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The solvothermal synthesis and characterization of a three-dimensional, interpenetrated uranyl dicyanoaurate coordination polymer, [K.sub.2][(U[O.sub.2]).sub.2][(U[O.sub.2]).sub.2][(Au[(CN).sub.2]).sub.2][(O).sub.2][(N[O.sub.3]).sub.4], from U[O.sub.2][(N[O.sub.3]).sub.2]*6[H.sub.2]O and KAu[(CN).sub.2] is described. The structure contains a three-dimensional (3D) lattice of planar tetranuclear uranyl-oxo-nitrate clusters connected by dicyanoaurate linkers, with the rotation of the clusters providing the increased dimensionality. The material undergoes a reversible single-crystal to single-crystal transformation on exposure to water vapour, which is taken up in the channels of the 3D system. A second uranyl dicyanoaurate coordination polymer of the form [U[O.sub.2][(DMSO).sub.3]([H.sub.2]O)(Au[(CN).sub.2])][Au[(CN).sub.2]] was structurally characterized as a linear chain of dicyanoaurate units connected by gold-gold bonds with pendant uranyl-water-DMSO adducts that are hydrogen bonded into a two-dimensional sheet. Both materials exhibit emission arising from both the uranyl moiety and the gold(I) centre and represent the first multidimensional uranyl-dicyanoaurate coordination polymers. Key words: coordination polymer, aurophilic interactions, uranyl, cyanide, emission. Nous decrivons la synthese solvothermale d'un polymere de coordination tridimensionnel interpenetre forme de dicyanoaurate d'uranyle, le [K.sub.2][(U[O.sub.2]).sub.2][(U[O.sub.2]).sub.2][(Au[(CN).sub.2]).sub.2][(O).sub.2][(N[O.sub.3]).sub.4], a partir de U[O.sub.2][(N[O.sub.3]).sub.2]*6[H.sub.2]O et de KAu[(CN).sub.2], et nous presentons la caracterisation de ce polymere. La structure se compose d'un reseau tridimensionnel d'agregats tetranucleaires planaires formes d'unites d'uranyl-oxo-nitrate reliees par des espaceurs dicyanoaurate, dans lequel la rotation des agregats constitue une dimension supplementaire. Cette substance subit une transformation monocristal a monocristal reversible sous l'effet de la vapeur d'eau, qui s'introduit dans les canaux du systeme tridimensionnel. Nous avons caracterise un second polymere de coordination a base de dicyanoaurate d'uranyle de formule [U[O.sub.2][(DMSO).sub.3]([H.sub.2]O)(Au[(CN).sub.2])][Au[(CN).sub.2]] se presentant sous la forme d'une chaine lineaire d'unites de dicyanoaurate reliees par des liaisons Au-Au, a laquelle sont attaches des adduits d'uranyleau-DMSO maintenus par des liaisons hydrogene et disposes en pendentifs dans un feuillet bidimensionnel. Les deux substances presentent des proprietes d'emission provenant des motifs uranyle et des centres Au(I) et constituent les premiers polymeres de coordination multidimensionnels a base de dicyanoaurate d'uranyle. [Traduit par la Redaction] Mots-cles: polymere de coordination, interactions aurophiles, uranyle, cyanure, emission., Introduction The creation of coordination polymers through self-assembly allows for the design and generation of functional materials. The modular construction of coordination polymers from linking units, metal centres, and ancillary [...]

In this work, synthesis, characterization, and antioxidant activities of two Schiff base monomers (1 and 2) and their corresponding oxidation products (3 and 4) were reported. The monomers were prepared by condensation of 8-amino-2-naphthol with 2,4-dihydroxybenzaldehyde and 3,4-dihydroxybenzaldehyde, and then, they were oxidized to in alkaline medium by NaOCl to obtain the corresponding oxidation products. The compounds 1-4 were characterized by various spectral techniques. The analysis results indicated that the oxidation products had a chain structure consisting of randomly ordered phenylene and oxyphenylene units. In vitro antioxidant activities of 1-4 were evaluated against a ABTS cation radical and a DPPH free radical and compared with standard natural antioxidants, vitamin C (ascorbic acid), and vitamin E ([alpha]-tocopherol). The ferric reducing antioxidant power and ferrous-ion chelating activities of 1-4 were also determined. Key words: oxidative polymerization, Schiff base, phenol, antioxidant activity. Dans le cadre des presents travaux, nous decrivons la synthese, la caracterisation et l'activite antioxydante de deux bases de Schiff employees comme monomeres (1 et 2) et de leurs produits d'oxydation respectifs (3 et 4). Nous avons prepare les monomeres par condensation du 8-amino-2-naphtol avec le 2,4-dihydroxybenzaldehyde et le 3,4-dihydroxybenzaldehye, puis nous les avons soumis a une oxydation par le NaOCl en milieu alcalin pour obtenir les produits d'oxydation correspondants. Nous avons caracterise les composes 1 a 4 a l'aide de diverses techniques spectrales. Les resultats de l'analyse indiquent que les produits d'oxydation presentent une structure en chaine composee d'unites de phenylene et d'oxyphenylene ordonnees de maniere aleatoire. Nous avons evalue l'activite antioxydante in vitro des composes 1 a 4 a l'egard du radical cationique ABTS et du radical libre DPPH, et nous l'avons comparee a celle d'antioxydants naturels, a savoir la vitamine C (acide ascorbique) et la vitamine E ([alpha]-tocopherol). Nous avons egalement soumis les composes 1 a 4 au test de capacite de reduction des ions ferriques et au test de capacite chelatrice des ions ferreux. [Traduit par la Redaction] Mots-cles : polymerisation oxydante, base de Schiff, phenol, activite antioxydante., Introduction The polymers we use in our daily life are often exposed to various oxidative stresses. This leads to deterioration in their physical and mechanical properties and shortens their shelf [...]

