SARS‐CoV‐2 main protease (Mpro) is an enzyme for viral replication and an target for antiviral drugs due to its evolutionary conservation across coronaviruses and the absence of closely related human homologs. Tetrahydroisoquinoline (THIQ) derivatives represent a structurally diverse class of nitrogen‐containing heterocycles with proven versatility in medicinal chemistry. Thirty newly synthesized compounds, including THIQ‐based molecules and structurally related amine analogs, were evaluated for their inhibitory activity against Mpro. Six compounds exhibited significant inhibitory potency (IC 50 < 50 μM). Compound 3ia, containing nitro and para ‐bromophenyl groups, was the most active candidate with an IC 50 of 6.61 μM. Fluorescence quenching and thermodynamic analyses revealed that the interactions between active compounds and Mpro occurred predominantly via static quenching. Results demonstrated that compound binding induced conformational changes in Mpro. Differential scanning fluorimetry (DSF) showed that all active compounds increased the thermal stability of Mpro, and microscale thermophoresis (MST) confirmed high‐affinity binding ( K d = 25.92 μM for 3ia ). Molecular docking further revealed that the THIQ scaffold of 3ia inserts into the Mpro substrate‐binding pocket, forming π–sulfur interactions with the catalytic Cys145. This work confirms THIQ as a promising lead scaffold for Mpro inhibitors and supports the structure‐based design of improved anticoronavirus candidates.
The synthesis and structural characterization of two metal-organic frameworks constructed from tetratopic polycarboxylate ligands are described. The acid forms of the ligands, 5,5 '-(9,10-dioxo-9,10-dihydroanthracene-1,5-diyl)diisophthalic acid (H2(1,5-AQ-DIPA)) and 5,5 '-(9,10-dioxo-9,10-dihydroanthracene-1,4-diyl)diisophthalic acid (H2(1,4-AQ-DIPA)) are based on a polycyclic anthraquinone core, not previously considered for the crystallization of coordination polymers, and synthesis routes to both are reported. Subsequent solvothermal synthesis between each acid form of the ligand and copper(II) nitrate in a DMF/water mixture yields distinct frameworks whose structures are determined using single-crystal X-ray diffraction: MIL-179 and MIL-180. Both frameworks contain the copper paddle-wheel dimer {Cu2(COO)4}, but the distinct molecular structures of the two ligands lead to different framework topologies. MIL-179 has the nbo topology, while MIL-180 possesses the ssa topology. The three-dimensionally connected structures are compared with other frameworks reported in the literature for the same secondary building units linked by other tetratopic linkers, and isoreticular relationships are identified.
We report ZnFe2O4 (ZFO) thin film photoanodes with controlled (111), (311), and (110) orientations grown by pulsed laser deposition (PLD). Orientation control was achieved via growth of conductive Nb-doped SnO2 buffer layers on differently oriented sapphire single-crystal substrates. Inductively coupled plasma optical emission spectroscopy (ICP-OES) shows similar bulk cation compositions, whereas X-ray photoelectron spectroscopy reveals pronounced orientation-dependent surface iron enrichment, with the (111) surface being considerably more Fe-rich than the (311) and (110) surfaces. Thus, out-of-plane orientation has little effect on the bulk composition but strongly influences the extent of surface zinc depletion during PLD growth. Conductive atomic force microscopy shows that this surface chemistry correlates with distinct electronic behavior: the (311) and (110) films conduct under both bias polarities, whereas the (111) film is strongly rectifying. Consistent with this, linear sweep voltammetry measurements under simulated solar illumination show that the (111) film, despite its more negative flat-band potential, exhibits the most positive water-oxidation onset, while the (311) and (110) films show onsets approximate to 70 mV more negative. These findings reveal a correlation between crystallographic orientation, surface stoichiometry, and interfacial electronic behavior in ZFO, highlighting surface cation composition as an important factor in complex-oxide photoanode performance.
Development of high-performance and low-cost electrocatalysts is essential for commercialization of alkaline water electrolysis. The fabrication of nickel-copper (NiCu) thin films is reported with a Ni:Cu atomic ratio of 3:1, directly deposited onto nickel foam using sputtering. The as-prepared films are used as dual-activity self-supported electrodes for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline media. The 270 nm thick film (NiCu4) was the nominally best-performing HER electrode, although the differences between film thicknesses were within experimental variability. Initially, the electrode requires an overpotential of 215 mV to deliver a current density of -50 mA cm-2. Remarkably, after 72 h of stability testing, the overpotential significantly decreased to 136 mV. Operando electrochemical impedance spectroscopy and Raman spectroscopy were used to investigate the HER mechanism and dynamic surface state changes on the NiCu4 electrode. This improvement originates from surface structural changes of the Ni Cu alloy under HER conditions. For OER, NiCu4 and Ni on Ni foam exhibit equal OER performance in alkaline media, demonstrating a low onset potential of approximate to 335 mV and an overpotential of 370 mV at 10 mA cm-2. These results showcase sputtering as a robust, reproducible, waste-free method for the development of electrocatalysts.
The photocatalytic cycloaddition of CO2 with epoxides offers a sustainable approach for CO2 fixation and value-added carbonate synthesis, yet developing well-defined photocatalysts that integrate narrow bandgap, abundant active sites, and strong CO2 enrichment ability remains challenging. Herein, a new conjugated metal-organic framework (MOF) using hexahydroxytriphenylene as linkers and hexanuclear [Nd6(mu 6-CO3)O12]8- as inorganic nodes is constructed. The obtained FDM-154 possesses interconnected 13.6 & Aring; pores and a surface area of 532 m2 g-1, enabling efficient CO2 enrichment (28.5 cm3 g-1). Furthermore, FDM-154 features a narrow optical bandgap of 1.12 eV, which facilitates photogenerated charge separation under visible light. Additionally, the MOF backbone is decorated with dense photoactive organic linkers and Nd3+ Lewis acid sites that serve as active centers to efficiently activate both CO2 and epoxide substrates during the photocatalytic process. FDM-154 photocatalyst achieves high yield for CO2 cycloaddition with epichlorohydrin under mild conditions, resulting from the combined effect of its suitable band structure, accessible active sites, and pore confinement effect.
