147 research outputs found
Conversion of Phthalimides to Isoindolines by Diborane
No full textReduction of N-alkylsubstituted phthalimides to the corresponding isoindolines by means of diborane is herein described.Fil: Strassert, Cristian A.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; ArgentinaFil: Awruch, Josefina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin
Rare Earth Chemistry De Gruyter STEM./ edited by Rainer Pöttgen, Thomas Jüstel, Cristian A. Strassert.
No full textDescription based upon print version of record.This work introduces into the chemistry, materials science and technology of Rare Earth Elements. The chapters by experienced lecturers describe comprehensively the recent studies of their characteristics, properties and applications in functional materials. Due to the broad range of covered topics as hydrogen storage materials, LEDs or permanent magnets this work gives an up-to-date presentation of this fascinating research.Intro -- Preface -- Contents -- List of contributors -- 1. The elements -- 1.1 Discovery of the rare-earth elements -- 1.2 Rare-earth minerals and rare-earth mining -- 1.3 Rare earth resources and processing -- 1.4 Rare earth metal production and refinement -- 1.5 Recycling aspects -- magnets -- 1.6 Recycling aspects -- phosphors -- 1.7 The structures of the elements -- 1.8 Electronic properties of the lanthanide ions -- 2. Reactivity and compounds -- 2.1 Halides of trivalent lanthanides -- 2.2 Lanthanide compounds with tetrahedral oxoanions -- 2.3 Lanthanide compounds with low valence2.4 Intermetallic compounds -- 2.5 Polyoxometalates -- 2.6 Coordination chemistry -- 2.7 Organometallic rare-earth chemistry -- 3. Characterization and properties -- 3.1 Analysis of rare-earth metals and their species -- 3.2 Rare earth toxicology -- 3.3 Rare earths magnetism -- condensed matter -- 3.4 Rare earth magnetism -- molecules -- 3.5 Optical characterization -- 3.6 Solid-state NMR and Mößbauer spectroscopy -- 3.7 Rare-earth ion spin dynamics as a source of structural information -- 3.8 Electrical and dielectric properties -- 4. Materials and applications -- 4.1 Optical materials -- molecules4.2 Optical materials -- microcrystalline powders -- 4.3 Optical materials -- ceramics -- 4.4 Crystal growth of rare-earth doped and rare-earth containing materials -- 4.5 Medical applications of rare earth compounds -- 4.6 Rare earth-based scintillators -- 4.7 Rare earth metals in heterogeneous catalysis -- 4.8 Materials for solid state cooling -- 4.9 Rare earth metal-based hydride materials -- 4.10 Lanthanide nanoparticles and their biological applications -- 4.11 Rare-earth-based hybrid materials -- 4.12 Rare earth based superconducting materials -- 4.13 Rare-earth-containing glasses4.14 Bioinorganic chemistry of the elements -- 4.15 Economic aspects -- Subject Index -- Formula Index1 online resource (670 p.)
A synthetic approach towards novel octa-substituted zinc(II) phthalocyanines with different solubility and photophysical properties
No full textThe synthesis and behavior in homogeneous solutions of 2,3,9,10,16,17,23, 24-octakis(3-phthalimidopropyloxy)phthalocyaninatozinc(II) (5) and 2,3,9,10,16,17,23,24-octakis(3-aminopropyloxy)phthalocyaninatozinc(II) (6) are reported.Fil: Strassert, Cristian A.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Rodriguez, Myriam E.. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Dicelio, Lelia Elina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Awruch, Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentin
Controlling Aggregation in Highly Emissive Pt(II) Complexes Bearing Tridentate Dianionic N∧N∧N Ligands. Synthesis, Photophysics, and Electroluminescence
No full textNeutral Pt(II) complexes bearing tridentate dianionic 2,6-bis(1H-1,2,4- triazol-5-yl)pyridine and ancillary alkyl-substituted pyridine ligands have been synthesized and characterized. They show bright green emission, reaching 73% photoluminescence quantum yield in deareated chloroform solution, which can be assigned to a predomi- nantly metal-perturbed ligand-centered phosphorescence. We have followed two strate- gies to preserve the spectral purity of the monomeric species by varying the substituents on the chromophoric or on the ancillary ligands. However, variations in the substitution patterns only modestly affected the radiative and radiationless deactivation rate constants of the monomers. Photophysical and electrochemical properties have been measured for all the complexes and correlated with calculations using time-dependent density func- tional theory. The electroluminescence spectra of the brightest, nonaggregating derivative showed a better color purity than that of iridium(III) tris(phenylpyridine), thus proving that aggregation was hindered in a running electroluminescent device
