Synthesis of Novel, Potentially Biologically Active Dibenzosuberone Derivatives

Novel representatives of the important group of biologically active dibenzosuberone derivatives were prepared, 3, 7-dibromo-5-(dimethylaminoethyl-oxyimino)-10, 11-dihydro-5H-dibenzo[a, d]cyclohepta-1, 4-diene (1), 3, 7-dibromo-5-(3-dimethylaminopropylidene)-10, 11-dihydro-5H-dibenzo[a, d]cycloheptene (2) and 1, 7-dibromo-5-(3-dimethylaminopropylidene)-10, 11-dihydro-5H-dibenzo[a, d]cycloheptene (3). These compounds are potential members of tricyclic antidepressants (TCAs), still in many countries the most frequently prescribed antidepressants

Potassium Phosphate/Benzyltriethylammonium Chloride as Efficient Catalytic System for Transesterification

Potassium phosphate (K(3)PO(4)) in the presence of benzyltriethylammonium chloride have been found to catalyses the transesterifications of a wide variety of aliphatic and aromatic esters with primary and secondary alcohols affording the corresponding esters in good-to-excel lent yields

Potassium Phosphate / Benzyltriethylammonium Chloride as Efficient Catalytic System for Transesterification

Potassium phosphate (K3PO4) in the presence of benzyltriethylammonium chloride have been found to catalyses the transesterifications of a wide variety of aliphatic and aromatic esters with primary and secondary alcohols affording the corresponding esters in good-to-excellent yields

Great Efficiency of Nucleosides as Organizing Tools

Bis-porphyrins with flexible linkers such as uridine or 2’-deoxyuridin pre-organize in a face-to-face conformation and form stable sandwich complexes with bidentate base such as DABCO. The gain in stability can be even greater when a dinucleotide linker is used. Such pre-organization increases the association constant by one to two orders of magnitude when compared to the one of DABCO with a reference porphyrin. Comparison with rigid tweezers shows a better efficiency of nucleosidic dimers. The choice of rigid spacers is not the only way to pre-organize bis-porphyrins, and well-chosen nucleosidic linkers offer an interesting option for the synthesis of such devices

Efficiency of Dinucleosides as the Backbone to Pre-Organize Multi-Porphyrins and Enhance Their Stability as Sandwich Type Complexes with DABCO

Flexible linkers such as uridine or 2′-deoxyuridine pre-organize bis-porphyrins in a face-to-face conformation, thus forming stable sandwich complexes with a bidentate base such as 1, 4-diazabicyclo[2.2.2]octane (DABCO). Increased stability can be even greater when a dinucleotide linker is used. Such pre-organization increases the association constant by one to two orders of magnitude when compared to the association constant of DABCO with a reference porphyrin. Comparison with rigid tweezers shows a better efficiency of nucleosidic dimers. Thus, the choice of rigid spacers is not the only way to pre-organize bis-porphyrins, and well-chosen nucleosidic linkers offer an interesting option for the synthesis of such devices

Oligonucléotides à Porphyrines Pendantes : vers des Nano-Matériaux Multi-Porphyriniques Auto-Assemblés

