Rh(III)-Catalyzed One-Step Synthesis of ortho-Alkynylated Perylene Imide Dyes: Optical and Electrochemical Properties of New Derivatives

A one-step Rh-catalyzed site-selective ortho-C−H alkynylation of perylene as well as naphthalene mono- and diimides is reported. A single step regioselective access to ortho-C−H alkynylated derivatives of these ryleneimides not only increases the step economy of the ortho-functionalization on these dyes but also provides a quick access route towards highly functionalized dyes that have potential optoelectronic applications. Increased solubility of tetra(triisopropylsilyl)acetylenyl PDIs in organic solvents greatly enhances their utility for further derivatization.     

Close‐Packed Two‐Dimensional Silver Nanoparticle Arrays: Quadrupolar and Dipolar Surface Plasmon Resonance Coupling

Silver nanoparticles (NPs) ranging in size from 40 to 100 nm were prepared in high yield by using an improved seed‐mediated method. The homogeneous Ag NPs were used as building blocks for 2D assembled Ag NP arrays by using an oil/water interface. A close‐packed 2D array of Ag NPs was fabricated by using packing molecules (3‐mercaptopropyltrimethoxysilane) to control the interparticle spacing. The homogeneous 2D Ag NP array exhibited a strong quadrupolar cooperative plasmon mode resonance and a dipolar red‐shift relative to individual Ag NPs suspended in solution. A well‐arranged 2D Ag NP array was embedded in polydimethylsiloxane film and, with biaxial stretching to control the interparticle distance, concomitant variations of the quadrupolar and dipolar couplings were observed. As the interparticle distance increased, the intensity of the quadrupolar cooperative plasmon mode resonance decreased and dipolar coupling completely disappeared. The local electric field of the 2D Ag NP array was calculated by using finite difference time domain simulation and qualitatively showed agreement with the experimental measurements.     

A Photoluminescent Ag10Cu6 Cluster Stablized by a PNNP Ligand and Phenylacetylides Selectively and Reversibly Senses Ammonia in Air and Water

A photoluminescent bimetallic cluster [Ag₁₀Cu₆(bdppthi)₂(C≡CPh)₁₂(MeOH)₂(H₂O)](ClO₄)₄ ( 1 , bdppthi=N,N’-bis(diphenylphosphanylmethyl)-tetrahydroimidazole} was synthesized from the PNNP type ligand bdppthi generated in-situ. Upon excitation at 365 nm, 1 exhibited strong phosphorescent emission at 630 nm, which was selectively quenched by NH₃ in air or water. The sensing of NH₃ was rapid and recoverable, with detection limits of 53 ppm (v/v) in N₂ and 21 μmol/L (0.36 ppm, w/w) for NH₃ ⋅ H₂O in water. Cluster 1 could potentially serve as a bifunctional chemical sensor for the efficient detection of ammonia in waste-gas and waste-water.     

Response surface methodology toward the optimization of high-energy carotenoid extraction from Aristeus antennatus shrimp

High-energy assisted extraction techniques, like ultrasound assisted extraction (UAE) and microwave assisted extraction (MAE), are widely applied over the last years for the recovery of bioactive compounds such as carotenoids, antioxidants and phenols from foods, animals and herbal natural sources. Especially for the case of xanthophylls, the main carotenoid group of crustaceans, they can be extracted in a rapid and quantitative way with the use of UAE and MAE.     

Design of broadband achromatic metasurface device based on phase-change material Ge2Sb2Te5

Based on the phase-change material Ge₂Sb₂Te₅ (GST), achromatic metasurface optical device in the longer-infrared wavelength is designed. With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST, the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5 μm to 13 μm are realized. The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband. The simulation calculation results show that the full-width at half-maximum (FWHM) of the focusing spot reaches the diffraction limit at each wavelength. In addition, the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°. The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces, but also provides new possibilities for the integration of optical imaging, optical coding and other related optical systems.     

A self-penetrating and chemically stable zinc (ii)-organic framework as multi-responsive chemo-sensor to detect pesticide and antibiotics in water

Guided by the self-penetrating features can improve the stability of metal organic frameworks (MOFs), an unprecedented 3D self-penetrated framework, {[Zn (tptc)_0.5(bimb)]·H₂O}_n ( NUC-6 , here NUC corresponding to North University of China), with 3D (4,4)-c {8⁶} net, was designed. Benefit from the high chemical stability and excellent luminescent property, NUC-6 can be act as an efficient multi-response chemo-sensor in detecting dichloronitroaniline pesticide and nitrofuran antibiotics in water with the detection limits are 116 ppb for DCN pesticide, 16 ppb for NFT antibiotic, and 12 ppb for NTZ antibiotic. Besides, the mechanisms of luminescence quenching were revealed from the viewpoint of internal filter effect (IFE) and photo-induced electron transfer (PET), implied by the optical spectroscopy and quantum chemical calculation. This work provides a promising strategy to design stable MOFs by improving the self-penetrating features and to expand their practical applications in the detection of organic pollutants in aqueous medium.     

