Organometallic assembling of chitosan‐Iron oxide nanoparticles with their antifungal evaluation against Rhizopus oryzae

The ever‐increasing resistance of plant microbes towards fungicides and bactericides has been causing serious threat to plant production in recent years. For the development of an effective antifungal agent, we introduce a novel hydrothermal protocol for synthesis of chitosan iron oxide nanoparticles (CH‐Fe₂O₃ NPs) using acetate buffer of low pH 5.0 for intermolecular interaction of Fe₂O₃ NPs and CH. The composite structure and elemental elucidation were carried out by using X‐ray power diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X‐ray (EDX), Transmission Electron Microscopy (TEM), Fourier Transformed Infrared Spectroscopy (FTIR) and Ultraviolet Visible Absorption Spectroscopy (UV–vis spectroscopy). Additionally, antifungal activity was evaluated both In vitro and In vivo against Rhizopus oryzae which is causing fruit rot disease of strawberry. We compared different concentrations (0.25%, 0.50%, 075% and 1%) of CH‐Fe₂O₃ NPs and 50% synthetic fungicide (Matalyxal Mancozab) to figure out suitable concentration for application in the field. XRD analysis showed a high crystalline nature of the NPs with average size of 52 nanometer (nm). SEM images revealed spherical shape with size range of 50–70 nm, whereas, TEM also revealed spherical shape, size ranging from 0 nm to 80 nm. EDX and FTIR results revealed presence of CH on surface of Fe₂O₃ NPs. The band gap measurement showed peak 317–318 nm for bare Fe₂O₃ NPs and CH‐Fe₂O₃ NPs respectively. Antifungal activity in both In vitro and In vivo significantly increased with increase in concentration. The overall results revealed high synergetic antifungal potential of organometallic CH‐Fe₂O₃ NPs against Rhizopus oryzae and suggest the use of CH‐Fe₂O₃ NPs against other Phyto‐pathological diseases due to biodegradable nature.     

Synthesis and Single Crystal X-ray Studies of 3-(3,5-Bis(trifluoromethyl)phenyl) Quinoline and 3-(4-Fluoro-3-methylphenyl) Quinoline

The title compounds 3-(3,5-bis(trifluoromethyl)phenyl)quinoline(1) and 3-(4-fluoro-3-methylphenyl)quinoline(2) were synthesized through Suzuki-Miyaura Cross coupling reaction of 3-bromoquinoloine with aryl boronic acids.The title compounds were characterized by single-crystal X-ray diffraction,1H NMR,13C NMR,EI-MS,elemental analysis and IR.The crystals of 3-(3,5-bis(trifluoromethyl)phenyl)quinoline(C17H9F6N,Mr = 341.25) belongs to the monoclinic system,space group P21n,a = 12.3072(13),b = 4.9378(6),c = 24.493(2) ,V = 1473.1(3) 3,Z = 4,Dc = 1.539 Mg m-3,λ = 0.71073 ,μ = 0.144 mm-1,F(000) = 688,the final R = 0.0715 and wR = 0.1873 for 1875 observed reflections with I 2σ(I) and the crystal of 3-(4-fluoro-3-methylphenyl)quinoline(C16H12FN,Mr = 237.27) belongs to the orthorhombic system,space group Pca21,a = 23.794(2),b = 3.9094(3),c = 25.669(2) ,V = 2387.7(4) 3,Z = 8,Dc = 1.320 Mg m-3,λ = 0.71073 ,μ = 0.088 mm-1,F(000) = 992,the final R = 0.0534 and wR = 0.1188 for 2270 observed reflections with I 2σ(I).     

