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Scientific imaging of a large fragile work of art can be especially challenging, but especially rewarding to better grasp the complexity and changes that have occurred during its creation and lifetime. Here, noninvasive imaging, macro X-ray fluorescence (MAXRF) imaging spectroscopy and reflectance imaging spectroscopy, from the visible to the near infrared spectral range, are utilized to document a 14-m-long Japanese narrative handscroll, The Miraculous Interventions of Jizō Bosatsu. Due to the scroll's age and its handling during past use as a teaching tool, it has a number of conservation needs and shows evidence of past repairs. The scroll has extensive and severe creasing, breaks and tears, as well as unstable and powdering pigments. Microscopic observation and scientific analyses were performed both to document the current condition of the scroll and to better understand its long history. Combining RIS and MAXRF allowed for pigment characterization through elemental and molecular information. While RIS and MAXRF previously have been applied to the study of other painted materials, their application to East Asian paintings is rare. The obstacles of the scroll's length and fragile uneven surface were overcome by optimizing the setups of the two imaging systems. The MAXRF and RIS analyses, here focused on a select scene of the scroll, found certain original pigments common in early Japanese scroll paintings were used frequently, such as vermilion, iron-based compounds (yellow and red ochres), and copper-containing greens, while others occurred sparingly, such as azurite and red lead. A chloride-containing lead-based white pigment was employed. Faded organic colorants, notably indigo as well as an organic yellow/brown, could be detected but their vibrancy has been muted over the centuries. In the case of indigo, it may be visibly observed in some areas; however, analysis revealed its previously unknown presence mixed with a copper green in a select area. This focused study sets a foundation for further studies on both this object and other Asian works of art. [ABSTRACT FROM AUTHOR]

A manganese-catalyzed hydrogenation of esters has been accomplished with TONs up to 1000, using cheap, environmentally benign, potassium carbonate and simple alcohols as activator and solvent, respectively. The weakly basic conditions lead to good functional group tolerance and enable the hydrogenation of enantiomerically enriched α-chiral esters with essentially no loss of stereochemical integrity. [ABSTRACT FROM AUTHOR]

This account describes studies on the catalytic hydrogenation of carbonyl groups that are not readily reduced. The development of well-defined chiral phosphine-diamine ruthenium catalysts for hydrogenation of ketones and esters is described. These chiral catalysts promote the hydrogenation of ketones functionalised with tertiary alkyl and gem-dimethyl groups with enantioselectivities of up to 98% ee. They also reduce a range of heterocyclic and nitrilefunctionalised ketones that react slowly with or inhibit other catalysts. Changing from ruthenium to iridium complexes gives highly selective catalysts that also hydrogenate (the more reactive) secondary alkyl functionalised ketones, including those with unprotected amines. These catalysts operate rapidly at room temperature, require low catalysts loadings, and deliver up to 98% ee. Achiral variants of these catalysts also promote the hydrogenation of esters under mild conditions. This account also describes our studies that shed light on the mechanism of action of these catalysts, and a stereochemical model is proposed. [ABSTRACT FROM AUTHOR]

Enantioselective transfer hydrogenation of benzofuranyl aryl ketones proceeds with moderate to good enantioselectivity even when the aryl group is not sterically differentiated by ortho-substituents. The best results are obtained with substrates that are functionalised by electron-withdrawing aryl groups that contrast with the electron-rich benzofuran, which is consistent with [Ru-ArC-H]˙Ar π interactions acting as a control element. Enantioselective pressure hydrogenation gives lower enantioselectivity irrespective of electronic effects, unless the aryl group is ortho-substituted, in which case up to 86% ee can be realised. [ABSTRACT FROM AUTHOR]

A convenient and chemoselective method for deoxygenation of pyridine N-oxide derivatives by transfer oxidation of triethylamine-catalysed by [Pd(OAc)2]/dppf is described. [ABSTRACT FROM AUTHOR]

Abstract: There is a demand for methodology that can rapidly produce families of catalysts for catalyst–structure–performance studies. The results reported here show microwave accelerated Suzuki coupling of a range of boronic acids with chloro-aryl phosphine-oxides can give high yields of arylated phosphine oxides. Chloro-aryl phosphine-oxide substrates have been found to be unreactive in previous studies, but in these examples, the combination of a highly active (but short lived) catalyst and instantaneous microwave heating at 140°C allows the reactions to proceed. These cross-coupling reactions are being used as the basis for a rapid synthesis of phosphine ligands (readily available by microwave-assisted reduction of the phosphine oxides). [Copyright &y& Elsevier]

