Synthesis, Mesomorphism, Photophysics, and Device Properties of Liquid-Crystalline Pincer Complexes of Gold(III) Containing Semiperfluorinated Chains.

Gold(III) complexes of -coordinating 2,6-diphenylpyridine pincer ligands with arylacetylide co-ligands are known triplet emitters at room temperature. We have reported previously that by functionalizing both the pincer ligand and the phenylacetylene with alkoxy chains, liquid crystallinity may be induced, with the complexes showing columnar mesophases. We now report new derivatives in which the phenylacetylene incorporates one, two, or three 1,1,2,2-perfluoroalkyl chains.

N-Terminal speciation for native chemical ligation.

Native chemical ligation (NCL) enables the chemical synthesis of peptides via reactions between N-terminal thiolates and C-terminal thioesters under mild, aqueous conditions at pH 7-8. Here we demonstrate quantitatively how thiol speciation at N-terminal cysteines and analogues varies significantly depending upon structure at typical pH values used in NCL.

21st century developments in the understanding and control of molecular solids.

The first decades of the 21st Century have seen very significant advances in the understanding, prediction and control of molecular solids. Advances in crystallization techniques, polymorphism, co-crystals, co-amorphous materials, crystal engineering and instrumentation have all contributed to what is now an extremely active field. There are huge fundamental implications as well as applications particularly in the pharmaceutical, agrochemicals and energetic materials sectors.

Synthesis, Mesomorphism, and Photophysics of 2,5-Bis(dodecyloxyphenyl)pyridine Complexes of Platinum(IV).

It has been shown for the first time that the Pt complex cis-[Pt(N^C-tolpy) Cl ] (tolpy=2-(4-tolyl)pyridinyl) can be prepared in a one-pot reaction from K [PtCl ], although analogous complexes containing 2,5-bis(4-dodecyloxyphenyl)pyridine (=HL) could be prepared using existing routes. The resulting complexes cis-[Pt(N^C-L) Cl ] are liquid crystals and small-angle X-ray scattering suggests formation of a lamellar mesophase. Surprisingly, heating [Pt(κ -N^C-L) Cl(κ -N^C-LH)] also leads to a mesomorphic compound, which results from thermally induced oxidation to cis-[Pt(N^C-L) Cl ] and what is presumed to be another geometric isomer of the same formula.

Repurposing as a strategy for the discovery of new anti-leishmanials: the-state-of-the-art.

Leishmaniasis is a vector-borne neglected tropical disease caused by protozoan parasites of the genus Leishmania for which there is a paucity of effective viable non-toxic drugs. There are 1·3 million new cases each year causing considerable socio-economic hardship, best measured in 2·4 million disability adjusted life years, with greatest impact on the poorest communities, which means that desperately needed new antileishmanial treatments have to be both affordable and accessible. Established medicines with cheaper and faster development times may hold the cure for this neglected tropical disease.

Pharmaceutical cocrystals, salts and multicomponent systems; intermolecular interactions and property based design.

As small molecule drugs become harder to develop and less cost effective for patient use, efficient strategies for their property improvement become increasingly important to global health initiatives. Improvements in the physical properties of Active Pharmaceutical Ingredients (APIs), without changes in the covalent chemistry, have long been possible through the application of binary component solids. This was first achieved through the use of pharmaceutical salts, within the last 10-15years with cocrystals and more recently coamorphous systems have also been consciously applied to this problem.

Metal 'turn-off', anion 'turn-on' gelation cascade in pyridinylmethyl ureas.

Pyridinylmethyl ureas form strong gels in aromatic solvents. The gels are weakened or destroyed by addition of transition metal ions but gelation is recovered by adding bromide anions giving rise to a gel-sol-gel chemically triggered cascade.

Trimeric cyclamers: solution aggregation and high Z' crystals based on guest structure and basicity.

