Carbon and boron nitride quantum dots as optical sensor probes for selective detection of toxic metals in drinking water: a quantum chemical prediction through structure- and morphology-dependent electronic and optical properties.

Toxic metals present in drinking water pose a serious threat to the environment and human beings when present in abundance. In this work, we investigated the sensing ability of quantum dots (pristine CQDs, boron/nitrogen/sulphur (B/N/S)-doped CQDs, and BNQDs) of various sizes and morphologies (rectangular, circular, and triangular) towards toxic metals such as arsenic (As), cobalt (Co), nickel (Ni), copper (Cu), and lead (Pb) using quantum chemical density functional theory calculations in both gas and water phases. We probed the structural, electronic, and optical properties of the QDs.

Isolable Si=B Analogue of a Vinyl Halide: A Building Block for Facile Access toward Silicon-Boron Multiple Bonded Species.

Compared to the outstanding development in the synthesis of Si-B single bonded species, borylsilanes and their application to organic synthesis, the chemistry of Si=B double bonded species, borasilenes and boratasilenes have only made little progress, first of all, due to the difficulties in accessing such double bonds. Herein we report the synthesis of the first Si=B analogue of a vinyl halide, a bromoboratasilene, via formal borylene insertion to the coordination sphere of a monoatomic Si(0) complex, using a dihaloborane as the borylene source. The treatment of bromoboratasilene toward neutral or anionic Lewis bases gives access to new boratasilenes, all of which were proved to possess significant Si=B double bond character by XRD analysis and DFT calculations.

Consecutive π-Lewis acidic metal-catalysed cyclisation/photochemical radical addition promoted by generated 2-benzopyrylium as the photoredox catalyst.

A π-Lewis acidic metal-catalysed cyclisation/photochemical radical addition sequence was developed, which utilises generated 2-benzopyrylium cation intermediates as photoredox catalysts and electrophilic substrates to form 1-isochromene derivatives in good yields in most cases. The key 2-benzopyrylium intermediates were generated through the activation of the alkyne moiety of -carbonyl alkynylbenzene derivatives by such π-Lewis acidic metal catalysts as AgNTf and Cu(NTf), and the subsequent intramolecular cyclisation and proto-demetalation using trifluoroacetic acid. Further photo-excitation of the 2-benzopyrylium intermediates facilitated single-electron transfer from a benzyltrimethylsilane derivative as a donor molecule to promote the radical addition of arylmethyl radicals to the 2-benzopyrylium intermediates.

An Isolable THF-Coordinated Dialkylgermanone.

A stable dialkylgermanone was generated by mixing a solid of the corresponding dialkylgermylene and gaseous NO. While the dialkylgermanone is marginally persistent in solution and gradually converts to its head-to-tail dimer at room temperature, the addition of THF to the dialkylgermanone provided an isolable THF-coordinated dialkylgermanone. The THF-coordinated dialkylgermanone reacts with HO, THF, and B(CF) similar to the corresponding base-free two-coordinate dialkylsilanone.

Coordination-Induced Migration of Aryl Groups in the Reactions of a Dialkylsilanone with a Series of Triarylboranes.

Although carbonyl compounds are activated by the coordination of a Lewis acid to the carbonyl oxygen atom, a similar activation process of R Si=O species remains unclear. We report herein the reactions of a silanone (1, Scheme 1) with a series of triarylboranes to afford the corresponding boroxysilanes. Experimental results and computational studies indicate that the electrophilicity of the unsaturated silicon atom is enhanced by the complexation of 1 with triarylboranes, and the subsequent aryl migration from the boron atom to the electrophilic silicon atom proceeds.

Deep-red fluorogenic cyanine dyes carrying an amino group-terminated side chain for improved RNA detection and nucleolar RNA imaging.

The introduction of an amino-group-terminated side chain into deep-red emissive benzo[,]indole-quinoline monomethine cyanine dye has led to the improved detection of RNAs as well as the imaging of nucleolar RNAs in cells.

-Hydroxysuccinimide crosslinked graphene oxide-gold nanoflower modified SPE electrode for sensitive detection of chloramphenicol antibiotic.

Here we introduce a composite material that consists of graphene oxide (GO) sheets crosslinked with -hydroxysuccinimide (NHS) and functionalized with gold nanoflowers (AuNFs). Furthermore, a screen printed electrode (SPE) modified with the introduced composite is electrochemically reduced to obtain an SPE/rGO-NHS-AuNFs electrode for sensitive and selective determination of chloramphenicol (CAP) antibiotic drug. The morphological structure of the as-prepared nanocomposite was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry, Fourier-transform infrared spectroscopy and electrochemical impedance spectroscopy.

Quinoid-Aromatic Resonance for Very Small Optical Energy Gaps in Small-Molecule Organic Semiconductors: A Naphthodithiophenedione-oligothiophene Triad System.

Organic semiconductors with very small optical energy gaps have attracted a lot of attention for near-infrared-active optoelectronic applications. Herein, we present a series of donor-acceptor-donor (D-A-D) organic semiconductors consisting of a highly electron-deficient naphtho[1,2-b:5,6-b']dithiophene-2,7-dione quinoidal acceptor and oligothiophene donors that show very small optical energy gaps of down to 0.72 eV in the solid state.

