Enhanced π‐Backdonation from Gold(I): Isolation of Original Carbonyl and Carbene Complexes

The specific electronic properties of bent o‐carborane diphosphine gold(I) fragments were exploited to obtain the first classical carbonyl complex of gold [(DPCb)AuCO]⁺ (ν(CO)=2143 cm^?1) and the diphenylcarbene complex [(DPCb)Au(CPh₂)]⁺, which is stabilized by the gold fragment rather than the carbene substituents. These two complexes were characterized by spectroscopic and crystallographic means. The [(DPCb)Au]⁺ fragment plays a major role in their stability, as substantiated by DFT calculations. The bending induced by the diphosphine ligand substantially enhances π‐backdonation and thereby allows the isolation of carbonyl and carbene complexes featuring significant π‐bond character.     

Synthesis of a C(sp2)-bridged Phosphine-Borane by Ionic Coupling

The vinyl carbenoid H₂C=CBr(Li) has been used as key precursor to prepare a geminal C(sp²)-bridged phosphine-borane. Starting from bromoethene, two sequences of lithiation/electrophilic trapping, with ClPiPr₂ and FBMes₂ respectively, affords iPr₂P–C(=CH₂)–BMes₂ 3 [Mes = 2,4,6-(H₃C)₃C₆H₂]. This new phosphine-borane 3 was characterized by multi-nuclear NMR and mass spectroscopy. It adopts a monomeric open structure without P→B interaction. A few crystals of a secondary product 4 were analyzed by X-ray diffraction, revealing an unusual dimeric structure.     

Analysis of Fatty Acids,Amino Acids and Volatile Profile of Apple By-Products by Gas Chromatography-Mass Spectrometry

Apple industrial by-products are a promising source of bioactive compounds with direct implications on human health. The main goal of the present work was to characterize the Jonathan and Golden Delicious by-products from their fatty acid, amino acid, and volatile aroma compounds’ point of view. GC-MS (gas chromatography-mass spectrometry) and ITEX/GC-MS methods were used for the by-products characterization. Linoleic and oleic were the main fatty acids identified in all samples, while palmitic and stearic acid were the representant of saturated ones. With respect to amino acids, from the essential group, isoleucine was the majority compound identified in JS (Jonathan skin) and GS (Golden skin) samples, lysine was the representant of JP (Jonathan pomace), and valine was mainly identified in GP (Golden pomace). A total number of 47 aroma volatile compounds were quantified in all samples, from which the esters groups ranged from 41.55–53.29%, aldehydes 29.75–43.99%, alcohols from 4.15 to 6.37%, ketones 4.14–5.72%, and the terpenes and terpenoids group reached values between 2.27% and 4.61%. Moreover, the by-products were valorized in biscuits manufacturing, highlighting their importance in enhancing the volatile aroma compounds, color, and sensorial analysis of the final baked goods.     

Evaluation of Phoma sp. Biomass as an Endophytic Fungus for Synthesis of Extracellular Gold Nanoparticles with Antibacterial and Antifungal Properties

The aim of our study was to examine the different concentrations of AuNPs as a new antimicrobial substance to control the pathogenic activity. The extracellular synthesis of AuNPs performed by using Phoma sp. as an endophytic fungus. Endophytic fungus was isolated from vascular tissue of peach trees (Prunus persica) from Baft, located in Kerman province, Iran. The UltraViolet-Visible Spectroscopy (UV–Vis spectroscopy) and Fourier transform infrared spectroscopy provided the absorbance peak at 526 nm, while the X-ray diffraction and transmission electron microscopy images released the formation of spherical AuNPs with sizes in the range of 10–100 nm. The findings of inhibition zone test of Au nanoparticles (AuNPs) showed a desirable antifungal and antibacterial activity against phytopathogens including Rhizoctonia solani AG1-IA (AG1-IA has been identified as the dominant anastomosis group) and Xanthomonas oryzae pv. oryzae. The highest inhibition level against sclerotia formation was 93% for AuNPs at a concentration of 80 μg/mL. Application of endophytic fungus biomass for synthesis of AuNPs is relatively inexpensive, single step and environmentally friendly. In vitro study of the antifungal activity of AuNPs at concentrations of 10, 20, 40 and 80 μg/mL was conducted against rice fungal pathogen R. solani to reduce sclerotia formation. The experimental data revealed that the Inhibition rate (RH) for sclerotia formation was (15, 33, 74 and 93%), respectively, for their corresponding AuNPs concentrations (10, 20, 40 and 80 μg/mL). Our findings obviously indicated that the RH strongly depend on AuNPs rates, and enhance upon an increase in AuNPs rates. The application of endophytic fungi biomass for green synthesis is our future goal.     

