Vanadium(V) Complexes Containing Unsymmetrical N-Heterocyclic Carbene Ligands: Highly Efficient Synthesis and Catalytic Behavior towards Ethylene/Propylene Copolymerization

The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.

Deficiency of mitochondrial aldehyde dehydrogenase increases type 2 diabetes risk in males via autophagy dysregulation

Metrics To the editor:The diabetes epidemic has increasingly become a major public health concern worldwide.In 2014,there were 102.9 million diabetic adults in China,representing 24.4%of the world's diabetic population,even though China only comprised 18.7%of the global population at the time.[1]Furthermore,the estimated overall prevalence of diabetes and prediabetes was 10.9%and 35.7%,respectively,indicating China as one of the countries with the highest prevalence of diabetes in the world.[2]Although factors,including sedentary lifestyles and energy-dense diets,drive the diabetes epidemic,genetic architecture may also contribute to the susceptibility of an individual's response to environmental challenges.Aldehyde dehydrogenase(ALDH)2 is a key enzyme that eliminates toxic aldehydes by catalyzing their oxidation to non-reactive acids.Emerging evidence has suggested that individuals with ALDH2 deficiency have an increased risk of cardiovascular and metabolic diseases,in addition to alcohol intolerance,nitroglycerin tolerance,and carcinoma.[3]Notably,a unique ALDH2 loss-of-function allele,ALDH2∗2,is found in approximately 50%of the East Asian and 8%of the global populations.It has been reported that this ALDH2 mutation is associated with a higher prevalence of diabetes in coronary artery disease(CAD)patients,accompanied with increased C-reactive protein(CRP)levels.[4]ALDH2 mutation is also related to various diabetes risk factors,but the direct correlation remains elusive.Herein,we have explored the potential pathogenicity and mechanisms of ALDH2 deficiency in the development of type 2 diabetes in both laboratory and clinical settings.