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Porphyrins bearing two external coordination sites allowed the stepwise preparation of polymetallic oligomers connected by metal centers.

A general synthetic strategy for the preparation of polyazamacrocycles containing long aliphatic chains is reported. These compounds are 22- or 24-membered hexaazamacrocycles incorporating two diethylenetriamine subunits (H2NCH2CH2NHCH2CH2NH2) linked together either by two CH2CH2OCH2CH2 (see 4–6), two tetramethylene (see 7), or two pentamethylene (see 8) fragments. Whereas for compound 4, one of the centrally located amine functionalities of the triamine subunit bears a hexadecyl chain, for compound 5, two of such chains are centrally attached to both subunits. In macrocycles 6–8, all six amino functionalities bear hexadecyl chains. Compounds 4–8 are potential candidates for the construction of selective chemical sensors such as specific electrodes for adenosine mono-, di-, and tri-phosphate. They may also be used for nucleoside polyphosphates extraction and/or transport.

Ring contraction of nickel meso-tetraarylporphyrins produced nonaromatic divalent corroles bearing a benzoyloxy function. We investigated their reactivity under electrophilic conditions: formylation, halogenation, nitration. We also found that the benzoate function could be eliminated to afford deoxocorroles, and we tested the formylation and nitration in this deoxo series. These corroles were generally very stable under the reaction conditions, and in both series, the directly bonded pyrroles were the most reactive. The nitration reaction produced a series of corrole dimers via electron transfer initiated coupling.

This article describes the synthesis of several new nickel porphyrins bearing peripheral chelating groups conjugated with the macrocyclic pi system. These monomeric nickel porphyrins display quite unusual chromophoric properties, some of them absorbing in the near-infrared region. Extension of the aromatic core of the porphyrin was realized by connecting meso-aryl groups with pyrroles by ketone functionalities. Further functionalizations led to bisenaminoketones or bisenaminothioketones, which are useful building blocks for the elaboration of oligomeric porphyrins linked by metal ions. All new compounds were studied by electrochemistry, some of them showing up to six electron transfers and/or splitting of the first oxidation wave.

[reaction: see text] Upon tandem Reformatsky reaction, easily accessible porphyrinic ketones give "locked" chlorinic diester. Both ketones and diesters, as bases or palladium complexes, efficiently generate singlet dioxygen, as demonstrated by trapping with cholesterol.

Reaction of nickel meso-tetraarylporphyrins with benzoic anhydride and tin tetrachloride, followed by air oxidation under basic conditions, results in ring contraction, yielding divalent corroles.

This article describes the preparation of several new porphyrins bearing chelating peripheral groups fully conjugated with the macrocyclic pi-system. Treatment of a 2-nitro-meso-tetraarylporphyrin with phosphite gave a cyclic enamine, whose formylation gave an enaminoaldehyde. The thio analogue was obtained on treatment with Lawesson's reagent. The same reagent was also used to obtain the isomeric thioenaminoketone chelates. A enaminoketone ligand was prepared from a porphyrinic pyrrolone. All these ligands, as internal nickel complexes, could be metalated with palladium to yield porphyrinic dimers. The dimers obtained from enaminoketones and thioketones show a trans geometry, while in the enaminoaldehyde and -thioaldehyde series the cis isomer is thermodynamically favored. The bathochromic shifts of the electronic spectra of the aldehyde-derived dimers illustrate the strong electronic effect of peripheral metalation and dimerization. However, in the case of the pyrrolone-derived ligand, opposite effects were observed, due to partial reconstitution of the porphyrin chromophore on complexation. As with the dimers derived from enaminoketones, the dimers derived from the new ligands show typical splitting (up to 190 mV) of the electrochemical waves confirming large porphyrin-porphyrin interactions.

Under Friedel-Crafts conditions, meso-tetraarylporphyrins give porphyrin spiro dimers in good yield. This reaction involves acylation, acid-catalyzed cyclization, and dimerization. A stable dimer possessing three additional six-membered rings could be isolated and its structure determined. By modifying the substrate and reagents, intermediates could be isolated and characterized. The reactivity of the substrates, the side-reactions, and the concentration requirements to form the dimers, all explain why this reaction remained apparently unexplored in the widely used meso-tetraarylporphyrin series. [reaction: see text]

The preparation, isolation, and characterization of several new peripherally functionalized monomeric porphyrins and metalloporphyrins and of porphyrin dimers are described. These dimers are obtained by linking with metal ions two monomeric porphyrins bearing at their periphery an enaminoketone chelate fully conjugated with the aromatic ring. Porphyrin dimers linked by metal ions display large interactions in the ground state as evidenced by their electronic spectra and their electrochemical behavior. Compared to the monomeric analogue, these dimers show absorption spectra with intensified red-shifted Q-bands and their first oxidation potentials are substantially lowered and split into two distinct redox steps.

