Design,Synthesis And Photoelectric Properties Of Donor-acceptor Discotic Liquid-crystallines

A series of novel discotic liquid-crystalline donor-acceptor dyads?D-A?and triads?A-D-A and D-A-D?were designed and synthesized based on triphenylene and perylene units which linked by non-conjugated flexible alkyl linkages.First of all,a series of novel dyads 5D10Am were synthesized by using 2-hydroxy-3,6,7,10,11-pentapentyloxytriphenylene as donor and perylene diester monoanhydride that differ in the number of methylenic units from alkoxycarbonyl side chains on their periphery from 4 to 8?m=4-8?as acceptor linked by a alkyl linkage(-C₁₀H₂₀-).Based on 5D10Am derivatives,4D10A4 was synthesized by using 2-hydroxy-3,6,7,10,11-pentabutoxy-triphenylene as donor and perylene diester monoanhydride?m=4?as acceptor linked by a alkyl linkage(-C₁₀H₂₀-).Based on 5D10A4,5DnA4 derivatives were synthesized by changing linkage length?n=5,6,8,9,10?.Based on the above,the triad ADA and DAD were obtained by coupling triphenylene diamine with perylene diester monoanhydride,and triphenylene monoamine with perylene tetracarboxylic acid.The main aim of this study was to systematically investigate effect on mesomorphism properties via changing length of linkages,length of side chains and proportion of donor-acceptor.The chemical structures of these compounds were characterized by using nuclear magnetic resonance(¹H NMR and ¹³C NMR),fourier transform infrared spectroscopy?FT-IR?Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry?MALDI-TOF-MS?and elemental analysis?EA?.The mesomorphism properties and their self-assembly behaviors were studied by differential scanning calorimetry?DSC?,polarized optical microscopy?POM?,one-dimensional wide-angle X-ray diffraction?1D WAXD?,small angle X-ray scattering?SAXS?and two-dimensional wide-angle X-ray diffraction?2D WAXD?.Charge carrier mobilities were characterized by time-of-flight?TOF?device.5D10Am derivatives exhibited more ordered mesophase structure with decreasing of side chain lengths of perylene unite.However,4D10A4 exhibited lower ordered mesophase structure with decreasing of side chain length of triphenylene unite.For 5DnA4 derivatives,a minor change on linkages drastically perturbed self-assembly behaviors and abundant columnar phase,which suggested that linkages dominated self-assembly process of D-A dyads.5D5A4 and 5D10A4 assembled into a long-range ordered 2D superlattice structure.The different effects of perylene unit proportion made a significant influence,which lead to serious changes on phase behaviors and formations of abundant columnar phase behaviors.Compounds exhibited more ordered mesophase structure with decreasing of perylene unit proportion.DAD triad with decreasing of perylene unit proportion assembled into a long-range ordered 2D superlattice structure.These discotic liquid-crystalline compounds exhibited highly efficient ambipolar charge-transport properties and the charge carrier mobility can reach the order of 10^-3 cm² V^-1 S^-1 by segregated donor-acceptor columns which were a long range ordered 2D superlattice,providing potential utility of the strategy in organic optoelectronic applications.