Infrared Evidence for Hoffman Reaction During Calcination of Surfactant-Templated Silica Films and Analysis of the Resulting Surface Sites

Fourier Transform Infrared transmission spectroscopy is used to characterize surfactant-templated silica films on glass. The calcination process is followed in situ and evidence for the removal of the surfactant along the Hoffman reaction is given. Once calcined, the surface of the pores of the mesoporous films is proven by deuteration experiment to be hydroxylated. Bands are attributed to isolated and hydrogen-bonded silanols. Silylation reaction with hexamethyldisilazane only occurs with isolated silanol groups.     

Reversible coordinative chain transfer polymerization of styrene by rare earth borohydrides,chlorides/dialkylmagnesium systems

The ability of various rare earth borohydride and chloride complexes/n‐butylethylmagnesium systems to operate styrene chain transfer polymerization in mild conditions has been assessed. Thirteen precatalysts have been considered: the rare earth trisborohydrides Ln(BH₄)₃(THF)_x (x = 3, Ln = Nd (1), La (2), Sm (3), x = 2, Ln = Y (4), Sc (5)), the rare earth chlorides LnCl₃(THF)_x (x = 3, Ln = Nd (6), La (7), Sm (8), Y (9), x = 2, Ln = Sc (10)), the mixed La(BH₄)₂Cl(THF)_2.6 (11) and the half‐lanthanidocenes Cp*Ln(BH₄)₂(THF)₂ (Ln = Nd (12), La (13)). Six systems were found to be active precatalysts for the polymerization of styrene. 1 , 2 , and 11 led to an efficient transmetalation of the growing polystyrene chain with the simultaneous occurrence of βH elimination, whereas 7 , 12 , and 13 led to catalyzed chain growth behavior. It is noteworthy that the catalyzed chain growth obtained with 12 and 13 occurs with significant stereoselectivity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 802–814, 2010     

Synthesis of the trans-fusarinine scaffold

The trans-fusarinine backbone is a common feature encountered in many fungal siderophores. This monomer is notably the structural base of N^α-methyl coprogen B and dimerumic acid. Both siderophores are known to be secreted by Scedosporium apiospermum, an emerging pathogenic fungus studied for its high involvement in invasive infections of immunocompromised patients. The strategy developed here for the synthesis of the trans-fusarinine scaffold relies on the preparation of both N-hydroxyornithine and 3-anhydroxymevalonic acid subunits starting from l-ornithine and 3-butyn-1-ol, respectively. The coupling of these two building blocks led to the expected protected backbone.     

A versatile route to 3-(pyrimidin-4-yl)-imidazo[1,2-a]pyridines and 3-(pyrimidin-4-yl)-pyrazolo[1,5-a]pyridines

A two-step synthesis of 3-(2-chloropyrimidin-4-yl)imidazo[1,2-a]pyridines is presented. The late stage elaboration of the imidazopyridine through a cyclocondensation allows a rapid access to a variety of substitution patterns. The intermediate enol ethers were obtained from inexpensive reagents in a ligand-free Heck coupling. This methodology has been extended to the formation of pyrazolo[1,5-a]pyridines via a formal 1,3-dipolar cycloaddition.     

Electrosynthesis of well-organized nanoporous poly(3,4-ethylenedioxythiophene) by nanosphere lithography

The electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) films from aqueous surfactant solution through a two-dimensional poly(styrene) (PS) template onto indium tin oxide (ITO) substrate has been investigated. The polymer grows in the interstitial spaces of the self-assembled PS spheres which were subsequently removed by dissolution in tetrahydrofuran (THF). Surface characterization by scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveals that two-dimensional nanoporous honeycomb PEDOT structures can easily be obtained by using PS spheres of different sizes. Gold electrodeposition onto the nanostructured PEDOT electrode was investigated and SEM images show preferential formation of nanoparticles (NP) on the wall and the rim of the PEDOT film but metal clusters inside the pores are also observed.     

Automating a 96-well microtiter plate assay for identification of AGEs inhibitors or inducers: application to the screening of a small natural compounds library

Advanced glycation end-products (AGEs) are involved in the pathogenesis of numerous affections such as diabetes and neurological diseases. AGEs are also implied in various changes in tissues and organs. Therefore, compounds able to break them or inhibit their formation may be considered as potential drugs, dietary supplements, or bioactive additives. In this study, we have developed a rapid and reliable (Z′ factor calculation) anti-AGEs activity screening based on the overall fluorescence of AGEs. This method was successfully evaluated on known AGEs inhibitors and on a small library of natural compounds, yielding coherent results when compared with literature data.     

The influence of phenolic hydroxy substitution on the electron transfer and anti-cancer properties of compounds based on the 2-ferrocenyl-1-phenyl-but-1-ene motif

The ferrocenyl compound 2-ferrocenyl-1,1-bis(4-hydroxyphenyl)-but-1-ene (), is very cytotoxic against breast cancer cells (IC(50) = 0.44 microM against MDA-MB-231). We now report the synthesis of a new series of para- and meta- substituted mono- and di- ferrocenyl phenols [2-ferrocenyl-1-(3-hydroxyphenyl)-1-phenyl-but-1-ene (), 2-ferrocenyl-1-(3-hydroxyphenyl)-1-(4-hydroxyphenyl)-but-1-ene (), 1,2-di-ferrocenyl-1-(4-hydroxyphenyl)-but-1-ene (), and 1,2-di-ferrocenyl-1-(3-hydroxyphenyl)-but-1-ene ()] and their electrochemical and biochemical properties, especially in comparison to the previously reported "standard" compounds [2-ferrocenyl-1-(4-hydroxyphenyl)-1-phenyl-but-1-ene () and ()]. We also report the synthesis and characterization of the diphenyl analogue, 2-ferrocenyl-1,1-diphenyl-but-1-ene (). This structure-activity relationship study was motivated by our hypothesis that the cytotoxicity of is related to its ability to form a quinone methide structure after two in situ 1-electron oxidations, a process which requires the presence of at least one p-phenol. The mono-ferrocenyl compounds (including those previously reported) are reasonably well recognized by the oestrogen receptors alpha (RBAs = 0.9-9.6%) and beta (RBAs = 0.28-16.3%), although the bulkier di-ferrocenyl compounds show very little affinity. In vitro, the cytotoxic effects of the phenolic complexes are related to the positioning of the hydroxyl group (para- superior to meta-), and to the number of ferrocenyl groups (one superior to two), with IC(50) values against the MDA-MB-231 cell line ranging from 0.44-3.5 microM. On the hormone-dependent breast cancer cell line MCF-7, the observed effect seems to be the result of two components, one cytotoxic (antiproliferative) and one estrogenic (proliferative). Electrochemical studies show that only the compounds with a p-phenol engage in proton-coupled intramolecular electron transfer.