Anne-Marie Caminade

Dendrimers : towards catalytic, material and biomedical uses

This book will be mainly focussed on the properties and uses of dendrimers and dendrons. The aim of this book is to be the reference book about dendrimers applications. It will not describe all details, but it will give the reader a unique overview of what has currently been done with dendrimers, with numerous references and illustrations. It will be divided in four main parts: Part 1) Generalities, syntheses, characterizations and properties; Part 2) Applications in catalysis; Part 3) Applications for the elaboration or modification of materials; and Part 4) Applications in biology/medicine. The role of the nanometric size and the multiple functions of dendrimers on the properties will be emphasized.

Mannodendrimers prevent acute lung inflammation by inhibiting neutrophil recruitment

Mycobacterium tuberculosis mannose-capped lipoarabinomannan inhibits the release of proinflammatory cytokines by LPS-stimulated human dendritic cells (DCs) via targeting the C-type lectin receptor DC-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN). With the aim of mimicking the bioactive supramolecular structure of mannose-capped lipoarabinomannan, we designed and synthesized a set of poly(phosphorhydrazone) dendrimers grafted with mannose units, called mannodendrimers, that differed by size and the number and length of their (α1→2)-oligommanoside caps. A third-generation dendrimer bearing 48 trimannoside caps (3T) and a fourth-generation dendrimer bearing 96 dimannosides (4D) displayed the highest binding avidity for DC-SIGN. Moreover, these dendrimers inhibited proinflammatory cytokines, including TNF-α, production by LPS-stimulated DCs in a DC-SIGN–dependent fashion. Finally, in a model of acute lung inflammation in which mice were exposed to aerosolized LPS, per os administration of 3T mannodendrimer was found to significantly reduce neutrophil influx via targeting the DC-SIGN murine homolog SIGN-related 1. The 3T mannodendrimer therefore represents an innovative fully synthetic compound for the treatment of lung inflammatory diseases.

Laser irradiation of a diphosphene: evidence for the first cis–trans isomerization

Low temperature laser irradiation of trans-diphosphene (1), followed using u.v., and 31P and 1H n.m.r. spectroscopy, gives an equilibrium between (1) and the unstable cis-isomer (2): the activation free energy of the (2)→(1) reaction is 20.3 kcal mol–1(1 kcal = 4.18 kJ).

Low temperature synthesis of ordered mesoporous stable anatase nanocrystals: the phosphorus dendrimer approach

The scarcity of low temperature syntheses of anatase nanocrystals prompted us to explore the use of surface-reactive fourth generation phosphorus-dendrimers as molds to control the nucleation and growth of titanium-oxo-species during the sol-gel mineralization process. Unexpectedly, the dendritic medium provides at low temperature, discrete anatase nanocrystals (4.8 to 5.2 nm in size), in marked contrast to the routinely obtained amorphous titanium dioxide phase under standard conditions. Upon thermal treatment, heteroatom migration from the branches to the nanoparticle surface and the ring opening polymerization of the cyclophosphazene core provide stable, interpenetrating mesoporous polyphosphazene-anatase hybrid materials (-P[double bond, length as m-dash]N-)n-TiO2. The steric hindrance of the dendritic skeleton, the passivation of the anatase surface by heteroatoms and the ring opening of the core limit the crystal growth of anatase to 7.4 nm and prevent, up to 800 °C, the commonly observed anatase-to-rutile phase transformation. Performing this mineralization in the presence of similar surface-reactive but non-dendritic skeletons (referred to as branch-mimicking dendrimers) failed to generate crystalline anatase and to efficiently limit the crystal growth, bringing thus clear evidence of the virtues of phosphorus dendrimers in the design of novel nanostructured materials.

Unexpected synthesis of a 1,2 λ3azaphosphoridine

Abstract 1,2 λ 3 azaphosphiridines 4a,b are obtained by reacting a dihalogenated phospha-alkene (Me 3 Si) 2 Nue5f8Pue5fbCCl 2 with two equivalents of lithium silylated amides.

Nouveaux trioxophosphetanes generateurs d'oxygene singulet a basse temperature

Abstract We have prepared phosphite ozonides 1b – 3b which are efficient and clean singlet oxygene generators at low temperature.

Ozonolyse d'oléfines perfluorées

Abstract We have obtained unusually stable secondaxy ozonides ( 2a-c ) by heating neat perfluoroalkenes ( 1a-c ) with ozone.

ATTEMPTED SYNTHESIS OF PHOSPHORUS CRYPTANDS

Abstract Reaction of the aldehyde monoacetal OHC-C≡C-CH(OEt), 4 with the phosphorhydrazide (S)P[N(CH3)NH2]3 3 leads to the phosphorhydrazide (S)P[N(CH3)N=CH-C≡C- CH(OEt)2]3 5. Formolysis of 5 yields the new multifunctionalized 1.11.11′ phosphotrihydrazide (S)P[N(CH3)-N=CH-C≡C-CHO]3 6. Treatment of 3 either with 6 or with various 1.3 or 1.4 dialdehydes does not afford phosphorus cryptands but leads to phosphorus polymers possessing macrocyclic phosphorus sequencies.

Ozonization: An Efficient Method for the Oxidation of Halophosphines

Abstract The ozonization of various halophosphines 1a-j leads with quantitative yields to the corresponding phosphine oxides 2a-j. Ozonization is a convenient method of oxidation, in particular of compounds with bulky ligands (1c, 1d, 1e).

Hydrogen Migration and Reductive Elimination of Alkyne in Fe(CO)4 P(tBu) (C °CPh)H Induced by the Action of Co2 (CO)8

Abstract One of the possible ways of getting phosphacumulene complexes could be the complexation of phosphinoalkynes, which might induce the migration of hydrogen from phosphorus to the β carbon of the alkynyl group.