Heterometallic complex formation on p-sulfonatothiacalix[4]arene platform resulting in pH- and redox-modification of [Ru(bpy)3]2+ luminescence

The pH-dependent heterometallic complex formation with p-sulfonatothiacalix[4]arene (TCAS) as bridging ligand in aqueous solutions was revealed by the use of spectrophotometry, nuclear magnetic relaxation and fluorimetry methods. The novelty of the structural motif presented is that the appendance of emission metal center ([Ru(bpy)3]2+) is achieved through the cooperative non-covalent interactions with the upper rim of TCAS. The second metal block (Fe(III), Fe(II) and Mn(II)), bound with the lower rim of TCAS in the inner sphere coordination mode is serving as quencher of [Ru(bpy)3]2+ emission. The difference between the complex ability of Fe(III) and Fe(II) ions provides pH conditions for redox-dependent emission of [Ru(bpy)3]2+. © 2009 Elsevier B.V. All rights reserved

Photophysical and electrochemical properties of the outer-sphere associate of [Ru(bipy)3]2+ with p-sulfonatothiacalix[4]arene

1H NMR titration and X-ray diffraction analysis revealed that [Ru(bipy)3]2+ forms an outer-sphere inclusion complex with p-sulfonatothiacalix[4]arene in a ratio of 1: 1 in both aqueous solutions and the solid state. According to cyclic voltammograms and fluorimetric data, the outer-sphere association of [Ru(bipy)3]2+ with p-sulfonatothiacalix[4]arene changes the reversible character of the electrochemical oxidation of [Ru(bipy)3]2+ and lowers its emission intensity. © 2008 Springer Science+Business Media, Inc

Outer-sphere association of p-sulfonatothiacalix[4]arene and tetrasulfonatomethylated calix[4]resorcinarene with cobalt(III) tris(dipyridyl): the effect on the spectral and electrochemical properties of the latter

According to the 1H NMR and X-ray data, the outer-sphere association of [Co(dipy)3]3+ with cyclophanic anions p-sulfonatothiacalix[4]arene and tetrasulfonatomethylated calix[4]resorcinarene is accompanied by the inclusion of the dipyridyl moiety of the former into the cavities of the cyclophanic anions in aqueous and aqueous-DMSO solutions and in the solid state. The first-step dissociation of p-sulfonatothiacalix[4]arene does not change the inclusion mode, but the increase in DMSO content leads to a shallower inclusion of [Co(dipy)3]3+. The electrochemical property changes of [Co(dipy)3]3+ with both receptors undergoing ion pairing indicate the stabilization of the tris-(dipyridyl) cobalt complexes in lower oxidation states. The effect of the cyclophanic anions on the cyclic voltammograms of [Co(dipy)3]3+ correlates with the efficiency of binding of the latter with tetrasulfonatomethylated calix[4]resorcinarene and p-sulfonatothiacalix[4]arene. © 2005 American Chemical Society [email protected] A. E. Arbuzov Institute of Organic & Physical Chemistry Kazan State University

Highly active Pd-Ni nanocatalysts supported on multicharged polymer matrix

© The Royal Society of Chemistry 2017. In this article, we report the synthesis of mono- and bimetallic Pd-Ni nanocomposites supported on a multicharged polymeric matrix for catalytic applications. The morphology and catalytic properties of the composites depend on the Pd-Ni ratio. In the Suzuki-Miyaura coupling reaction, the composite with an equal amount of palladium and nickel is the most active and the reaction occurs within six hours in water at room temperature

Highly active Pd-Ni nanocatalysts supported on multicharged polymer matrix

© The Royal Society of Chemistry 2017. In this article, we report the synthesis of mono- and bimetallic Pd-Ni nanocomposites supported on a multicharged polymeric matrix for catalytic applications. The morphology and catalytic properties of the composites depend on the Pd-Ni ratio. In the Suzuki-Miyaura coupling reaction, the composite with an equal amount of palladium and nickel is the most active and the reaction occurs within six hours in water at room temperature

Surface decoration of silica nanoparticles by Pd(0) deposition for catalytic application in aqueous solutions

© 2015 Elsevier B.V.. The work introduces chemical and electrochemical synthetic routes to obtain Pd(0) nanoparticles (PdNPs) deposited onto silica supports in aqueous media. The former route is performed through reduction of Na2[PdCl4] by ascorbic acid in the presence of amino-modified silica nanoparticles (SiO2-NH2). The time-dependent variation of pH and the reductant concentration is the simple synthetic route to get uniform deposition of 215nm sized silica supports by Pd(0) nanoparticles (3-10nm). The methylviologen-mediated electrochemical synthetic route results in small PdNPs (3-9nm) located both onto and beyond the silica supports. Thus, the chemical synthetic route provides more homogeneous Pd(0)-SiO2-NH2 aqueous colloids. The results reveal that attractive interactions of amino/ammonium groups of SiO2-NH2 with both [PdCl4]2- and ascorbate-stabilized Pd(0) seeds are the key reasons for the better Pd(0)-deposition onto silica supports. The chemically deposited Pd(0)-SiO2-NH2 nanoparticles catalyze the chemiluminescence of luminol resulted from the H2O2-facilitated oxidation in alkaline aqueous solutions

Heterometallic CoIII-LnIII (Ln = Gd, Tb, Dy) complexes on a p-sulfonatothiacalix[4]arene platform exhibiting redox-switchable metal-to-metal energy transfer

Nuclear magnetic relaxation along with pH metric data have been used to reveal pH-dependent heterometallic CoIII-LnIII (Ln = Gd, Tb, and Dy) complex formation on a p-sulfonatothiacalix[4]arene (TCAS) platform in aqueous solution. The previously obtained 1D and 2D 1H NMR spectroscopic and X-ray data prove the outer sphere binding of the Co III block with the upper rim of TCAS, whereas the LnIII ion is coordinated with the phenolate groups of the lower rim of TCAS. The inclusive outer-sphere binding of CoIII tris(dipyridyl) and tris(ethylendiaminate) complexes with the upper rim of TCAS favors binding of the inner-sphere lanthanide ions through the lower rim of TCAS, whereas noninclusive binding of CoIII bis(histidinate) provides no effect on the binding of lanthanide ions. The emission properties of [Co(dipy) 3]3+-LnIII (Ln = Gd, Tb, Dy) complexes indicate the quenching of 4f luminescence by the 3d block. This quenching can be switched off by electrochemical CoIII/CoII reduction with further switching on by reoxidation. © Wiley-VCH Verlag GmbH & Co. KGaA, 2008