Search

Nucleoside free radicals have important functions in organisms and play a crucial role in DNA damage. Accurately understanding the structure of nucleoside free radicals is crucial for studying their properties, reaction mechanisms, and interactions with other biomolecules. The high vacuum in the mass spectrometer provides an inert environment for free radicals. Further tandem mass spectrometry combined with theoretical calculation is crucial for achieving their structural informations. This article reviewed gas phase studies of base and nucleoside radicals based on mass spectrometry in the past two decades, and provided a detailed introduction and comparison of their production methods, structural research methods and progress. Different methods were developed for the generation of the free radical ions, including collision induced dissociation of precursor ions of ternary transition metal complexes or those introducing free radical initiators, electron transfer dissociation of precursor ions charge-tagged, and UV photodissociation of precursor ions including C-I bonds. Besides, the methods for studying the structure of free radical ions in gas phase have gradually enriched, including commonly used tandem mass spectrometry, UV-visible and IR photodissociation spectroscopy. Based on the above methods, many different base and nucleoside free radical ions were generated and structurally determined in gas phase. On the other hand, the research of the highly active free radical intermediates and the selective generation of free radical isomers still pose challenges, and there is an urgent need to develop new experimental method.

The measurement of gas phase collision cross section (CCS) of ions can provide complementary structure information to those typically obtained from mass spectrometry or tandem mass spectrometry. Thus, the ion mobility spectrometry is typically coupled with a mass spectrometer to achieve the advantage after the combination. Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) is characterized by its ultra high resolution and tandem mass spectrometry capabilities. Due to the collisions with neutral molecules, the image current caused by the cyclotron motion of ions in the analysis cell gradually decays under high vacuum condition. Based on this feature, the CCS of ions can be calculated by selecting an appropriate theoretical model and combining with the corresponding algorithm. This method can be directly applied to obtain the value of CCS of the selected ion through the analysis of high-resolution mass spectrometry data without increasing the cost of instrument hardware. With the development and promotion of FT-ICR MS instruments in recent years, such methods have developed rapidly in the past decade and have attracted extensive attention. There are three different ion-neutral collision models (Langevin collision model, hard-sphere collision model and energetic hard-sphere model) which have been applied to connect ion CCS and image current of FT-ICR MS instruments. Time-domain analysis, frequency-domain analysis and time-frequency analysis are three types of data analysis method used to measure ion CCS based on FT-ICR MS. Although the reliability and accuracy of the CCS data provided by such methods need to be further improved, it has been demonstrated its unique advantages in the dynamic CCS measurement and potentials in isomerization study. Such methods can be further combined with ion mobility technology to provide multi-dimensional ion structure information with the help of FT-ICR′s superior mass resolution and superior ion manipulation capabilities.

The use of non–precious metals for electrocatalytic hydrogen reaction (HER) is particularly important for energy conservation and environmental protection. In this work, three new cobalt corroles containing o−, m−, and p−nitrobenzyl (1, 2, 3) at the meso 10−position of the corrole macrocycle were synthesized, and their electrocatalytic hydrogen evolution reaction in organic and neutral aqueous systems was also investigated. The results show that these three cobalt corroles have significant catalytic HER activity in both systems, and the catalytic efficiency follows 1 > 3 > 2, which indicates that the position of the nitro group can affect the catalytic property of the complexes. In the organic phase, when using trifluoroacetic acid or p−toluenesulfonic acid as the proton source, the electrocatalytic HER may undergo an EECC (E: electron transfer, C: proton coupling) pathway. In a neutral aqueous system, the HER turnover frequency value of 1 is up to 137.4 h−1 at 938 mV overpotential. [ABSTRACT FROM AUTHOR]

In this study, we have successfully synthesized two non‐metallic‐based silicon corrole complexes (F10C−Si, F10C−CN−Si) and used them as HER electrocatalysts for the first time. Electrochemical studies indicate the electrocatalytic HER may go via EE‐CEEC (E: electron transfer step, C: chemical step) pathway. Notably, it can be seen that the introduction of electron‐withdrawing cyano group on the meso‐phenyl of the corrole macrocycle may enhance the catalytic activity of silicon corrole complexes. In DMF with TsOH as the proton source, F10C−CN−Si exhibits a turnover frequency (TOF) of 331.48 s−1 and a high catalytic efficiency (C.E) of 1.29. Furthermore, the catalytic prowess of the silicon corrole complexes extends to neutral aqueous solution, with F10C−CN−Si achieving a TOF of 52.72 h−1 at an overpotential of 1188 mV. This study extends the application of non‐metallic‐based silicon corrole molecular catalysts in the electrocatalytic HER field. [ABSTRACT FROM AUTHOR]

The study of the hydrogen evolution reaction (HER) by non-noble transition metals is of great significance for the production of hydrogen energy. In this work, a new 5,15-bis-(pentafluorophenyl)-10-[4-(1H-imidazole) phenyl]-corrole and its metal complexes (metal = Co, Cu, Fe) were synthesized and used for electrocatalyzed HER in DMF organic solvent and aqueous media. The prepared cobalt corrole showed the best catalytic performance in both media. Its turnover frequency (TOF) and catalytic efficiency (C.E) could reach 265 s−1 and 1.04 when TsOH was used as the proton source in a DMF solvent. In aqueous media, its TOF could also reach 405 h−1. The catalytic HER may go through an EECEC or ECEC (E: electron transfer, C: chemical step) pathway for these catalysts, depending on the acidity and concentration of the proton source. The present work successfully demonstrates that imidazole at a meso-phenyl group may improve the electrocatalytic HER activity of transition metal corroles. [ABSTRACT FROM AUTHOR]