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Iridium(I) compounds featuring bridge-functionalized bis-NHC ligands (NHC = N-heterocyclic carbene), [Ir(cod)(bis-NHC)] and [Ir(CO)2(bis-NHC)], have been prepared from the appropriate carboxylate- or hydroxy-functionalized bis-imidazolium salts. The related complexes [Ir(cod)(NHC)2]+ and [IrCl(cod)(NHC)(cod)] have been synthesized from a 3-hydroxypropyl functionalized imidazolium salt. These complexes have been shown to be robust catalysts in the oxidative dehydrogenation of glycerol to lactate (LA) with dihydrogen release. High activity and selectivity to LA were achieved in an open system under low catalyst loadings using KOH as a base. The hydroxy-functionalized bis-NHC catalysts are much more active than both the carboxylate-functionalized ones and the unbridged bis-NHC iridium(I) catalyst with hydroxyalkyl-functionalized NHC ligands. In general, carbonyl complexes are more active than the related 1,5-cyclooctadiene ones. The catalyst [Ir(CO)2{(MeImCH2)2CHOH}]Br exhibits the highest productivity affording TONs to LA up to 15,000 at very low catalyst loadings.

A series of mixed bis-NHC rhodium(I) complexes of type RhCl(η2-olefin)(NHC)(NHC’) have been synthesized by a stepwise reaction of [Rh(μ-Cl)(η2-olefin)2]2 with two different NHCs (NHC = N-heterocyclic carbene), in which the steric hindrance of both NHC ligands and the η2-olefin is critical. Similarly, new mixed coumarin-functionalized bis-NHC rhodium complexes have been prepared by a reaction of mono NHC complexes of type RhCl(NHC-coumarin)(η2,η2-cod) with the corresponding azolium salt in the presence of an external base. Both synthetic procedures proceed selectively and allow the preparation of mixed bis-NHC rhodium complexes in good yields.

Es difícil definir de dónde brota la armonía que se respira en esta iglesia: de los fuertes claroscuros de la cubierta y de la «movida» pared del fondo, del candor del mármol del presbiterio, de las luces de tonalidades diversas procedentes de las vidrieras, de los ornatos sobrios de la balaustrada y del pulpito, del a l tar con el Sagrario de bello diseño moderno...; todas son notas ligadas en acordes de sonoridad, suaves y naturales. De esta iglesia se sale de puntillas, para no romper ese encanto misterioso que posee, incluso cuando está en soledad y silencio. Después de visitar el interior, se comprenden mejor los alzados exteriores, la sobriedad de sus líneas, la coherencia de la estructura, la severidad de las fachadas, y, sobre todo, su valor de «isla sagrada» en un barrio donde las casas se hablan en un lenguaje inarticulado y uniforme. En materia de edificios religiosos no se debe entender por éxito la aprobación de la crítica o incluso de la masa, sino la de los fieles de todas las categorías, basada en la posibilidad de «rezar bien en su interior», y esto lo ha conseguido plenamente la iglesia de San Lucas, en la cual, y merced a una meditación profunda, la técnica ha prestado los medios de sostén y expresión.

El conjunto escolar que constituye el Instituto Massimo, comprende: diez edificios, en los cuales se desarrollan actividades docentes—enseñanza primaria y secundaria—con un gran atrio de distribución; gimnasio; una capilla mayor y una menor; el edificio para los padres rectores del conjunto; el de las monjas; el de los almacenes y servicios; la portería; etc. La capacidad del Instituto es de 1.500 alumnos, y lo más característico de su composición es la red de pasajes cubiertos que enlaza, con gran agilidad plástica, los diferentes edificios.

The synthesis of novel heterobimetallic derivatives of general formula [RuClCp(PPh3)-μ-dmoPTA-1κP:2κ2N,N′-M(acac-κ2O,O′)2] (M = Ni (3), Zn (4); dmoPTA = 3,7-dimethyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane) is described. The preparations of the ruthenium–cobalt analogue (M = Co (2)) and the starting compound [RuClCp(HdmoPTA-κP)(PPh3)](CF3SO3) have been revised and their yield improved. Similar to 2, the solid state structures of 3and 4show that the dmoPTA-P and the dmoPTA-NCH3atoms are involved in the coordination to the {RuCpCl(PPh3)} and {M(acac)2} moieties, respectively. The size of the diffusing units is almost the same for the three binuclear complexes, indicating that they exhibit similar solution structures. The diamagnetic ruthenium–zinc derivative was fully characterized in solution at 193 K by NMR as two diastereomeric pairs of enantiomers (R-Ru, Δ-Zn; R-Ru, Λ-Zn; S-Ru, Δ-Zn; S-Ru, Λ-Zn). Finally, the electrochemical properties of the complexes have been investigated by cyclic voltammetry. [ABSTRACT FROM AUTHOR]