Towards CRISPR powered electrochemical sensing for smart diagnostics

Even though global health has been steadily improved, the global disease burden associated with communicable and non-communicable diseases extensively increased healthcare expenditure. The present COVID-19 pandemic scenario has again ascertained the importance of clinical diagnostics as a basis to make life-saving decisions. In this context, there is a need for developing next-generation integrated smart real-time responsive biosensors with high selectivity and sensitivity. The emergence of clustered regularly interspaced short palindromic repeats (CRISPR)/Cas biosensing systems has shown remarkable potential for developing next-generation biosensors. CRISPR/Cas integrated electrochemical biosensors (E-CRISPR) stands out with excellent properties. In this opinionated review, we illustrate the rapidly evolving applications for E-CRISPR-integrated detection systems towards biosensing and the future scope associated with E-CRISPR based diagnostics.     

CW laser-induced photothermal conversion and shape transformation of gold nanodogbones in hydrated chitosan films

We investigate the photothermal conversion and transformation of gold nanoparticles with an initial dogbone shape after dispersion in hydrated chitosan films, which is a representative model of biological tissue, and excitation by a CW diode laser for 1 min. Gold nanodogbones are observed to undergo a distinct modification above a sharp threshold of ~11 W cm⁻² and 110 °C. Surprisingly, the very same modification is achieved up to at least 36 W cm⁻² and 250 °C. We use an analytical model derived from Gans theory to associate the change in color of the films with the change in shape statistics of these gold nanoparticles. This model proves both convenient and dependable. We interpret the photothermal transformation as a rearrangement of particles with a dogbone shape and an aspect ratio of 4.1 into rods with an aspect ratio of 2.5, where material from the end lobes of the dogbones may relocate to the waists of the rods. In turn, additional transitions to stable gold nanospheres may exhibit fairly slower kinetics.     

Parallel or classical kinetic resolution of a planar chiral ferrocenylketone through asymmetric reductions

Racemic 1-acetyl-2-methoxymethylferrocene, (±)-1 was subjected to asymmetric reduction with two different methodologies and complementary results were obtained. When the reduction of (±)-1 was carried out in the presence of CBS-oxazaborolidine catalyst and BH₃·Me₂S as the hydrogen source, both enantiomers of the substrate were converted with comparable reaction rates and selectivities. The corresponding diastereoisomeric ferrocenylalcohols 3a and 3b were obtained in a 1:1 ratio and >90% enantiomeric excess; this reaction profile being related with a parallel kinetic resolution with high ds₁ and ds₂ diastereofacial selectivities. On the contrary, the transfer hydrogenation of (±)-1 with HCOOH/triethylamine in the presence of (R,R)-Noyori’s catalyst proceeded via classical kinetic resolution, so that the formed (?)-3b or unreacted (+)-1 could be obtained in highly enantiopure form before or beyond 50% of the substrate conversion, respectively. Alcohol 3b with an (1R_p,S)- or (1S_p,R)-configuration is not easily accessible by the diastereoselective metallation/electrophilic quenching sequence routinely applied in the synthesis of planar chiral ferrocenes. As a result, the described procedures provide a valuable access to this useful starting material for the synthesis of homochiral related derivatives.     

Structural Effects in Visible‐Light‐Responsive Metal–Organic Frameworks Incorporating ortho‐Fluoroazobenzenes

The ability to control the interplay of materials with low‐energy photons is important as visible light offers several appealing features compared to ultraviolet radiation (less damaging, more selective, predominant in the solar spectrum, possibility to increase the penetration depth). Two different metal–organic frameworks (MOFs) were synthesized from the same linker bearing all‐visible ortho‐fluoroazobenzene photoswitches as pendant groups. The MOFs exhibit different architectures that strongly influence the ability of the azobenzenes to isomerize inside the voids. The framework built with Al‐based nodes has congested 1D channels that preclude efficient isomerization. As a result, local light–heat conversion can be used to alter the CO₂ adsorption capacity of the material on exposure to green light. The second framework, built with Zr nodes, provides enough room for the photoswitches to isomerize, which leads to a unique bistable photochromic MOF that readily responds to blue and green light. The superiority of green over UV irradiation was additionally demonstrated by reflectance spectroscopy and analysis of digested samples. This material offers promising perspectives for liquid‐phase applications such as light‐controlled catalysis and adsorptive separation.