L'edat d'or de l'or

A finals del segle passat, l'ús de l'or com a catalitzador tenia un interès escàs a causa de la seva reconeguda manca d'activitat. L'investigador japonès Masatake Haruta, però, va demostrar que, quan l'or es presenta dividit molt finament, aleshores la seva capacitat catalítica augmenta d'una manera extraordinària. Aquest article, amb una intencionalitat divulgativa clara, explica que la immobilització, tant de nanopartícules com d'àtoms de l'or aïllats sobre un suport insoluble, incrementa enormement el potencial catalític d'aquests sistemes en nombroses reaccions químiques d'interès industrial

Transformación de una asignatura en una comunidad de práctica, experimentación y aprendizaje

Esta presentación se plantea como un recorrido por el trabajo de ideación, gestión e implementación de la asignatura Introducción al Proyecto de Diseño del primer curso del grado de Diseño. Su planteamiento es el de alejarse de la idea “clásica” de asignatura como agrupación cerrada, temporalmente limitada y con un programa y resultados predeterminados, transformándose en una comunidad de práctica, experimentación y aprendizaje colectivo de profesores y alumnos. Sin dejar el entorno educativo que la universidad ofrece, se intenta ampliar a nuevos entornos de producción de conocimiento para ser consecuentes con la naturaleza propia de una asignatura proyectual que requiere de procesos creativos, implicación personal e inmersión para obtener resultados que superen los previstos de antemano

Pyridinethiolate titanocene metalloligands and their self-assembly reactions to yield early–late metallamacrocycles

New titanocene pyridinethiolate compounds [(RCp)2Ti(4-Spy)2] (R = H (1), Me (2); Cp = cyclopentadienyl; 4-Spy = pyridine-4-thiolate) and [Cp2Ti(2-Spy)2] (3; 2-Spy = pyridine-2-thiolate) have been prepared by reaction of the corresponding Li(Spy) salt with the appropriate compound [(RCp)2TiCl2]. Compounds 1 and 2 have been used as metalloligands in self-assembly reactions with the acceptor late-transition-metal compounds [M(H2O)2(dppp)](OTf)2 (M = Pd (a) Pt (b); dppp = 1,3-bis(diphenylphosphino)propane), and the series of early–late tetranuclear metallamacrocycles [{(RCp)2Ti(4-Spy)2}{M(dppp)}]2(OTf)4 (R = H, M = Pd (12a2); R = H, M = Pt (12b2); R = Me, M = Pd (22a2); R = Me, M = Pt (22b2)) arising from the anti isomer of the titanocene metalloligands have been obtained. Only ligand transfer reactions from Ti to either Pd or Pt atoms have been observed when the pyridine-2-thiolate derivative 3 has been assayed in self-assembly processes. The obtained species have been characterized by NMR spectroscopy and ESI(+) mass spectrometry. The supramolecular assemblies have shown to be nonrigid in solution, and their fluxional behavior has been studied by VT 1H NMR spectroscopy. A DFT study including ab initio molecular dynamics in order to elucidate the structures and the relative stability of the isomers has been performed.Financial support for this work was provided by the Ministerio de Economía y Competitividad (MINECO/FEDER) of Spain (CTQ2013-42532-P and CTQ2012-31335), Diputación General de Aragón (Group E07) and Fondo Social Europeo. E.R. thanks Generalitat de Catalunya for an ICREA Academia fellowship.Peer reviewe

Pyridinethiolate titanocene metalloligands and their self-assembly reactions to yield early-late metallamacrocycles

New titanocene pyridinethiolate compounds [(RCp)(2)Ti(4-Spy)(2)] (R = H (1), Me (2); Cp = cyclo-pentadienyl; 4-Spy = pyridine-4-thiolate) and [Cp2Ti(2-Spy)(2)] (3; 2-Spy = pyridine-2-thiolate) have been prepared by reaction of the corresponding Li(Spy) salt with the appropriate compound [(RCp)(2)TiCl2]. Compounds 1 and 2 have been used as metalloligands in self-assembly reactions with the acceptor late-transition-metal compounds [M(H2O)(2)(dppp)]-(OTf)(2) (M = Pd (a) Pt (b); dppp = 1,3-bis-(diphenylphosphino)propane), and the series of early-late tetranuclear metallamacrocycles [{(RCp)(2)Ti(4-Spy)(2)}{M-(dppp)}](2)(OTf)(4) (R = H, M = Pd (1(2)a(2)); R = H, M = Pt (1(2)b(2)); R = Me, M = Pd (2(2)a(2)); R = Me, M = Pt (2(2)b(2))) arising from the anti isomer of the titanocene metalloligands have been obtained. Only ligand transfer reactions from Ti to either Pd or Pt atoms have been observed when the pyridine-2-thiolate derivative 3 has been assayed in self-assembly processes. The obtained species have been characterized by NMR spectroscopy and ESI(+) mass spectrometry. The supramolecular assemblies have shown to be nonrigid in solution, and their fluxional behavior has been studied by VT H-1 NMR spectroscopy. A DFT study including ab initio molecular dynamics in order to elucidate the structures and the relative stability of the isomers has been performed

Dinuclear pyridine-4-thiolate-bridged rhodium and iridium complexes as ditopic building blocks in molecular architecture