Abstract: Sum frequency generation (SFG) vibrational spectroscopy has been applied to examine the molecular structures of proteins adsorbed at various interfaces, especially polymer/protein solution interfaces in situ. A thin film model was adopted to interpret interfacial protein SFG spectra. A polarization mapping method was developed that can help to analyze complicated protein SFG spectra more reliably, from which more structural information of various interfacial proteins can be deduced. SFG signals in different frequency ranges, including C–H, N–H, O–H stretching and amide I ranges, can be collected from proteins at interfaces. Different proteins, including bovine serum albumin, ubiquitin, fibrinogen, factor XII, and some selectively or randomly deuterated proteins, have been examined in SFG studies. Our research shows that proteins can have different conformations at various interfaces, and also that time-dependent structural changes of proteins after adsorption can be varied. SFG can be developed into a powerful and unique technique to elucidate interfacial protein structures at the molecular level in situ after continued success in the application of SFG to examine interfacial protein structures. [Copyright &y& Elsevier]

Sum frequency generation (SFG) vibrational spectroscopy has been employed to study a variety of interesting biological phenomena occurring at interfaces. This review summarizes recent SFG studies on proteins, lipid monolayers and bilayers, and other biological molecules. Molecular level details revealed by SFG in these studies show that SFG is a powerful technique for characterizing conformation, orientation and ordering of biological molecules at interfaces. [ABSTRACT FROM AUTHOR]

A "polarization mapping" method has been applied to improve the fitting quality of sum frequency generation (SFG) vibrational spectra of complicated systems and validate the data analysis of simple SFG spectra. Using such a method, two-dimensional SFG spectra can be constructed, from which more reliable spectral information can be obtained from a surface/interface. Model calculations as well as experiments have been employed to illustrate the power of the polarization mapping method for spectral analysis of SFG spectra. By using a deuterated polystyrene surface and interfacial protein molecules as examples, we demonstrate that this method is especially important for complicated molecules, such as polymers and proteins. [ABSTRACT FROM AUTHOR]

This study characterizes the molecular surface structures of polyurethane (PU) and plasticized PU films in air, in water, and in albumin solution in situ using a nonlinear optical technique, sum frequency generation (SFG) vibrational spectroscopy. Two different plasticizers are investigated: dioctyl sebacate (DOS) and o-nitrophenyl octyl ether (NPOE). Plasticization of PU is common for biosensors to achieve better adhesion, malleability, elasticity, and permeability; however, this can adversely affect biocompatibility. Our research indicates that plasticizers can segregate to the PU surface not only in air but also in water. In addition, plasticizer content can affect protein adsorption behaviors of PU surfaces. This is the first lime surface-sensitive SFG has been applied to deduce plasticizer surface behavior in situ. More specifically, we found that DOS dominates the surface of the film with DOS surface concentrations higher than DOS bulk concentrations both in air and in contact with an aqueous environment NPOE has a reduced effect at the surface compared to DOS in both air and aqueous environments. Addition of either DOS or NPOE to PU was also found to cause a change in albumin adsorption. [ABSTRACT FROM AUTHOR]

A convenient synthesis of several ‘phosphomide’ ligands (P adjacent to carbonyl group) from secondary phosphines is reported. The new anisoyl substituted phosphines are considerable more stable to hydrolysis, and are stronger σ-donor ligands than P-acetyl-diphenylphosphine as determined by the measurement of ν(CO) for the corresponding rhodium carbonyl complexes trans-[RhL2(CO)Cl]. In contrast, a new phosphomide derived from perfluoro-octanoyl chloride was found to be a highly unstable, electron poor π-acceptor ligand. The crystal structure of [RhCp*Cl2{Ph2PC(O)CH3}] showed a normal pseudo-octahedral piano-stool molecular geometry with a Rh&z.sbnd;P bond length of 2.3186(5) A˚. The extra stability observed for the P-anisoyl phosphomides has led us to apply this class of ligand in rhodium catalysed hydroformylation for the first time. [Copyright &y& Elsevier]

The first ‘fluorous soluble’ metal complexes derived from a phosphino-amine are reported. Attaching a single perfluorinated ‘ponytail’ to the (C6F5)2P fragment is sufficient to give rhodium complexes that show high partition co-efficients between perfluoromethylcyclohexane and toluene. [Copyright &y& Elsevier]

