Desorption/ionization on porous silicon mass spectrometry (DIOS) of model cationized fatty acids.

Desorption/ionization on porous silicon (DIOS) is a very useful technique in the case of small molecular weight compounds, compared to the matrix-assisted laser desorption ionization (MALDI). This is because MALDI generates matrix-related ions that overlap with the mass range of interest. The aim of our work was to investigate the suitability of the DIOS technique in the case of fatty acids in negative ion mode.

Photodynamic efficiency of diethylene glycol-linked glycoconjugated porphyrins in human retinoblastoma cells.

Photodynamic therapy (PDT) is emerging as a new strategy for the conservative treatment of hereditary retinoblastoma. The glycoconjugated porphyrins TPP(p-Deg-O-alpha-GalOH)(3), TPP(p-Deg-O-beta-GalOH)(3), TPP(p-Deg-O-alpha-ManOH)(3), and their S-analogues were synthesized to obtain efficient photosensitizers with some retinoblastoma cell affinity. In these systems, a sugar motif and porphyrin core were linked by a diethylene glycol spacer (Deg).

De novo synthesis of sugar-aza-crown ethers via a domino Staudinger aza-Wittig reaction.

A short and highly efficient route to sugar-aza-crown (SAC) ethers has been developed. The key step of the transformation is a one-pot cyclodimerization of C-glycosyl azido aldehydes via a domino Staudinger aza-Wittig reaction. This process allows the preparation of various orthogonally protected SAC ethers, from both alpha- and beta-C-glycosyl azido aldehydes.

The use of desorption/ionization on porous silicon mass spectrometry for the detection of negative ions for fatty acids.

The study of low molecular weight compounds by matrix-assisted laser desorption/ionization (MALDI) is difficult because of the presence of ions originating from the matrix in the low-m/z range. In order to resolve these problems, new matrix-free approaches were developed based on laser desorption/ionization from the surface of various materials such as graphite and porous silicon. Our work involves the use of 'desorption ionization on porous silicon mass spectrometry' (DIOS-MS) in the negative ion mode to study fatty acid compounds.

From simple monopyridine clusters [Mo6Br13(Py-R)][n-Bu4N] and hexapyridine clusters [Mo6X8(Py-R)6][OSO2CF3]4 (X = Br or I) to cluster-cored organometallic stars, dendrons, and dendrimers.

Hexasubstitution of apical triflate ligands in the octahedral clusters [M]2[Mo6X8(CF3SO3)6] (M = n-Bu4N or Cs, X = Br or I) and monosubstitution in [n-Bu4N]2[Mo6Br13(CF3SO3)] was carried out in tetrahydrofuran at 60 degrees C with simple pyridines and then extended to organometallic pyridines, yielding cluster-cored stars, and to dendronic polyallyl- and polyferrocenylpyridines, yielding cluster-cored polyallyl and polyferrocenyl dendrimers and dendrons. The orange pyridine-substituted clusters, whose pyridine protons are deshielded in 1H NMR (a practical tool for characterization), are air-stable and thermally stable with simple pyridines, light- and air-sensitive with organometallic pyridines, and air-fragile and thermally fragile with large dendronized pyridines.

Synthesis of orthogonally protected cyclic homooligomers from sugar amino acids.

Two new families of orthogonally protected cyclic homooligomers with two to four sugar units were synthesized from pyranoid sugar amino acids. Cyclic oligomers composed of amide-linked sugar amino acids (1-3) were prepared by cyclization of linear oligomers of the novel orthogonally protected pyranoid sugar amino acid 12 using a solution-phase coupling method. These orthogonally protected cyclic molecules can be selectively or fully deprotected, affording the macrocycles ready to further functionalization.

New organosilyl derivatives of the Dawson polyoxometalate [alpha2-P2W17O61(RSi)2O]6-: synthesis and mass spectrometric investigation.

In the field of functionalized polyoxometalates, organosilyl derivatives of polyoxotungstate constitute a special class of hybrid organic-inorganic system. The first organosilyl derivative of the monovacant Dawson heteropolyoxotungstate [alpha2-P2W17O61]10- was obtained by three different methods. The use of two organosilanes as reagents enabled the preparation of the functionalized polyoxometalate [alpha2-P2W17O61(RSi)2O]6- in good yield.

Copper-free monomeric and dendritic palladium catalysts for the Sonogashira reaction: substituent effects, synthetic applications, and the recovery and re-use of the catalysts.

A series of bis(tert-butylphosphine)- and bis(cyclohexylphosphine)-functionalized Pd(II) monomers and polyamino (DAB) dendritic catalysts were synthesized and investigated for Sonogashira carbon-carbon coupling reactions in a copper-free procedure. The influence of phosphine substituents (tBu versus Cy) on the reaction kinetics was investigated by a GPC technique to monitor the reactions. The dendritic catalysts containing the cyclohexylphosphine ligands could be recovered and reused without loss of efficiency until the fifth cycle.

Solution- and crystal-phase covalent modification of lysozyme by a purpose-designed organoruthenium complex. A MALDI-TOF MS study of its metal binding sites.

Study of the reaction between the transition organometallic complex 4-ruthenocenyl 2,6-dimethylpyrylium tetrafluoroborate and the enzyme hen egg white lysozyme (HEWL) in solution and by diffusion in crystals was performed by use of a combination of spectroscopic and chromatographic methods. Conjugation involving the lysine residues of lysozyme appeared to occur readily, yielding very stable ruthenocenyl pyridinium adducts with average degrees of incorporation ranging from 0.2 to 1.

