Formation of a stable p-n junction in a liquid-gated MoS2 ambipolar transistor.

Molybdenum disulfide (MoS2) has gained attention because of its high mobility and circular dichroism. As a crucial step to merge these advantages into a single device, we present a method that electronically controls and locates p-n junctions in liquid-gated ambipolar MoS2 transistors. A bias-independent p-n junction was formed, and it displayed rectifying I-V characteristics. This p-n diode could perform a crucial role in the development of optoelectronic valleytronic devices.

Stereocontrolled phosphorothioate synthesis using chiral phosphite triesters.

We describe stereocontrolled synthesis of phosphorothioate oligonucleotides including stereospecific transesterification to form chiral phosphite triester backbone under basic conditions. Substrate phosphite triesters with phenoxy derivative substituents as leaving groups were separated into individual stereoisomers and reacted with hydroxyl-containing compounds to form chiral phosphite triester backbone. Subsequent stereoretentive sulfurization and deprotection gave desired stereocontrolled phosphorothioate linkages.