Properties Of Chemical Sensors Based On Solution-Processed Porphyrin/Phthalocyanine Materials

Porphyrins and phthalocyanines have received wide attention because of their unique physical and chemical properties.The chemical and physical properties of porphyrins and phthalocyanines can be tuned by introducing various substitutes on the periphery of the phthalocyanine and/or porphyrin macrocycle（s）,various metals at its central cavity and extendingπ-networks along the axis perpendicular to the macrocycle plane.In this thesis,several phthalocyaninato and/or porphyrinato rare earth complexes are designed and synthesized.Then these molecules are self-assembled into nano/microstructures with different morphology depending on various intermolecular interactions.The relationship between molecular structures,nano/microstructures and the semiconducting performance of the complexes has been established.The main contents of this thesis include the following points:1.High-performance ambipolar responses toward oxidizing NO₂ and reducing NH₃ based on the self-assembled film of an amphiphilic tris（phthalocyaninato）europium complexA heteroleptic amphiphilic tris（phthalocyaninato）europium triple-decker complex,（Pc）Eu{Pc[（OC₂H₄）₃OCH₃]₈}Eu{Pc[（OC₂H₄）₃OCH₃]₈},is designed and synthesized successfully.The hydrophilic polyoxyethylene substituents attached onto the periphery of two phthalocyanine rings in the sandwich-type phthalocyaninato triple-decker,not only increase the solubility and improve the film-forming ability,but importantly ensure the suitable HOMO and LUMO energy levels and thus successfully realize amphiphilic ambipolar organic semiconductor.The solution-processed thin film of the complex is prepared by a simple and low-cost quasi-Langmuir-Sh?fer（QLS）method.Importantly,within the dynamic exposure period of 30 s,highly sensitive,stable,reproducible n type response towards electron-accepting gas NO₂ in 50-500 ppb range and p type response to electron-donating gas NH₃in 5-25 ppm range,respectively,have been first revealed,based on the QLS film of complex at the room temperature,depending on the optimized molecular packing in J aggregation mode with large specific surface area and good film-conductivity.Furthermore,the responses of the QLS film are all linearly correlated to either NO₂or NH₃ with good sensitivity of 0.06%ppb^-1 and 0.17%ppm^-1,respectively,indicating the great potential of phthalocyanine-based rare earth triple-decker complexes in the field of chemical sensors.The present result provides a new strategy to obtain high performance room-temperature gas sensors by the molecular design combined with a low-cost solution-based method.2.High-sensitive NO₂ sensor based on a series of fluorine substituted metal phthalocyanineIn this thesis,three phthalocyanine-based compounds with electron-withdrawing trifluoroethoxyl substituents,H₂[Pc（OCH₂CF₃）₈]（1）,Co[Pc（OCH₂CF₃）₈]（2）and Eu[Pc（OCH₂CF₃）₄]₂（3）have been synthesized and fabricated into organic microstructures by a phase-transfer method.The UV-vis spectra showed that the electron absorption peaks of the three aggregations are blue-shifted relative to their monomers,which can be ascribed to the formation of face-to-face packing mode（H type aggregates）.In addition,the order for the intensity of intermolecular interactions is（3）<（2）<（1）.Different molecular structures and intermolecular interactions result in the morphology of compounds（1）and（3）as three-dimensional micro rods and microspheres and compounds（2）as one-dimensional nanoribbon.Notably,the resulting microstructures are revealed to show good semiconducting properties and the conductivity of Co[Pc（OCH₂CF₃）₈](9.75×10^-7 S cm^-1),Eu[Pc（OCH₂CF₃）₄]₂(3.333×10^-6 S cm^-1)and H₂[Pc（OCH₂CF₃）₈](4.266×10^-6 S cm^-1)is increasing sequentially.Moreover,during the dynamic exposure period of 30 s,the excellently sensitive,stable and reproducible n type responses toward electron-accepting gas NO₂ have been revealed for three aggregations at room temperature.Co[Pc（OCH₂CF₃）₈]with larger specific surface area and low background current exhibits excellent gas sensing properties with the highest sensitivities(0.035%ppb^-1)and the lowest detection limit（100 ppb）among the three aggregations.3.Excellent-performance chemical sensors based on a novel multifunctional porphyrinIn this thesis,a novel porphyrin-cyclodextrin compound 2,4,6-trimethoxy cyclodextrin-porphyrin(Zn T[(OC₈H₁₇)₃（M-CD）]PP)has been successfully designed and synthesized.The film of compound assembled by quasi-Langmuir-Sh?fer（QLS）method.The results imply that the molecules are enforced to adopt the J aggregation mode with uniform-sized micropartricles in the QLS films.At the room temperature,the highly sensitive,stable and selective response to NO₂,in addition,the selective detection of bisphenol A（BPA）are revealed based on the QLS films.Furthermore,an electrochemically active layer has been successfully constructed by a mixture of Zn T[(OC₈H₁₇)₃（M-CD）]PP with graphene oxide（GO）.The resulting electrochemical sensor exhibits a highly sensitive performance toward bisphenol A（BPA）with a detection limit as low as 0.33μM.The present work provides a promising strategy towards developing dual functional electrochemical sensors by taking advantage of both the molecular recognition of cyclodextrin macrocycles and good catalytic activity of porphyrins.