Rhodium/Trialkylamines Catalyzed Reductive Hydroformylation in Ionic Liquid/Heptane Medium: An Unexpected Concept for Catalyst Recycling in Batch and Continuous Flow Processes.

We report here the rhodium catalyzed reductive hydroformylation of methyl 10-undecenoate. Our approach is based on an ionic liquid/heptane biphasic system associated with commercially available trialkylamines. The effects of various reaction parameters such as amine type, amine amount, temperature, syngas pressure and composition were studied in order to minimize the rhodium leaching and increase the production of primary alcohols.

Evaluation of Microbiological Susceptibility and Long-term Adhesive Properties to Dentin of Primers with Terminalia catappa Linn.

Purpose: To investigate the antibacterial effects of Terminalia catappa Linn (TCL) leaf extracts at different concentrations and the effects of these extracts used as primers on the long-term adhesive properties of two universal adhesives.

Materials And Methods: After extract preparation, the antimicrobial and antibacterial activities of TCL against Streptococcus mutans (UA 159) were assessed in microdilution assays to provide the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Additionally, to provide quantitative data on the ability of TCL extract to reduce cell viability, colony forming units (CFU) were counted.

Long-term Evaluation of Dentin Bonding Properties of the Photoinitiator System Contained in Universal Adhesives Used in Fiber-Post Luting Procedures.

Purpose: This study evaluated the long-term push-out bond strength (PBS) and nanoleakage (NL) of universal adhesives with different photo-initiator systems in the root canals of teeth in which fiber posts were luted.

Materials And Methods: One-hundred twenty endodontically treated human premolars were randomly divided into 12 groups based on the following factors: adhesives (Scotchbond Universal [SBU], Ambar Universal [AMB], and Ambar Universal APS [AMB-APS]); adhesive strategy (etch-and-rinse and self-etch), and time of testing (immediately vs after 2 years). The posts were cemented, sectioned into slices, tested for PBS at 0.

In-office dental bleaching in adolescents using 6% hydrogen peroxide with different application tips: randomized clinical trial.

Objective: Despite the availability of in-office bleaching gels with a 6% concentration of hydrogen peroxide (HP), these gels have not been evaluated in younger patients. They are commercially available with a tip, associated or not with a brush, where the tip with a brush spreads the gel over the entire surface to have a smaller thickness (thin layer) since the manufacturers indicate the application of a thin layer of gel. This randomized, split-mouth, double-blind clinical trial evaluated the efficacy of in-office bleaching with 6% HP in adolescents using different application tips, as well tooth sensitivity (TS) and aesthetic self-perception.

Long-term Evaluation of Bonding Performance of Universal Adhesives based on Different Dentinal Moisture Levels.

Purpose: To evaluate the microtensile bond strength (μTBS) and silver nitrate uptake (SNU) of three universal adhesives used in etch-and-rinse (ER) and self-etch (SE) modes on dry, wet, and oversaturated dentin surfaces after 24 h and 1 year of water storage. The morphology of the hybrid layer (MHL) and the degree of conversion (DC) were also evaluated.

Materials And Methods: Human molars were divided into 36 groups according to combinations of the following variables: (i) universal adhesives (Ambar Universal APS [AMB], Prime&Bond Active [PBA], Scotchbond Universal Adhesive [SBU]), (ii) adhesive strategies (ER or SE), (iii) moisture level (dry, wet, or oversaturated dentin surface), and (iv) storage time (24 h or 1 year).

Does the Application of Additional Hydrophobic Resin to Universal Adhesives Increase Bonding Longevity of Eroded Dentin?

This paper evaluates the effect of an additional hydrophobic resin coat (extra HL) associated with universal adhesives on sound and eroded dentin and evaluated immediately or after 2 years of water storage to improve the microtensile bond strength (μTBS) and nanoleakage (NL) when compared to the use of universal adhesives only. Sixty-four molars were assigned to eight groups using the following combinations: 1. dentin substrate, including sound and eroded dentin; 2.

Bonding Efficacy of Universal Adhesives to Fluorotic Enamel after Pre-conditioning with EDTA.

Purpose: To compare the effect of active pre-conditioning with 17% ethylenediaminetetraacetic acid (EDTA) vs 37% phosphoric acid (PA) on the resin-enamel microshear bond strength (µSBS), enamel-etching pattern, and in situ degree of conversion (in situ DC) of four universal adhesives on sound and fluorotic enamel.