A novel low-band-gap chromophore (5, 0.86 eV) having fluorene as a donor, benzobisihiadiazole (BBTD) as an acceptor, and pyrrole as a π-spacer was successfully designed and synthesized, to probe the effect of π-spacer on the band-gap level of the donor-π-acceptor-π-donor type of chromophores. Compared with the thiophene spacer analogue (in compound 3), the intramolecular hydrogen bonding between the pyrrole and the neighboring BBTD unit pushes the absorption maximum and fluorescence emission of chromophore 5 into the near-infrared spectral region with a red shift of 172 and 158 nm, respectively. The same red-shift phenomenon can also be realized by addition of Lewis acid (e.g., B[F.sub.3]) to the BBTD-containing chromophores with other spacers. Attempt of using low-band-gap chromophore 5 in bulk heterojunction (BHJ) solar cells was made, showing a non-optimized photovoltaic device with the power conversion efficiency of 0.01%. A precursor approach to introduction of the alkaline-labile BBTD acceptor into the polymer backbone has been demonstrated by successful synthesis of low-band-gap polymer P2. The same strategy can be in principle applied to the synthesis of a series of low-band-gap chromophores or polymers with strong acceptors. Key words: donor-π-acceptor-π-donor, chromophore, low band gap, bulk heterojunction (BHJ), precursor polymer. Afin de pouvoir etudier l'effet d'un espaceur π sur le niveau d'energie interbande des chromophores de type donneur-π-accepteur-π-donneur, on a developpe et synthetise un nouveau chromophore de basse energie interbande (5, 0,86 eV) comportant un fluorene comme donneur, un benzobisthiadiazole (BBTD) comme accepteur et un noyau pyrrole comme espaceur π. Par comparaison avec l'analogue comportant un espaceur thiophene (dans le compose 3), la liaison hydrogene intramoleculaire entre le pyrrole et l'unite adjacente BBTD deplace le maximum d'absorption et l'emission de fluorescence du chromophore 5 dans la region spectrale du proche infrarouge avec des deplacements vers le rouge de respectivement 172 et 158 nm. On peut observer le meme phenomene de deplacement vers le rouge par l'addition d'un acide de Lewis (tel le B[F.sub.3]) a des chromophores comportant du BBTD et d'autres espaceurs. On a essaye d'utiliser le chromophore 5 a faible energie interbande dans des cellules solaires a heterojonction globale (HJG); on a obtenu un dispositif non voltaique non optimise ayant une efficacite de conversion de pouvoir de 0,01 %. On a demontre l'applicabilite d'une autre approche a l'introduction de l'accepteur BBTD labile aux produits alcalins dans le squelette d'un polymere en effectuant avec succes la synthese du polymere P2 de faible energie interbande. En theorie, la meme strategie peut etre appliquee a la synthese d'une serie de chromophores ou de polymeres de faible energie interbande avec des accepteurs forts. Mots-cles: donneur-π-accepteur-π-donneur, chromophore, faible energie interbande, heterojonclion globale (HJG), polymere preeurseur., [Traduit par la Redaction] Introduction Research on low-band-gap organic materials (e.g.. chromophores and polymers), whose band-gap levels, defined as the difference between the highest occupied molecular orbital (HOMO) and the [...]