The reaction of several tertiary amine functionalised phosphines with [Pt(COD)Cl2] has been studied. Reactions with ratios of L:Pt=2 proceeded cleanly to give either cis or trans complexes depending on the cone angle of the phosphines. The trans complexes could also be prepared by reaction with Zeise''s salt. Reactions of [Pt(COD)Cl2] with L:Pt=1 are less straightforward, and a mixture of cis and trans monodentate complexes, and in one example, a chelate complex have been isolated. The X-ray crystal structures of [PtCl2(η2-iPr2PN(Me)CH2CH2NMe2)] and a monodentate complex [trans-PtCl2(η1-iPr2PNH-c-NC5H10)2] are reported. [Copyright &y& Elsevier]

Asymmetric hydrogenation of dibenzoyl-difluoro�methane has been studied for the first time. In contrast to �BINAL-H, baker’s yeast and CBS reduction procedures, ruthenium-catalysed hydrogenation using axially chiral diphosphine ligands provides excellent yield, diastereoselectivity and good enantioselectivity (up to 72% ee). Enantiomer enrichment by recrystallisation allows for the pure fluorinated diol to be isolated as a single enantiomer in moderate yield. [ABSTRACT FROM AUTHOR]

Rhodium catalysed hydroformylation of unsaturated esters has been studied. A pronounced temperature dependence was observed on the regioselectivity and catalytic activity for these reactions, and under the appropriate conditions, it is possible to obtain preferentially either linear or quaternary products. A quaternary selective hydroformylation of methyl atropate to give 1,3-aldehydic esters has also been developed. [Copyright &y& Elsevier]

Phospholane-phosphites are known to show highly unusual selectivity towards branched aldehydes in the hydroformylation of terminal alkenes. This paper describes the synthesis of hitherto unknown unsaturated phospholene borane precursors and their conversion to the corresponding phospholene-phosphites. The relative stereochemistry of one of these ligands and its Pd complex was assigned with the aid of X-ray crystal structure determinations. These ligands were able to approach the level of selectivity observed for phospholane-phosphites in the rhodium-catalysed hydroformylation of propene. High-pressure infra-red (HPIR) spectroscopic monitoring of the catalyst formation revealed that whilst the catalysts showed good thermal stability with respect to fragmentation, the C=C bond in the phospholene moiety was slowly hydrogenated in the presence of rhodium and syngas. The ability of this spectroscopic tool to detect even subtle changes in structure, remotely from the carbonyl ligands, underlines the usefulness of HPIR spectroscopy in hydroformylation catalyst development. [ABSTRACT FROM AUTHOR]

Manganese catalysed ester reduction using ethanol as a hydrogen transfer agent in place of dihydrogen is reported. High yields can be achieved for a range of substrates using 1 mol% of a Mn(I) catalyst, with an alkoxide promoter. The catalyst is derived from a tridentate P,N,N ligand. [ABSTRACT FROM AUTHOR]

Wiley‐VCH, Weinheim 2016. 2 volumes, 702 pp., hardcover, € 299.00.—ISBN 978‐3527335527 [ABSTRACT FROM AUTHOR]

Wiley‐VCH, Weinheim 2016. 2 Bände, 702 S., geb., 299.00 €.—ISBN 978‐3527335527 [ABSTRACT FROM AUTHOR]

High diastereoselectivity was observed in the Rh-catalysed reductive amination of 3-arylcyclohexanones to form tertiary amines. This was incorporated into a one-pot enantioselective conjugate addition and diastereoselective reductive amination, including an example of assisted tandem catalysis. [ABSTRACT FROM AUTHOR]

A manganese catalyst of a facially coordinating P,N,N ligand catalyses the hydrogenation of imines derived from indanone derivatives with high enantioselectivity. There is no requirement for an activating group and imines can be generated in situ. The selectivity can be rationalised by DFT calculations. [ABSTRACT FROM AUTHOR]

Review: [40 refs. [ABSTRACT FROM AUTHOR]

Review: 36 refs. [ABSTRACT FROM AUTHOR]

DFT calculations on the full catalytic cycle for manganese catalysed enantioselective hydrogenation of a selection of ketones have been carried out at the PBE0‐D3PCM//RI‐BP86PCM level. Mn complexes of an enantiomerically pure chiral P,N,N ligand have been found to be most reactive when adopting a facial coordination mode. The use of a new ligand with an ortho‐substituted dimethylamino‐pyridine motif has been calculated to completely transform the levels of enantioselectivity possible for the hydrogenation of cyclic ketones relative to the first‐generation Mn catalysts. In silico evaluation of substrates has been used to identify those likely to be reduced with high enantiomer ratios (er), and others that would exhibit less selectivity; good agreements were then found in experiments. Various cyclic ketones and some acetophenone derivatives were hydrogenated with er's up to 99 : 1. [ABSTRACT FROM AUTHOR]

