Linear porphyrin dimers with fluorenyl arms linked by an ethynyl bridge

International audienceA series of porphyrin monomers bearing fluorenyl donor groups is presented; successively, compounds 10, 11, 12, and 13 bearing three fluorenyl groups. Starting from these building blocks, the synthesis of new porphyrin ethynyl-linked dimers 7 and 8, bearing in totally six peripheral fluorenyl arms is attempted. Dimers are obtained by coupling two porphyrin monomers, using a palladium catalyst, by a rigid bridge. Luminescence studies of new dimers 7 and 8 are presented. We can then compare the detailed luminescence properties of these dimers with former porphyrin monomer possessing four fluorenyl arms TFP (2), which is the precursor model of this work, to porphyrin dendrimers bearing various numbers of fluorenyl arms (3 and 4) and finally to corresponding supramolecular assemblies (5 and 6)

Enhanced two-photon absorption cross-sections of zinc(II) tetraphenylporphyrins peripherally substituted with d(6)-metal alkynyl complexes

International audienceThe syntheses of new Zn(II) tetraphenylporphyrin (ZnTPP) derivatives functionalized with electron-rich d6-transition metal alkynyl complexes at their periphery are reported. Z-scan measurements reveal remarkably large effective two-photon absorption (TPA) cross-sections in the visible range for these compounds

Les porphyrines (des briques multifonctionelles pour l optique)

Au cours de cette thèse, nous avons synthétisé et caractérisé de nouveaux composés en utilisant le macrocycle porphyrinique comme brique moléculaire de départ, le but de ce travail étant l étude de leurs propriétés optiques. Après avoir effectué une présentation bibliographique générale sur les porphyrines, nous avons considéré leurs implications dans le système photosynthétique naturel en tant que collecteur de lumière. D autre part, nous avons considéré l unité fluorène qui possède des propriétés photophysiques très intéressantes comme antenne collectrice de lumière. Premièrement, nous avons abordé des méthodes de synthèse permettant d associer le macrocycle porphyrinique avec de nombreuses unités fluorènes. Cette association a pu être réalisée de différentes manières: soit de façon dendritique ou soit par connexion directe sur la porphyrine. Puis, comme exemple d application, nous avons reporté la fabrication d une diode électroluminescente (OLED) émettant dans le rouge. Nous avons également décrit l obtention de nouveaux matériaux par électropolymérisation, à partir des briques moléculaires porphyriniques. Des études STM sur ces matériaux ont permis obtenir des informations sur leurs organisations moléculaires. Lors de la dernière partie de mes travaux de thèse, j ai synthétisé une nouvelle famille de porphyrines substituées par des groupements organométalliques de type acétylure de ruthénium et/ou de fer pour l optique non linéaire de troisième ordre (ONL TO).In this thesis, we have synthesized and characterized new compounds using the porphyrin macrocycle as molecular building blocks, the aim of this work is to study their optical properties. After a general bibliographic presentation on porphyrins, we have considered their implications in the natural photosynthetic system as light collector. On the other hand, we have considered the fluorene unit presenting very interesting photophysical properties as an antenna for collecting light. First, we discussed methods to associate porphyrin macrocycle with many fluorenes units. This association has been achieved in different ways: either dendritic or either by direct connection on the porphyrin. Then, as application example, we have reported an Organic Light Emitting Diode (OLED) emitting in the red. We have also described the production of new materials by electropolymerization from porphyrin building blocks. STM studies on these materials gave us informations on the molecular organization. During the last part of my thesis, I synthesized a new family of porphyrins substituted by organometallic acetylide ruthenium and/or iron for Non Linear Optical Third-Order (NLO TO) studies.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Fluorenyl dendrimer porphyrins: synthesis and photophysical properties

International audienc

Synthesis and Photophysical Properties of Porphyrins with Fluorenyl Pendant Arms

International audienceSymmetrical-A 4-porphyrins bearing four fluorene donor moieties TOFP (5,10,15,20-tetra(4-(2 methyloxyfluorenyl)phenyl)porphyrin as well as eight fluorene arms OOFP (5,10,15,20-octa(3,5-(2 methyloxyfluorenyl)phenyl)porphyrin, were synthesized and characterized. Preliminary photophysical properties are reported. In comparison to the reference tetraphenylporphyrin TPP, the luminescence properties are slightly improved. The fluorescence quantum yields of tetrafluorenylporphyrin TOFP (1) and octafluorenylporphyrin OOFP (2) are 0.10 and 0.13, respectively

A Family of Fluorenyl Dendrons For Porphyrin Dendrimers synthesis

International audienceA series of dendrons bearing various number of fluorenyl donor groups have been synthesized. First, the reference compound 2-(bromomethyl)-9H-fluorene (8) with one fluorenyl unit, then dendron 10, with two fluorenyl arms, and finally new generation dendrons, 11 and 12, bearing four peripheral fluorenyl arms were synthesized and characterized. A series of different generations of porphyrin dendrimers, obtained from these dendrons are also presented. Preliminary results on higher generation dendrimers are reported as well. Under mild basic conditions, surprisingly, a new compound 1 incorporating a fluorenyl unit in the cycle and three pendant fluorenyl arms was obtained by an intramolecular reaction of brominated tetrapod dendron 12

