Microwave assisted synthesis,docking and antimalarial evaluation of hybrid PABA-substituted 1,3,5-triazine derivatives

A series of novel PABA-substituted 1,3,5-triazine derivatives were developed via microwave assisted synthesis and subsequently tested for antimalarial activity against chloroquine sensitive 3D7 strain of Plasmodium falciparum using chloroquine as standard. Antimalarial screening result showed that synthesized compounds exhibited IC₅₀ in the range of 4.46 to 79.72 μg mL⁻¹. Among the tested compounds, 4c and 4f showed significant antimalarial activity with low binding energies (BE) -172.32 and 160.41 kcal mol⁻¹ via interacting with Arg122 through the involvement of COOH of the phenyl linked to 1,3,5-triazine. In conclusion, these core scaffolds can be used for future antimalarial drug development.     

Physical–chemical characterization studies of ketoprofen for orodispersible tablets

The objective of this work was to investigate the thermal, morphological, spectroscopic and cytotoxicity of hydroxyapatite–wollastonite powders obtained via sol–gel synthesis and of biocomposites chitosan–hydroxyapatite–wollastonite. A mixture of wollastonite, calcium nitrate tetrahydrate and ammonium dihydrogen phosphate with a ratio of 1:2:1.2 or 2:2:1.2, respectively, was produced following drying and heat treatment where the final composite was macerated. These powders were added to a chitosan solution where it was further dried and neutralized. The ceramic loads were used in various ratios. The materials were characterized by TG, DSC, DRX, MEV, FTIR and cytotoxicity. Based on the studied properties, it can be said that the sol–gel process proved to be effective in obtaining hydroxyapatite–wollastonite powders. By TG, it was verified that the thermal stability of the powders increased when a greater percentage of wollastonite was used. For biocomposites with higher percentages of load, there was increase in thermal stability, probably attributed to the higher compaction of the biocomposites when compared to the pure. By DSC, there was a tendency of displacement of the endothermic and exothermic peaks, suggesting that the biocomposite with higher load has greater capacity of retention and interaction stronger with molecules of water, but also has greater thermal stability. The samples present biomaterial potential with prospects of endodontic use, which showed cell viability in L929 fibroblast cell culture above 70.00%.     

Density functional study on the structure and stability of positive iron rare-gas complexes, FeXn (X=Ar, Xe; n=1–6)

The structures and atomization energies of positively charged complexes of iron with argon and xenon, Fe⁺X_n (X=Ar, Xe; n=1–6) are investigated by density functional theory calculations. We explain the special stability of some of these complexes (“magic numbers”) – that has been observed in previous laser ablation and multi-photon ionization experiments – and predict their geometries.     

Structure of radicals from X-irradiated guanine derivatives. 2. An experimental and computational study of 9-ethylguanine single crystals

An EPR (electron paramagnetic resonance) and ENDOR (electron-nuclear double resonance) study of 9-ethylguanine crystals X-irradiated at 10 K detected evidence for three radical forms. Radical R1, characterized by three proton and two nitrogen hyperfine interactions, was identified as the product of net hydrogenation at N7 of the guanine unit. R1, which evidently formed by protonation of the primary electron addition product, exhibited an unusually distorted structure leading to net positive isotropic components of the alpha-coupling to the hydrogen attached to C8 of the guanine unit. Radical R2, characterized by two nitrogen and three proton hyperfine couplings, was identified as the primary electron loss product, *G+. Distinguishing between *G+ and its N1-deprotonated product is difficult because their couplings are so similar, and density functional theory (DFT) calculations were indispensable for doing so. The results for R2 provide the most complete ENDOR characterization of *G+ presented so far. Radical R3 exhibited a narrow EPR pattern but could not be identified. The identification of radicals R1 and R2 was supported by DFT calculations using the B3LYP/6-311+G(2df,p)//6-31+G(d,p) approach. Radical R4, detected after irradiation of the crystals at room temperature, was identified as the well-known product of net hydrogenation at C8 of the guanine component. Spectra from the room temperature irradiation contained evidence for R5, an additional radical that could not be identified. Radical concentrations from the low temperature irradiation were estimated as follows: R1, 20%; R2, 65%; R3, 15%.     

Chemical Tailoring Assisted non-TADF to TADF Switching in Carbazole-Benzophenone Emitter – An In-silico Investigation

Organic light-emitting diodes (OLEDs) have become one of the most popular lighting technologies since they offer several advantages over conventional devices. In carbazole-benzophenone (CzBP) OLED devices, the polymeric form of the compound is previously reported to be Thermally Activated Delayed Fluorescence (TADF)-active (ΔE_ST ≈0.12 eV), while the monomer ( CzBP ) (ΔE_ST≈0.39 eV) does not. The present study examines the effect of chemical tailoring on the optical and photophysical properties of CzBP using DFT and TDDFT methods. The introduction of a single −NO₂ group or di-substitution (−NO₂, −COOH or −CN) in the selected LUMO region of the reference CzBP monomer significantly reduces ΔE_ST≈0.01 eV, projecting these systems as potential TADF-active emitters. Furthermore, the chemical modification of CzBP -LUMO alters the two-step TADF mechanism (T₁→T₂→S₁) in CzBP (E_S₁>E_T2>E_T₁) to the Direct Singlet Harvesting (T₁→S₁) mechanism (E_T2>E_S₁>E_T₁), which has recently been identified in the fourth-generation OLED materials.     

ChemInform Abstract: Synthesis of Novel Zerumbone Derivatives via Regioselective Palladium Catalyzed Decarboxylative Coupling Reaction: A New Class of α‐Glucosidase Inhibitors.

A strategy for the synthesis of novel zerumbone derivatives via a regioselective palladium catalyzed decarboxylative coupling reaction using arene carboxylic acids is described.     

Mulberry Leaves (Morus Rubra)-Derived Blue-Emissive Carbon Dots Fed to Silkworms to Produce Augmented Silk Applicable for the Ratiometric Detection of Dopamine

Silk fibers (SF) reeled from silkworms are constituted by natural proteins, and their characteristic structural features render them applicable as materials for textiles and packaging. Modification of SF with functional materials can facilitate their applications in additional areas. In this work, the preparation of functional SF embedded with carbon dots (CD) is reported through the direct feeding of a CD-modified diet to silkworms. Fluorescent and mechanically robust SF are obtained from silkworms (Bombyx mori) that are fed on CDs synthesized from the Morus rubra variant of mulberry leaves (MB-CDs). MB-CDs are introduced to silkworms from the third instar by spraying them on the silkworm feed, the mulberry leaves. MB-CDs are synthesized hydrothermally without adding surface passivating agents and are observed to have a quantum yield of 22%. With sizes of ≈4 nm, MB-CDs exhibited blue fluorescence, and they can be used as efficient fluorophores to detect Dopamine (DA) up to the limit of 4.39 nM. The nanostructures and physical characteristics of SF weren't altered when the SF are infused with MB-CDs. Also, a novel DA sensing application based on fluorescence with the MB-CD incorporated SF is demonstrated.