Synthesis And Characterization Of Organic Photoelectric Materials Based On Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons refer to a class of aromatic hydrocarbons containing two or more benzene rings.As compounds with unique electronic structure and high degree of electronic conjugation,they show special optical,electrical and magnetic properties.They are used in organic functional materials.The field has excellent application prospects.However,some PAH molecules with special edge structures theoretically have an open-shell electronic ground state,which has become a hot spot in the research field of organic optoelectronic magnetic materials.Due to the limitation of the structure of the open-shell PAH itself,the high reactivity,poor stability,and poor solubility of the molecules all limit the preparation and performance characterization of the molecules.Therefore,how to prepare open-shell polycyclic aromatic hydrocarbon molecules with controllable edge structure through rational molecular design and wet chemical synthesis technology is a very challenging topic in the current research field.Based on this,a series of polycyclic aromatic hydrocarbons with unique structures were designed and synthesized,and their optical,electrical and magnetic properties were studied.1.A series of perylene derivatives centered on nitrogen atom were designed and synthesized.The key reaction steps were regioselective bromination,intramolecular ring closure and oxidative dehydrogenation,and 2,4,6-trichlorophenyl was introduced at the end of the molecule.The large sterically hindered electron withdrawing group increases the stability of the molecule,and stable closed-shell（Per-2N,Per-FN,Per-DFN）and open-shell（2Per-FN,2Per-DFN）molecules were successfully prepared.The properties were measured by nuclear magnetic resonance（¹H NMR）or variable temperature nuclear magnetic resonance（VT-¹H NMR）,ultraviolet absorption spectroscopy（UV-Vis）,electrochemical testing（CV）,electron spin resonance（ESR）,density functional theory（DFT）)theoretical calculation and other means for testing and auxiliary characterization.The results show that Per-2N,Per-FN and Per-DFN are closed shell systems,the ground states of 2Per-FN and2Per-DFN are singlet biradical polycyclic aromatic hydrocarbon systems,and the biradical indices are y₀=0.59 and 0.58,respectively.At the same time,the molecule has good stability.2.Taking the naphthalene unit as the skeleton,through Suzuki coupling,selective bromination,intramolecular ring closure and oxidative dehydrogenation,a push-pull structure of pentaleno-naphthalene derivatives（PN-2CN）was designed and synthesized.The results show that the PN-2CN molecule is a closed-shell polycyclic aromatic hydrocarbon,and the double-substituted naphthalene ring and the cyano functional group in the molecule constitute a push-pull electronic structure.After studying the optical properties of the molecule,it is found that the absorption wavelength of the molecule has an obvious red shift compared with the same type of molecule,and the photochemical energy level(E_g^Opt=1.34 e V)is narrower,adding a new member to the near-infrared dye family.3.Based on the study of pentaleno-naphthalene,we designed a novel Y-type molecule Ythrene with a high spin ground state.Using mono-brominated acenaphthylene molecule as raw material,the methyl group was introduced into the highly reactive site to avoid the five-membered ring-forming reaction in the molecule.The theoretical calculation results of the molecule show that the molecule is a biradical polycyclic aromatic hydrocarbon with an open-shell triplet ground state.It is expected that the synthesis of this molecule can provide a reference for the construction of a stable open-shell triplet polycyclic aromatic hydrocarbon system with a high-spin ground state.