Material And Methods: In this study, 448 extracted human molars (224 without fluorosis and 224 with fluorosis) were sectioned into four parts and divided into 16 experimental groups based on the enamel surface (sound or fluorotic enamel), adhesive (Clearfil Universal Bond [CUB], Futurabond U [FBU], iBond Universal [IBU], or Scotchbond Universal [SBU]), and enamel conditioning agent (PA or EDTA). The specimens were stored for 24 h and tested under shear stress at 1.

Unnatural cyclodextrins can be accessed from enzyme-mediated dynamic combinatorial libraries.

Dynamic systems of cyclodextrins (CDs) enabled by a native cyclodextrin glucanotransferase (CGTase) can incorporate unnatural glucopyranose-derived building blocks, expanding the applicability of enzyme-mediated dynamic combinatorial chemistry by using synthetically modified substrates. Starting dynamic combinatorial libraries from CDs with a single 6-modified glucopyranose results in a dynamic mixture of CDs containing several modified glucopyranoses. The relative concentrations of modified α, β or γ-CDs can be controlled by the addition of templates, providing a novel way to access modified CDs.

Synthesis and hydroformylation evaluation of Fréchet-type organometallic dendrons with N,O-salicylaldimine Rh(i) complexes at the focal point.

A series of organometallic dendrons containing N,O-salicylaldimine entities at the focal point were synthesised by reacting the N,O-salicylaldimine-functionalised Fréchet dendrons (G0, G1 and G2) with a [Rh(μ-Cl)(η2:η2-COD)]2 dimer to yield the corresponding Rh(COD) [COD = cyclooctadiene] complexes. These Rh(COD) complexes were exposed to an atmosphere of CO to yield a new class of rhodium carbonyl organometallic dendrons with Rh(CO)2 units at the focal point. All the compounds were characterised using standard spectroscopic and analytical techniques, these include nuclear magnetic resonance, infrared spectroscopy, mass spectrometry and single-crystal X-ray diffraction for compounds 1, 4 and 7.

Transition Metal Complexes Coordinated by Water Soluble Phosphane Ligands: How Cyclodextrins Can Alter the Coordination Sphere?

The behaviour of platinum(II) and palladium(0) complexes coordinated by various hydrosoluble monodentate phosphane ligands has been investigated by P{¹H} NMR spectroscopy in the presence of randomly methylated β-cyclodextrin (RAME-β-CD). This molecular receptor can have no impact on the organometallic complexes, induce the formation of phosphane low-coordinated complexes or form coordination second sphere species. These three behaviours are under thermodynamic control and are governed not only by the affinity of RAME-β-CD for the phosphane but also by the phosphane stereoelectronic properties.

Aqueous biphasic hydroformylation in the presence of cyclodextrins mixtures: evidence of a positive synergistic effect.

Mixtures of randomly methylated cyclodextrins of various sizes have been evaluated in the rhodium-catalysed hydroformylation of higher olefins in an aqueous biphasic medium. A marked positive non-linear effect on 1-tetradecene conversion is observed when the CD molar ratio in the mixture is modified. The formation of 2:1 ternary inclusion complexes between RAME-CDs and the olefin is supposed to be responsible for the extra conversion observed.

A property-matched water-soluble analogue of the benchmark ligand PPh3.

A series of sulfonated biphenylphosphanes were readily prepared from commercially available, inexpensive, and air-stable organic compounds. Of these, the trisulfonated trisbiphenylphosphane can be considered as a true water-soluble analogue of PPh(3) as the cone angle and basicity of both phosphanes are very close and result in a similar coordination mode on palladium and rhodium complexes. The catalytic performance of the trisulfonated trisbiphenylphosphane was evaluated in the aqueous hydroformylation of 1-decene and the Tsuji-Trost reaction.

Complexation of phosphine ligands with peracetylated beta-cyclodextrin in supercritical carbon dioxide: spectroscopic determination of equilibrium constants.

The interaction between peracetylated beta-cyclodextrin and several triphenyl phosphine derivatives was studied in supercritical carbon dioxide (scCO2) by UV-visible spectroscopy. The equilibrium constant for a 1:1 complexation reaction was obtained from titration spectra and calculated using two established mathematical models. The values of the equilibrium constants are 1-3 orders of magnitude smaller than those obtained in aqueous solution with analogous phosphines.