Ureidosalicylic acid forms remarkable trimeric cyclamer-like crystal structures with either three or six independent molecules in the asymmetric unit as a result of the excess of hydrogen bond donors and guest inclusion within the centre of the cyclamer. The structures persist in solution in hydrogen bond acceptor solvents suggesting a role for solution pre-association in forming high Z' structures.

Pharmaceutical crystallization with nanocellulose organogels.

Carboxylated nanocellulose forms organogels at 0.3 wt% in the presence of a cationic surfactant. The resulting gels can be used as novel crystallization media for pharmaceutical solid form control, resulting in isolation a new sulfapyridine solvate, morphology modification and crystallization of an octadecylammonium salt of sulfamethoxazole.

Stabilisation of an amorphous form of ROY through a predicted co-former interaction.

The highly polymorphic compound ROY, notorious for the colour of its crystals, was the subject of an optimised high-throughput ultrasound-based co-crystal screen. This screen involved a computational pre-screen which highlighted an interaction between ROY and the potential co-former pyrogallol. We have shown that the presence of pyrogallol stabilises the amorphous form of ROY, highlighting the potential for future prediction of co-amorphous behaviours.

Self-assembly and mesophase formation in a non-ionic chromonic liquid crystal system: insights from dissipative particle dynamics simulations.

Results are presented from a dissipative particle dynamics (DPD) simulation of a model non-ionic chromonic system, TP6EO2M, composed of a poly(ethylene glycol) functionalised aromatic (triphenylene) core. The simulations demonstrate self-assembly of chromonic molecules to form single molecule stacks in solution at low concentrations, the formation of a nematic mesophase at higher concentrations and a columnar phase in the more concentrated regime. The simulation model used allows very large system sizes, of many thousands of particles, to be studied.

In-situ cryocrystallization of 1,2-dimethyl-3-nitrobenzene and 2,4-dimethyl-1-nitrobenzene.

The crystal structures of 1,2-dimethyl-3-nitrobenzene, C8H9NO2, and 2,4-dimethyl-1-nitrobenzene, C8H9NO2, which are liquids at room temperature, have been obtained through in-situ cryocrystallization. Weak C-H..

Yeast as a potential vehicle for neglected tropical disease drug discovery.

High-throughput screening (HTS) efforts for neglected tropical disease (NTD) drug discovery have recently received increased attention because several initiatives have begun to attempt to reduce the deficit in new and clinically acceptable therapies for this spectrum of infectious diseases. HTS primarily uses two basic approaches, cell-based and in vitro target-directed screening. Both of these approaches have problems; for example, cell-based screening does not reveal the target or targets that are hit, whereas in vitro methodologies lack a cellular context.

The utility of yeast as a tool for cell-based, target-directed high-throughput screening.

Many Neglected Tropical Diseases (NTDs) have recently been subject of increased focus, particularly with relation to high-throughput screening (HTS) initiatives. These vital endeavours largely rely of two approaches, in vitro target-directed screening using biochemical assays or cell-based screening which takes no account of the target or targets being hit. Despite their successes both of these approaches have limitations; for example, the production of soluble protein and a lack of cellular context or the problems and expense of parasite cell culture.

Sphingolipid synthesis and scavenging in the intracellular apicomplexan parasite, Toxoplasma gondii.

Sphingolipids are essential components of eukaryotic cell membranes, particularly the plasma membrane, and are involved in a diverse array of signal transduction pathways. Mammals produce sphingomyelin (SM) as the primary complex sphingolipid via the well characterised SM synthase. In contrast yeast, plants and some protozoa utilise an evolutionarily related inositol phosphorylceramide (IPC) synthase to synthesise IPC.

Proton transfer reactions of triazol-3-ylidenes: kinetic acidities and carbon acid pKa values for twenty triazolium salts in aqueous solution.

Second-order rate constants have been determined for deuteroxide ion-catalyzed exchange of the C(3)-proton for deuterium, k(DO) (M(-1) s(-1)), of a series of 20 triazolium salts in aqueous solution at 25 °C and ionic strength I = 1.0 (KCl). Evidence is presented that the rate constant for the reverse protonation of the triazol-3-ylidenes by solvent water is close to that for dielectric relaxation of solvent (10(11) s(-1)).

