Inhibition of the urea-urease reaction by the components of the zeolite imidazole frameworks-8 and the formation of urease-zinc-imidazole hybrid compound

In the past decade, much effort has been devoted to using chemical clock-type reactions in material design and driving the self-assembly of various building blocks. Urea-urease enzymatic reaction has chemical pH clock behavior in an unbuffered medium, in which the induction time and the final pH can be programmed by the concentrations of the reagents. The urea-urease reaction can offer a new alternative in material synthesis, where the pH and its course in time are crucial factors in the synthesis. However, before using it in any synthesis method, it is important to investigate the possible effects of the reagents on the enzymatic reaction. Here we investigate the effect of the reagents of the zeolite imidazole framework-8 (zinc ions and 2-methylimidazole) on the urea-urease reaction. We have chosen the zeolite imidazole framework-8 because its formation serves as a model reaction for the formation of other metal–organic frameworks. We found that, besides the inhibition effect of the zinc ions which is well-known in the literature, 2-methylimidazole inhibits the enzymatic reaction as well. In addition to the observed inhibition effect, we report the formation of a hybrid urease-zinc-2-methylimidazole hybrid material. To support the inhibition effect, we developed a kinetic model which reproduced qualitatively the experimentally observed kinetic curves.

Synthesis, crystal structure, vibrational study, optical properties and Hirshfeld surface analysis of a new centrosymmetric hybrid material, bis(3-aminoquinolium) tetrachloridocobaltate (II)

Background: The title compound (C9H9N2)2[CoCl4] belongs to a large compound’s family, enriching the new technologies materials range. Objective: The chemical synthesis and the crystal structure are the main goals to reach in this study. In addition, the optoelectronic properties and the material behavior are investigated. Methods: The single-crystal diffraction, photoluminescence, infrared spectroscopy, and several computations are applied in this work to characterize the studied compound. Results: At room temperature, the synthesized (C9H9N2)2[CoCl4] crystallizes in the monoclinic C2/c space group. The cohesion of the 0-D crystal structure is ensured by hydrogen interactions and confirmed by the Hirshfeld surface analysis. Conclusion: A new hybrid compound is discovered and added to the structural database ICDD. The structural study, the spectroscopic investigations, particularly the photoluminescence, indicate that the newly obtained material is promising for interesting application as a non-linear optical material.

Tuning the magnetic properties of NiPS3 through organic-ion intercalation

Atomically thin van der Waals magnetic crystals are characterized by tunable magnetic properties related to their low dimensionality. While electrostatic gating has been used to tailor their magnetic response, chemical approaches like intercalation remain largely unexplored. Here, we demonstrate the manipulation of the magnetism in the van der Waals antiferromagnet NiPS3 through the intercalation of different organic cations, inserted using an engineered two-step process. First, the electrochemical intercalation of tetrabutylammonium cations (TBA+) results in a ferrimagnetic hybrid compound displaying a transition temperature of 78 K, and characterized by a hysteretic behavior with finite remanence and coercivity. Then, TBA+ cations are replaced by cobaltocenium via an ion-exchange process, yielding a ferrimagnetic phase with higher transition temperature (98 K) and higher remanent magnetization. Importantly, we demonstrate that the intercalation and cation exchange processes can be carried out in bulk crystals and few-layer flakes, opening the way to the integration of intercalated magnetic materials in devices.

Excited State Proton Transfers in Hybrid Compound Based on Indoline Spiropyran of the Coumarin Type and Azomethinocoumarin in the Presence of Metal Ions

Spectral-luminescence properties of a hybrid compound containing a coumarin-type spiropyran and an azomethinocoumarin fragment in toluene-acetonitrile solution in the presence of Li+, Ca2+, Zn2+ and Mg2+ ions are reported. Two excited state proton transfers can occur in the hybrid compound—the transfer of a proton from the OH group of the 7-hydroxy coumarin tautomer to the N atom of the C=N bond of the azomethine fragment leading to green ESIPT fluorescence with a maximum at 540 nm and from the OH group of the 7-hydroxy coumarin tautomer to the carbonyl group of the pyrone chromophore, which leads to the formation of the 2-hydroxyl-tautomer T of coumarin with blue fluorescence with a maximum at 475 nm. Dependence of these excited state proton transfers on the metal nature and irradiation with an external UV source is discussed.

Studies of Potency and Efficacy of an Optimized Artemisinin-Quinoline Hybrid against Multiple Stages of the Plasmodium Life Cycle

A recently developed artemisinin-quinoline hybrid, named 163A, has been shown to display potent activity against the asexual blood stage of Plasmodium, the malaria parasite. In this study, we determined its in vitro cytotoxicity to mammalian cells, its potency to suppress P. berghei hepatic infection and to decrease the viability of P. falciparum gametocytes, in addition to determining whether the drug exhibits efficacy of a P. berghei infection in mice. This hybrid compound has a low level of cytotoxicity to mammalian cells and, conversely, a high level of selectivity. It is potent in the prevention of hepatic stage development as well as in killing gametocytes, denoting a potential blockage of malaria transmission. The hybrid presents a potent inhibitory activity for beta-hematin crystal formation, in which subsequent assays revealed that its endoperoxide component undergoes bioactivation by reductive reaction with ferrous heme towards the formation of heme-drug adducts; in parallel, the 7-chloroquinoline component has binding affinity for ferric hemin. Both structural components of the hybrid co-operate to enhance the inhibition of beta-hematin, and this bitopic ligand property is essential for arresting the growth of asexual blood parasites. We demonstrated the in vivo efficacy of the hybrid as an erythrocytic schizonticide agent in comparison to a chloroquine/artemisinin combination therapy. Collectively, the findings suggest that the bitopic property of the hybrid is highly operative on heme detoxification suppression, and this provides compelling evidence for explaining the action of the hybrid on the asexual blood stage. For sporozoite and gametocyte stages, the hybrid conserves the potency typically observed for endoperoxide drugs, and this is possibly achieved due to the redox chemistry of endoperoxide components with ferrous heme.