A porphyrin bearing a peripheral enaminoketone function allows the preparation of conjugated dimeric porphyrins linked through metal ions.

Bonding the Rh III complex [(C 5 Me 5 )Rh (bpy)(H 2 O)] 2+ to polyethylene glycol (MW 20000) leads to a high molecular weight redox catalyst suitable for continuous generation of the cofactors NADH and NADPH. With the aid of a newly designed flow-through membrane reactor it has proven possible to achieve an NAD ○+ conversion of 40-45% (turnover number 16.9 h -1 , space-time yield 44.3 mmol L -1 d -1 ). Since the reactivity towards polyethylene glycol-bound NAD ○+ remains constant, this catalyst is also suited to use in a continuously operating enzyme-membrane reactor

Homogeneous catalysts, which are often highly efficient and selective even at low reaction temperatures, have usually been restricted to use in batch processes. On the other hand, heterogeneous catalysts, though well suited for continuous processes, often exhibit low selectivity. Only moderate success has been achieved so far in attempts to exploit the potential advantages of homogeneous catalysts by binding them to polymers in order to make them heterogeneous. Many problems remain to be solved; these include the nonuniform and partly unknown structures of the heterogeneous catalysts thereby obtained, hindered diffusion due to extensive crosslinking of the polymer matrix, low catalytic activity, loss of metal, and self-poisoning of the active centers.['] Recently, we reported that the Rh"' complex 1 is an effective homogeneous catalyst for regeneration of the enzyme cosubstrates nicotinamide adenine dinucleotide (NADH) and nicotinamide adenine dinucleotide phosphate (NADPH) either with formate as hydride donorf2I or electrochemically. The rhodium catalyst reacts with NAD(P)" much faster than with carbonyl compounds, thereby allowing selective reduction of the cofactors, provided that suitable concentration ratios are chosen.[31 After 100 catalytic cycles involving 1, no formation of 1,6-NADH could be detected enzymatically.

There is a true need for a rational approach to the synthesis of one-, two- and three-dimensional solids. Molecular tectonics based on iterative assembly of individual modules may be a viable route to the design and manufacture of large size molecules with strictly controlled structures. We describe our approach and results to the synthesis of one- and two-dimensional solids based on iterative assembling processes engaging complementary charged tectons capable of hydrogen bonding.

Porphyrins bearing two external coordination sites allowed the stepwise preparation of polymetallic oligomers connected by metal centers.

A porphyrin bearing a peripheral enaminoketone function allows the preparation of conjugated dimeric porphyrins linked through metal ions.

Electrochemical or Na2S2O4 reduction of N-arylporphyrins gives stable phlorins epimeric to those obtained by tosylhydrazine or NaBH4 reduction.

A one-pot synthesis of three new macrocycles containing two, three or four 2,2′-bipyridine units is described; the X-ray analysis of the bis-bipyridine ligand reveals a cyclophane type structure; the X-ray structure of one of the diastereoisomers of the dinuclear ruthenium complex is also described and shows two metal centres held in close proximity.

Strict self-assembly of complementary dianionic and dicationic tetrahydrogen bond donors and acceptors leading to infinite molecular chains in the solid state is achieved in aqueous solution using both directionally controlled hydrogen bonding and ion-pairing electrostatic interactions.

Using [Cp(Me)5Rh(bipy)C1]C1 (1) as redox catalyst for the continous NADH regeneration it was possible to perform an electrochemically driven enzymatic reduction of pyruvate to D-lactate catalyzed by D-LDH at a rate of 5 turnovers per hour. This is by a factor of 20 faster than the best results obtained until now. Current yields of 50 to 70 % may be obtained.

