Search Results (13)

The development of green, efficient, and reusable photocatalysts is important for pollution degradation. In recent years, Cs₃Bi₂I₉ has been shown to be an effective photocatalyst. However, the rapid recombination of electrons and holes weakens the photocatalytic activity. In this work, the photogenerated electron transfer rate was promoted by ZIF-8 compositing with Cs₃Bi₂I₉, which effectively improved the pollutant degradation. After 50 min of visible light irradiation, Cs₃Bi₂I₉/ZIF-8 removed up to 98.2% of methylene blue (MB), which was 4.15 times higher than that of Cs₃Bi₂I₉ alone. In addition, the Cs₃Bi₂I₉/ZIF-8 composite still exhibited high photocatalytic activity after three cycling experiments. Our research offers a simple and efficient method for enhancing the photocatalytic activity of lead-free halide perovskites. Full article

In recent years, halide perovskite materials have become widely used in solar cells, photovoltaics, and LEDs, as well as photocatalysis. Lead-free perovskite Cs₃Bi₂I₉ has been demonstrated as an effective photocatalyst; however, the fast recombination of the photogenerated carriers hinders further improvements of its photocatalytic activity. In this work, Ti₃C₂ was composited with Cs₃Bi₂I₉ to promote the transfer and separation of photogenerated carriers, and thus the pollutant degradation efficiency was effectively improved. The visible-light photocatalytic reduction of Cs₃Bi₂I₉/Ti₃C₂ on rhodamine B (RhB), methylene blue (MB), and malachite green (MG) was as high as 97.3%, 96%, and 98.8%, respectively, improvements of almost 31.2%, 37.8%, and 37.2% compared to that of sole Cs₃Bi₂I₉. Our study provides a simple way to enhance the photocatalytic activity of lead-free halide perovskites. Full article

The aqueous instability of halide perovskite seriously hinders its direct application in water as a potential photocatalyst. Here, we prepared a new type of polyvinylpyrrolidone (PVP) passivated δ-CsPbI₃ (δ-CsPbI₃@PVP) microcrystal by a facile method. This material can be uniformly dispersed in water and stably maintain its crystal structure for a long time, breaking through the bottleneck of halide perovskite photocatalysis in water. Under visible light, δ-CsPbI₃@PVP can almost completely photodegrade organic dyes (including Rhodamine B, methylene blue, and crystal violet) in only 20 min. The efficient photocatalytic activity is attributed to the enhanced visible light absorption arising from PbI₂ defects in δ-CsPbI₃@PVP and the intrinsic low photoluminescence quantum yield of δ-CsPbI₃, which induces efficient light absorption and photocatalytic activity. We highlight δ-CsPbI₃@PVP as an effective aqueous photocatalyst, and this study provides new insights into how to exploit the potential of halide perovskite in photocatalytic applications. Full article

Candidiasis is very common and complicated to treat in some cases due to increased resistance to antifungals. Antimicrobial photodynamic therapy (aPDT) is a promising alternative treatment. It is based on the principle that light of a specific wavelength activates a photosensitizer molecule resulting in the generation of reactive oxygen species that are able to kill pathogens. The aim here is the in vitro photoinactivation of three strains of Candida spp., Candida albicans ATCC 10231, Candida parapsilosis ATCC 22019 and Candida krusei ATCC 6258, using aPDT with different sources of irradiation and the photosensitizer methylene blue (MB), alone or in combination with chlorhexidine (CHX). Irradiation was carried out at a fluence of 18 J/cm² with a light-emitting diode (LED) lamp emitting in red (625 nm) or a white metal halide lamp (WMH) that emits at broad-spectrum white light (420–700 nm). After the photodynamic treatment, the antimicrobial effect is evaluated by counting colony forming units (CFU). MB-aPDT produces a 6 log₁₀ reduction in the number of CFU/100 μL of Candida spp., and the combination with CHX enhances the effect of photoinactivation (effect achieved with lower concentration of MB). Both lamps have similar efficiencies, but the WMH lamp is slightly more efficient. This work opens the doors to a possible clinical application of the combination for resistant or persistent forms of Candida infections. Full article