Body dissatisfaction and disordered eating attitudes in 7- to 11-year-old girls: testing a sociocultural model.

We examined the sociocultural model of body dissatisfaction and disordered eating attitude development in young girls for the first time. According to the model, internalizing an unrealistically thin ideal body increases the risk of disordered eating via body dissatisfaction, dietary restraint, and depression. Girls aged 7-11 years (N=127) completed measures of thin-ideal internalization, body dissatisfaction, dieting, depression, and disordered eating attitudes.

Total internal reflection Raman spectroscopy.

Total internal reflection (TIR) Raman spectroscopy is an experimentally straightforward, surface-sensitive technique for obtaining chemically specific spectroscopic information from a region within approximately 100-200 nm of a surface. While TIR Raman spectroscopy has long been overshadowed by surface-enhanced Raman scattering, with modern instrumentation TIR Raman spectra can be acquired from sub-nm thick films in only a few seconds. In this review, we describe the physical basis of TIR Raman spectroscopy and illustrate the performance of the technique in the diverse fields of surfactant adsorption, liquid crystals, lubrication, polymer films and biological interfaces, including both macroscopic structures such as the surfaces of leaves, and microscopic structures such as lipid bilayers.

Surfactant adsorption kinetics by total internal reflection Raman spectroscopy. 1. Pure surfactants on silica.

Total internal reflection Raman spectroscopy provides a sensitive probe of surfactants adsorbed at an interface. A visible laser passes through a silica hemisphere and reflects off the flat silica-water interface. An evanescent wave probes ∼100 nm of solution below the surface, and the Raman scattering from this region provides chemically specific information on the molecules present.

Surfactant adsorption kinetics by total internal reflection Raman spectroscopy. 2. CTAB and Triton X-100 mixtures on silica.

Total internal reflection (TIR) Raman spectroscopy has been used to study the kinetics of adsorption, desorption, and displacement of mixed surfactant systems at the silica-water interface. The limited penetration depth of the evanescent wave provides surface sensitivity while the chemical sensitivity of Raman scattering permits the determination of the time-dependent composition of the adsorbed film. Principal component analysis is used to deconvolute the Raman spectra with a time resolution of 2 s and a precision of 5% of a monolayer.

pKas of the conjugate acids of N-heterocyclic carbenes in water.

pK(a) values of 19.8-28.2 are reported for the conjugate acids of a large series of NHCs in water.

Bond catastrophes in rhodium complexes: experimental charge-density studies of [Rh(C7H8)(P(t)Bu3)Cl] and [Rh(C7H8)(PCy3)Cl].

Rhodium complexes have potential uses in both catalysis and promoting the cleavage of C-C bonds. In order to further our understanding of these species and their potential applications, it is vital to obtain insight into the bonding within the species, particularly the Rh-C interactions, and to this end experimental charge-density studies have been undertaken on the title complexes. High-resolution single-crystal datasets to sin θ/λ = 1.

Antimicrobial peptides for leishmaniasis.

Leishmaniasis is a parasitic disease that is endemic to American, African, Asian and southern European countries. More than 350 million individuals in 88 countries are at risk of infection from this neglected tropical disease. No effective vaccinations are available against leishmaniasis, and control of the disease relies entirely on toxic drug treatments, some of which were developed as early as the 1940s.

Statistical temperature molecular dynamics simulations applied to phase transitions in liquid crystalline systems.

The recently developed statistical temperature molecular dynamics (STMD) method [Kim et al., Phys. Rev.

Molecular order in a chromonic liquid crystal: a molecular simulation study of the anionic azo dye sunset yellow.

We have carried out a detailed atomic simulation study of molecular order within a chromonic liquid crystalline material (sunset yellow) in aqueous solution. Self-assembly occurs in dilute solutions to form stacked aggregates, which show a preference for head-to-tail stacking and antiparallel dipole order. This feature is independent of solution concentration and aggregate size.