Michel Granier

Studies of the hydrolysis of ethyl and tert-butyl phosphonates covalently bonded to silica xerogels

The mild cleavage of phosphonodiester groups supported on a silica matrix has been investigated. The use of TMSBr (bromotrimethylsilane) with diethyl phosphonates has been revisited, and interactions of phosphonoacids with silicon species are described. An alternative route utilising di-tert-butyl phosphonate group has also been studied and in this case cleavage has been demonstrated in very mild conditions.

SYNTHESIS AND REACTIVITY OF BIS(TRIETHOXYSILYL)METHANE, TRIS(TRIETHOXYSILYL)METHANE AND SOME DERIVATIVES

Abstract Syntheses of new poly(trifunctional-silyl)alkanes, which are potent coupling agents of hybrid organic–inorganic materials have been thoroughly examined. Optimization of the Benkeser reaction using chloroform, trichlorosilane and tri- n -butylamine (respective ratios 1:4.5:3) afforded bis(trichlorosilyl)methane isolated as bis(triethoxysilyl)methane after ethanolysis (overall yield 60%). With nine equivalents of trichlorosilane, tris(trichlorosilyl)methane is preferentially formed, isolated as tris(triethoxysilyl)methane (30% yield). C-Substituted bis(triethoxysilyl) methanes were obtained after metallation of the α -carbon and trapping experiments with the corresponding alkyl halides. In the case of tris(triethoxysilyl)carbanion, only MeI and Br 2 were able to give the anticipated products. Unexpectedly, CO 2 insertion afforded the stable ketene, [(EtO) 3 Si] 2 CCO.

Phosphonate derivatives of pyridine grafted onto oxide nanoparticles

The synthesis of phosphonate derived stilbazole 1 by using a Heck reaction is described. The reactivity of the pyridine moiety is studied. After hydrolysis of the ethyl phosphonate groups, the grafting of phosphonic acid derived stilbazole 5 on metal oxides TiO2 or SnO2 is reported. The accessibility and reactivity of the pyridine moiety at the surface is demonstrated.

Grafting of Metallacarboranes onto Self-Assembled Monolayers Deposited on Silicon Wafers

nucleophilic anion. Recently, Teixidor and co-workers reported that this cosane presented an amphiphilic character that led to the formation of monolayer vesicles at low concentration in water and small micelles at higher concentrations. All these properties make it suitable for the stabilization of transient complex cation particles in catalysis and for use as a strong non-oxidizing acid or as a solid electrolyte. It has also been proposed as a doping agent in conducting polymers and as an extractant of radionuclides. The cobaltabisdicarbollide and its derivatives have several applications in medicine, for instance as specific inhibitors of HIV protease and for boron neutron capture therapy of cancer (BNCT). The use of cobaltabisdicarbollide in ion-selective poly(vinyl chloride) membrane electrodes for chiral amino acids and tuberculosis drug analysis has been recently published. Great expectations have risen from these promising pharmaceutical tectons, and studies about their type of binding in the solid state, or association in solution, are being developed in order to understand the behavior of these borane compounds and their influence on biological mechanisms. The modification of surfaces with boron clusters to obtain new materials with specific properties and applications resulting from the presence of these compounds has recently attracted much attention. The functionalization of gold, silver, and magnetic nanoparticle surfaces with charge-neutral ortho-carborane derivatives has been reported. Nevertheless, to our knowledge very few examples of surface functionalization with the cobaltabisdicarbollide anion have been described. Recently, we reported the surface functionalization of TiO2 nanoparticles with the cobaltabisdicarbollide anion, in which two phosphorous-containing cobaltabisdicarbollide derivatives Cs ACHTUNGTRENNUNG[1,1’-m-(HO)(O)P-3,3’-Co(1,2C2B9H10)2], and Cs ACHTUNGTRENNUNG[8,8’-m-(OH)(O)-P(O)2-3,3’-Co(1,2C2B9H10)2] were grafted to the nanoparticles. [13]

Studies of organic-inorganic solids possessing sensitive oligoarylene-vinylene chromophore-terminated phosphonates

The syntheses of xerogels possessing a phosphonate group covalently linked to a silica matrix through a fluorescent carbon backbone are described. BET and fluorescent analyses showed different behaviors for closely related structures. Hydrolysis of Et and t-Bu phosphonates in the presence of sensitive π-conjugated anthryl chromophore is described.

COCHO-modified oxides nanoparticles by using phosphonic acid as grafting agent

Abstract The synthesis of phosphonic acid 4 possessing a protected COCHO group, by using the Heck reaction is described. After grafting of the phosphonic acid 4 on metal oxides Al 2 O 3 , TiO 2 or SnO 2 , the cleavage of the dithiane group was successful. The reactivity of the supported-COCHO group was examined by using model reactions with hydroxylamine and hydrazine derivatives.

Synthesis and chemical reactivity of semicarbazide-supported silicas

The synthesis of xerogels possessing a Fmoc-protected semicarbazide group covalently linked to a silica matrix is described. BET and fluorescence analyses showed the homogeneity of the xerogels. The xerogels were deprotected and further reacted with aldehydes to give novel materials.

Studies of the functionalisation of organic–inorganic hybrid materials by using the Heck reaction

Cogelation of 4-styryltrimethoxysilane was performed using NH4F as catalyst. The functionalisation of the styryl group was then studied by using Hecks reaction with ethyl 4-bromobenzyl- or 4-bromoarylvinylbenzyl-phosphonates. The efficiency of the solid-phase reaction was highly dependent on the texture of the solids.