DFT calculations on the full catalytic cycle for manganese catalysed enantioselective hydrogenation of a selection of ketones have been carried out at the PBE0‐D3PCM//RI‐BP86PCM level. Mn complexes of an enantiomerically pure chiral P,N,N ligand have been found to be most reactive when adopting a facial coordination mode. The use of a new ligand with an ortho‐substituted dimethylamino‐pyridine motif has been calculated to completely transform the levels of enantioselectivity possible for the hydrogenation of cyclic ketones relative to the first‐generation Mn catalysts. In silico evaluation of substrates has been used to identify those likely to be reduced with high enantiomer ratios (er), and others that would exhibit less selectivity; good agreements were then found in experiments. Various cyclic ketones and some acetophenone derivatives were hydrogenated with er's up to 99 : 1. [ABSTRACT FROM AUTHOR]

As an alternative to conventional asymmetric hydroformylation (AHF), asymmetric transfer hydroformylation (ATHF) by using formaldehyde as a surrogate for syngas is reported. A catalyst derived from commercially available [Rh(acac)(CO)2] (acac=acetylacetonate) and 1,2-bis[(2 S,5 S)-2,5-diphenylphospholano]ethane(1,5-cyclooctadiene) (Ph-BPE) stands out in terms of both activity and enantioselectivity. Remarkably, not only are high selectivities achievable, the reactions are very simple to perform, and higher enantioselectivity (up to 96 % ee) and/or turnover frequencies than those achievable by using the same catalyst (or other leading catalysts) can be obtained by using typical conditions for AHF. [ABSTRACT FROM AUTHOR]

Enantioselective hydrogenation of ketones is a key reaction in organic chemistry. In the past, we have attempted to deal with some unsolved challenges in this arena by introducing chiral tridentate phosphine-diamine/Ru catalysts. New catalysts and new applications are presented here, including the synthesis of phosphine-amino-alcohol P,N,OH ligands derived from (R,S)-1-amino-2-indanol, (S,S)-1-amino-2-indanol and a new chiral P,N,N ligand derived from (R, R)-1,2-diphenylethylenediamine. Ruthenium pre-catalysts of type [RuCl2(L)(DMSO)] were isolated and then examined in the hydrogenation of ketones. While the new P,N,OH ligand based catalysts are poor, the new P,N,N system gives up to 98% e.e. on substrates that do not react at all with most catalysts. A preliminary attempt at realising a new delta lactone synthesis by organocatalytic Michael addition between acetophenone and acrylonitrile, followed by asymmetric hydrogenation of the nitrile functionalised ketone is challenging in part due to the Michael addition chemistry, but also since Noyori pressure hydrogenation catalysts gave massively reduced reactivity relative to their performance for other acetophenone derivatives. The Ru phosphine-diamine system allowed quantitative conversion and around 50% e.e. The product can be converted into a delta lactone by treatment with KOH with complete retention of enantiomeric excess. This approach potentially offers access to this class of chiral molecules in three steps from the extremely cheap building blocks acrylonitrile and methyl-ketones; we encourage researchers to improve on our efforts in this potentially useful but currently flawed process. [ABSTRACT FROM AUTHOR]

Abstract: The application of electronic structure calculations to a key transition state in the reaction manifold of the Morita–Baylis–Hillman reaction allows the design of two bis(thiourea) cocatalysts capable of accelerating this reaction through the hydrogen bond mediated recognition of both the nucleophile and the electrophile. [Copyright &y& Elsevier]

Abstract: The influence of surface modifications, including carboxyl-, amine-, and mercaptoundecanoicacid-functionalized chemistries, on the dynamic fluorescence properties of single quantum dots (QDs) are probed using a combined confocal fluorescence microscopy and spectroscopy system. Water-soluble QDs with carboxyl- or amine-functionalized surfaces prepared through a linker arm show significant fluorescence intermittency and appear statistically identical. In contrast, water-soluble QDs functionalized via mercaptoundecanoicacid, an electron-donating thiol group, demonstrate suppressed fluorescence intermittency suggesting the photostability of water-soluble QDs is strongly dependant upon the method of surface functionalization. In addition, the long-term photostability of the mercaptoundecanoicacid-functionalized QD demonstrates an excitation-time-dependent blue-shift in the fluorescence emission spectra. Our measurement and analysis techniques promise a wealth of insight in elucidating the photophysics of bio-conjugated QDs and assessing and designing bio-conjugated QDs for biomedical applications requiring long-term photostabililty. [Copyright &y& Elsevier]