A series of dinuclear pyridine-4-thiolate (4-Spy)-bridged rhodium and iridium compounds [M(μ-4-Spy)(diolef)]2 [diolef = 1,5-cyclooctadiene (cod), M = Rh (1), Ir (2); diolef = 2,5-norbornadiene (nbd), M = Rh (3)] were prepared by the reaction of Li(4-Spy) with the appropriate compound [M(μ-Cl)(diolef)]2 (M = Rh, Ir). The dinuclear compound [Rh(μ-4-Spy)(CO)(PPh3)]2 (4) was obtained by the reaction of [Rh(acac)(CO)(PPh3)] (acac = acetylacetonate) with 4-pySH. Compounds 1-4 were assessed as metalloligands in self-assembly reactions with the cis-blocked acceptors [M(cod)(NCCH3)2](BF 4) [M = Rh (a), Ir (b)] and [M(H2O)2(dppp)] (OTf)2 [M = Pd (c), Pt (d); dppp = 1,3-bis(diphenylphosphino)propane] . The homometallic hexanuclear metallomacrocycles [{M2(μ-4-Spy) 2(cod)2}2{M(cod)}2](BF 4)2 (M = Rh [(1a)2], Ir [(2b)2]) and the heterometallic hexanuclear metallomacrocycles [{Rh2(μ-4-Spy) 2(cod)2}2{Ir(cod)}2](BF 4)2 [(1b)2], [{Rh2(μ-4-Spy) 2(cod)2}2{M′(dppp)}2](OTf) 4 (M′ = Pd [(1c)2], Pt [(1d)2]), and [{Ir2(μ-4-Spy)2(cod)2}2{M′ (dppp)}2](OTf)4 (M′ = Pd [(2c)2], Pt [(2d)2]) were obtained. NMR spectroscopy in combination with electrospray ionization mass spectrometry was used to elucidate the nature of the metalloligands and their respective supramolecular assemblies. Most of the synthesized species were found to be nonrigid in solution, and their fluxional behavior was studied by variable-temperature 1H NMR spectroscopy. An X-ray diffraction study of the assemblies (1a)2 and (1d)2 revealed the formation of rectangular (9.6 Å × 6.6 Å) hexanuclear metallomacrocycles with alternating dinuclear (Rh2) and mononuclear (Rh or Pt) corners. The hexanuclear core is supported by four pyridine-4-thiolate linkers, which are bonded through the thiolate moieties to the dinuclear rhodium units, exhibiting a bent-anti arrangement, and through the peripheral pyridinic nitrogen atoms to the mononuclear corners.Financial support for this work was provided by the Ministerio de Economía y Competitividad (MINECO/FEDER) of Spain (Projects CTQ2010-15221 and CTQ2012-31335), Diputación General de Aragón (Group E07), and Fondo Social Europeo.Peer Reviewe

A general approach to fabricate fe3O4 nanoparticles decorated with Pd, Au, and Rh: Magnetically recoverable and reusable catalysts for Suzuki C-C cross-coupling reactions, hydrogenation, and sequential reactions

A facile strategy has been explored for loading noble metals onto the surface of ferrite nanoparticles with the assistance of phosphine-functionalized linkers. Palladium loading is shown to occur with participation of both the phosphine function and the surface hydroxyl groups. Hybrid nanoparticles containing simultaneously Pd and Au (or Rh) are obtained by successive loading of metals. Similarly, ferrite nanoparticles decorated with Pd, Au, and Rh have also been formed by using the same strategy. The catalytic properties of the new nanoparticles are evidenced in processes such as reduction of 4-nitrophenol or hydrogenation of styrene. Besides, the sequential process involving a cross-coupling reaction followed by reduction of 1-nitrobiphenyl has been successfully achieved by employing Pd/Au decorated nanoferrite particles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Postprint (published version

Dinuclear Pyridine-4-thiolate-bridged rhodium and iridium complexes as ditopic building blocks in molecular architecture

A series of dinuclear pyridine-4-thiolate rhodium and iridium compounds [M(μ-4-Spy)(diolef)]2 (diolef = 1,5-cyclooctadiene, cod; M = Rh (1), Ir (2); 2,5-norbornadiene, nbd; M = Rh (3)) have been prepared by reaction of Li(4-Spy) with the appropriate compound [M(μ-Cl)(diolef)]2 (M = Rh, Ir). The dinuclear compound [Rh(μ-4-Spy)(CO)(PPh3)]2 (4) has been obtained by reaction of [Rh(acac)(CO)(PPh3] with 4-pySH. Compounds 1-4 have been assessed as metalloligands in self-assembly reactions with the cis-blocked [M(cod)(NCCH3)2](BF4) (M = Rh (a) and M = Ir (b)) and [M(H2O)2(dppp)](OTf)2 (M = Pd (c), Pt (d)) (dppp = 1,3-bis(diphenylphosphino)propane) acceptors. Homo [{M2(μ-4-Spy)2(cod)2}2{M(cod)}2](BF4)2 (M = Rh (1a)2, and M = Ir (2b)2), and hetero [{Rh2(μ-4-Spy)2(cod)2}2{Ir(cod)}2](BF4)2 (1b)2, [{Rh2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 ( M' = Pd (1c)2 and M'= Pt (1d)2) and [{Ir2(μ-4-Spy)2(cod)2}2{M'(dppp)}2](OTf)4 ( M' = Pd (2c)2 and M'= Pt (2d)2) hexanuclear metallomacrocycles have been obtained. NMR spectroscopy, in combination with ESI mass spectrometry has been used to elucidate the nature of the metalloligands and their respective supramolecular assemblies. Most of synthesized species have shown to be non-rigid in solution and their fluxional behavior has been studied by VT 1H NMR spectroscopy. An X-ray diffraction study on the assemblies (1a)2 and (1d)2 revealed the formation of rectangular (9.6 x 6.6 Å) hexanuclear metallomacrocycles with alternating dinuclear (Rh2) and mononuclear (Rh or Pt) corners. The hexanuclear core is supported by four pyridine-4-thiolate linkers, which are bonded through the thiolate moiety to the dinuclear rhodium units, exhibiting a bent-anti arrangement, and through the peripheral pyridinic nitrogen atoms to the mononuclear corners