Synthesis of five generations of redox-stable pentamethylamidoferrocenyl dendrimers and comparison of amidoferrocenyl- and pentamethylamidoferrocenyl dendrimers as electrochemical exoreceptors for the selective recognition of H2PO4-, HSO4-, and adenosine 5'-triphosphate (ATP) anions: stereoelectronic and hydrophobic roles of cyclopentadienyl permethylation.

A family of five metallodendrimers with pentamethylamidoferrocenyl termini were synthesized from the DSM dendrimers G(n)-DAB-dend-(NH(2))(x) (x=4, 8, 16, 32, 64) and characterized by standard techniques, including prominent molecular peaks (broad for x=64) in their MALDI-TOF mass spectra. Oxidation of G(4)-DAB-dend-(NHCOFc*)(x) (Fc*=C(5)H(4)FeCp*, Cp*=eta(5)-C(5)Me(5)) with SbCl(5) in CH(2)Cl(2) yields the stable 17-electron pentamethylferrocenium analogue, which can be characterized by ESR and Mössbauer spectroscopy and reduced back to the initial Fe(II) dendrimer, the cycle being carried out without decomposition. The cyclic voltammograms (CVs) of all dendrimers, recorded in CH(2)Cl(2) or DMF, show a fully reversible ferrocenyl wave without adsorption.

Construction of giant dendrimers using a tripodal building block.

Giant pentane-soluble organo-silicon dendrimers have been synthesized using a triallylphenol brick according to a new divergent construction that uses a hydrosilylation-nucleophilic substitution sequence up to the ninth generation (G(9)). All the reactions were monitored by (1)H, (13)C, and (29)Si NMR until G(9), indicating that they were clean at the NMR accuracy until this last generation. MALDI TOF mass spectra were recorded for G(1) to G(4) and show the nature and amounts of defects that are intrinsic to the divergent construction.

Redox-robust pentamethylamidoferrocenyl metallodendrimers that cleanly and selectively recognize the H2PO4- anion.

The first pentamethylferrocenyl (Fc*) dendrimers are synthesized from DSM polyamine dendrimers (generations 1 to 5) and cleanly and selectively recognize the H2PO4- anion.

Nanoscopic assemblies between supramolecular redox active metallodendrons and gold nanoparticles: synthesis, characterization, and selective recognition of H2PO4-, HSO4-, and adenosine-5'-triphosphate (ATP2-) anions.

Tri- and nonaferrocenyl thiol dendrons have been synthesized and used to assemble dendronized gold nanoparticles either by the ligand-substitution method from dodecanethiolate-gold nanoparticles (AB(3) units) or Brust-type direct synthesis from a 1:1 mixture of dodecanethiol and dendronized thiol (AB(9) units). The dendronized colloids are a new type of dendrimers with a gold colloidal core. Two colloids containing a nonasilylferrocenyl dendron have been made; they bear respectively 180 and 360 ferrocenyl units at the periphery.

Synthesis and photochemical behavior of phosphorus dendrimers containing azobenzene units within the branches and/or on the surface.

We describe the synthesis of three series of phosphorus-containing dendrimers having azobenzene derivatives specifically placed at some generations in the interior and/or on the surface. The largest compound obtained possesses 48 azobenzene groups on the surface. Irradiation at 350 nm induces isomerization of the azobenzene groups from the E form to the Z form, whatever their location.

General route from simple methyl, alkyl, and cycloalkyl arenes to polycyclic cyclopentenyl aryl derivatives. The CpFe(+) group as an activator and tag.

[reaction: see text] The CpFe(+) group activates the perallylation of the benzylic groups of arenes using KOH and allylbromide under ambient conditions. This reaction can be followed by ruthenium-catalyzed RCM metathesis using Grubbs' catalyst at room temperature to give polycyclic aromatic derivatives in high yields, and these products are easily separated from the catalyst by extraction using ether. Alternatively, the RCM metathesis can be best carried out in ionic liquids at 80 degrees C, and extraction using ether is then facile.

[FeCp]+-induced hexafunctionalization of hexamethylbenzene with dendrons for the direct synthesis of redox-active iron-centered metallodendrimers.

Phenol tri- and nonaallyl dendrons (3 and 7, respectively) were functionalized at the focal position to give the new triallyl dendrons 4 and 6 and the nonaallyl dendrons 11 and 13 that contain a iodoalkyl or a bromobenzyl termini. All these dendrons were used for the [FeCp]+-induced hexafunctionalization of hexamethylbenzene in [FeCp(eta6-C6Me6)][PF6] (1) under mild conditions in the presence of KOH. These reactions directly yielded the 18-allyl and 54-allyl dendrimers 9, 10, and 14 with a [FeCp(eta6-arene)]+ unit located at the dendrimer core.

A Polycationic Metallodendrimer with 24 [Fe(η -C Me )(η -N-Alkylaniline)] Termini That Recognizes Chloride and Bromide Anions.

Pronounced dendritic effects are shown by the title compound 1 in the recognition of Cl and Br -this is shown by the comparison with a mononuclear compound with one dendrimer arm and a trinuclear compound with a tripodal dendrimer branch. Thus, 1 differs distinctly from 24-ferrocene dendrimers of comparable topology.