In this work, we demonstrate the feasibility to collect off-electronic resonance chiral sum frequency generation (SF6) vibrational spectra from interfacial proteins and peptides at the solid/liquid inter- face in situ. It is difficult to directly detect a chiral SF6 vibrational spectrum from interfacial fibrinogen molecules. By adopting an interference enhancement method, such a chiral SF6 vibrational spectrum can be deduced from interference spectra between the normal achiral spectrum and the chiral spectrum. We found that the chiral SF6 vibrational spectrum of interfacial fibrinogen was mainly contributed by the β-sheet structure. For a β-sheet peptide tachyplesin 1, which may be quite ordered at the solid/liquid interface, chiral SF6 vibrational spectra can be collected directly. We believe that these chiral signals are mainly contributed by electric dipole contributions, which can dominate the chiroptical responses of uniaxial systems. For the first time, to our knowledge, this work indicates that the off-electronic resonance SF6 technique is sensitive enough to collect chiral SFG vibrational spectra of interfacial proteins and peptides, providing more structural information to elucidate interfacial protein and peptide structures. [ABSTRACT FROM AUTHOR]

Unsymmetrical diphosphine ligands of the type Ph2P(CH2)nNHPPri 2 [n=2 (1), 3 (2)] have been obtained by reacting the appropriate (diphenylphosphino)alkylamine, Ph2P(CH2)nNH2 with chlorodi-iso-propylphosphine, in the presence of triethylamine. Reaction of Ph2P(CH2)2NHPPri 2 with PdCl2(PhCN)2, PtCl2(PhCN)2, PtMe2(cod) and PtClMe(cod), NiCl2·6H2O and Fe(CO)2(η5-C5H5)I gives the corresponding chelate complexes, PdCl2L, PtX2L, NiCl2L and Fe(CO)(η5-C5H5)L. Reaction of Ph2P(CH2)3NHPPri 2 with PtCl2(PhCN)2, PtMe2(cod) and PdCl2(PhCN)2 yields the chelate complexes and reaction with PtClMe(cod) led to a 50:50 mixture of chelate isomers. [Copyright &y& Elsevier]

As part of a programme aimed at exploiting lignin as a chemical feedstock for less oxygenated fine chemicals, several catalytic C-C bond forming reactions utilising guaiacol imidazole sulfonate are demonstrated. These include the cross-coupling of a Grignard, a non-toxic cyanide source, a benzoxazole, and nitromethane. A modified Meyers reaction is used to accomplish a second constructive deoxygenation on a benzoxazole functionalised anisole. [ABSTRACT FROM AUTHOR]

The use of Rh catalysts derived from a phospholane‐phosphite ligand were found to be more productive than the classic rhodium/BINAP system in enantioselective conjugate additions. These catalysts enable the use of lower amounts of aryl boronic acid in an asymmetric arylation reaction that required an impractical excess of nucleophile. This catalyst was also found to enable the coupling of a poorly reactive Michael acceptor, N‐CBz‐2‐3‐dehydro‐4‐piperidone, or the coupling of poorly reactive 2‐furyl boronic acids at ambient or near temperatures. [ABSTRACT FROM AUTHOR]

The scope of carbon monoxide‐free Asymmetric Transfer HydroFormylation (ATHF) procedures using a highly active single catalyst system derived from 1,2‐bis‐((2,5)‐diphenylphospholano)ethane as chiral ligand has been studied. This reveals some highly successful reactions, but also significant limitations. The development of a new protocol in which a catalyst for formaldehyde decomposition to CO and H2 is combined with the catalyst of choice for the subsequent asymmetric hydroformylation is described. This enables ATHF reactions that were problematic to be significantly improved. The new method has been used in the synthesis of several key precursors to biologically active molecules. [ABSTRACT FROM AUTHOR]

The hydroformylation of propene to give predominantly iso‐butanal has been achieved; class‐leading selectivity is possible even at higher temperatures that deliver fast conversion. Racemic rhodium complexes of bidentate phospholane phosphites derived from tropos‐biphenols and unusual solvent systems are the key to the selectivity observed. [ABSTRACT FROM AUTHOR]

