Suzuki-Miyaura Cross-Coupling Reaction Using Palladium Catalysts Supported on Phosphine Periodic Mesoporous Organosilica.

Phosphine periodic mesoporous organosilicas (R-P-PMO-TMS: R=Ph, tBu), which possess electron-donating alkyl substituents on the phosphorus atom, were synthesized using bifunctional compounds with alkoxysilyl- and phosphino groups, bis[3-(triethoxysilyl)propyl]phenylphosphine borane (1 a) and bis[3-(triethoxysilyl)propyl]-tert-butylphosphine borane (1 b). Immobilization of Pd(0) species was performed to give R-P-Pd-PMO-TMS: R=Ph (2 a), tBu (3 a), respectively. The Pd(0) immobilized 2 a and 3 a were applicable as catalysts for Suzuki-Miyaura cross-coupling reactions of aryl chlorides with phenylboronic acid.

Reversible CO Fixation and Release by a Trinuclear Zn(II) Cryptate Complex and Operando Analysis of the Complex Structure.

Metal complexes inspired by carbonic anhydrase (CA), which is a metalloenzyme containing Zn(II), have been investigated as alternatives for CO fixation systems operating under ambient temperature and pressure conditions. In this study, we designed a trinuclear Zn(II) cryptate complex (Zn L) and demonstrated rapid CO fixation with carbonation of CO using Zn L. The CO fixation performance of Zn L surpassed that of a standard CO absorbent, KOH(aq) solution, under conditions of the same solute concentration.

1,10-Phenanthroline-based periodic mesoporous organosilica: from its synthesis to its application in the cobalt-catalyzed alkyne hydrosilylation.

1,10-Phenanthroline (Phen) is a typical ligand for metal complexation and various metal/Phen complexes have been applied as a catalyst in several organic transformations. This study reports the synthesis of a Phen-based periodic mesoporous organosilica (Phen-PMO) with the Phen moieties being directly incorporated into the organosilica framework. The Phen-PMO precursor, 3,8-bis[(triisopropoxysilyl)methyl]-1,10-phenanthroline (1a), was prepared the Kumada-Tamao-Corriu cross-coupling of 3,8-dibromo-1,10-phenanthroline and [(triisopropoxysilyl)methyl]magnesium chloride.

Hydrogen Production from Methanol-Water Mixture over Immobilized Iridium Complex Catalysts in Vapor-Phase Flow Reaction.

Invited for this month's cover is the group of Shinji Inagaki from Toyota Central R&D Laboratories Inc. and Ken-ichi Fujita from Kyoto University. The image shows iridium complexes immobilized on the channel walls of periodic mesoporous organosilica, which catalyze the dehydrogenation of a methanol-water mixture to produce hydrogen and carbon dioxide.

Hydrogen Production from Methanol-Water Mixture over Immobilized Iridium Complex Catalysts in Vapor-Phase Flow Reaction.

CO-free hydrogen production from methanol and water by using transition metal complex catalysts has attracted increasing attention. However, liquid-phase batch reactions using homogeneous catalysts are impractical for large-scale operations, owing to the consumption of bases and the use of organic solvents or additives. This study concerns a novel method for continuous hydrogen production from a simple methanol-water solution under vapor-phase flow.

Lanthanide-Grafted Bipyridine Periodic Mesoporous Organosilicas (BPy-PMOs) for Physiological Range and Wide Temperature Range Luminescence Thermometry.

2,2'-Bipyridine is the most widely used chelating ligand for developing metal complexes in coordination and supramolecular chemistry. Here, we present a series of three bipyridine periodic mesoporous organosilicas (BPy-PMOs) grafted with lanthanide β-diketonate complex for the purpose of obtaining thermochromic materials, which can be employed as ratiometric temperature sensors. Such thermometers are based on the ratio of two emission intensity peaks and are not affected by factors such as alignment or optoelectronic drift of the excitation source and detectors.

Fast and stable vapochromic response induced through nanocrystal formation of a luminescent platinum(II) complex on periodic mesoporous organosilica.

A hybrid vapoluminescent system exhibiting fast and repeatable response was constructed using periodic mesoporous organosilica with bipyridine moieties (BPy-PMO) and a Pt(II) complex bearing a potentially luminescent 2-phenylpyridinato (ppy) ligand. An intense red luminescence appeared when the Pt(II)-complex immobilised BPy-PMO was exposed to methanol vapour and disappeared on exposure to pyridine vapour. The ON-OFF vapochromic behaviour occurred repeatedly in a methanol/pyridine/heating cycle.

Cooperative Catalysis of an Alcohol Dehydrogenase and Rhodium-Modified Periodic Mesoporous Organosilica.

The combined use of a metal-complex catalyst and an enzyme is attractive, but typically results in mutual inactivation. A rhodium (Rh) complex immobilized in a bipyridine-based periodic mesoporous organosilica (BPy-PMO) shows high catalytic activity during transfer hydrogenation, even in the presence of bovine serum albumin (BSA), while a homogeneous Rh complex exhibits reduced activity due to direct interaction with BSA. The use of a smaller protein or an amino acid revealed a clear size-sieving effect of the BPy-PMO that protected the Rh catalyst from direct interactions.

Heterogeneous hydrosilylation reaction catalysed by platinum complexes immobilized on bipyridine-periodic mesoporous organosilicas.

The utility of a bipyridine periodic mesoporous organosilica, BPy-PMO, as a support material of a hydrosilylation catalyst was investigated in the hydrosilylation of phenylacetylene with trimethoxysilane. [PtMe2(BPy-PMO)] (1) exhibited a moderate catalytic activity, whereas the reaction was successfully catalysed by [PtMe2(BPy-PMO-TMS)] (2) bearing end-capped TMS groups on the surface. Spectroscopic analyses of 2 revealed that the porous structure of BPy-PMO-TMS remained almost unchanged through the reaction.

