Amidyl Radical Directed Remote Allylation of Unactivated sp C-H Bonds by Organic Photoredox Catalysis.

The development of visible-light-mediated allylation of unactivated sp C-H bonds is reported. The remote allylation was directed by the amidyl radical, which was generated by photocatalytic fragmentation of a pre-functionalized amide precursor. Both aromatic and aliphatic amide derivatives could successfully deliver the remote C-H allylation products in good yields.

Solar UV-treatment of water samples for stripping-voltammetric determination of trace heavy metals in Awash river, Ethiopia.

We report about testing a new mobile and sustainable water sample digestion method in a preliminary field trial in Ethiopia. In order to determine heavy metals at the ultra-trace level by stripping voltammetric techniques in water samples from Awash River, we applied our new method of solar UV-assisted sample pretreatment to destroy the relevant interfering dissolved organic matter. The field tests revealed that 24 h of solar UV irradiation were sufficient to achieve the same sample pretreatment results as with classic digestion method based on intense and hard UV.

Sequence and Temperature Influence on Kinetics of DNA Strand Displacement at Gold Electrode Surfaces.

Understanding complex contributions of surface environment to tethered nucleic acid sensing experiments has proven challenging, yet it is important because it is essential for interpretation and calibration of indispensable methods, such as microarrays. We investigate the effects of DNA sequence and solution temperature gradients on the kinetics of strand displacement at heated gold wire electrodes, and at gold disc electrodes in a heated solution. Addition of a terminal double mismatch (toehold) provides a reduction in strand displacement energy barriers sufficient to probe the secondary mechanisms involved in the hybridization process.

Palladium catalyzed synthesis and physical properties of indolo[2,3-b]quinoxalines.

A series of indolo[2,3-b]quinoxaline derivatives were efficiently synthesized from 2,3-dibromoquinoxaline by two pathways. A one-pot approach using Pd-catalyzed two-fold C-N coupling and C-H activation reactions gave indolo[2,3-b]quinoxaline derivatives in good yields, but with limited substrate scope. In addition, a two-step approach to indolo[2,3-b]quinoxalines was developed which is based on Pd-catalyzed Suzuki coupling reactions and subsequent annulation by Pd-catalyzed two-fold C-N coupling with aromatic and aliphatic amines.

Hybridization detection of enzyme-labeled DNA at electrically heated electrodes.

In this report we describe an electrochemical DNA hybridization sensor approach, in which signal amplification is achieved using heated electrodes together with an enzyme as DNA-label. On the surface of the heatable low temperature co-fired ceramic (LTCC) gold electrode, an immobilized thiolated capture probe was hybridized with a biotinylated target using alkaline phosphatase (SA-ALP) as reporter molecule. The enzyme label converted the redox-inactive substrate 1-naphthyl phosphate (NAP) into the redox-active 1-naphthol voltammetrically determined at the modified gold LTCC electrode.