Design, synthesis and X-ray structure of protein-ligand complexes: important insight into selectivity of memapsin 2 (beta-secretase) inhibitors

Structure-based design, synthesis, and X-ray structure of protein-ligand complexes of memapsin 2 are described. The inhibitors are designed specifically to interact with S2- and S3-active site residues to provide selectivity over memapsin 1 and cathepsin D. Inhibitor 6 has exhibited exceedingly potent inhibitory activity against memapsin 2 and selectivity over memapsin 1 (>3800-fold) and cathepsin D (>2500-fold). A protein-ligand crystal structure revealed cooperative interactions in the S2- and S3-active sites of memapsin 2. These interactions may serve as an important guide to design selectivity over memapsin 1 and cathepsin D.     

High-efficiency (7.2%) flexible dye-sensitized solar cells with Ti-metal substrate for nanocrystalline-TiO2 photoanode

High-efficiency flexible dye-sensitized solar cells were fabricated with a Ti-metal foil substrate for photo anode and using a Pt-electrodeposited counter electrode on ITO/polyethylene naphthalate (ITO/PEN); these devices were characterized by incident photon-to-current efficiency (IPCE), optical transmittance and electrical impedance spectroscopy.     

Non‐Planar and Flexible Hole‐Transporting Materials from Bis‐Xanthene and Bis‐Thioxanthene Units for Perovskite Solar Cells

Two new hole‐transporting materials (HTMs), BX‐OMeTAD and BTX‐OMeTAD , based on xanthene and thioxanthene units, respectively, and bearing p‐methoxydiphenylamine peripheral groups, are presented for their use in perovskite solar cells (PSCs). The novelty of the newly designed molecules relies on the use of a single carbon‐carbon bond ‘C?C’ as a linker between the two functionalized heterocycles, which increases the flexibility of the molecule compared with the more rigid structure of the widely used HTM spiro‐OMeTAD. The new HTMs display a limited absorbance in the visible region, due to the lack of conjugation between the two molecular halves, and the chemical design used has a remarkably impact on the thermal properties when compared to spiro‐OMeTAD. BX‐OMeTAD and BTX‐OMeTAD have been tested in ([(FAPbI₃)_0.87(MAPbBr₃)_0.13]_0.92[CsPbI₃]_0.08)‐based PSC devices exhibiting power conversion efficiencies of 14.19 and 16.55 %, respectively. The efficiencies reached, although lower than those measured for spiro‐OMeTAD (19.63 %), are good enough to consider the chemical strategy used as an interesting via to design HTMs for PSCs.     

Synthesis of Amphiphilic RuII Heteroleptic Complexes Based on Benzo[1,2‐b:4,5‐b′]dithiophene: Relevance of the Half‐Sandwich Complex Intermediate and Solvent Compatibility

The detailed synthesis and characterization of four ruthenium(II) complexes [RuLL′(NCS)₂] is reported, in which L represents a 2,2′‐bipyridine ligand functionalized at the 4,4′ positions with benzo[1,2‐b:4,5‐b′]dithiophene derivatives (BDT) and L′ is 2,2′‐bipyridine‐4,4′‐dicarboxylic acid unit (dcbpy) (NCS=isothiocyanate). The reaction conditions were adapted and optimized for the preparation of these amphiphilic complexes with a strong lipophilic character. The photovoltaic performances of these complexes were tested in TiO₂ dye‐sensitized solar cell (DSSC) achieving efficiencies in the range of 3–4.5 % under simulated one sun illumination (AM1.5G).     