Photofunctional surfaces for quantitative fluorescence microscopy: monitoring the effects of photogenerated reactive oxygen species at single cell level with spatiotemporal resolution
No full textHerein, we report on the implementation of photofunctional surfaces for the investigation of cellular responses by means of quantitative fluorescence microscopy. The developed substrates are able to produce reactive oxygen species under the fluorescence microscope upon irradiation with visible light, and the behavior of cells grown on these surfaces can be consequently investigated in situ and in real time. Moreover, a suitable methodology is presented to simultaneously monitor phototriggered morphological changes and the associated molecular pathways with spatiotemporal resolution employing time-resolved fluorescence anisotropy at the single cell level. The results showed that morphological changes can be complemented with a quantitative evaluation of the associated molecular signaling cascades for the unambiguous assignment of reactive oxygen species-related photoinduced apoptosis. Indeed, similar phenotypes are associated with different cellular processes. Our methodology facilitates the in vitro design and evaluation of photosensitizers for the treatment of cancer and infectious diseases with the aid of functional fluorescence microscopy.Fil: Stegemann, Linda. Westfalische Wilhelms Universitat; AlemaniaFil: Schuermann, Klaus C.. Institut Max Planck Fur Molekulare Physiologie; AlemaniaFil: Strassert, Cristian A.. Westfalische Wilhelms Universitat; AlemaniaFil: Grecco, Hernan Edgardo. Institut Max Planck Fur Molekulare Physiologie; Alemania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; Argentin
Author Correction: A molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids
No full textOxygen-Insensitive Aggregates of Pt(II) Complexes as Phosphorescent Labels of Proteins with Luminescence Lifetime-Based Readouts
No full textThe synthesis and photophysical properties
of a tailored Pt(II) complex are presented. The phosphorescence of
its monomeric species in homogeneous solutions is quenched by interaction
with the solvent and therefore absent even upon deoxygenation. However,
aggregation-induced shielding from the environment and suppression
of rotovibrational degrees of freedom trigger a phosphorescence turn-on
that is not suppressed by molecular oxygen, despite possessing an
excited-state lifetime ranging in the microsecond scale. Thus, the
photoinduced production of reactive oxygen species is avoided by the
suppression of diffusion-controlled Dexter-type energy transfer to
triplet molecular oxygen. These aggregates emit with the characteristic
green luminescence profile of monomeric complexes, indicating that
Pt–Pt or excimeric interactions are negligible. Herein, we
show that these aggregates can be used to label a model biomolecule
(bovine serum albumin) with a microsecond-range luminescence. The
protein stabilizes the aggregates, acting as a carrier in aqueous
environments. Despite spectral overlaps, the green phosphorescence
can be separated by time-gated detection from the dominant autofluorescence
of the protein arising from a covalently bound green fluorophore that
emits in the nanosecond range. Interestingly, the aggregates also
acted as energy donors able to sensitize the emission of a fraction
of the fluorophores bound to the protein. This resulted in a microsecond-range
luminescence of the fluorescent acceptors and a shortening of the
excited-state lifetime of the phosphorescent aggregates. The process
that can be traced by a 1000-fold increase in the acceptor’s
lifetime mirrors the donor’s triplet character. The implications
for phosphorescence lifetime imaging are discussed
Energy Transfer between CNT Surface and -Re(CO)3(phen)+∗ Pendants Grafted to P4VP in Nanohybrid Shish-Kebob-like Structures
No full textThe adsorption of a Re(CO)3(phen)-poly(4-vinylpyridine) polymer, RePVP, on multiwall carbon nanotubes surfaces is studied by transmission electron microscopy and absorption spectroscopy in combination with chemometric techniques in MeOH/H2O solvent mixture. Nanohybrid structures like a shish-kebab (NHSK) are observed by TEM when RePVP is wrapped around carbon nanotubes (CNTs) surfaces. The association between RePVP and CNTs studied by absorption spectroscopy suggests the coexistence of CNTs with a high or low content of adsorbed RePVP on their surface. In the absence of CNTs, the photophysical properties of RePVP (i.e., luminescence quantum yield, ΦL, and amplitude-weighted average lifetimes, ⟨τ⟩) are strongly dependent on the morphology of the polymer as witnessed by the dependence of ΦL on the concentration of RePVP (CRePVP) and the fact that in CH3CN ΦL and ⟨τ⟩ are sensitive to O2 while in a MeOH/H2O solvent mixture they are not. In the NHSK, an energy-transfer process between excited −[Re(CO)3(phen)]+* pendent chromophores and the CNTs surface, with static and dynamic components, is responsible for the quenching of the RePVP luminescence by CNTs.Fil: Maisuls, Iván. Westfälische Wilhelms Universität; AlemaniaFil: Ostendorp, Stefan. Westfälische Wilhelms Universität; AlemaniaFil: Wilde, Gerhard. Westfälische Wilhelms Universität; AlemaniaFil: Parola, A. Jorge. Universidade Nova de Lisboa; PortugalFil: Strassert, Cristian A.. Westfälische Wilhelms Universität; AlemaniaFil: Wolcan, Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin
