Study On The Synthesis And Properties Of Multiphenylthio (Seleno) Substituted Porphyrins

Porphyrins are a group of aromatic molecules.Four central N atoms inside the macrocycle lead to its relatively high HOMO.Thus electron transfer from porphyrin to LUMO of other molecules is often observed.As both-SR and-SeR are well-known electron-donating groups,decoration of multiphenylthio(seleno)in porphyrins further elevates the electron density of the porphyrin core.In this dissertation,the author investigated the synthesis and properties of multiphenylthio(seleno)porphyrins.The author also studied the oxidation products of multiphenylthio(seleno)porphyrins.The introduction of excellent electron-donating substituents-SPh to porphyrin core has attracted much attention of scientists due to their potential application in materials.But the methodology to achieve these compounds are still limited.In this dissertation,the authors synthesized various porphyrins bearing multiphenylthio groups by classical SNAr reaction via mixing halogenated porphyrins with PhSNa.β,β-,β,meso-,and β,meso,β-multiphenylthio porphyrins were achieved.Their structures were characterized by 1H NMR,13C NMR,and HR-MALDI-TOF-MS spectroscopy.The structures of some typical compounds were confirmed by X-ray single crystal diffraction.The UV/vis absorption spectra of a series of multiphenylthio porphyrins showed that porphyrins bearing multiphenylthio groups displayed red-shifted Soret and Q bands and smaller extinction coefficients comparing with the corresponding starting materials.These changes in UV/vis absorption spectra can be mainly attributed to the increases of electron density in the porphyrin ring affected by-SPh.Among chemical bonds three-electron σ-bonds are a type of nonclassical chemical bonds,which are composed of two electrons on the bonding orbital and one electron on the antibonding orbital.Although the concept of the three-electron σ bond was first proposed by Linus Pauling in 1931,the currently known compounds containing three-electron σbonds were very limited.In this paper,the author synthesized neutral multiphenylseleno porphyrins in good yields by SNAr reaction.Subsequently oxidation of multiphenylseleno porphyrins by using single electeon oxidants AgSbF6 or[NO]+[SbF6]-led to the compounds containing Se∴Se∴Se.The structures of compounds containing Se∴Se∴Se were confirmed by 1H NMR and X-ray single crystal diffraction.According to DFT calculations,the properties of compounds containing Se∴Se∴Se were affected by substituents of porphyrins:The major population structure of compound containing Se∴Se∴Se supported by 3,5-di-tert-butylphenylporphyrin is triplet.While the major population structure of compound containing Se∴Se∴Se supported by 3,5-ditrifluoromethylphenylporphyrin is singlet.