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Abstract: Human African trypanosomiasis is causing thousands of deaths every year in the rural areas of Africa. In this manuscript we describe the optimization of a family of phtalazinone derivatives. Phosphodiesterases have emerged as attractive molecular targets for a novel treatment for a variety of neglected parasitic diseases. Compound 1 resulted to be a potent TbrPDEB1 inhibitor with interesting activity against T. brucei in a phenotypic screen. Derivative 1 was studied in an acute in vivo mouse disease model but unfortunately showed no efficacy due to low metabolic stability. We report structural modifications to achieve compounds with an improved metabolic stability while maintaining high potency against TbrPDEB1 and T. brucei. Compound 14, presented a good microsomal stability in mouse and human microsomes and provides a good starting point for future efforts.

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Abstract: Carbon dots on photoactive semiconductor nanomaterials have represented an effective strategy for enhancing their photoelectrochemical (PEC) activity. By carefully designing and manipulating carbon dots/support composite, a high photocurrent could be obtained. Currently, there is not much fundamental understanding of how the interaction between such materials can facilitate the reaction process. This hinders the wide applicability in PEC devices. To address this need of improving the fundamental understanding of carbon dots/semiconductor nanocomposite, we have taken the TiO2 case as a model semiconductor system with nitrogen-doped carbon dots (NCDs). We present here with in-depth investigation of the structural hybridization and energy transitions in the NCDs/TiO2 photoelectrode via high-resolution scanning transmission microscopy (HR-STEM), electron energy loss spectroscopy (EELS), UV-Vis absorption, electrochemical impedance spectroscopy (EIS), Mott-Schottky (M-S), time-correlated single photon counting (TCSPC) and ultra-violet photoelectron spectroscopy (UPS), which shed some light on the charge transfer process at the carbon dots and TiO2 interface. We show that N doping in carbon dots can effectively prolong the carrier lifetime, and the hybridisation of NCDs and TiO2 is able not only to extend TiO2 light response into the visible range but also to form heterojunction at the NCDs/TiO2 interface with properly aligned band structure that allows a spatial separation of the charges. This work is arguably the first to report the direct probing of the band positions of carbon dots-TiO2 nanoparticle composite in a PEC system for understanding the energy transfer mechanism, demonstrating the favourable role of NCDs in the photocurrent response of TiO2 for water oxidation process. This study reveals the importance of combining structural, photophysical and electrochemical experiments to develop a comprehensive understanding of the charge injection/electronic communication between the carbon dots and their current collectors or catalyst supports.

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Abstract: Metal chalcogenide compounds have attracted interest as materials for next generation semiconductors, catalysts, and device architectures. Hybrid compounds containing both a metal chalcogenide architecture and a supporting organic lattice combine the interesting structural and electronic properties of the material class with a configurable hybrid component that can lead to a wide range of tailorable materials. However, many of the methods available for preparing inorganic coordination polymers in this class require specialized solution-phase chemical preparations that are incompatible with solid-state fabrication techniques. Here we prepare metal-organic chalcogenolates (MOChas) of copper, indium, lead, and tin from benzeneselenol or benzenethiol directly from the organochalcogen and corresponding metal in a tube furnace at a relatively modest temperature. Scanning electron microscopy and X-ray diffraction confirmed conversion of the precursors to crystalline MOChas. X-ray photoelectron spectroscopy was used to investigate the chemical bonding for each of the materials and provides insight into the elemental composition of the synthesized compounds. This straightforward approach for preparing crystalline hybrid materials may be generalizable for the preparation of a wide variety of coordination compounds and complexes in form factors useful for subsequent development of device architectures.

Open Access

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Abstract: The carrier type of Sb2Se3 was evaluated for both thin films and bulk crystals via a range of complementary techniques. X-ray photoelectron spectroscopy (XPS), hot-probe, hall effect and surface photo-voltage spectroscopy showed material synthesized from Sb2Se3 granulate mate-rial to be n-type with chlorine identified as an unintentional n-type dopant via secondary ion mass spectrometry analysis. The validity of chlorine as a dopant was con-firmed by synthesis of intrinsic crystals from metallic precursors and subsequent n-type doping by the addition of MgCl2. Chlorine was also shown to be a substitutional n-type shallow dopant by density functional theory calculations. TiO2/Sb2Se3 n-n isotype heterojunction solar cells of 7.3% efficiency based are demonstrated with band alignment analyzed via XPS.

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Abstract: An experimental setup to perform high-pressure resonant X-ray scattering (RXS) experiments at low temperature on I16 at Diamond Light Source is presented. The setup consists of a membrane-driven diamond anvil cell, a panoramic dome and an optical system that allows pressure to be measured in situ using the ruby fluorescence method. The membrane cell, inspired by the Merrill–Bassett design, presents an asymmetric layout in order to operate in a back-scattering geometry, with a panoramic aperture of 100° in the top and a bottom half dedicated to the regulation and measurement of pressure. It is specially designed to be mounted on the cold finger of a 4 K closed-cycle cryostat and actuated at low-temperature by pumping helium into the gas membrane. The main parts of the body are machined from a CuBe alloy (BERYLCO 25) and, when assembled, it presents an approximate height of 20–21 mm and fits into a 57 mm diameter. This system allows different materials to be probed using RXS in a range of temperatures between 30 and 300 K and has been tested up to 20 GPa using anvils with a culet diameter of 500 µm under quasi-cryogenic conditions. Detailed descriptions of different parts of the setup, operation and the developed methodology are provided here, along with some preliminary experimental results.