Biological entities as chemical reactors for synthesis of nanomaterials: Progress,challenges and future perspective

Synthesis of nanomaterials is being gained extensive attention in the fields of chemistry, applied physics, catalysis, drug delivery and the most important in diagnosis and therapeutic applications. Recently, many reports have been published on physical and chemical synthesis of magnetic as well as metallic nanoparticles (NPs) with viable surface functionalization, but still there is a dire need of such strategies that can combine synthetic methodology with stable surface modification found in nature. Synthesis of NPs via biological methods is the possible way to solve these barriers. However, systematized summary and outlooks of NPs synthesis via biological entities with various influencing factors e.g. temperature, pH, concentration of reactants and reaction time has rarely been reported. This review will present the distinct advantages of biological synthesis of NPs over physical and chemical methods. It will also highlight the recent progress on synthesis of NPs via various biological systems i.e. plant, fungus, bacteria, and yeast. Furthermore, it will explain various factors that control the size, shape, and morphology of these NPs. Finally, it would present the future perspectives of green chemistry for the development of nano-science and -biotechnology.     

Herbicidal activity of pure compound isolated from rhizosphere inhabiting Aspergillus flavus

In the quest for bioactive natural products of fungal origin, Aspergillus flavus was isolated from rhizosphere of Mentha piperita using Potato Dextrose Agar (PDA) and Czapec Yeast Broth (CYB) nutrient media for metabolites production. In total, three different metabolites were purified using HPLC/LCMS and the structures were established using 500 Varian NMR experiments. Further the isolated metabolites in different concentrations (10, 100, 1000 μg/mL) were tested for herbicidal activity using Completely Randomized design (CRD) against the seeds of Silybum marianum and Avena fatua which are major threats to wheat crop in Pakistan. Among the isolated metabolites, one compound was found active against the test weed species whose activity is reported in the present work. The chemical name of the compound is 2-(1, 4-dihydroxybutan-2-yl)-1, 3-dihydroxy-6, 8-dimethoxyanthracene-9, 10(4aH, 9aH)-dione with mass of 388. Results showed that all seeds germinated in control treatment; however, with the metabolite treated, the growth was retarded to different levels in all parts of the weeds. At a dose of 1000 μg/mL of the pure compound, 100% seeds of S. marianum and 60% seeds of A. fatua were inhibited. Interestingly, the pure compound exhibited less inhibition of 10% towards the seeds of common wheat (Triticum aestivum).     

Copolymerization of Carbonyl Sulfide and Propylene Oxide via a Heterogeneous Prussian Blue Analogue Catalyst with High Productivity and Selectivity

This study demonstrates the superiority of a stable and well-defined heterogeneous cobalt hexacyanocobaltate (Co₃[Co(CN)₆]₂), a typical cobalt Prussian Blue Analogue (CoCo-PBA) that catalyzes the copolymerization of carbonyl sulfide (COS) and propylene oxide (PO) to produce poly(propylene monothiocarbonate)s (PPMTC). The number-average molecular weights of the PPMTC were 66.4 to 139.4 kg/mol, with a polydispersity of 2.0–3.9. The catalyst productivity reached 1040 g polymer/g catalyst (12.0 h). The oxygen-sulfur exchange reaction (O/S ER), which would generate random thiocarbonate and carbonate units, was effectively suppressed, and thus the selectivity of the monothiocarbonate over carbonate linkages was up to >99%. It was shown that no cyclic thiocarbonate byproduct was produced during the heterogeneous catalysis of COS/PO copolymerization using CoCo-PBA as the catalyst. The content of monothiocarbonate and ether units in the copolymer chain could be regulated by tuning the feeding amount of COS.     

Nonlinear optical characteristics of monolayer MoSe2

In this study, we utilized picosecond pulses from an Nd:YAG laser to investigate the nonlinear optical characteristics of monolayer MoSe₂. Two‐step growth involving the selenization of pulsed‐laser‐deposited MoO₃ film was employed to yield the MoSe₂ monolayer on a SiO₂/Si substrate. Raman scattering, photoluminescence (PL) spectroscopy, and atomic force microscopy verified the high optical quality of the monolayer. The second‐order susceptibility χ⁽²⁾ was calculated to be ～50 pm V^?1 at the second harmonic wavelength ～810 nm, which is near the optical gap of the monolayer. Interestingly, our wavelength‐dependent second harmonic scan can identify the bound excitonic states including negatively charged excitons much more efficiently, compared with the PL method at room temperature. Additionally, the MoSe₂ monolayer exhibits a strong laser‐induced damage threshold ～16 GW cm^?2 under picosecond‐pulse excitation_. Our findings suggest that monolayer MoSe₂ can be considered as a promising candidate for high‐power, thin‐film‐based nonlinear optical devices and applications.     

