Possible transition from rod-like to disc-like behaviour in ortho-metallated imine complexes of palladium(II): crystal and molecular structure of three palladium complexes

Two series of ortho-metallated palladium imine complexes are reported that contain a coordinated β-diketonate group. In one group the chain length of the imine is varied while the β-diketone is unchanged; in the other the imine chains are both fixed as methoxy and the structure of the β-diketonate is varied. The mesomorphism of these new complexes is reported and discussed in relation to the search for materials showing a biaxial nematic phase.     

Phonon dispersion in Xe

The predictions of the Mie-Lennard-Jones potentials for phonon dispersion in solid Xe at 10°K and at 77°K are compared with the results of recent measurements. The dynamics of the crystal are described by the first order self-consistent phonon theory for the imaginary part of the one phonon Green's function. The fit obtained is quite poor though we point out that no conclusion can be drawn about the size of three-body forces. We conclude that improved potentials are needed to account for the experimental data.     

Towards the automatic analysis of NMR spectra: part 7. Assignment of 1H by employing both 1H and 1H/13C correlation spectra

A reliable method of automatically assigning one-dimensional proton spectra is described. The method relies on the alignment of the proton spectrum with an associated heteronuclear single-quantum coherence (HSQC) spectrum, transferring the stoichiometry and couplings to the HSQC. The HSQC spectrum is then assigned using a linear assignment procedure in which a fitness function incorporating (1)H chemical shifts, (1)H couplings and (13)C shifts are employed. The method uniquely employs a sequential procedure in which only correlations of like stoichiometry are assigned at the same time.     

Confocal/TEM overlay microscopy: a simple method for correlating confocal and electron microscopy of cells expressing GFP/YFP fusion proteins.

Genetic manipulation allows simultaneous expression of green fluorescent protein (GFP) and its derivatives with a wide variety of cellular proteins in a variety of living systems. Epifluorescent and confocal laser scanning microscopy (confocal) localization of GFP constructs within living tissue and cell cultures has become routine, but correlation of light microscopy and high resolution transmission electron microscopy (TEM) on components within identical cells has been problematic. In this study, we describe an approach that specifically localizes the position of GFP/yellow fluorescent protein (YFP) constructs within the same cultured cell imaged in the confocal and transmission electron microscopes. We present a simplified method for delivering cell cultures expressing fluorescent fusion proteins into LR White embedding media, which allows excellent GFP/YFP detection and also high-resolution imaging in the TEM. Confocal images from 0.5-microm-thick sections are overlaid atop TEM images of the same cells collected from the next serial ultrathin section. The overlay is achieved in Adobe Photoshop by making the confocal image somewhat transparent, then carefully aligning features within the confocal image over the same features visible in the TEM image. The method requires no specialized specimen preparation equipment; specimens are taken from live cultures to embedding within 8 h, and confocal transmission overlay microscopy can be completed within a few hours.     

Crystal Structure and NMR of an α,δ-Peptide Foldamer Helix Shows Side-Chains are Well Placed for Bifunctional Catalysis: Application as a Minimalist Aldolase Mimic**

We report the first NMR and X-ray diffraction (XRD) structures of an unusual 13/11-helix (alternating i, i+1 {NH−O=C} and i, i+3 {C=O−H−N} H-bonds) formed by a heteromeric 1 : 1 sequence of α- and δ-amino acids, and demonstrate the application of this framework towards catalysis. Whilst intramolecular hydrogen bonds (IMHBs) are the clear driver of helix formation in this system, we also observe an apolar interaction between the ethyl residue of one δ-amino acid and the cyclohexyl group of the next δ-residue in the sequence that seems to stabilize one type of helix over another. To the best of our knowledge this type of additional stabilization leading to a specific helical preference has not been observed before. Critically, the helix type realized places the α-residue functionalities in positions proximal enough to engage in bifunctional catalysis as demonstrated in the application of our system as a minimalist aldolase mimic.     

