Studies On The Electronic Structure And Photodynamic Properties Of [Fe₂S₂(NO)₄]^2- Clusters

Nitric oxide(NO)is an important physiological signal small molecule in the organism,it plays an important role in mammalian vasodilation,nerve signal transduction and immunology.The coordination and combination of metal ions with NO affect the metabolism and transport of NO,and regulate its physiological functions.Therefore,nitric oxide derivatives including metal nitrosyl complexes have attracted wide attention from scientists.In recent years,the discovery of protein-bound low molecular weight dinitrosyl iron complexes(DNIC)indicates that such compounds may play an important role in the storage,transportation and function of NO in biological systems.In this paper,a typical nitrosyl iron-sulfur cluster,namely Roussin's Red Salt,(Me₄N)₂[Fe₂S₂(NO)₄],was synthesized and systematically studied.The structure and physicochemical properties of the cluster were determined and analyzed by single crystal diffraction technique.The infrared spectrum and absorption spectrum were obtained by spectral characterization,and the influence of solvent polarity on cluster stability was explored by Fourier infrared transform technology.It was found that the larger the solvent polarity,the more stable the cluster was.The theoretical calculation of[Fe₂S₂(NO)₄]^2-is carried out by using density functional theory,the molecular structure and energy,molecular orbital and vibration frequency of the complex with different spin multiplicity in different solvents are analyzed.The singlet state of the cluster is determined to be its ground state,and the influence of solvent polarity on cluster stability is explained from the perspective of energy,and the lower the energy,the more stable the system is.The conclusion obtained is consistent with the experimental conclusion.In addition,the corresponding calculated infrared spectra are obtained,which match well with the experimental infrared spectra,which achieves the purpose of unifying theory and practice.Fourier transform infrared spectroscopy(FTIR)was used to track the kinetic reaction process of the cluster in different solvents.It was confirmed that the Roussin's red salt would be converted into Roussin's black salt,and capturing the infrared spectrum of the intermediate state of the light reaction.The effect of light on the transformation of the cluster was investigated,and it was found that light could promote the transformation of the cluster,which proved that the cluster had certain photosensitivity.Moreover,the electron paramagnetic resonance spectrum of the complex were recorded and analyzed using the NO spin trapped technology to monitor the reaction of the NO release from complex in different solvents upon photoirradiation.Some intermediate NO clusters and their possible products have been analyzed by using the computer fitting spectra.In this thesis,the electronic structure and photodynamic properties of Roussin's Red Salt((Me₄N)₂[Fe₂S₂(NO)₄])are studied in detail,which provides a basis for future exploration of the intermediate state structure of complexes,it makes the foundation for the future development of drugs related to NO complexes.