A DNA Switch for Detecting Single Nucleotide Polymorphism within a Long DNA Sequence Under Denaturing Conditions

DNA detection is usually conducted under nondenaturing conditions to favor the formation of Watson–Crick base-paring interactions. However, although such a setting is excellent for distinguishing a single-nucleotide polymorphism (SNP) within short DNA sequences (15–25 nucleotides), it does not offer a good solution to SNP detection within much longer sequences. Here we report on a new detection method capable of detecting SNP in a DNA sequence containing 35–90 nucleotides. This is achieved through incorporating into the recognition DNA sequence a previously discovered DNA molecule that forms a stable G-quadruplex in the presence of 7 molar urea, a known condition for denaturing DNA structures. The systems are configured to produce both colorimetric and fluorescent signals upon target binding.     

Dynamically Induced Excitonic Instability in Pumped Dirac Materials

Driven and non-equilibrium quantum states of matter have attracted growing interest in both theoretical and experimental studies in condensed matter physics. Recent progress in realizing transient collective states in driven or pumped Dirac materials (DMs) is reviewed herein. In particular, the focus is on optically pumped DMs which are a promising platform for transient excitonic instabilities. Optical pumping combined with the linear (Dirac) dispersion of the electronic spectrum offers a knob for tuning the effective interaction between the photoexcited electrons and holes, and thus provides a way of reducing the critical coupling for excitonic instability. As a result, a transient excitonic condensate could be achieved in a pumped DM while it is not feasible in equilibrium. A unifying theoretical framework is provided for describing transient collective states in 2D and 3D DMs. The experimental signatures are described and numerical estimates of the size of the dynamically induced excitonic gaps and the values of the critical temperatures for several specific systems, are summarized. In addition, general guidelines for identifying promising material candidates are discussed. Finally, comments are provided regarding recent experimental efforts in realizing transient excitonic condensate in pumped DMs, and outstanding issues and possible future directions are outlined.     

Recent trends in capillary and micro-chip electrophoretic instrumentation for field-analysis

Technical advances in the development of field-deployable capillary and microchip electrophoretic instruments and reports of their deployment between 2013 and 2017 were reviewed. Strategies and considerations in the design of the injection, separation and detection hardware, chemistry and associated infrastructure were discussed from an in-field perspective, with portability, robustness and automation/“ease of use” featuring as key requirements. Integration of functionality is important for adequate in-field performance. Progress was made towards the use of multiple channel devices for increased throughput and/or resolving power, mixing devices for on-line/in-line sample derivatization, battery operation and temperature control. The strengths and weaknesses of the various approaches described in the literature are discussed from the perspective of in-field operation. An overview of the applications of the field electrophoretic instruments is provided, including environmental science and planetary investigation.     

Sensitive chemically amplified electrochemical detection of ruthenium tris-(2,2′-bipyridine) on tin-doped indium oxide electrode

Optimized combination of chemical agents was selected for sensitive electrochemical detection of dissolved ruthenium tris-(2,2′-bipyridine) (Ru-bipy). The detection was based on the chemical amplification mechanism, in which the anodic current of a redox-active analyte was amplified by a sacrificial electron donor in solution. On indium-doped tin oxide (ITO) electrodes, electrochemical reaction of the analyte was reversible, but that of the electron donor was greatly suppressed. Several transition metal complexes, such as ferrocene and tris-(2,2′-bipyridine) complexes of osmium, iron and ruthenium, were evaluated as model analyte. A correlation between the amplified current and the standard potential of the complex was observed, and Ru-bipy generated the largest current. A variety of organic bases, acids and zwitterions were assessed as potential electron donor. Sodium oxalate was found to produce the largest amplification factor. With Ru-bipy as the model analyte and oxalate as the electron donor, the analyte concentration curve was linear up to 50 μM, with a lower detection limit of approximately 50 nM. Preliminary work was presented in which a Ru-bipy derivative was attached to bovine serum albumin and detected electrochemically. Although the combination of Ru-bipy, oxalate and ITO electrode has been used before for electrochemiluminescent detection of Ru-bipy and oxalate, as well as electrochemical detection of oxalate, its utility in amplified voltammetric detection of Ru-bipy as a potential electrochemical label has not been reported previously.