| Phthalocyanines and porphyrins complexes with high chemical and thermal stability and unique macrocyclic π-conjugated electronic structures are the important member of organic semiconductors.They are also the good gas sensing materials because their semiconducting properties can be changed after exposing them to electron-donating or electron-accepting gases.In this thesis,three sandwich-type phthalocyanine/porphyrin europium complexes are synthesized and their structures were characterized by various techniques.Their supramolecular aggregates are prepared by a solution-based self-assembly.The gas sensing properties are studies.The main contents are as follows.1.An amphiphilic mixed(phthalocyaninato)(porphyrinato)europium triple-decker complex Eu2(Pc)2(TPyP)[TPyP=dianion of 5,10,15,20-tetra(4-tert-pyridyl)porphyrin,Pc=phthalocyaninate]has been synthesized and characterized.Introducing electron-withdrawing pyridyl substituents onto the meso-position of porphyrin ring in the triple-decker to ensure the sufficient hydrophilicity and suitable HOMO and LUMO energy levels and thus successfully realize amphiphilic ambipolar organic semiconductor.Importantly,high sensitive,reproducible p-type and n-type responses towards NH3 and NO2 respectively,based on the self-assembled film of the Eu2(Pc)2(TPyP)fabricated by a simple solution-based Quasi-Langmuir-Shafer(QLS)method,have been first revealed.The good conductivity and crystallinity for the QLS film of Eu2(Pc)2(TPyP)render it excellent sensing property for both electron-donating gas NH3 in 5-30 ppm range and electron-accepting gas NO2 in 400-900 ppb range due to the optimized molecular packing in the uniform-sized nanoparticles depending on the effective intermolecular interaction between the triple-decker molecules,among the best results of phthalocyanine-based chemical sensors for room-temperature detection of NH3 and NO2,respectively.Furthermore,the responses of the QLS film are all linearly correlated to both NH3 and NO2 with an excellent sensitivity of 0.04%ppm-1 and 31.9%ppm-1,respectively,indicating the great potential of semiconducting tetrapyrrole rare earth triple-decker compounds in the field of chemical sensors2.A mixed(phthalocyaninato)(porphyrinato)europium triple-decker complex,named(TPyP)Eu2[Pc(OC4H9)8]2[TPyP=dianion of 5,10,15,20-tetra(4-tert-pyridyl)porphyrin,Pc(OC4H9)8=2,3,9,10,16,17,23,24-octabutoxyphthalocyaninate]is synthesized and characterized by MALDI-TOF,1HNMR,UV-visible spectra and differential pulse voltammetry techniques.Introduction of electron-donating butoxy groups at the periphery of the phthalocyanine ligands and electron-withdrawing pyridyl substituents onto the meso-positions of porphyrin ring not only increases the solubility of the triple-decker but successfully tunes the HOMO and LUMO energy levels into a soluble ambipolar organic semiconductor.A simple quasi-Langmuir-Shafer(QLS)method is used to fabricate a self-assembled film of(TPyP)Eu2[Pc(OC4H9)8]2.The excellent sensitivity,reproducible n-type and p-type responses to electron-accepting gas NO2 and electron-donating gas NH3 are found for the films of(TPyP)Eu2[Pc(OC4H9)8]2 complex at room temperature.Detection limit towards NO2 and NH3 is as low as 0.4 ppm and 1 ppm,respectively,with percentage current change of 4.2%and 1.6%,depending on the uniform molecular packing and intermolecular interactions among the triple-decker molecules.The present results represent not only the excellent example of ambipolar triple-decker phthalocyanine-based sensors obtained by a solution-based method but more importantly,provides a new strategy for the molecular design to obtain soluble ambipolar organic semiconductors in sensor device fabrication3.A new hybrid is developed by mixing Eu[Pc(OC4H9)8]2 with acidified multiwalled carbon nanotubes(aMWCNTs)through non-covalent interactions.The formation of hybrid increases the conductivity of Eu[Pc(OC4H9)8]2 and the surface area of phthalocyanine double-decker.The obtained hybrid is fabricated by a simple Quasi Langmuir Shafer(QLS)technique.The stacking mode observed in both Eu[Pc(OC4H9)8]2/aMWCNTs hybrid and Eu[Pc(OC4H9)8]2 is J-type aggregates.Ambipolar gas sensing response is observed for both Eu[Pc(OC4H9)8]2/aMWCNTs hybrid and Eu[Pc(OC4H9)8]2 double-decker complex.The n-type and p-type response is shown by the Eu[Pc(OC4H9)8]2/aMWCNTs hybrid film at room temperature.However,aMWCNTs are sensitive to only oxidizing NO2 gas.The sensitivity and detection limit of the hybrid film are better than those of pure Eu[Pc(OC4H9)8]2.The detection limit of hybrid for ammonia and nitrogen dioxide gas is 0.5 ppm and 0.3 ppm,respectively... |
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