N-Heterocyclic Olefin-Ligated Palladium(II) Complexes as Pre-Catalysts for Buchwald–Hartwig Aminations

New N-heterocyclic olefins (NHOs) are described with functionalization on the ligand heterocyclic backbone and terminal alkylidene positions. Various Pd^II–NHO complexes have been formed and their use as pre-catalysts in Buchwald–Hartwig aminations was explored. The most active system for catalytic C−N bond formation between hindered arylamine and arylhalide substrates was accessed by combining a backbone methylated NHO with [Pd(cinnamyl)Cl]₂ in the presence of NaOtBu as a base. In these active systems evidence suggests that catalysis is mediated by colloidal palladium metal, highlighting a different coordination ability of NHOs in comparison with commonly used N-heterocyclic carbene co-ligands.     

Spirulina-based composites for 3D-printing

With material consumption increasing, the need for biodegradable materials derived from renewable resources becomes urgent, particularly in the popular field of 3D-printing. Processed natural fibers have been used as fillers for 3D-printing filaments and slurries, yet reports of utilizing pure biomass to 3D-print structures that reach mechanical properties comparable to synthetic plastics are scarce. Here, we develop and characterize slurries for extrusion-based 3D-printing comprised of unprocessed spirulina and varying amounts of cellulose fibers (CFs). Tuning the micro-morphology, density, and mechanical properties of multilayered structures is achieved by modulating the CF amount or drying method. Densified morphologies are obtained upon desiccator-drying, while oven incubation plasticizes the matrix and leads to intermediate densities. Freeze-drying creates low-density foam microstructures. The compressive strengths of the structures follow the same trend as their density. CFs are critical in the denser structures, as without the fibers, the samples do not retain their shape while drying. The compressive strength and strain to failure of the composites progressively increase with increasing filler content, ranging between 0.8 and 16 MPa and 12%–47%, respectively, at densities of 0.51–1.00 g/cm³. The measured properties are comparable to other biobased composites and commercial plastic filaments for 3D-printing.     

Automated self-organising vehicles for Barclays Cycle Hire

Self-organisation is a distributed and asynchronous process in which global pattern or behaviour emerge from local components of the system. Neither central control nor external intervention is necessary during this process. Self-organising systems are adaptive and robust, which are appealing properties from a design and engineering point of view. In this paper, we present an innovative self-organisation approach for a dynamic vehicle routing problem, the Barclay Cycle Hire truck dispatch. In addition, we introduce an evolutionary algorithm capable of automatically configuring the “self-organising trucks”. Experimental results show the evolutionary algorithm improves the overall fitness of the self-organising trucks; and we observe global emergent behaviour in the way trucks self-organise.     

A family of double-bowl pseudo metallocalix[6]arene discs

We report the synthesis and magnetic characterisation of a series of planar [M?] (M= Ni(II), Zn(II)) disc complexes [Ni?(OH)?(L?)?](NO?)? (1), [Ni?(OH)?(L?)?](NO?)?·2MeOH (2), [Ni?(OH)?(L?)?](NO?)?·3MeNO? (3), [Ni?(OH)?(L?)?](NO?)?·2MeCN (4), [Zn?(OH)?(L?)?](NO?)?·2MeOH·H?O (5) and [Zn?(OH)?(L?)?](NO?)?·3MeNO? (6) (where HL? = 2-iminomethyl-6-methoxy-phenol, HL? = 2-iminomethyl-4-bromo-6-methoxy-phenol). Each member exhibits a double-bowl pseudo metallocalix[6]arene topology whereby the individual [M?] units form molecular host cavities which are able to accommodate various guest molecules (MeCN, MeNO? and MeOH). Magnetic susceptibility measurements carried out on complexes 1 and 4 indicate weak exchange between the Ni(II) centres.     

