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.     

2,4‐Di­hydroxy‐1,3‐bis­(methoxy­carbonyl­methoxy)­calix­[4]­arene and 1,3‐bis­(ethoxy­carbonyl­methoxy)‐2,4‐di­hydroxy­calix­[4]­arene chloro­form solvate

The two title calix­[4]­arene compounds, C₃₄H₃₂O₈, (I), and C₃₆H₃₆O₈·CH₃Cl, (II), respectively, which differ only in the size of the alkyl function on the pendant ester group, are compared. Compound (I) forms a novel supramolecular array, whilst (II) fails to do so due to accommodating a chloro­form guest molecule in the lower‐rim cavity.     

A tilted ferroelectric smectic phase emerging from monomer/polymer mixtures

Mixtures of a fluorescent liquid crystalline side chain polyacrylate and its corresponding ferroelectric monomer were studied by optical microscopy, DSC, X-ray and electro-optic techniques. For some of these mixtures we surprisingly found the emergence of the ferroelectric S*_x phase, which is not exhibited by the single components. The crystalline phase of the monomer is completely suppressed by polymer concentrations above 25 per cent. The 50 per cent polymer-containing mixture shows a clear eutectic effect for the tilted phases and allows electro-optic switching close to room temperature, more than 40 K below the melting point of the monomer.     

A coloured ferroelectric side chain polymer

Coloured ferroelectric liquid-crystalline side chain copolymers containing 5 per cent and 15 per cent of an azo dye were synthesized and characterized by DSC, GPC and optical microscopy. Order parameters, S, of the azo compound exceeding 0·8 were measured in the frozen smectic phase for the 5 per cent copolymer. The copolymers exhibit fast electrooptic switching in the range of a few hundred microseconds to milliseconds in the S_c* phase. Both linear (i.e. electroclinic-like) and ferroelectric switching have been observed. Tilt angles of ∼19° and spontaneous polarization of ∼300nC cm^-2 have been recorded in the S_c* phase.     

Cycloheptatriene-rhodium(I) acetylacetonate

Cycloheptatriene-rhodium(I) acetylacetonate has been prepared; the d₇ analogue undergoes deuterium scrambling at 60°.     

Bi−P Bond Homolysis as a Route to Reduced Bismuth Compounds and Reversible Activation of P4

Bismuth diphenylphosphanides Bi(NON^R)(PPh₂) (NON^R=[O(SiMe₂NR)₂], R=tBu, 2,6‐iPr₂C₆H₃, Aryl) undergo facile decomposition via single‐electron processes to form reduced Bi and P species. The corresponding derivatives Bi(NON^R)(PCy₂) are stable. Reaction of the isolated Bi^II radical ^.Bi(NON^Ar) with white phosphorus (P₄) proceeds with the reversible and selective activation of a single P?P bond to afford the bimetallic μ,η^1:1‐bicyclo[1.1.0]tetraphosphabutane compound.     

A rapid and reliable method for Pb isotopic analysis of peat and lichens by laser ablation-quadrupole-inductively coupled plasma-mass spectrometry for biomonitoring and sample screening

An analytical protocol for rapid and reliable laser ablation-quadrupole (LA-Q)- and multi-collector (MC-) inductively coupled plasma-mass spectrometry (ICP-MS) analysis of Pb isotope ratios (²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb) in peats and lichens is developed. This technique is applicable to source tracing atmospheric Pb deposition in biomonitoring studies and sample screening. Reference materials and environmental samples were dry ashed and pressed into pellets for introduction by laser ablation. No binder was used to reduce contamination. LA-MC-ICP-MS internal and external precisions were <1.1% and <0.3%, respectively, on both ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb ratios. LA-Q-ICP-MS internal precisions on ²⁰⁷Pb/²⁰⁶Pb and ²⁰⁸Pb/²⁰⁶Pb ratios were lower with values for the different sample sets <14.3% while external precisions were <2.9%. The level of external precision acquired in this study is high enough to distinguish between most modern Pb sources. LA-MC-ICP-MS measurements differed from thermal ionisation mass spectrometry (TIMS) values by 1% or less while the accuracy obtained using LA-Q-ICP-MS compared to solution MC-ICP-MS was 3.1% or better using a run bracketing (RB) mass bias correction method. Sample heterogeneity and detector switching when measuring ²⁰⁸Pb by Q-ICP-MS are identified as sources of reduced analytical performance.     

Switching-On Fluorescence by Copper (II) and Basic Anions: A Case Study with a Pyrene-Functionalized Squaramide

The new symmetric acyclic N,N’-bis(1-pyrenyl) squaramide (H₂L) functionalized with the pyrene moiety as a fluorogenic fragment has been designed and its ability to selectively detect specific anions and metals investigated. H₂L selectively binds Cl⁻ both in solution (DMSO 0.5% H₂O and MeCN) and in the solid state, and allows to selectively detect Cu²⁺ in MeCN with the formation of a 2:1 metal-receptor complex, with a green intense emission appreciable by naked eye under the UV lamp. The H₂L copper complex preserves its emission properties in the presence of Cl⁻. The addition of basic anions (OH⁻, CN⁻, and F⁻) up to 10 equivalents caused the deprotonation of the squaramide NHs and a dramatic change of the emission properties of the H₂L copper complex.     

Formation and Structural Characterization of Metal Complexes derived from Thiosalicylic Acid

The formation and structural aspects of some metal complexes of thiosalicylic acid (TSA) were studied. The μ‐bridging tetra‐coordinated Ru complex, [Ru(C₆H₄(CO₂)(μ‐S)(H₂O)]₂ ( 1 ) was formed by hydrothermal reaction of TSA with RuCl₃. The complexes [M(dtdb)(phen)(H₂O)]_n ( 2 – 4 ) (M = Zn^II, Co^II, Ni^II, dtdb = 2,2′‐dithiodibenzoate anion, phen = 1,10‐phenanthroline) were obtained by the slow diffusion technique and the in situ S–S bond formation was confirmed by elemental, spectral and X‐ray analysis. Reaction of TSA with CuCl₂ and 2,2′‐bipyridine (bipy) under the slow diffusion technique yielded the dimer [Cu(tdb)(bipy)] ( 5 ) (tdb = thiodibenzoic acid), where the in situ generation of 2,2′‐thiodibenzoic acid was observed.