Investigation Of Radical Properties Based On Azine Derivative Molecules

In recent years,there has been growing interest among researchers in the study of radicals,particularly diradicals,due to their unique properties such as redox abilities,outstanding infrared absorption,and intriguing electromagnetic and optical characteristics.Diradicals can also act as special organic semiconductors,making them useful for applications in organic field-effect transistors(OFETs),organic photodetectors,and organic batteries.While research on diradicals has mainly focused on symmetrically conjugated molecular systems,particularly those with common π-bridge cores like Azobenzene,thiophene,and diketopyrrolopyrrole(DPP),there has been little research on diradicals with azine as the core.This is despite azine structures being known for their single-crystal isomerism,coordination bonds with atoms like Si,Ge,P,and As,and their applications in medicinal chemistry.So far,only the redox systems and interconversion efficiencies of these diradicals have been superficially explored,leaving their electromagnetic and optical properties unclear.Phenoxy radical,which possesses excellent stability and strong diradical properties,has received much attention from researchers.However,there has been little investigation into the combination of azine derivatives and phenoxy radicals.To address this gap in knowledge,this dissertation explores the impact of changing the linkers of azine derivatives,such as the introduction of benzene rings and thiophenes,on the electron spin distribution and the effect of different chemical connection sites on phenoxy radical interactions.This analysis could provide a deeper insight into the field of organic electronics.The dissertation is divided into two parts.The first part involves the successful synthesis of a range of PNP-n(n=1,2,3,4)molecules with increasing amounts of thiophene.The structure of the synthesized molecules displays excellent infrared absorption properties,with the maximum absorption wavelength reaching 1041 nm.The benzene ring in the structure exhibits stronger aromaticity and resonance energy,leading to stronger diradical properties in the entire radical molecule,while thiophene’s weaker aromaticity and improved planarity result in enhanced conjugation and stability throughout the molecule.The spin distribution of the molecules was studied through a combination of DFT calculations and analysis via ESR,SQUID,and X-ray single-crystal diffraction.Building upon the research on PNP-n(n=1,2,3,4)from the previous chapter,the second part explores the impact of linking sites on the single triplet energy difference and spin distribution of diradicals.To this end,the dissertation details the design and synthesis of PNP-5,which has a linking site in the ortho position.UV-vis absorption spectrum analysis and ESR analysis were conducted and showed different results compared to PNP-2,with no diradical-specific absorption appearing in the spectrum.The molecule’s electrochemical properties were also characterized.