Various coordination modes of the bis(di(o-N,N-dimethylanilinyl)phosphino)methane ligand in mononuclear and binuclear complexes of group 8 and group 9 metals

The synthesis and characterization of a series of compounds involving the bis(di(o-N,N-dimethylanilinyl)phosphino)methane (dmapm) ligand are described. The mononuclear complexes [MCl(CO)(P,N-dmapm)] (M = Rh, Ir) have a square-planar geometry in which the dmapm ligand chelates via a phosphine functionality and an adjacent amino group. The carbonyl ligand lies opposite the amine, while the chloro ligand is trans to the phosphine. The related complex [RhI(CO)(P,N-dmapm)] has also been prepared. All compounds are highly fluxional by at least three independent processes, as discussed for the rhodium-chloro species. A diiridium complex, [Ir(2)Cl2(CO)2(P,N,P',N'-dmapm)], and the closely related rhodium/iridium analogue, [RhIrCl2(CO)2(P,N,P',N'-dmapm)], have been prepared in which the metals are bridged by the diphosphine group while an amino group at each end of the diphosphine is also coordinating to each metal on opposite faces of the MIrP2 plane (M = Ir or Rh). For the Ir2 species, the carbonyl and chloro groups are again shown to be opposite the amine and phosphine functionalites, respectively. The mononuclear complex [Ru(CO)3(P,P'-dmapm)] has also been prepared. In contrast to the mononuclear species of rhodium and iridium, the dmapm group chelates the ruthenium center through both phosphorus atoms, occupying one axial and one equatorial site of Ru in a distorted trigonal bipyramidal geometry. Reaction of this Ru species with 1/2 equiv of the complexes [RhClL2]2 (L2 = COD, (C2H4)2, (CO)2) yields the unstable Rh/Ru product [RhRuCl(CO)3(P,N,P',N'-dmapm)].     

Synthesis of 1-deoxysphingosine derivatives with conformationally restricted pyrrolidinediol head groups

[structure: see text] A family of cyclic 1-deoxysphingolipid derivatives of structure 4 has been designed and synthesized, which may serve as tumorigenesis suppressors for various cancers. Compound 4 is a second-generation analogue developed from sphingosine (1), in which a hydroxyl substituent is moved from C1 to C5 and a methylene is added for conformational rigidity between the C2-nitrogen substituent and C4. The synthetic chemistry for pyrrolidine ring closure at C3-C4 features ring-closing metathesis followed by hydroboration-oxidation.     

Tuning "kappticity" of tripodal ligands

The synthesis and structural characterization of a series of tripodal tris(phosphine) ligands, containing SiMe2 elbow groups, is described. The significant steric congestion in these ligands, due to the silylmethyl substituents, is manifest both in the solid-state structures and in the solution NMR spectra of the free ligands. Variable temperature 1H{31P} NMR studies of one of the ligands, CH3C(SiMe2PEt2)3 (4b) gave an estimated barrier to rotation around the Si-Capical bonds of approximately 10.4 kcal mol(-1). Octahedral kappa2- and kappa3-molybdenum complexes of these ligands also demonstrate the impact of the additional bulk imparted by the SiMe2 substituents, and the high Lewis basicity of these phosphines, with subtle changes at the apical and phosphine substituents changing the overall coordination chemistry observed.     

Optimization of a direct analysis in real time/time-of-flight mass spectrometry method for rapid serum metabolomic fingerprinting

Metabolomic fingerprinting of bodily fluids can reveal the underlying causes of metabolic disorders associated with many diseases, and has thus been recognized as a potential tool for disease diagnosis and prognosis following therapy. Here we report a rapid approach in which direct analysis in real time (DART) coupled with time-of-flight (TOF) mass spectrometry (MS) and hybrid quadrupole TOF (Q-TOF) MS is used as a means for metabolomic fingerprinting of human serum. In this approach, serum samples are first treated to precipitate proteins, and the volatility of the remaining metabolites increased by derivatization, followed by DART MS analysis. Maximum DART MS performance was obtained by optimizing instrumental parameters such as ionizing gas temperature and flow rate for the analysis of identical aliquots of a healthy human serum samples. These variables were observed to have a significant effect on the overall mass range of the metabolites detected as well as the signal-to-noise ratios in DART mass spectra. Each DART run requires only 1.2 min, during which more than 1500 different spectral features are observed in a time-dependent fashion. A repeatability of 4.1% to 4.5% was obtained for the total ion signal using a manual sampling arm. With the appealing features of high-throughput, lack of memory effects, and simplicity, DART MS has shown potential to become an invaluable tool for metabolomic fingerprinting.