Antidepressant Effect of Crocin in Mice with Chronic Mild Stress

This study aimed to investigate the antidepressant property of crocin (Crocetin digentiobiose ester) using a chronic mild stress (CMS)-induced depression model in experimental mice. The tail suspension test (TST) and the sucrose preference test were used to evaluate the antidepressant effect on albino mice of either sex after three weeks of CMS. The period of immobility in the TST and percentage preference for sucrose solution were recorded. By monitoring brain malondialdehyde (MDA) level, catalase (CAT) activity, and reduced glutathione (GSH) level, the antioxidant potential was assessed. Three dosages of crocin (4.84, 9.69, and 19.38 mg/kg) were evaluated. When compared to controls, animals that received crocin administration during three periods of CMS had considerably shorter immobility times during the TST. Crocin treatment also raised the percentage preference for sucrose solution in a dose-dependent manner, bringing it to parity with the conventional antidepressant, imipramine. Animals that received a high dose of crocin had a much greater spontaneous locomotor activity. Furthermore, a high dose of crocin remarkably lowered plasma corticosterone and nitrite levels brought on by CMS. Additionally, high doses of crocin given during CMS greatly enhanced reduced glutathione levels while considerably reducing the brain’s MDA and catalase activities. In conclusion, high doses of crocin may have an antidepressant effect in an animal model through several mechanisms. However, further studies should be carried out to explore the role of neurotransmitters for their antidepressant property.     

Ca(II)-catalyzed diastereoselective formal [4+2] annulation of a 3-component solvent-free povarov reaction

Diastereoselective, three-component annulation reaction involving glyoxals, anilines and dienophiles is developed under calcium catalysis. When indene is the dienophile, the reaction gave excellent diastereoselectivity to yield tetrahydro-indenoquinolines, these were further aromatized to get indenoquinolines in one-pot. Aryl acetylenes are used as dienophiles to get 2-acyl quinolines in good yields.     

Fully Aromatic Self-Assembled Hole-Selective Layer toward Efficient Inverted Wide-Bandgap Perovskite Solar Cells with Ultraviolet Resistance

Ultraviolet-induced degradation has emerged as a critical stability concern impeding the widespread adoption of perovskite solar cells (PSCs), particularly in the context of phase-unstable wide-band gap perovskite films. This study introduces a novel approach by employing a fully aromatic carbazole-based self-assembled monolayer, denoted as (4-(3,6-dimethoxy-9H-carbazol-9-yl)phenyl)phosphonic acid (MeO-PhPACz), as a hole-selective layer (HSL) in inverted wide-band gap PSCs. Incorporating a conjugated linker plays a pivotal role in promoting the formation of a dense and highly ordered HSL on substrates, facilitating subsequent perovskite interfacial interactions, and fostering the growth of uniform perovskite films. The high-quality film could effectively suppress interfacial non-radiative recombination, improving hole extraction/transport efficiency. Through these advancements, the optimized wide-band gap PSCs, featuring a band gap of 1.68 eV, attain an impressive power conversion efficiency (PCE) of 21.10 %. Remarkably, MeO-PhPACz demonstrates inherent UV resistance and heightened UV absorption capabilities, substantially improving UV resistance for the targeted PSCs. This characteristic holds significance for the feasibility of large-scale outdoor applications.     

Hybrid Thermoelastic Stress Analysis of a Pinned Joint

Mechanical joints such as bolted or pinned connections are commonly used to fasten mechanical or structural members together. Inadequate knowledge of the stresses at the edge of the loaded holes can render it difficult to stress analyze such mechanical fasteners theoretically or numerically. Thermoelastic stress analysis (TSA) is utilized here to analyze a plane-stressed pin-loaded plate. The approach combines the recorded temperature information with an Airy stress function, plus imposes the traction-free conditions on the non-contacting edge of the hole and on the external boundaries of the plate. Individual components of stress are determined full-field as well as on the pin-plate interface. In addition to agreeing with the frequently assumed interface contact stresses in mechanical connections having zero clearance, the TSA results satisfy force equilibrium, are compatible with residual markings on the contacted surfaces of the pin and the hole, and correlate with FEM predictions. Significant advantages of TSA here include neither needing to know the elastic modulus nor to differentiate the recorded information.     

Highly Efficient Perovskite Solar Cells Employing an Easily Attainable Bifluorenylidene‐Based Hole‐Transporting Material

The 4,4′‐dimethoxydiphenylamine‐substituted 9,9′‐bifluorenylidene ( KR216 ) hole transporting material has been synthesized using a straightforward two‐step procedure from commercially available and inexpensive starting reagents, mimicking the synthetically challenging 9,9′‐spirobifluorene moiety of the well‐studied spiro‐OMeTAD. A power conversion efficiency of 17.8 % has been reached employing a novel HTM in a perovskite solar cells.