Temperature- and pH-triggered reversible transfer of doubly responsive hairy particles between water and a hydrophobic ionic liquid

This article reports on the synthesis of thermo- and pH-sensitive polymer-brush-grafted silica particles ("hairy" particles) and the study of their phase-transfer behavior between water and a hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIM][TFSA]), in response to temperature and pH changes. The hairy particles were made by the surface-initiated atom transfer radical polymerization of methoxytri(ethylene glycol) methacrylate (TEGMMA) and tert-butyl methacrylate with a molar ratio of 100:11 in the presence of a free initiator and the subsequent removal of tert-butyl groups. The cloud points (CPs) of poly(TEGMMA-co-methacrylic acid), obtained after the treatment of the free polymer with trifluoroacetic acid, in both water and [EMIM][TFSA]-saturated water increased with the increase in pH and can be tuned over a wide temperature range. The hairy particles moved spontaneously from the aqueous phase to the [EMIM][TFSA] phase upon heating at 80 °C and returned to the aqueous layer upon cooling at 10 °C. This process can be repeated many times regardless of whether the pH of the aqueous phase is 2.99, 5.00, or 7.02. UV-vis absorbance measurements showed that the transfer temperature (T(tr)) of hairy particles from water to [EMIM][TFSA] increased with the increase in the pH of the aqueous phase. A linear relationship was observed between the T(tr) of hairy particles and the CP of the corresponding free polymer. By taking advantage of the tunability of the T(tr) of hairy particles, we demonstrated the pH-driven reversible transfer of hairy particles at a fixed temperature by changing the pH of the aqueous phase and multiple phase-transfer processes by controlling both the temperature and pH.     

Functionalism about Truth and the Metaphysics of Reduction

Functionalism about truth is the view that truth is an explanatorily significant but multiply-realizable property. According to this view the properties that realize truth vary from domain to domain, but the property of truth is a single, higher-order, domain insensitive property. We argue that this view faces a challenge similar to the one that Jaegwon Kim laid out for the multiple realization thesis. The challenge is that the higher-order property of truth is equivalent to an explanatorily idle disjunction of its realization bases. This consequence undermines the alethic functionalists’ non-deflationary ambitions. A plausible response to Kim’s argument fails to carry over to alethic functionalism on account of significant differences between alethic functionalism and psychological functionalism. Lynch’s revised view in his book Truth as One and Many (2009) fails to answer our challenge. The upshot is that, while mental functionalism may survive Kim’s argument, it mortally wounds functionalism about truth.     

The highly regiospecific synthesis and crystal structure determination of 1,1′-2,5′ substituted ring-locked ferrocenes

1,1′-Ferrocene biscarboxaldehyde (1) has been prepared and the aldehyde groups were subsequently protected with acetal groups to produce 1,1′-bisacetalferrocene (2). A ring-locked ferrocene was synthesised by further derivatisation of the cyclopentadiene rings at the 2,2′ positions with phosphine substituents to produce 2,2′-bis-(acetal)-1,1′-diphenylphosphinoferrocene (3), which was subsequently coordinated to either a nickel chloride (5) or nickel bromide (6) metal centre. The ring-locked ferrocene complexes produced 2,5′-bis-(acetal)-1,1′-diphenylphosphinoferrocene substitution patterns. The acetal protecting groups of 2,2′-bis-(acetal)-1,1′-diphenylphosphinoferrocene were removed to produce 1,1′-bis-carboxaldehyde-2,2′-diphenylphosphinoferrocene (4). The Cp rings of 1,1′-bisacetalferrocene were also further derivatised at the 2,2′ positions with a silane to produce the ring-locked 1,1′-siloxane-2,5′-bisacetalferrocenophane (7). The acetal protecting groups were removed from this to produce 1,1′-siloxane-2,5′-ferrocenophanecarboxaldehyde (8). For both the phosphine and siloxane electrophiles, the substitution on the Cp rings gives chiral products (obtained as racemic mixtures). Due to the highly regioselective nature of the reaction and diastereoselectivity in the products only C₂-symmetric compounds were observed without the presence of meso diastereoisomers. Subsequent ring-locking forced the Cp rings to rotate, leading to 1,1′-ring-locked ferrocenes with 2,5′-arrangement of the acetal groups (i.e. on opposite faces of the ferrocene unit).     

Practical synthesis of chiral vinylphosphine oxides by direct nucleophilic substitution. Stereodivergent synthesis of aminophosphine ligands

[reaction: see text] A practical synthesis of optically pure alkylphenylvinylphosphine oxides is described, utilizing a nucleophilic displacement at phosphorus to install the vinyl moiety. The products were used to prepare classes of P-stereogenic aminophosphine (PN) and aminohydroxyphosphine (PNO) ligands. Stereocontrol can be exerted at various stages of the synthesis, to provide specific combinations of chirality in the final product. The effect of the stereogenic phosphorus and match-mismatch of chiralities of PNO ligands were examined in the asymmetric ruthenium-catalyzed hydrogen transfer reduction of three aryl ketones.