Selenium containing macrocycles:transformation between Se-N/Se-S/Se-Se bonds

Macrocycles possess potential applications in supramolecular chemistry and biosystems. Thus development of new kinds of macrocycles is of significance. Herein, novel macrocycles containing Se-Se/Se-S bonds were synthesized via transformation between selenium related dynamic covalent bonds. A monomer containing two ebselen moieties was synthesized (M1). The Se-N bonds in M1 were reduced by dithiothreitol, forming Se-S linked dimer (D1). To realize the transformation from Se-S bonds to Se-Se bonds, guest molecules were added as template, triggering the formation of Se-Se linked dimer (D2). The formation of these two new kinds of macrocycles was determined by H-1 NMR and Se-77 NMR, and the necessity of guest molecules was also confirmed. The introduction of ebselen moieties and Se-S bonds or Se-Se bonds into macrocycles may endow it with new responsiveness and bioactivities, as well as new types of host-guest chemistry.

Selenium-functionalized metal-organic frameworks as enzyme mimics

The development of artificial enzyme mimics has been rapidly growing in recent years, and it is attracting increasing attention owing to their remarkable advantages over natural enzymes. Herein, we developed a general and facile method to fabricate efficient glutathione peroxidase （GPx） mimics by grafting selenium-containing molecules （phenylselenylbromide, PhSeBr） to a Zr（W）-based UiO-66-NH2 framework. In the presence of glutathione （GSH） serving as substrate, the fabricated UiO-66-Se catalysts can catalyze the reduction of hydroperoxides. The as-prepared UiO-66-Se systems show good catalytic activity over three cycles. These high-efficiency GPx mimic metal-organic frameworks （MOFs） are endowed with excellent thermal and structural stability, providing a promising avenue for the development of artificial enzyme mimics.

Cancer Therapy by Targeting Thioredoxin Reductase Based on Selenium-Containing Dynamic Covalent Bond

Thioredoxin Reductase(TrxR)plays a pivotal role in defending cells against reactive oxygen species(ROS)and maintaining a reduced intracellular environment.It has been discovered that TrxR is elevated significantly in human cancer,evidenced by its association with the promotion of tumor cell proliferation,inhibiting tumor cell apoptosis,as well as enhancing tumor drug resistance.Hence,finding highly selective inhibitors of TrxR is urgently needed.Herein,we developed a selenium-containing small molecule(EbD),which had two Se–N bonds.Under reduction conditions,the two Se–N bonds reacted with Se–H bond and S–H bond in TrxR to form new Se–Se bond and Se–S bonds,respectively.Subsequently,the newly formed bonds were able to disrupt the thioredoxin(Trx)reduction catalytic cycle,and thus,inhibited the TrxR activity irreversibly,which resulted in the collapse of the antioxidant system.As a consequence,ROS levels elevated that triggered cancer cell apoptosis.This strategy,based on selenium-containing dynamic covalent bonds,provides a new avenue for cancer therapy via targeting TrxR.

Multi-functional supramolecular polymer produced from natural small molecules in a facile route

Polymeric materials are important substrates for the realization of different functions.Despite the rapid progress, there are still two big challenges in this field:(1)how to fabricate the materials in a simplified procedure and (2)how to achieve both sophisticated properties and integrated functions in one system.To address these problems,Qu, Feringa and Tian et al.[1]recently reported a novel multifunctional supramolecular polymer system synthesized from simple commercial small molecules via a very easy and mild route.