Covering: up to the end of 2010 [ABSTRACT FROM AUTHOR]

The reaction of HTIMP3(HTIMP3= tris[1-(diphenylphosphino)-3-methyl-1H-indol-2-yl]methane) with [RhCl(COD)]2and Rh(acac)(CO)2produces RhHCl(TIMP3) (1H) and Rh(TIMP3)(CO) (2), respectively, both exhibiting tetradentate κC,κ3P-coordination of the TIMP3moiety. The reaction of RhHCl(TIMP3) with nucleophiles (L) in the presence of AgBF4or AgPF6produces different compounds depending on the nature of L. Indeed, cationic Lewis adducts of formula [RhH(L)(TIMP3)]+(2H+-5H+) are obtained when L is CO, CNCH2Ph, pyridine or CH2CHCN. On the other hand, when the incoming nucleophile is CH3COOH the hydride-free complex [Rh(CH3COO)(TIMP3)]+(6+) is obtained. Finally, the reaction of RhHCl(TIMP3) with PhCCPh and CH2CHCOOMe in the presence of AgPF6leads to the insertion products [Rh(PhCCHPh)(TIMP3)]+(7+) and [Rh(CH2CH2COOMe)(TIMP3)]+(8+), respectively. The solid state structure has been determined by single crystal X-ray diffraction in selected cases (1H, 6+). [ABSTRACT FROM AUTHOR]

In microorganisms and plants, chromium (Cr) is not essential for any metabolic process, and can ultimately prove highly deleterious. Due to its widespread industrial use, chromium has become a serious pollutant in diverse environmental settings. The presence of Cr leads to the selection of specific algal populations able to tolerate high levels of Cr compounds. The varying Cr-resistance mechanisms displayed by microorganisms include biosorption, diminished accumulation, precipitation, reduction of Cr6+to Cr3+, and chromate efflux. In this paper we describe the effects of Cr6+(the most toxic species) on the photosynthetic and photoreceptive apparatus of two fresh water microalgae, Eudorina unicoccaand Chlorella kessleri. We measured the effect of this heavy metal by means of in vivoabsorption microspectroscopy of both the thylakoid compartments and the eyespot. The decomposition of the overall absorption spectra in pigment constituents indicates that Cr6+effects are very different in the two algae. In E. unicoccathe metal induced a complete pheophinitization of the chlorophylls and a modification of the carotenoids present in the eyespot after only 120 h of exposition at a concentration equal or greater than 40 µM, which is the limit for total Cr discharge established by US EPA regulations. In C. kessleri, chromium concentrations a hundred times higher than this limit had no effect on the photosynthetic machinery. The different tolerance level of the two algae is suggested to be due to the different properties of the mucilaginous envelope and cell wall covering, respectively, the colonies of Eudorinaand the single cells of Chlorella, which binds chromium cations to a different extent. [ABSTRACT FROM AUTHOR]

For over 100 years, Euglena gracilis has represented a major subject for photobiological studies. This unicellular flagellate is well suited for such investigations because of its special complement of organelles that may be considered an ancient, yet complete "visual" system. The actual photoreceptive roles of the cytoplasmic eyespot and the photoreceptor (old terminology: paraflagellar swelling) of E. gracilis are still under debate, because of the different experimental evidence produced by the different research groups still working on this organism. This paper presents the analysis of the spectroscopical measurements performed by our group, which forms the basis of a possible model for Euglena photoresponses. [ABSTRACT FROM AUTHOR]

A microspectrophotometer is a digital microscope used to measure absorption and fluorescence spectra. In this paper we describe a polychromator-based microspectrophotometer that performs in vivo absorption or emission measurements at the same time on different subcellular compartments such as photoreceptive and photosynthetic structures of algal cells. In this system, a flat field imaging concave grating polychromator is connected to the slit-shaped exit pupil of a light-guide probe mounted onto a microscope equipped with an epifluorescence module. The subcellular components, on which the spectra will be measured, are placed in the microscope field and finely adjusted. The outer bundle of the probe is used for centering the objects, while the central bundle of the probe, containing 19 light guides, is used for acquiring either transmitted or emitted light (i.e. fluorescence). The light transmitted or emitted by the subcellular components is collected by the probe mounted in the back focal plane of the ocular. The exit pupil of this probe, connected to a flat field imaging concave grating polychromator, produces a dispersion image that in turn is focused onto a digital slow scan cooled CCD camera. Absorption and emission spectra of algal subcellular compartments are presented