The hydroformylation of propene to give predominantly iso‐butanal has been achieved; class‐leading selectivity is possible even at higher temperatures that deliver fast conversion. Racemic rhodium complexes of bidentate phospholane phosphites derived from tropos‐biphenols and unusual solvent systems are the key to the selectivity observed. [ABSTRACT FROM AUTHOR]

Post‐synthetic modification of the hafnium metal–organic framework MOF‐808(Hf) to include triarylphosphine ligands is reported. Sulfonated phenylphosphines are incorporated without oxidation to give a "MOF ligand" that can complex late transition metals such as Ir and Rh to give a bifunctional catalyst containing both metal–phosphine complexes and the Lewis acidic framework hafnium metal sites. The metallated phosphine‐bearing MOFs act as fully heterogeneous bifunctional catalysts for tandem reductive amination and hydroaminomethylation reactions. Post‐synthetic modification of hafnium MOF‐808 with sulfonated arylphosphines and precious metal catalyst pre‐cursors generates highly active and tunable bifunctional catalysts for reductive amination reactions, including alkene hydroaminomethylation. [ABSTRACT FROM AUTHOR]

This paper reports experimental and computational studies on the mechanism of a rhodium-catalyzed hydroformylation that is selective for branched aldehyde products from unbiased alkene substrates. This highly unusual selectivity relies on a phospholane-phosphite ligand prosaically called BOBPHOS. Kinetic studies using in situ high pressure IR (HPIR) and the reaction progress kinetic analysis methodology suggested two steps in the catalytic cycle were involved as turnover determining. Negative order in CO and positive orders in alkene and H2 were found and the effect of hydrogen and carbon monoxide partial pressures on selectivity were measured. Labeling studies found rhodium hydride addition to the alkene to be largely irreversible. Detailed spectroscopic HPIR and NMR characterization of activated rhodium-hydrido dicarbonyl species were carried out. In the absence of H2, reaction of the rhodiumhydrido dicarbonyl with allylbenzene allowed further detailed spectroscopic characterization of four- and five-coordinate rhodium-acyl species. Under single-turnover conditions, the ratios of branched to linear acyl species were preserved in the final ratios of aldehyde products. Theoretical investigations uncovered unexpected stabilizing CH-π interactions between the ligand and substrate which influenced the high branched selectivity by causing potentially low energy pathways to become unproductive. Energy span and degree of TOF control analysis strongly support experimental observations and mechanistic rationale. A three-dimensional quadrant model was built to represent the structural origins of regio- and enantioselectivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ spectroscopic study of hydroformylation catalysts at typical reaction concentrations. • Two ligands in the literature found to not coordinate to rhodium in the presence of syngas. • The highly active Rh/1,3,5,7-Tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane catalyst system studied by in situ HPIR spectroscopy and found to be mixture of resting states, with the composition tuneable by reaction conditions. The paper describes the composition of the resting states of several catalysts for alkene hydroformylation derived from bulky monophosphorus ligands. The results presented assess how bulky ligands compete with CO for the rhodium, and hence the role of 'unmodified' catalysts in alkene hydroformylation in the presence of these ligands. High Pressure Infra-Red (HPIR) spectroscopy was carried out at the rhodium and syngas concentrations typically used during catalysis experiments. These HPIR studies revealed that two ligands previously studied in Rh-catalysed hydroformylation react with [Rh(acac)(CO) 2 ] and H 2 /CO to give the unmodified rhodium cluster, [Rh 6 (CO) 16 ], as the only detectable species. Both less bulky phosphoramidites, and 1,3,5,7-Tetramethyl-6-phenyl-2,4,8-trioxa-6-phosphaadamantane, on the other hand, do not show the presence of [Rh 6 (CO) 16 ], and hence catalysis proceeds by purely ligand modified species under normal conditions. In the case of the Rh/phosphaadamantane catalysts, anecdotal evidence that this only forms a particularly useful catalyst above a certain pressure threshold can be understood in terms of how the catalyst composition varies with pressure. The ligands discussed have all been assessed in the hydroformylation of propene to separate their innate branched selectivity from their ability to isomerise higher alkenes to internal isomers. [ABSTRACT FROM AUTHOR]