Acid-catalyzed deprotection of tert-butoxycarbonyl (t-Boc) pendant groups present in a polymer film is one of the most common chemical reactions in photolithography. We present here a novel method to determine the catalytic chain length of this reaction under different development conditions. We demonstrate this in model PMMA thin films containing triphenylsulphonium triflate as a photoacid generator, acid sensor coumarin 6, t-Boa protected coumarin 4, and base 2-piperidin-l-yl-ethanol (2-PE). Deprotection of the t-Boa group, catalyzed by the photogenerated acid, during the post-exposure bake leads to formation of coumarin 4, a strongly fluorescent molecule whose concentration is monitored using fluorescence. We take advantage of the change in the emission spectra of coumarin 6 upon protonation to monitor acid formation. To quantify the amount of acid, an acid-base titration is done in the polymer film using 2-PE. Knowing the amount of deprotected probe and the amount of acid, we are able to calculate the number of moles of deprotected C4-t-Boc per mol of acid, which is the actual catalytic chain length. Key words: photolithography, chemical amplification, catalytic chain length, fluorescent sensors, photoacid generator. La deprotection acidocatalysee des groupes pendants tert-butoxycarbonyles (t-Boc) presents dans un film de polymere est une des reactions chimiques les plus communes en photolithographie. Dans ce travail, on presente une nouvelle methode pour determiner la longueur de la chaine catalytique de cette reaction dans diverses conditions de developpement. Ceci est demontre dans des films minces modeles de PMMA contenant du triflate de triphenylsulfonium comme generateur photoacide, le detecteur d'acide coumarine 6, la coumarine 4 portant un groupe protecteur t-Boc et la base 2-piperidin-l-yl-ethanol (2-PE). La deprotection du groupe t-Boc, catalysee par l'acide photogenere au cours de la cuisson suivant l'exposition, conduit a la formation de la coumarine 4, une molecule fortement fluorescente dont on peut determiner la concentration par fluorescence. On tire avantage du changement dans le spectre d'emission de la coumarine 6 lors de la protonation pour deceler la formation d'acide. Afin de quantifier la quantite d'acide, on realise un titrage acide-base dans le film de polymere a l'aide du 2-PE. Connaissant la quantite de sonde deprotonee et la quantite d'acide, il est possible de calculer le nombre de moles de C4-t-Boc deprotege par mol d'acide, ce qui correspond a la longueur de la chaine catalytique. Mots cles : photolithographie, amplification chimique, longueur d'une chaine catalytique, detecteurs fluorescents, generateur photoacide. [Traduit par la Redaction]

Silicon based polymers obtained by ammonolysis of organochlorosilylboranes and their pyrolytic transformation into Si-B-C-N ceramics were studied by a detailed solid-state NMR investigation. Sol-gel polymerisation/pyrolysis routes were applied to form Si-B-C-N materials with exceptional high-temperature stability. The polymer to ceramic conversion was analyzed by [sup.11]B, [sup.13]C, [sup.15]N, and [sup.29]Si MAS NMR spectroscopy as well as by thermal analysis measurements coupled with mass spectroscopy (TGA-MS). The results showed that a significant change in the carbon-, silicon-, and boron-coordination environments occurs during pyrolysis. An evolution of cleavage of silcon-carbon-boron bridges and the formation of new B[N.sub.3] sites was observed. The NMR data obtained suggest the presence of a rather homogeneous dispersion of the boron atoms in the as synthesized silicon carbonitride phase, supporting the high thermal stability with respect to decomposition found in these compounds. Key words: organosilicon polymers, polymer pyrolysis, SiBCN ceramics, solid-state NMR.

The 5,11- and 5,17-diisocyano-25,26,27,28-tetra-n-propoxycalix[4]arene bridging ligands [(calix(NC).sub.2]) have been prepared in four steps with 34 and 30% global yields, respectively. Their corresponding Ag(I) complexes have been prepared from the direct reaction of the ligand with AgB[F.sub.4] and are characterized from various spectroscopic and physical techniques. The MALDI-TOF spectra indicate the presence of polymers or oligomers of the type {Ag(calix[(NC).sub.2])(B[F.sub.4])}n. The compounds have been characterized further from TGA, DSC, and XRD and compared with the oligomeric species 5,11,17,23-tetraisocyano-25,26, 27,28-tetra-n-propoxycalix[4]arene silver(I) (as a B[F.sup.-.sub.4] salt). Key words: silver, calix[4]arene, polymer, isocyanide, photosensitive, thermal gravimetric analysis.

The synthesis and characterization of stable bis(dihydroxymethylsilyl) derivatives are described. These compounds were obtained as microcrystalline powders by controlled hydrolysis in a biphasic medium (ethyl ether--water) of the corresponding bis(dimethoxymethylsilyl) organic precursors containing phenyl, biphenyl, stilbenyl, diphenylacetylene, and diphenylbut-l,3-diyne groups. All the solids obtained exhibited a layered structure. Condensation of the bis-silanediols could be effected by fluoride catalysis in solution at ambient temperature or simply by heating in solid state. The polysiloxanes obtained from the bis-silanediols have been compared with those obtained by hydrolysispolycondensation of the corresponding bis-dimethoxysilanes. The thermal route led to highly polycondensed solids arranged into thin plates as evidenced by TEM analysis; furthermore, in the case of the longer spacer, the organization was controlled by the arrangement of the Si-O-Si layers instead of the spacer. The X-ray study of these materials clearly evidenced the drastic influence of the length of the organic spacer, the polycondensation route and the nature of the leaving group (hydroxy or methoxy) on the short-range organization of the solids. Key words: silanols, hybrid materials, polycondensation, polysiloxanes.