Bacteria belonging to the genus Aminobacter are metabolically versatile organisms thriving in both natural and anthropized terrestrial environments. To date, the taxonomy of this genus is poorly defined due to the unavailability of the genomic sequence of A. anthyllidis LMG 26462^T and the presence of unclassified Aminobacter strains. Here, we determined the genome sequence of A. anthyllidis LMG 26462^T and performed phylogenomic, average nucleotide identity and digital DNA-DNA hybridization analyses of 17 members of genus Aminobacter. Our results indicate that 16S rRNA-based phylogeny does not provide sufficient species-level discrimination, since most of the unclassified Aminobacter strains belong to valid Aminobacter species or are putative new species. Since some members of the genus Aminobacter can utilize certain C1 compounds, such as methylamines and methyl halides, a comparative genomic analysis was performed to characterize the genetic basis of some degradative/assimilative pathways in the whole genus. Our findings suggest that all Aminobacter species are heterotrophic methylotrophs able to generate the methylene tetrahydrofolate intermediate through multiple oxidative pathways of C1 compounds and convey it in the serine cycle. Moreover, all Aminobacter species carry genes implicated in the degradation of phosphonates via the C-P lyase pathway, whereas only A. anthyllidis LMG 26462^T contains a symbiosis island implicated in nodulation and nitrogen fixation. Full article

The regioselective synthesis of novel functionalized condensed organochalcogen compounds by chalcogenocyclofunctionalization reactions based on chalcogen halides and the natural products thymol and carvacrol has been developed. The reactions of selenium dibromide with allyl thymol and allyl carvacrol proceeded in methylene chloride at room temperature in the presence of NaHCO₃ affording bis[(7-isopropyl-4-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] and bis[(4-isopropyl-7-methyl-2,3-dihydro-1-benzofuran-2-yl)methyl] selenides in 90–92% yield. Similar sulfides were obtained in 70–72% yields by the reaction of sulfur dichloride in chloroform under reflux. Trihalotellanes containing the same organic moieties were synthesized from allyl thymol, allyl carvacrol and tellurium tetrachloride or tetrabromide in quantitative yields. Corresponding functionalized ditellurides were prepared in 91–92% yields by the reduction of the trichlorotellanes with sodium metabisulfite in two-phase solvent system. The comparison of reactivity of sulfur, selenium and tellurium halides in chalcogenocyclofunctionalization and distinguishing features of each reaction were discussed. Full article

4-(4-Aminophenyl)-1-thia-4-azaspiro[4.5]decan-3-one 1 was prepared and allowed to react with nitrogen nucleophiles to give the corresponding hydrazones 2–4. Further, compound 1 underwent diazotization and afforded the parallel hydrazono derivative 5; moreover, compound 1 refluxed with active methylene derivatives yielded the corresponding aminospirothiazolo pyridine–carbonitrile derivative 6 and spirothiazolopyridinone–carbonitrile derivative 7. Condensation of spirothiazolidine 1 with 4-chlorobenzaldehyde gave the corresponding spiro arylidiene derivative 8, which was utilized as a component of Micheal addition to react with excess of nitrogen nucleophiles to yield novel ring frameworks 4-(3′-(4-chlorophenyl)–spiro [cyclohexane-1,5′-pyrazolo[3,4-d]thiazol]-6′(1′H)-yl)aniline (9) and 4-(3′-(4-chlorophenyl)-6′H- spiro[cyclohexane-1,5′-thiazolo[5,4-d]isoxazol]-6′-yl)aniline (10). Finally, when spirothiazolo pyridinone–carbonitrile derivative 7 sodium salt generated in situ was reacted with different alkyl halides, it produced the corresponding N-derivatives 12–16. Three compounds, 6, 14, and 16, showed high significantly anticancer activities compared with Doxorubicin® (positive control) against human breast carcinoma (MCF-7) and human liver carcinoma (HepG-2) cell lines. On the other hand, compounds 6 and 9 showed higher therapeutic indices for both of alpha-amylase inhibitor and alpha-glucosidase inhibitor than the other tested compounds compared with the antidiabetic Acarbose (positive control). Full article

The preparation of unprecedented 6,12-disubstituted methanodibenzo[b,f][1,5]dioxocins from pyrrolidine catalyzed self-condensation of 2′-hydroxyacetophenones is herein described. This method provides easy access to this highly bridged complex core, resulting in construction of two C–O and two C–C bonds, a methylene bridge and two quaternary centers in a single step. The intricate methanodibenzo[b,f][1,5]dioxocin compounds were obtained in up to moderate yields after optimization of the reaction conditions concerning solvent, reaction times and the use of additives. Several halide substituted methanodibenzo[b,f][1,5]dioxocins could be prepared from correspondent 2′-hydroxyacetophenones. Full article