A new hydrogenation catalyst based on a manganese complex of a chiral P,N,N ligand has been found to be especially active for the hydrogenation of esters down to 0.1 mol % catalyst loading, and gives up to 97 % ee in the hydrogenation of pro-chiral deactivated ketones at 30-50 °C. [ABSTRACT FROM AUTHOR]

A new hydrogenation catalyst based on a manganese complex of a chiral P,N,N ligand has been found to be especially active for the hydrogenation of esters down to 0.1 mol % catalyst loading, and gives up to 97 % ee in the hydrogenation of pro-chiral deactivated ketones at 30-50 °C. [ABSTRACT FROM AUTHOR]

An abstract of the article "Rapid Asymmetric Transfer Hydroformylation (ATHF) of Disubstituted Alkenes Using Paraformaldehyde as a Syngas Surrogate" by Rachael Pittaway and colleagues is presented.

This method uses low catalyst loadings and is suitable for the hydrogenation of tetrasubstituted enamines. [ABSTRACT FROM AUTHOR]

The synthesis of a range of phosphine-diamine, phosphine-amino-alcohol, and phosphine-amino-amide ligands and their ruthenium(II) complexes are reported. Five of these were characterised by X-ray crystallography. The activities of this collection of catalysts were initially compared for the hydrogenation of two model ester hydrogenations. Catalyst turnover frequencies up to 2400 h−1 were observed at 85 °C. However, turnover is slow at near ambient temperatures. By using a phosphine-diamine RuII complex, identified as the most active catalyst, a range of aromatic esters were reduced in high yield. The hydrogenation of alkene-, diene-, and alkyne-functionalised esters was also studied. Substrates with a remote, but reactive terminal alkene substituent could be reduced chemoselectively in the presence of 4-dimethylaminopyridine (DMAP) co-catalyst. The chemoselective reduction of the ester function in conjugated dienoate ethyl sorbate could deliver (2 E,4 E)-hexa-2,4-dien-1-ol, a precursor to leaf alcohol. The monounsaturated alcohol ( E)-hex-4-en-1-ol was produced with reasonable selectivity, but complete chemoselectivity of CO over the diene is elusive. High chemoselectivity for the reduction of an ester over an alkyne group was observed in the hydrogenation of an alkynoate for the first time. The catalysts were also active in the depolymerisation reduction of samples of waste poly(ethylene terephthalate) (PET) to produce benzene dimethanol. These depolymerisations were found to be poisoned by the ethylene glycol side product, although good yields could still be achieved. [ABSTRACT FROM AUTHOR]

The trivalent metal cations Al3+, Cr3+, and Fe3+ were each introduced, together with Sc3+, into MIL-100(Sc,M) solid solutions (M=Al, Cr, Fe) by direct synthesis. The substitution has been confirmed by powder X-ray diffraction (PXRD) and solid-state NMR, UV/Vis, and X-ray absorption (XAS) spectroscopy. Mixed Sc/Fe MIL-100 samples were prepared in which part of the Fe is present as α-Fe2O3 nanoparticles within the mesoporous cages of the MOF, as shown by XAS, TGA, and PXRD. The catalytic activity of the mixed-metal catalysts in Lewis acid catalysed Friedel-Crafts additions increases with the amount of Sc present, with the attenuating effect of the second metal decreasing in the order Al>Fe>Cr. Mixed-metal Sc,Fe materials give acceptable activity: 40% Fe incorporation only results in a 20% decrease in activity over the same reaction time and pure product can still be obtained and filtered off after extended reaction times. Supported α-Fe2O3 nanoparticles were also active Lewis acid species, although less active than Sc3+ in trimer sites. The incorporation of Fe3+ into MIL-100(Sc) imparts activity for oxidation catalysis and tandem catalytic processes (Lewis acid+oxidation) that make use of both catalytically active framework Sc3+ and Fe3+. A procedure for using these mixed-metal heterogeneous catalysts has been developed for making ketones from (hetero)aromatics and a hemiacetal. [ABSTRACT FROM AUTHOR]