The electrocatalytic properties of Ni cyclam/sup 2 +/ in CO/sub 2/ reduction have been studies. The influence of various experimental factors on the course of the reaction has been investigated. Under given conditions, Ni cyclam/sup 2 +/ is remarkably efficient and selective for electroreduction of CO/sub 2/ into CO, even in water. The stability of the system has been tested in long range electrolysis, showing that even after thousands of catalytic cycles no deactivation occurs. The mechanistic investigation presently described points to the importance of molecular species adsorbed on the cathode surface. The contribution of reduced species in the bulk is marginal. In addition, during the electrocatalytic process, a nickel(I) carbonyl complex is present: (Ni(cyclam)(CO))/sup +/. The latter complex may be involved in the catalytic reaction leading to CO evolution. Surprisingly, the behavior of Ni cyclam/sup 2 +/ as electrocatalyst is unique. Among the numerous complexes investigated, only Ni cyclam/sup 2 +/ shows such a large selectivity for the electroreduction of CO/sub 2/ over the electroreduction of water. The size of the cyclam ligand and the presence of secondary amine groups (NH) might account for the very special properties of the electrocatalyst.

Co2is electroreduced efficiently to CO on a mercury cathode, in the presence [NiII(Cyclam)]2+; even in pure water, the selectivity for reduction of CO2vs. that of H2O is huge.

Cationic rhodium complexes catalyse very efficiently the reduction of pyridine coenzymes by sodium formate.

Linear assemblies of porphyrins linked by metal ions were prepared both in solution and at an HOPG/phenyloctane interface. In the first part of the project, controlling the size of the linear assemblies generated in solution was the main goal. Porphyrins bearing two different external coordination sites were used to prepare finite oligomers. Strong interactions between the subunits were found in these compounds. In a second part of the project, the organization of monomeric or dimeric porphyrins at a solid/liquid interface was studied. Finally, linear porphyrin oligomers were prepared directly by self-assembly at an HOPG/phenyloctane interface. These porphyrin nano-ribbons were visualized by STM and presented sizes of several dozen nanometers.; Des assemblages linéaires de porphyrines reliées par des cations métalliques ont été obtenus en solution et visualisés à l’interface HOPG-solvant par STM. Afin de contrôler la taille des assemblages synthétisés en solution, une stratégie par différenciation de la réactivité des deux sites de coordination externes des porphyrines a été exploitée. De fortes interactions électroniques ont été mises en évidence entre les sous-unités des assemblages multi-porphyriniques. Atteignant la limite de solubilité et de caractérisation en solution avec les molécules comportant six porphyrines, une seconde stratégie a été développée, afin de synthétiser les oligomères à l’interface HOPG-phényloctane. L’auto-assemblage de monomères de porphyrines possédant deux sites de coordination externes a été étudié par STM. Après ajout de l’ion connecteur, des nanorubans comportant plusieurs dizaines de porphyrines reliées par des cations métalliques ont été observés par STM à l’interface HOPG-solvant.

Linear assemblies of porphyrins linked by metal ions were prepared both in solution and at an HOPG/phenyloctane interface. In the first part of the project, controlling the size of the linear assemblies generated in solution was the main goal. Porphyrins bearing two different external coordination sites were used to prepare finite oligomers. Strong interactions between the subunits were found in these compounds. In a second part of the project, the organization of monomeric or dimeric porphyrins at a solid/liquid interface was studied. Finally, linear porphyrin oligomers were prepared directly by self-assembly at an HOPG/phenyloctane interface. These porphyrin nano-ribbons were visualized by STM and presented sizes of several dozen nanometers., Des assemblages linéaires de porphyrines reliées par des cations métalliques ont été obtenus en solution et visualisés à l’interface HOPG-solvant par STM. Afin de contrôler la taille des assemblages synthétisés en solution, une stratégie par différenciation de la réactivité des deux sites de coordination externes des porphyrines a été exploitée. De fortes interactions électroniques ont été mises en évidence entre les sous-unités des assemblages multi-porphyriniques. Atteignant la limite de solubilité et de caractérisation en solution avec les molécules comportant six porphyrines, une seconde stratégie a été développée, afin de synthétiser les oligomères à l’interface HOPG-phényloctane. L’auto-assemblage de monomères de porphyrines possédant deux sites de coordination externes a été étudié par STM. Après ajout de l’ion connecteur, des nanorubans comportant plusieurs dizaines de porphyrines reliées par des cations métalliques ont été observés par STM à l’interface HOPG-solvant.

