Effect of molecular weight on reaction-induced phase separation of epoxy resin modified with fluorocarbon chain terminated polyetherimide

A series of fluorocarbon chain terminated polyetherimide is added to epoxy resin,and the effect of molecular weight on the process of phase separation is studied by time-resolved light scattering(TRLS),differential scanning calorimeter(DSC),scanning microscopy(SEM).The results indicate that the phase separation rate decreases due to the preventing effect in-duced by low surface energy of fluorocarbon chain terminated polyetherimide.In addition,evolu-tion time of morphology is shortened and the domain size decreases with the introduction of fluorocarbon chain terminated polyetherimide.Furthermore,when the molecular weight of fluorocarbon chain terminated polyetherimide increases,the morphology can change from dis-persed phase to co-continuous phase.Thus,changing the molecular weight of fluorocarbon chain terminated polyetherimide can control the morphology of the epoxy/polyetherimide blend,which is of great significance in many industries.

Modulation of terminal alkyl chain length enables over 15% efficiency in small-molecule organic solar cells

In small-molecule organic solar cells(SM-OSCs),it remains a big challenge to obtain favorable bulk heterojunction morphology by donor material design.Herein,we design and synthesize three small-molecule donors BPF3T-C4,BPF3T-C6 and BPF3T-C8,with different terminal alkyl chains.Although they possess similar absorption profiles and molecular energy levels,their crystallinity gradually decreases with the chain length of the terminal alkyl chains.After blending with an electron acceptor of BO-4Cl,the crystallinity is suppressed and the packing orientations of these donors changed from edge-on to face-on.Simultaneously,the crystallinity of BO-4Cl is gradually weakened with the chain length of the terminal alkyl chain of donor materials.Finally,The BPF3T-C6 with moderate crystallinity exhibits the best phase-separation morphology among these blend films.As a result,the BPF3T-C6:BO-4Cl-based SM-OSC shows an impressive power conversion efficiency of 15.1%.

Targeting Tyrosyl-DNA phosphodiesterase I to enhance toxicity of phosphodiester linked DNA-adducts

Our genomic DNA is under constant assault from endogenous and exogenous sources,which needs to be resolved to maintain cellular homeostasis.The eukaryotic DNA repair enzyme Tyrosyl-DNA phosphodiesterase I(Tdp1)catalyzes the hydrolysis of phosphodiester bonds that covalently link adducts to DNA-ends.Tdp1 utilizes two catalytic histidines to resolve a growing list of DNA-adducts.These DNA-adducts can be divided into two groups:small adducts,including oxidized nucleotides,RNA,and non-canonical nucleoside analogs,and large adducts,such as(drug-stabilized)topoisomerase-DNA covalent complexes or failed Schiff base reactions as occur between PARP1 and DNA.Many Tdp1 substrates are generated by chemotherapeutics linking Tdp1 to cancer drug resistance,making a compelling argument to develop small molecules that target Tdp1 as potential novel therapeutic agents.Tdp1’s unique catalytic cycle,which is centered on the formation of Tdp1-DNA covalent reaction intermediate,allows for two principally different targeting strategies:(1)catalytic inhibition of Tdp1 catalysis to prevent Tdp1-mediated repair of DNA-adducts that enhances the effectivity of chemotherapeutics;and(2)poisoning of Tdp1 by stabilization of the Tdp1-DNA covalent reaction intermediate,which would increase the half-life of a potentially toxic DNA-adduct by preventing its resolution,analogous to topoisomerase targeted poisons such as topotecan or etoposide.The catalytic Tdp1 mutant that forms the molecular basis of the autosomal recessive neurodegenerative disease spinocerebellar ataxia with axonal neuropathy best illustrates this concept;however,no small molecules have been reported for this strategy.Herein,we concisely discuss the development of Tdp1 catalytic inhibitors and their results.