Dynamic parallel kinetic resolution of α-ferrocenyl cation initiated by chiral Brønsted acid catalyst.

The dynamic parallel kinetic resolution (DPKR) of an α-ferrocenyl cation intermediate under the influence of a chiral conjugate base of a chiral phosphoric acid catalyst has been demonstrated in an S1 type substitution reaction of a racemic ferrocenyl derivative with a nitrogen nucleophile. The present method provides efficient access to a ferrocenylethylamine derivative in a highly enantioselective manner, which is potentially useful as a key precursor of chiral ligands for metal catalysis. The mechanism of the present intriguing resolution system was elucidated by control experiments using the enantio-pure precursor of relevant α-ferrocenyl cation intermediates and the hydroamination of vinylferrocene.

Observation of liquid-liquid phase separation of ataxin-3 and quantitative evaluation of its concentration in a single droplet using Raman microscopy.

Liquid-liquid phase separation (LLPS) plays an important role in a variety of biological processes and is also associated with protein aggregation in neurodegenerative diseases. Quantification of LLPS is necessary to elucidate the mechanism of LLPS and the subsequent aggregation process. In this study, we showed that ataxin-3, which is associated with Machado-Joseph disease, exhibits LLPS in an intracellular crowding environment mimicked by biopolymers, and proposed that a single droplet formed in LLPS can be quantified using Raman microscopy in a label-free manner.

Detection of xanthine in food samples with an electrochemical biosensor based on PEDOT:PSS and functionalized gold nanoparticles.

An innovative biosensor assembly relying on glassy carbon electrodes modified with nanocomposites consisting of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a host matrix with functionalized gold nanoparticles (GCE/PEDOT:PSS-AuNPs) is presented for the selective and sensitive detection of xanthine (XA). The developed sensor was successfully applied for the quantification of XA in the presence of significant interferents like hypoxanthine (HXA) and uric acid (UA). Different spectroscopy and electron microscopy analyses were done to characterize the as-prepared nanocomposite.

Acyclic, Linear Oligo-meta-phenylenes as Multipotent Base Materials for Highly Efficient Single-layer Organic Light-emitting Devices.

Oligo-meta-phenylenes have been designed and synthesized as multipotent base materials of single-layer organic light-emitting devices. Simple molecular structures of oligo-meta-phenylenes composed of linear phenylene arrays benefited from the wealth of modern reactions available for biaryl couplings and were concisely synthesized in a series. Structure-performance relationship studies with the first seven congeners revealed key features important for the multipotent materials in single-layer devices.

Co-translational folding of α-helical proteins: structural studies of intermediate-length variants of the λ repressor.

Unlabelled: Nascent polypeptide chains fold cotranslationally, but the atomic-level details of this process remain unknown. Here, we report crystallographic, modeling, and spectroscopic studies of intermediate-length variants of the λ repressor N-terminal domain. Although the ranges of helical regions of the half-length variant were almost identical to those of the full-length protein, the relative orientations of these helices in the intermediate-length variants differed.

Constitutively overexpressing a tomato fructokinase gene (LeFRK1) in cotton (Gossypium hirsutum L. cv. Coker 312) positively affects plant vegetative growth, boll number and seed cotton yield.

Increasing fructokinase (FRK) activity in cotton (Gossypium hirsutum L.) plants may reduce fructose inhibition of sucrose synthase (Sus) and lead to improved fibre yield and quality. Cotton was transformed with a tomato (Solanum lycopersicum L.

Nef reaction with molecular oxygen in the absence of metal additives, and mechanistic insights.

A Nef reaction has been developed that is conducted under mildly basic conditions with molecular oxygen as an oxidant, without the need for metal additives. Whereas nitroalkanes are converted into ketones in good yield, nitroalkenes are transformed into α,β-unsaturated ketones in one-pot by double-bond isomerization followed by the oxygen-mediated Nef reaction. The reaction protocol is both mild and general, and tolerates acid- and base-labile functionality or protecting groups.

Individual transcriptional activity of estrogen receptors in primary breast cancer and its clinical significance.

To predict the efficacy of hormonal therapy at the individual-level, immunohistochemical methods are used to analyze expression of classical molecular biomarkers such as estrogen receptor (ER), progesterone receptor (PgR), and HER2. However, the current diagnostic standard is not perfect for the individualization of diverse cases. Therefore, establishment of more accurate diagnostics is required.

Licensing for DNA replication requires a strict sequential assembly of Cdc6 and Cdt1 onto chromatin in Xenopus egg extracts.

Replication origins are licensed for a single initiation event by the loading of Mcm2-7 proteins during late mitosis and G1. Sequential associations of origin recognition complex, Cdc6 and Mcm2-7 are essential for completion of the licensing. Although Cdt1 also binds to the chromatin when the licensing reaction takes place, whether the binding is a requirement for Cdt1 to function is unclear.