The goal of this thesis was to synthesize and characterize linear porphyrins assemblies linked by metal ions. The reaction of porphyrins bearing an external coordination group with platinum(II) ions led to the formation of new homodimers and new dyads. Electrochemical measurements demonstrated an increase in the electronic communication between the two subunits of the Pt-linked dimers compared to Pd-linked systems. In addition, an ultrafast energy transfer between the subunits was observed in the new dyads. Porphyrin monomers metalated at their periphery with palladium(II) and platinum(II) complexes were also prepared. Trimers and tetramers were obtained by reacting porphyrins with various external coordination sites with metal ions. With porphyrins bearing additional long alkyl chains, self assembly at the solid/liquid interface was also studied by STM. In particular, addition of metal ions to these self-assembled systems on HOPG led to linear porphyrin arrays., L’objectif de cette thèse a été de synthétiser et de caractériser des assemblages linéaires de porphyrines reliées par des ions métalliques. Par réaction de porphyrines possédant un site de coordination externe avec des ions platine(II), des nouveaux homodimères et de nouvelles dyades ont pu être obtenus. Les mesures photochimiques et électrochimiques de ces composés ont alors permis de mettre en évidence un accroissement des interactions électroniques entre les sous-unités par rapport aux systèmes reliés par du palladium(II). Des transferts d’énergie ultra-rapides ont notamment été mis en évidence. Une série de monomères de porphyrines métallées en périphérie avec du palladium(II) ou du platine(II) ont ensuite été préparées. Pour ces molécules, les propriétés électroniques varient très peu en modifiant le complexe porté par la porphyrine. Des assemblages incorporant une unité porphyrinique difonctionnalisée ont ensuite été développés. La méthodologie utilisée a permis d’accéder à des trimères et des tétramères en solution comportant des porphyrines de nickel(II) ou de palladium(II). L’étude physico-chimique de ces composés a montré que les porphyrines interagissaient peu à travers les ions métalliques connecteurs. Enfin,des porphyrines difonctionnalisées comportant de longues chaînes alkyles ont été préparées. Comme cela a été vu grâce à la STM, certaines de ces molécules peuvent s’auto-assembler sur surface de graphite (HOPG) et ont permis de former des oligomères en présence d’ions métalliques

The purpose of this thesis was to functionalize the meso position of a porphyrinWith azoles using the Ullmann coupling. Various azoles were introduced with good yieldsby using this reaction, leading to the formation of a carbon-nitrogen bond. With someazoles a double Ullmann coupling was possible, resulting in the formation of 5,15-diazolyl-porphyrins. Moreover, the same conditions were used to introduce one ortwo electron-donating groups (carbazole, phenoxazine, phenothiazine). The insertionof imidazole, triazole and benzimidazole at the meso position allowed, afteralkylation, their use as N-heterocyclic carbene (NHC). Coordination of twoequivalents of NHC to a palladium salt led to a porphyrin dimer, as a bis-carbene complex. X-Ray structures revealed that the complex’s geometry was trans-anti. Electrochemistry studies of the various dimers showed interactions between the porphyrins, highlighted by four successive oxidation peaks., L'objectif de cette thèse a été de mettre au point l'introduction d'azoles en meso d'une porphyrine par couplage d'Ullmann; Divers azoles ont pu être introduit par cette méthode avec de bons rendements, par formation d'une liaison carbone-azote. il a même été possible avec certains azotes de réaliser des doubles couplages d'Ullmann, conduisant ainsi à des 5.15-diazolyle-porphyrines. De plus, ces même conditions réactionnelles ont été utilisées pour introduire un ou deux dérivés donneurs d'électrons (carbazole, phénoxazine, phénothiazine). L'introduction d'imidazole, de triazole et de benzimidazole en meso a permis, après alkylation, d'obtenir des précurseurs de carbènes N-hétérocycles (NHC). La coordination de deux équivalents de NHC sur un sel de palladium conduit à un dimère de porphyrines via coordination exocyclique. La géométrie de coordination trans-anti autour du palladium a été confirmée par l'obtention de la structure radiocristallographique de deux complexes. Les études par électrochimie de ces complexes ont révélé une communication interporphyrinique à l'état fondamental, mise en évidence par une succession de quatre vagues monoélectroniques en oxydation.