Some N-substituted proline derivatives catalyse the reactions of alkyl aldehydes with electrophilic partners, and others give negligible amounts of product. The key reaction between the aldehyde and the proline derivative has been studied, and a rationale for the reactivity observed is presented. Simple proline amides derived from aromatic amines (poor catalysts) form stable imidazolidinones quite rapidly at the expense of enamines, the latter being detected, if at all, for less than an hour. Less basic proline amides form a kinetic diastereomer of an imidazolidinone that very slowly inverts its stereochemistry to give a final thermodynamic product. The stereochemistry of these diastereomers was fully assigned by 1H NMR, NOE, and TOCSY experiments. A proline amide derived from an alkylamine (good catalyst) forms high concentrations of enamine that is only slowly (days) converted into a single diastereomer of an inert imidazolidinone. In contrast, another good catalyst, a proline sulfonamide, immediately forms a reactive imidazolidinone, that rapidly ring-opens and exchanges with other aldehydes. This presumably drip-feeds iminium ions and enamines into the catalytic cycle. Thus, there are two quite different mechanistic regimes that lead to efficient catalysis. These mechanistic insights should now allow some element of rational design of prolinamides for enamine reactions using aldehydes. [ABSTRACT FROM AUTHOR]

We present a quantitative scheme for full-field polarization rotating fluorescence microscopy. A quarter-wave plate, in combination with a liquid crystal variable retarder, provides a tunable method to rotate polarization states of light prior to its being coupled into a fluorescence microscope. A calibration of the polarization properties of the incident light is performed in order to correct for elliptical polarization states. This calibration allows the response of the sample to linear polarization states of light to be recovered. Three known polarization states of light can be used to determine the average fluorescent dipole orientations in the presence of a spatially varying dc offset or background polarization-invariant fluorescence signal. To demonstrate the capabilities of this device, we measured a series of full-field fluorescence polarization images from fluorescent analogs incorporated in the lipid membrane of Burkitts lymphoma CA46 cells. The fluorescent lipid-like analogs used in this study are molecules that are labeled by either a DiI (1,1′-Dioctadecyl 3,3,3′,3′-Tetramethylindocarbocyanine) fluorophore in its head group or a Bodipy (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) molecule in its acyl chain. A spatially varying contrast in the normalized amplitude was observed on the cell surface, where the orientation of the DiI molecules is tangential to the cell membrane. The internally labeled cellular structures showed zero response to changes in linear polarization, and the net linear polarization amplitude for these regions was zero. This instrument provides a low cost calibrated method that may be coupled to existing fluorescence microscopes to perform investigations of cellular processes that involve a change in molecular orientations. [ABSTRACT FROM AUTHOR]

Abstract: The reactions of the very bulky phosphine ligands containing both tert-butyl and ortho-trifluoromethylphenyl substituents with [PdCl2(PhCN)2] have been studied, in order to assess the impact of steric and electronic effects on a ligand''s coordination ability. The palladium complexes of tert-butyl(ortho-trifluoromethylphenyl)methyl phosphine and tert-butyl(ortho-trifluoromethylphenyl)(n-butyl)phosphine were characterised by X-ray crystallography and shown to be good precatalysts for the hydroxy- and alkoxycarbonylation of alkenes relative to Pd complexes of tricyclohexylphosphine and triphenylphosphine. A notable feature of Pd complexes of tert-butyl(ortho-trifluoromethylphenyl)methyl phosphine is significantly enhanced regioselectivity relative to previous state-of-the-art catalysts in the hydroxycarbonylation of styrene, even if lithium chloride co-catalysts are not used. These catalysts derived from large cone angle ligands consistently give higher regioselectivity in the alkoxycarbonylation of styrene using ethanol, n-propanol, and i-propanol as nucleophiles. These Pd complexes are also active in the Suzuki coupling of activated aryl chlorides, and in both carbonylation and Suzuki reactions, tert-butyl(ortho-trifluoromethylphenyl)methyl phosphine gives more productive catalysts than its bulkier analogues. [Copyright &y& Elsevier]

Abstract: Reaction of [Rh(CO)2](μ-Cl)]2 with bis-1,2-(di{4-dimethylaminophenyl)phosphino-ethane (L) gives the monomeric Rh(I) complex of type cis-[RhCl(L)(CO)] that was separated from a side product of type [Rh(L)2]Cl, and characterised by X-ray crystallography. This complex reacts with methyl iodide at high temperature to give the Rh(III) acetyl complex, [Rh(I)2(C(O)Me)(L)], which was also structurally characterised by X-ray crystallography. There is no sign of quaternisation of the dimethylamino groups under these conditions. This complex is soluble in organic solvent and insoluble in the polar media used in methanol carbonylation (AcOH/H2O/MeOH). However, in the presence of HI, this complex is readily soluble in AcOH/H2O/MeOH, in contrast to [Rh(I)2(C(O)Me)(dppe)] and most other Rh-acetyl complexes of diphosphine ligands. [Copyright &y& Elsevier]