Synthesis And Optoelectronic Properties、 Acoustic Performance Of The New Porphyrin Discotic Liquid Crystal Compounds

Discotic liquid crystal (DLC) is a new type of organic semiconductor materials,it have a higher charge conduction in one-dimensional direction efficiency by theunique self-assemble into cylindrical structures.The DLC of porphyrins have alarge π-conjugated system with24centers and26electrons,the capable of beingself-assembly mainly driven by π-π interactions,allowing π-orbital overlapcolumnar direction a "line",significantly increasing the carrier charges,reducing thequenching of exciton.On the other hand,getting self-assembled to form more stableand structured,one-dimensional columnar phase by adjusting structurals.Increasingits solubility in organic solvents and lower the melting point.Furthermore,adjustingtheir frontline track gap by modifying the discotics.In this paper, in order to obtain discotic compounds,which have low meltingpoint,high solubility,low energy gap and self-assemble into one-dimensionalcolumnar structure, we increased porphyrin molecules conjugated system byintroducing two acetylene bond to reduce its energy gap and introducing a flexiblealkyl chains to reduce the melting point of the molecule.And we are using a newabsorbing mechanism of conductive,use of porphyrins discotic liquid crystal whichwe prepared、the graphite, PVDF material as raw material, attempting to develop aconductive polymer film material of sound absorption with bandwith frequency andexcellent sound absorption capability.These two which is the innovation of in thispaper.Our work including the following aspectes:（1）Using the Adler-Longo method, we design and synthesis of two series of12kinds of a median tetra-substituted phenyl porphyrin discotic liquid crystalwhich has the symmetrical structure.And their structure was characterized by1HNMR,13C NMR, IR.（2）Optoelectronic properties were studied by UV-Vis absoption spectra andFluorescence emission spectra.Studying its orbital energy level by cyclic voltammetry.Investigation the liquid crystal properties of the compounds bydifferential calorimetry (DSC) and polarized light microscope (POM). Absorptioncapability of porphyrins discotic liquid crystal thin films were studied By standingwave tube sound. The results showed that:①The fluorescence emissionwavelength and Soret absorption red-shift, fluores-cence quantum yieldssignificantly higher, reducing the highest occupied molecular orbital (HOMO)andlowest unoccupied molecular orbital(LUMO)energy gap by increasing theconjugated systems;②With the lexible alkyl side chain increases, the fluorescencequantum yield is reduced, and the energy gap of the compound is increases;③When rigidity enhanced, the fluorescence quantum yield is increasing, and theenergy gap of the compound increased;④The test of DSC and POM show that, thecompounds obtained has the characteristics of self-assembled stacked into aquasi-one-dimensional columnar discotic liquid crystal phase,and they have broadapplication prospects in the organic semiconductor material, organic solar cells, etc;⑤The film materials we prepard have the capability of sound absorption.With the ldistance of cavity increasing, the better the capability of sound absorption.Thecompound7a、PVDF blends film material has a excellentist absorption capabilityin the five film materials. In the sound waves125Hz~4000Hz frequency range, itgot average absorption coefficient was at74.9%at the distance of cavity was8cm,and the maximum absorption coefficients reached99.1%.