The light-harvesting antennae in the photosynthetic system consist of a large number of pigments, which are responsible for absorption of photons. The extraordinary efficiency of the excited state migration among the pigments is ascribed to their parallel orientation and favoured spacing within the light-harvesting complexes. This arrangement, controlled by weak interactions between pigments and polypeptides, assumes three ring-shaped light-harvesting antennae. Aiming to organize porphyrins in accordance with the natural system, we have chosen oligonucleotidic backbone for the elaboration of multi-porphyrinic nanosystems. In this respect, the synthesis of oligonucleotides functionalized with porphyrins was realized. The preparation of these systems was based on oligomerization at O-3' and O-5' positions of the 2'-deoxyuridine derivative functionalized with a porphyrin. Architecture of our system has been designed on the basis of rigid and flexible linkers. The porphyrins were appended to C-5 position of the uracile by a rigid linker and the uridines were mutually linked by a flexible linker, with the goal to work out parallel orientation of porphyrins via anticipated conformation of the oligonucleotidic chain. In this context, we have synthesized the mono-, di-, tetra- and octa-deoxynucleosides with pendant porphyrins.An appropriate arrangement of free-base and zinc(II) porphyrins within the oligonucleotidic molecular wire allowed us to highlight an energy transfer. The contribution of the zinc(II)-porphyrin to the emission of the free-base pophyrins was evidenced. The range of oligonucleotides have been metallated with zinc(II) targeting to examine effectiveness of the oligomerization degree of these molecular architectures on their ability to complex a bidentate base such as DABCO. We have observed that the coordination of DABCO is favoured as one goes toward higher degree of oligomerization due to imposed conformational pre-organization within the oligonucleotidic backbone. At last, we were interested in self-assembly by means of hydrogen bonding, which could be established between the uracil nucleobase and a complementary synton such as triazine functionalized with porphyrins. The quantitative studies of stability of those supramolecular architectures have evidenced an influence of secondary intermolecular p-p interactions between the porphyrins within the supramolecular complex.Les antennes collectrices d'énergie lumineuse du système photosynthétique sont constituées d'un grand nombre de pigments collecteurs de photons. L'extraordinaire efficacité de migration d'un état excité le long de ces pigments est attribuée à leur orientation parallèle et à leur positionnement favorable au sein des complexes collecteurs. Cet arrangement, contrôlé par des interactions faibles entre pigments et polypeptides, prend la forme de 3 anneaux qui constituent les antennes collectrices d'énergie lumineuse. Dans le but d'organiser des porphyrines dans l'espace de façon similaire au système naturel, un squelette oligonucléotidique a été choisi pour l'élaboration de nanosystèmes multi-porphyriniques. C'est dans cette optique que nous avons réalisé la synthèse d'oligodeoxynucléotides fonctionnalisés par des porphyrines. La préparation de ces systèmes est fondée sur l'oligomérisation en O-3'et O-5' d'un dérivé de la 2'-deoxyuridine fonctionnalisé par une porphyrine. L'architecture de ces systèmes a été dessinée sur la base de liaisons rigides et souples. Dans le but d'imposer par la conformation de la chaîne oligonucléotidique une organisation parallèle aux porphyrines, ces dernières sont greffées en C-5 de l'uracile par un espaceur rigide et les uridines reliées entre elles par une liaison souple. Un mono-, un di-, un tetra- et un octa-deoxynucléotides à porphyrines pendantes ont notamment été synthétisés. Un agencement approprié des porphyrines base-libre et métallées au Zn(II) au sein du fil moléculaire oligonucléotidique a permis de mettre en évidence un transfert d'énergie de l'état excité de la porphyrine de Zn(II) vers les porphyrines base-libre. On observe une nette contribution de la porphyrine de Zn(II) à l'émission des porphyrines base-libre. La série des oligonucléotides a été métallée au Zn(II) dans le but d'examiner l'effet du degré d'oligomérisation de ces architectures moléculaires sur leur capacité de complexation de bases bidendates telle que le DABCO. Nous avons pu montrer que la coordination de DABCO est favorisée au fur et à mesure de l'élévation du degré d'oligomérisation grâce à la pré-organisation conformationnelle qui s'instaure au sein du squelette oligonucléotidique.Enfin, nous nous sommes intéressés à l'auto-assemblage par liaisons hydrogène que peut établir la base nucléique uracile avec un synton complémentaire telle que la triazine fonctionnalisée par des porphyrines. Des études quantitatives de stabilisation des architectures supramoléculaires ont mis en évidence des interactions intermoléculaires secondaires de type p-p entre les porphyrines au sein du complexe supramoléculaire formé

Nucleosides as organizing agents

International audienceIn the present review, we discuss the results of the research we have done over the last decade on multiporphyrinic architectures bearing a nucleotidic backbone, compare all the data, offer a novel overview, and emphasize common capabilities of nucleosides appearing in various systems, providing a new insight on the preorganizing capabilities of nucleosidic backbones. The efficiency of nucleosides as preorganizing agents was investigated through the synthesis and study of various bisporphyrins bearing nucleosidic linkers, as well as through the investigation of the conformation of linear and arborescent multiporphyrins constructed on a nucleosidic backbone. The capacity of these molecules to complex guests with a high association constant was used as a tool to evaluate their degree of preorganization, as well as the investigation of the electronic coupling existing between their chromophores and their photo chemical capacities. Such an overview of one decade of scientific investigations documents the fact that rigid linkers between chromophores are not necessary for their spatial preorganization, opening new routes to the faster synthesis of flexible highly preorganized molecular architectures avoiding the long and tedious synthesis of rigid tweezers, especially for the preparation of rigid linkers which may bring solubility and stability problems