Ligand-Capped Ru Nanoparticles as Efficient Electrocatalyst for the Hydrogen Evolution Reaction

Altres ajuts: UAB and "Euroregió Pirineus Mediterrànea" PhD grants ; Serra Húnter ProgramMultielectron reductions such as the hydrogen evolution reaction (HER) play an important role in the development of nowadays energy economy. Herein, the application of the organometallic approach as synthetic method allows obtaining very small, ligand-capped but also highly active ruthenium nanoparticles (RuNPs) for the HER in both acidic and basic media. When deposited onto glassy carbon, the catalytic activity of this nanomaterial in 1 M H2SO4 solution is highly dependent on the oxidation state of the NPs surface, with metallic Ru sites being clearly more active than RuO2 ones. In sharp contrast, in 1 M NaOH as electrolyte, the original Ru/RuO2 mixture is maintained even under reductive conditions. Estimation of surface active sites and electrochemically active surface area (ECSA) allowed benchmarking this catalytic system, confirming its leading performance among HER electrocatalysts reported at both acidic and basic pH. Thus, in 1 M NaOH condition, it displays lower overpotentials (η0 ≈ 0 mV, η10 = 25 mV) than those of commercial Pt/C and Ruthenium black (Rub), and also fairly outperforms them in short- and long-term stability tests. In 1 M H2SO4 solution, it clearly outdoes commercial Rub and is competitive or even superior to commercial Pt/C, working at very low overpotentials (η0 ≈ 0 mV, η10 = 20 mV) with a Tafel slope of 29 mV·dec-1, achieving TOFs as high as 17 s-1 at η = 100 mV and reaching a current density of |j| = 10 mA·cm-2 for at least 12 h without any sign of deactivation

Scanning tunneling microscopy investigations of electropolymerized tetra-arylporphyrin complexes

International audienceScanning tunneling microscopy (STM) studies on poly(Zinc-tetraphenylporphyrin) (poly(ZnTPP)) and poly(Zn- or Pt-tetradimethoxyphenylporphyrins) (poly(Zn8OMeTPP) or poly(Pt8OMeTPP)) deposited through anodic oxidation on platinum surfaces are reported. STM investigations on these metalloporphyrin films were conducted to obtain informations on the supramolecular architecture of these polymers. These STM images indicate that poly(ZnTPP) covered the metallic electrode with a layered structure. For poly(Zn8OMeTPP) and poly(Pt8OMeTPP) a tendency to form regular molecular assemblies is obvious

Platinum and palladium complexes of fluorenyl porphyrins as red phosphors for light-emitting devices

International audiencePlatinum(II) and palladium(II) complexes of a porphyrin with fluorenyl groups linked directly at the meso-positions (TFP) have been synthesized and characterized. Their luminescence properties in solution have been studied under ambient conditions and at 77 K. Compared to the corresponding complexes of tetraphenylporphyrin TPP, the emission is red-shifted in both cases. Radiative rate constants are found to be enhanced by the fluorenyl substituents, although non-radiative decay rates are also increased in solution. Short-wavelength UV excitation leads to no detectable fluorenyl-based fluorescence, indicating that very efficient transfer of energy to the porphyrin occurs. An OLED in which PtTFP is used as a red phosphor has been prepared and its electroluminescence performance assessed. High current "roll-off" is significantly delayed to higher currents compared to previously described OLEDs that make use of standard platinum porphyrins as emitters, an effect which can be attributed to the shorter radiative lifetime of PtTFP

Can Ni complexes behave as molecular water oxidation catalysts?

The present report uncovers the borderline between homogeneous and heterogeneous water oxidation catalysis using a family of Ni complexes containing oxamidate anionic type of ligands. In particular, the Ni complex [(L1)NiII]2- (12-; L1 = o-phenylenebis(oxamidate)) and its modified analogues [(L2)NiII]2- (22- ;L2 = 4,5-dimethyl-1,2-phenylenebis(oxamidate)) and [(L3)NiII]2- (32- ;L2 = 4- methoxy-1,2-phenylenebis(oxamidate)) have been prepared and evaluated as molecular water oxidation catalysts at basic pH. Their redox features have been analyzed by mean of electrochemical measurements revealing a crucial involvement of the ligand in the electron transfer processes. Moreover, the stability of those complexes has been assessed both in solution and immobilized on graphene-based electrodes at different potentials and pHs. The degradation of the molecular species generates a NiOx layer, whose stability and activity as water oxidation catalyst has also been stablished. Electrochemical methods, together with surface characterization techniques, have shown the complex mechanistic scenario in water oxidation catalyzed by this family of Ni complexes, which consists of the coexistence of two catalytic mechanism: a homogeneous pathway driven by the molecular complex and a heterogeneous pathway based on NiOx. The electronic perturbations exerted through the ligand framework has manifested a strong influence over the stability of the molecular species under turnover conditions. Finally, 12- has been used as a molecular precursor for the formation of NiFeOx anodes that behave as extremely powerful water oxidation anodes