Design,Synthesis And Performance Study Of Organic Functional Molecules Based On Azulene And Naphthalene Diimide

Azulene is a non-benzenoid aromatic hydrocarbon,with beautiful blue color and a large molecular dipole moment（1.08 D）.Azulene is composed of an electron-deficient seven-membered ring and an electron-rich five-membered ring.Azulene has some unique characteristics such as non-mirror symmetry frontier molecular orbital（HOMO/LUMO）,low energy gap and anti-kasha regular fluorescence.Therefore,azulene is an ideal building block for constructing new organic functional molecules.In this thesis,a series of organic optoelectronic functional molecules based on azulene are designed and synthesized.Their physical/chemical properties,the performance of single molecule devices and organic field effect transistor（OFET）are studied.The dissertation mainly includes the following parts:1.The 2,6-azulene and 2,7-fluorene-based conjugated molecule T1 functionized by two end NH₂ groups was designed and synthesized,and its physicochemical properties were studied by TGA,DSC,UV-Vis absorption spectroscopy and cyclic voltammetry（CV）measurements.T1 has excellent thermal stability and reversible proton response.The molecular FET device of T1 was fabricated,and the performance of its single molecule device was studied preliminarily,where the obvious gate-response characteristic was observed with the switch ratio of up to 557.The results demonstrate great potential of azulene derivatives for single molecule FET.2.Two isomers of azulene and IDT-based compounds T2 and T3 were designed and synthesized,according to the different connections of azulene units with IDT through the electron-rich five-membered ring and the electron-deficient seven-membered ring of azulene,respectively.The physical and chemical properties of T2 and T3 were studied by TGA,DSC,UV-Vis absorption spectrum and CV measurements.The proton response of T2 and T3 was studied,both compounds have reversible proton-response characteristics.In addition,OFET device based on T2 and T3 showed an order of magnitude difference of charge mobility,with hole mobilities of 4.14×10^-33 cm²V^-1s^-1 and 1.05×10^-5 cm²V^-1s^-1, respectively.The different connections of IDT and azulene units through the electronic rich five-membered ring and the electronic deficient seven-membered ring of azulene greatly affect the device performance of IDT and azulene-based organic functional materials,providing valuable insights for developing azulene-based organic semiconductors and single molecular devices.3.Two isomeric conjugated small molecules based on 1,4,5,8-NDI and 1,2,5,6-NDI,T4 and T5,were designed and synthesized.Their physical and chemical properties were studied by TGA,DSC,UV-Vis absorption spectroscopy and CV measurements.The single molecular junctions of T4 and T5 were prepared,and their conductivity was measured in the ionic liquid BMIPF₆.When applied 0.1 V on the molecular junctions in BMIPF₆,the conductivities of T4 and T5 were 10^–3.7 G₀ and 10^–3.9 G₀,indicating that T4 has a better conductivity.The results indicate that the isomeric structure of conjugated molecules has great impact on the performance of single molecular devices,and provide valuable insights for designing NDI and azulene-based single molecular devices.