The intermolecular interaction in difluoromethane, dichloromethane, dibromomethane, and diiodomethane dimers has been investigated using high level quantum chemical methods. The potential energy curve of intermolecular interaction along the C⋯C bond distance obtained using the coupled-cluster theory with singles, doubles, and perturbative triples excitations CCSD(T) were compared with values given by the same method, but applying the local (LCCSD(T)) and the explicitly correlated (CCSD(T)-F12) approximations. The accuracy of other theoretical methods—Hartree–Fock (HF), second order Møller–Plesset perturbation (MP2), and dispersion corrected DFT theory—were also presented. In the case of MP2 level, the canonical and the local-correlation cases combined with the density-fitting technique (DF-LMP2)theories were considered, while for the dispersion-corrected DFT, the empirically-corrected BLYP-D and the M06-2Xexchange-correlation functionals were applied. In all cases, the aug-cc-pVTZ basis set was used, and the results were corrected for the basis set superposition error (BSSE) using the counterpoise method. For each molecular system, several dimer geometries were found, and their mutual orientations were compared with the nearest neighbor orientations obtained in recent neutron scattering studies. The nature of the intermolecular interaction energy was discussed. Full article

Synthesis and characterization of new thiadiazoles, bisthiadiazoles from the reaction of mono- and di-hydrazonoyl halides with various hydrazinecarbodithioate derivatives were studied. Treatment of hydrazonoyl halides with 2,5-dihydrazinyl-1,3,4-thiadiazole afforded new bistriazines containing thiadiazole; we also examined the reaction of 2,5-dihydrazinyl-1,3,4-thiadiazole with active methylene compounds to afford new pyrazoles containing thiadiazole compounds. The new synthesized compounds were identified by elemental analysis and various spectral data (Fourier transform infrared spectroscopy, mass spectrometry, 1H and 13C nuclear magnetic resonance). Full article

A number of interesting heterocycles were prepared through interaction of the intermediate 3-amino-8-hydroxy-4-imino-6-methyl-5-phenyl-4,5-dihydro-3H-chromeno-[2,3-d]pyrimidine (1) and reagents such as hydrazonyl halides 2 to furnish triazine derivatives 4a–l. Reaction of 1 with phenacyl bromide afforded compound 5. Moreover, the title compound 1 was subjected to condensation with active methylene compounds (ethyl acetoacetate and ethyl benzoylacetate) to give triazipinones 8a,b. The condensation with aromatic aldehydes afforded either the triazole derivatives 10a–d or Schiff base 11. In addition, the behaviour of compound 1 towards activated unsaturated compounds namely dimethyl acetylene dicarboxylate and ethoxymethylenemalonitrile was studied and it was found to furnish the triazine 13 and triazepine derivative 15, respectively. Combination of title compound 1 with chlorinated active methylene compounds delivered the triazine derivatives 18a–c. Reaction of 1 with chloroacetonitrile furnished compound 20. The structures of the products were elucidated based on their microanalyses and spectroscopic data. Finally, the antitumor activity of the new compounds 4a and 8a against human breast cell MCF-7 line and liver carcinoma cell line HepG2 were recorded. Full article

A novel series of 7,7-diphenyl-1,2-dihydroimidazo[2,1-c][1,2,4]triazin-6(7H)-one 6a–h, were easily prepared via reactions of novel 2-hydrazinyl-4,4-diphenyl-1H-imidazol-5(4H)-one (2) with hydrazonoyl halides 3a–h. In addition, we also examined the reaction of compound 2 with commercially available active methylene compounds to afford new pyrazoles containing an imidazolone moiety, expected to be biologically active. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, ¹H-NMR and mass spectral data. The antifungal and antibacterial activities of the newly synthesized compounds were evaluated. Full article

Enaminone 1 was reacted with hydrazonoyl halides 2a-d to yield 3,4-disubstituted pyrazoles 6a-d. Coupling with arenediazonium chlorides afforded the 2-(arylhydrazono)-3-(1-naphthalenyl)-3-oxopropionaldehydes 13a-c. Compounds 13 could be utilized for the synthesis of a variety of arylpyrazoles, arylazolopyrimidines, and pyridazinones via reaction with hydrazines, aminoazoles, and active methylene derivatives, respectively. A comparative study of aforementioned reactions was carried out with chitosan as a basic ecofriendly catalyst under conventional heating as well as under pressurized microwave irradiation conditions. Full article