom had such a big influence on the reaction that not one compound of the threee titanocene classes could be synthesised, and it was also not possible to obtain diarylmethyl-substituted titanocenes with the use of either of the fulvenes. When benzyl-substituted titanocene 6a was tested agianst pig kidney cells (LLC-PK), an antiproliferative effect that result in an IC50 value of 43 mu m, was observed. This IC50 value is in the lower range of the cytotoxicities evaluated for titanocenes up to now. ansa-Titanocene 4a surprisingly showed, when tested on the same cell line, a proliferative effect together with a fast rate of hydrolysis.

Efficiency and purity control in the preparation of pure and/or aluminum-doped barium ferrites by hydrothermal methods using ferrous ions as reactants

The synthesis of hexagonal barium ferrite (BaFe12O19) was studied under hydrothermal conditions by a method in which a significant amount of ferrous chloride was introduced along side ferric chloride among the starting materials. Though all of the Fe2+ ions in the starting material were converted to Fe3+ ions in the final product, Fe2+ was confirmed to participate differently from the Fe3+ used in the conventional method in the mechanism of forming barium ferrite. Indeed the efficiency of the synthesis and the quality of the product and the lack of impurities such as Fe2O3 and BaFe2O4 were improved when Fe2+ was included. However, the amount of ferrous ions that could be included to obtain the desired product was limited with an optimum ratio of 2:8 for FeCl2/FeCl3 when only 2h of reaction time were needed. It was also found that the role of trivalent Fe3+ could be successfully replaced by Al3+. Up to 50% of their on could be replaced by Al3+ in the reactants to produce Al- doped products. It was also found that the ratio of Fe2+/M3+ could be increased in the presence of Al3+ to produce high quality barium ferrite.

Mild and efficient one-pot synthesis of chiral beta-chalcogen amides via 2-oxazoline ring-opening reaction mediated by indium metal

A simple and efficient procedure for the synthesis of beta-seleno and beta-thio amides via the ring-opening reaction of chiral 2-oxazolines in the presence of indium metal has been developed. Features of this method include the following: (i) easily and accessible starting materials; (ii) indium metal is more stable and less expensive then its respective salts; (iii) useful to excellent yields of beta-chalcogen amides derivatives. (C) 2008 Elsevier B. V. All rights reserved.

Synthesis and application of chiral beta-amino disulfides as ligands for the enantioselective addition of diethylzinc to aldehydes

A new class of chiral beta-amino disulfides was synthesized from readily available and inexpensive starting materials by a straightforward method and their abilities as ligands were examined in the enantioselective addition of diethylzinc to aldehydes. Enantiomeric excesses of up to 99% have been obtained using 0.5 mol % of the chiral catalysts.