Amyloid-like Nanofibrillation of Metal-Organic Complex Arrays Ruled by Their Precisely Designed Metal Sequences.

Self-assembly of a series of dimetallic sequences constructed on a backbone with two successive tyrosine moieties (Fmoc-M1 -M2 -CO2 H) revealed that the resultant morphology is clearly dependent on the metal sequence, where Re-containing sequences such as homometallic Fmoc-Re-Re-CO2 H specifically afforded amyloid-like nanofibers. These findings further allowed to achieve the fibrillation of a longer metal sequence containing three different metals (Fmoc-Rh-Pt-Re-Re-CO2 H). Cyclic voltammetry of the fibrillated Fmoc-Re-Re-CO2 H demonstrated that the redox activity of the metal complexes in the sequence is preserved in the nanofibrous forms.

5-Hydroxymethylfurfural-Derived Boron-Dipyrromethene Immobilized on Resin Support as a Sustainable Catalyst for C-H Arylation of Heterocycles.

5-Hydroxymethylfurfural (HMF) was used as a sustainable raw material in the development of a resin-supported boron-dipyrromethene (BODIPY)-based photocatalyst. In the development of the catalyst, the brominated product (HMF-BODIPY-Br) and photocatalyst (HMF-BODIPY-Br-Suc) were isolated under a chromatography-free condition. The photocatalyst was loaded on polymeric resin by bridging alcohol functionality in HMF and amine functionality in polymeric resin using succinic anhydride. The resin-supported photocatalyst was used in light-mediated C-H arylation of various heterocycles using aryldiazonium salt. For representative examples, diazotization and photoarylation were carried out in one pot, and arylated furans were obtained in very good yields. C-H arylation was found to proceed via a photogenerated radical intermediate, and the radical intermediate was trapped by forming an adduct with TEMPO.

Simple admixture of 4-nitrobenzaldehyde and 2,4-dimethylpyrrole for efficient colorimetric sensing of copper(II) ions.

An easily accessible chemo-probe based on physical mixture of 2,4-dimethylpyrrole and 4-nitrobenzaldehyde has been developed. Based on NMR spectroscopic analysis, catalyst free formation of dipyrromethane was observed in the physical mixture of chemo-probe. The probe is utilized in effective colorimetric sensing of copper(II) ions present in environmental solutions by instantaneous appearance of red colour, even in the co-existence of various metal ions. The lowest detection limit of 2.51 µM for this chemo-probe towards copper(II) sensing is significantly lower than the WHO prescribed level (<30 µM of copper(II) ions) in potable water. The sensing mechanism is explained via rapid formation of bis(dipyrrinato)copper(II) complex, as confirmed by Jobs plot, UV-Vis spectroscopy and IR spectroscopy.

A Glutathione-Responsive Short Sequence of Metal-Organic Complex Array.

A short metal-organic complex array (MOCA) containing a sequence of RPtRRu (1Cl ) was found to exhibit unique responses to a major biothiol, glutathione (GSH). Upon binding of GSH to 1Cl , the resultant 1:1 complex (1GS ) formed nanofibrous assemblies that suggested supramolecular polymerization through the double-salt-bridge structure formation. The binding behavior of this MOCA sequence to calf thymus DNA was also dependent on GSH; a larger conformational change of DNA was observed upon binding with 1GS , relative to that with 1Cl .

C-H oxidation and chelation of a dipyrromethane mediated rapid colorimetric naked-eye Cu(ii) chemosensor.

Copper(ii) ion mediated C-H oxidation of dipyrromethanes (DPMs) to the corresponding dipyrrins followed by complexation invoked the selective sensing of copper(ii) ions in aqueous solutions. On the addition of copper, the colour of the DPM solution instantaneously changes from yellow to pink with the detection limit of 0.104 µM measured by absorption spectroscopy, whereas visible colour changes could be observed by the naked eye for concentrations as low as 3 µM.

