Synthesis And Properties Of Triphenylene And Perylene D-A Dimer Bridged By Nonoxyn

In this paper,a series of D-A dimer compounds D59nA based on triphenylene and perylene-diester units were synthesized,in which D5 is triphenylene,9 is the non-conjugated flexible alkyl linkages between triphenylene and perylene-diester?-OC9H18-?;A is perylene-diester,n is alkoxycarbonyl side chains of perylene-diester?n=4,5,6,7,8?.The purpose is to construct a double-gap polar transport molecular channel for bidirectional transport of electrons and holes.The research focused on the influence of the length of alkoxycarbonyl side chains on the liquid crystal properties of the compound.In the new discotic liquid crystal D-A dimer compounds?donor-acceptor?,triphenylene is used as donor which can be used as the hole transport material;perylene-diester is used as acceptor which can be used as the electron transport material.The columnar phase is formed between the disks by the intermolecular force?-?stacking,and the charges are moved along the column,forming two different paths for electron and hole.Chemical structure confirmation of compounds:nuclear magnetic carbon spectroscopy?13C NMR?,nuclear magnetic hydrogen spectroscopy?1H NMR?,fourier high transform resolution mass spectrometry?FT-MS?,infrared spectroscopy?FT-TR?and elemental analysis?EA?.The liquid crystal properties and thermal properties of the compounds were preliminarily confirmed by polarizing microscope?POM?,differential scanning calorimeter?DSC?,and thermogravimetric analysis?TG?.All of the compounds are liquid crystal.Mosaic texture was observed when the single-phase transition liquid crystal cooled,the thermal stability performance is excellent.The phase structure and orientation of the compound are further confirmed by one-dimensional wide-angle X-ray diffraction?1D WAXD?,two-dimensional X-ray diffraction?2D WAXD?,and small-angle X-ray scattering?SAXS?.The compounds have different phase at different temperatures:hexagonal columnar phase and rectangular columnar phase.The optical properties of the compound are confirmed by ultraviolet-visible spectroscopy?UV-VIS?and fluorescence spectroscopy.The spectral absorption range of the compounds are expanded compared with the monomer,new compounds have a wide spectrum absorption range.Absorption peaks appear at wavelengths of 200³00 nm and wavelengths of 450⁵50 nm.Excitation wavelengths are 280 nm and 485 nm,the compounds have fluorescence emission spectra.The charge mobility of the compounds?electrons and holes?was analyzed by time-of-flight.Compound D594A has a strong?-?interaction between molecules and stacked more closely.At room temperature,the charge mobility is high,reaching 10^-4cm²v^-1s^-1.It forms two different paths in one-dimensional direction to promote the charges transfer.