Functional Pt(II) and Re(I) Complexes with CO- and β-Carboline-Based Coligands: From Time-Resolved Photoluminescence Spectroscopy and Evaluation of 1O2 Photosensitization Efficiency toward in vitro (Photo)cytotoxicity
No full textIn this study, the synthesis, photophysical characterization, and (photo)biological assessment of functional rhenium(I)- and platinum(II)-based complexes are presented. These compounds feature anionic 1,2,4-triazolylpyridine-based chromophores and neutral βC-based monodentate coligands, specifically 9H-pyrido[3,4-b]indole (nHo) or 9-methyl-9H-pyrido[3,4-b]indole (MenHo), which have been chosen to promote their biological activity. The impact of transition metal cations, coordination geometries, substitution patterns of the luminophore and coligands on the properties of these complexes was thoroughly assessed, encompassing photoluminescence and singlet dioxygen (1O2) quantum yields, excited state lifetimes, and (non)radiative rate constants, across various temperatures and phases. Superior photophysical characteristics were attained by the Pt(II)-based complexes, while effective capabilities as photosensitizers of 1O2 were observed for all coordination compounds. Incorporation of these complexes into a polymeric matrix (PMMA) significantly enhanced their luminescence efficiencies by preventing diffusional quenching arising from triplet dioxygen (3O2). Furthermore, a comprehensive (photo)cytotoxicity study on human telomerase reverse transcriptase (hTERT)-immortalized cells was conducted to assess the potential applications of these complexes in photodynamic therapy. In summary, a versatile platform for designing photofunctional materials with photosensitizing properties is offered by this coordination chemical approach. Precise control of photophysical and (photo)biological attributes is achievable through the careful selection of metal centers, substitution patterns, and ancillary ligands.Fil: Kirse, Thomas M.. Universität Münster; AlemaniaFil: Maisuls, Iván. Universität Münster; AlemaniaFil: Denofrio, Maria Paula. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; ArgentinaFil: Hepp, Alexander. Universität Münster; AlemaniaFil: Cabrerizo, Franco Martín. Universidad Nacional de San Martin. Instituto Tecnologico de Chascomus. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - la Plata. Instituto Tecnologico de Chascomus.; ArgentinaFil: Strassert, Cristian A.. Universität Münster; Alemani
CeIV–GdIII Mixed Oxides as Hosts for ErIII-Based Upconversion Phosphors
No full textA family of ErIII and ErIII–YbIII based nanophosphors, hosted in monophasic oxidic CeIV–GdIII binary solid solutions, was prepared. The samples were formulated with a constant ErIII content as the activator, with the eventual addition of YbIII as a sensitizer. The amorphous Ce0.94−xGdxEr0.06(OH)CO3⋅H2O and Ce0.94−xGdxEr0.05Yb0.01(OH)CO3⋅H2O precursors were prepared by following the urea method to obtain monodispersed spheres of tunable size ranging from 30 to 450 nm. After being decomposed at 1273 K under an atmosphere of air, the precursors of 200 nm in diameter evolved into monophasic polycrystalline particles preserving the parent shape and size. The role of the composition of the binary matrices in the emission properties was evaluated for two different excitation wavelengths (976 nm and 780 nm) based on the upconversion (UC) emission spectra and their dependence on the incident power. The yield of the UC process is discussed in the framework of established and novel alternative mechanisms. The number of vacancies and mainly the symmetry of the ErIII environment play major roles in the deactivation pathways of the UC emission mechanisms. However, the colours obtained by employing bare CeIV or GdIII hosts are preserved in the related monophasic CeIV-rich or GdIII-rich binary hosts.Fil: Sorbello, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Gross, Petra. Carl von Ossietzky University; AlemaniaFil: Strassert, Cristian A.. Universität Münster; AlemaniaFil: Jobbagy, Matias. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; ArgentinaFil: Barja, Beatriz Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Inorgánica, Analítica y Química Física; Argentin
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