Copper-coordination polymer-controlled Cu@N-rGO and CuO@C nanoparticle formation: reusable green catalyst for A3-coupling and nitroarene-reduction reactions.

The intriguing structural properties of coordination polymers (COPs), together with the huge variety of metal ions and organic linkers to choose from, make COPs potential precursors for fabricating carbon-encapsulated metal and metal oxide nanoparticles (NPs). Herein, we have studied the role of the COP structural assembly, prepared through making subtle changes to the ligand structure, on the formation of NPs in a carbon matrix. Cu-COPs (Cu-COP-1-Cu-COP-7), generated using different amino acid-based reduced Schiff base phenolic chelating ligands, exhibited crystalline structures with differing structural organization in the solid state. Interestingly, the calcination of Cu-COP-1 and Cu-COP-5 at 330 °C produced pure CuNPs, whereas Cu-COP-2, Cu-COP-3, Cu-COP-4 and Cu-COP-7 gave CuONPs encapsulated by carbon matrix. The calcination of Cu-COP-6 produced both CuNPs and CuONPs together in the carbon matrix. The formation of CuNPs and CuONPs in the carbon matrices was unambiguously confirmed by PXRD and XPS studies. The sizes and morphologies of the Cu/CuONPs were analyzed using HR-TEM and FE-SEM. BET studies revealed higher surface areas with small pores for the CuNPs encapsulated by carbon and lower surface areas with higher porosity for the CuONP-carbon matrix. Raman spectra revealed the formation of a nitrogen-doped reduced graphene oxide (N-rGO) carbon matrix in CuNPs-1. The N-rGO coverage and high surface area with small pores provided CuNPs-1 with good stability in strong acid (10 M H2SO4). Importantly, the fabricated N-rGO-encapsulated CuNPs-1 and carbon-covered CuONPs-4 nanocomposites were used as green catalysts in solvent-free neat A3-coupling and nitroarene-reduction reactions, respectively. The products were confirmed using 1H-NMR spectra. The recovered CuNPs-1 and CuONPs-4 catalysts, after the completion of the reactions, also showed similar catalytic activity at up to five cycles, without significant loss of catalytic activity. Thus, the present studies demonstrate the influence of Cu-COP structural assembly on the formation of Cu/CuONPs as well as the carbon matrix, and open the possibility of fabricating functional nanomaterials from the vast number of available COPs with intriguing structural motifs.

Gut microbial degradation of organophosphate insecticides-induces glucose intolerance via gluconeogenesis.

BACKGROUND: Organophosphates are the most frequently and largely applied insecticide in the world due to their biodegradable nature. Gut microbes were shown to degrade organophosphates and cause intestinal dysfunction. The diabetogenic nature of organophosphates was recently reported but the underlying molecular mechanism is unclear. We aimed to understand the role of gut microbiota in organophosphate-induced hyperglycemia and to unravel the molecular mechanism behind this process. RESULTS: Here we demonstrate a high prevalence of diabetes among people directly exposed to organophosphates in rural India (n = 3080). Correlation and linear regression analysis reveal a strong association between plasma organophosphate residues and HbA1c but no association with acetylcholine esterase was noticed. Chronic treatment of mice with organophosphate for 180 days confirms the induction of glucose intolerance with no significant change in acetylcholine esterase. Further fecal transplantation and culture transplantation experiments confirm the involvement of gut microbiota in organophosphate-induced glucose intolerance. Intestinal metatranscriptomic and host metabolomic analyses reveal that gut microbial organophosphate degradation produces short chain fatty acids like acetic acid, which induces gluconeogenesis and thereby accounts for glucose intolerance. Plasma organophosphate residues are positively correlated with fecal esterase activity and acetate level of human diabetes. CONCLUSION: Collectively, our results implicate gluconeogenesis as the key mechanism behind organophosphate-induced hyperglycemia, mediated by the organophosphate-degrading potential of gut microbiota. This study reveals the gut microbiome-mediated diabetogenic nature of organophosphates and hence that the usage of these insecticides should be reconsidered.