Re(bpy)(CO) Cl Immobilized on Bipyridine-Periodic Mesoporous Organosilica for Photocatalytic CO Reduction.

This paper describes the physicochemical properties of a rhenium (Re) complex [Re(bpy)(CO) Cl] immobilized on a bipyridine-periodic mesoporous organosilica (BPy-PMO) acting as a solid support. The immobilized Re complex generated a metal-to-ligand charge transfer absorption band at 400 nm. This wavelength is longer than that exhibited by Re(bpy)(CO) Cl in the polar solvent acetonitrile (371 nm) and is almost equal to that in nonpolar toluene (403 nm).

Photocatalytic CO Reduction by Periodic Mesoporous Organosilica (PMO) Containing Two Different Ruthenium Complexes as Photosensitizing and Catalytic Sites.

A periodic mesoporous organosilica (PMO) containing 2,2'-bipyridine (bpy) ligands within the framework (BPy-PMO) has great potential for designing novel catalysts by modifying metal complexes. A photosensitizing site (Ru(PS)) was introduced by treating cis-[Ru(bpy) (dimethylsulfoxide)Cl]Cl with BPy-PMO. Then a catalytic site (Ru(Cat)) was brought in Ru(PS) -BPy-PMO by reaction with a ruthenium polymer [Ru(CO) Cl ] .

Heterogeneous Catalysis for Water Oxidation by an Iridium Complex Immobilized on Bipyridine-Periodic Mesoporous Organosilica.

Heterogenization of metal-complex catalysts for water oxidation without loss of their catalytic activity is important for the development of devices simulating photosynthesis. In this study, efficient heterogeneous iridium complexes for water oxidation were prepared using bipyridine-bridged periodic mesoporous organosilica (BPy-PMO) as a solid chelating ligand. The BPy-PMO-based iridium catalysts (Ir-BPy-PMO) were prepared by postsynthetic metalation of BPy-PMO and characterized through physicochemical analyses.

Ruthenium-Immobilized Periodic Mesoporous Organosilica: Synthesis, Characterization, and Catalytic Application for Selective Oxidation of Alkanes.

Periodic mesoporous organosilica (PMO) is a unique material that has a crystal-like wall structure with coordination sites for metal complexes. A Ru complex, [RuCl2 (CO)3 ]2 , is successfully immobilized onto 2,2'-bipyridine (BPy) units of PMO to form a single-site catalyst, which has been confirmed by various physicochemical analyses. Using NaClO as an oxidant, the Ru-immobilized PMO oxidizes the tertiary C-H bonds of adamantane to the corresponding alcohols at 57 times faster than the secondary C-H bonds, thereby exhibiting remarkably high regioselectivity.

Iridium-bipyridine periodic mesoporous organosilica catalyzed direct C-H borylation using a pinacolborane.

Heterogeneous catalysis for direct C-H borylation of arenes and heteroarenes in the combination of iridium (Ir) complex fixed on periodic mesoporous organosilica containing bipyridine ligands within the framework (Ir-BPy-PMO) and pinacolborane (HBpin) is reported. Ir-BPy-PMO showed higher catalytic activity toward the borylation of benzene with inexpensive HBpin compared to expensive bis(pinacolato)diboron (B2pin2). The precatalyst could be handled without the use of a glove box.

A solid chelating ligand: periodic mesoporous organosilica containing 2,2'-bipyridine within the pore walls.

Synthesis of a solid chelating ligand for the formation of efficient heterogeneous catalysts is highly desired in the fields of organic transformation and solar energy conversion. Here, we report the surfactant-directed self-assembly of a novel periodic mesoporous organosilica (PMO) containing 2,2'-bipyridine (bpy) ligands within the framework (BPy-PMO) from a newly synthesized organosilane precursor [(i-PrO)3Si-C10H6N2-Si(Oi-Pr)3] without addition of any other silane precursors. BPy-PMO had a unique pore-wall structure in which bipyridine groups were densely and regularly packed and exposed on the surface.

Ab initio molecular orbital study on the excited states of [2.2]-, [3.3]-, and siloxane-bridged paracyclophanes.

Paracyclophanes are simple idealized model molecules for the study of interacting π-stacking systems. In this study, the excited states of [2.2]paracyclophane ([2.

Enhanced fluorescence detection of metal ions using light-harvesting mesoporous organosilica.

Enhanced fluorescence detection of metal ions was realized in a system consisting of a fluorescent 2,2'-bipyridine (BPy) receptor and light-harvesting periodic mesoporous organosilica (PMO). The fluorescent BPy receptor with two silyl groups was synthesized and covalently attached to the pore walls of biphenyl (Bp)-bridged PMO powder. The fluorescence intensity from the BPy receptor was significantly enhanced by the light-harvesting property of Bp-PMO, that is, the energy funneling into the BPy receptor from a large number of Bp groups in the PMO framework which absorbed UV light effectively.

Synthesis of a spirobifluorene-bridged allylsilane precursor for periodic mesoporous organosilica.

A novel spirobifluorene-bridged allylsilane precursor, which can be easily purified by silica gel chromatography, was prepared by using a new molecular building block for allylsilane sol-gel precursors (MBAS) and successfully converted into a highly fluorescent periodic mesoporous organosilica film.

Visible-light-harvesting periodic mesoporous organosilica.

Highly ordered periodic mesoporous organosilica synthesized from a newly designed 9(10H)-acridone bridged organosilane precursor exhibited efficient light-harvesting antenna properties for visible light, at wavelengths up to 450 nm.