Photosensitized Generation of Singlet Oxygen from (Substituted Bipyridine)ruthenium(II) Complexes

Photophysical properties in dilute MeCN solution are reported for seven Ru^II complexes containing two 2,2′‐bipyridine (bpy) ligands and different third ligands, six of which contain a variety of 4,4′‐carboxamide‐disubstituted 2,2′‐bipyridines, for one complex containing no 2,2′‐bipyridine, but 2 of these different ligands, for three multinuclear Ru^II complexes containing 2 or 4 [Ru(bpy)₂] moieties and also coordinated via 4,4′‐carboxamide‐disubstituted 2,2′‐bipyridine ligands, and for the complex [(Ru(bpy)₂(L)]²⁺ where L is N,N′‐([2,2′‐bipyridine]‐4,4′‐diyl)bis[3‐methoxypropanamide]. Absorption maxima are red‐shifted with respect to [Ru(bpy)₃]²⁺, as are phosphorescence maxima which vary from 622 to 656 nm. The lifetimes of the lowest excited triplet metal‐to‐ligand charge transfer states ³MLCT in de‐aerated MeCN are equal to or longer than for [Ru(bpy)₃]²⁺ and vary considerably, i.e., from 0.86 to 1.71 μs. Rate constants k_q for quenching by O₂ of the ³MLCT states were measured and found to be well below diffusion‐controlled, ranging from 1.2 to 2.0⋅10⁹ dm³ mol⁻¹ s⁻¹. The efficiencies f of singlet‐oxygen formation during oxygen quenching of these ³MLCT states are relatively high, namely 0.53 – 0.89. The product of k_q and f gives the net rate constant k for quenching due to energy transfer to produce singlet oxygen, and k_q−k equals k, the net rate constant for quenching due to energy dissipation of the excited ³MLCT states without energy transfer. The quenching rate constants were both found to correlate with ΔG^CT, the free‐energy change for charge transfer from the excited Ru complex to oxygen, and the relative and absolute values of these rate constants are discussed.     

3 β ‐Acetoxy‐5 α ‐cholestan‐6‐one: A Steroid

The crystal and molecular structure of 3 β ‐Acetoxy‐5 α ‐cholestan‐6‐one has been determined by X‐ray crystallographic techniques. The compound crystallizes in the space group P2₁ with cell parameters : a = 13.060(3), b=6.299(2), c=17.152(6)Å; β =96.47(3)o, V = 1402.02ų, Z = 2, R = 0.072 for 1921 observed reflections. The six‐membered rings (A, B and C) exist in the chair conformations while the five‐membered ring‐d assumes half‐chair. All rings of the steroid skeleton are trans connected.     

Crystallographic Investigations of 3β‐acetoxy‐5α‐cholestan‐6‐one‐semicarbazone ‐ A Steroid

The crystal structure of 3b‐acetoxy‐5a‐cholestan‐6‐one‐semicarbazone (C₃₀H₅₁O₃N₃) has been determined by X‐ray diffraction methods. It crystallizes in the orthorhombic space group P2₁2₁2₁ with cell parameters a = 11.641(1), b = 16.552(1) c = 31.181(4) Å and Z = 8. The structure has been refined to an R‐value of 0.050 for 4407 observed reflections. Two molecules in the asymmetric unit have been observed. In both the crystallographically independent molecules, all the three six‐membered rings (A, B and C ) of steroid nucleus exist in chair conformation, while the five‐ membered ring D exists in 13β distorted‐envelope in molecule‐I and 13β, 14α half‐chair conformation in molecule‐II. Three intermolecular N‐H … O hydrogen bonds have been observed.