Spatial structure regulation towards armor-clad five-membered pyrroline nitroxides catholyte for long-life aqueous organic redox flow batteries

Five-membered pyrroline nitroxides with high-potential is fascinating as catholyte for aqueous organic redox flow batteries(AORFBs),however,it suffers from a primary deficiency of insufficient stability due to ring-opening side reaction.Herein we report a spatial structure regulation strategy by host-guest chemistry,encapsulating 3-carbamoyl-2,2,5,5-tetramethylpyrroline-1-oxyl(CPL)into hydrosoluble cyclodextrins(CDs)with an inclusion structure of N–O⋅head towards cavity bottom,to boost the solubility and cyclability of pyrroline nitroxides significantly.The armor-clad CPL(CPL⊂HP-β-CD)catholyte in 0.05–0.5 M presents a battery capacity fade rate as low as 0.002%/cycle(0.233%/day)compared to the sole CPL in 0.05 M(0.039%/cycle or 5.23%/day)over 500 cycles in assembled AORFBs.The optimized reclining spatial structure with N–O⋅head towards CD cavity bottom effectively inhibits the attack of Lewis base species on the hydrogen abstraction site in pyrroline ring,and thus avoids the ring-opening side reaction of pyrroline nitroxides.

Establishment and application of an accurate identification method for fragrant soybeans

In order to screen the aroma characteristics of soybean,a new method was established which can quickly quantify the content of 2-acetyl-1pyrroline(2-AP),an important compound related to soybean aroma,using gas chromatography-mass spectrometry(GC-MS).Based on peak profile,total peak area and retention time as test indexes,an accurate identification method for fragrant soybeans was established.The optimum parameters of the protocol consisted of column temperature70℃,sample injector temperature 180℃,optimum extraction alcohol content 1 m L,Na Cl content 0.1 g,ultrasonication time10 min,and extraction time 1 h,which were established by using the orthogonal test of single factors and three factors with four levels(L_9(3)^4).2-AP content of leaves had significant correlations with seeds,which were easier to measure.The protocol was simple and easy to carry out,consumed only small amounts of reagents,and provided accurate and reliable results with good reproducibility.A total of 101 soybean genotypes from different geographical sources were analyzed using this protocol.The results showed that the average content of 2-AP was 0.29 mg L^(–1),ranging from 0.094 to 1.816 mg L^(–1),and the genetic diversity index was 0.54.Among all genotypes-tested,they were classified into three grades,including seven elite genotypes identified as"grade one fragrant soybeans",which were Zhonglong 608,Heinong 88,Ha13-2958,Hongmiandou,Heinong 82,Huangmaodou,and Jiyu 21.These results provide both an identification technique and several elite aroma genotypes for gene discovery and good quality breeding in soybean.

Studies on the Solvent Effect of N-Carbamoyl-N-(1-Oxyl 2,2,5,5-Tetramethyl-Pyrrolin-3-yl) Ureas

The electron spin resonance spectra of N-carbamoyl-N-(l-oxyl-2,2,5,5-tetramethyl-pyrrolin-3-yl) urea compounds in ten solvents with different polarities were determined. It was found that the hyperfine splitting constant AN and spin density pN. as well as the energy difference between two adjacent energy levels E of different pyrroline nitroxides in the same solvent increase with the increase of electron-withdrawing α-bility of the substituted groups on the aromatic ring. There was a linear correlation between AN and Reichardt ET value, and between AN and Z value as well. Such a linear correlation was also found between solvent viscosity n and ESR rotational correlation time r. On the other hand, the correlation between T and the relative height hr of peak on high field was reverse. The results are discussed in the paper.