Design And Synthesis Of Molecular Diodes Based On Azulene Structure

A series of azulene contained molecular diodes were designed and the synthesis towards these new type of molecular diodes was carried out. The azulene backbone and its 2,6-modified derivatives were synthesized successfully. The compound 2-(naphthalen-2-yl)azulene (A-N), which was the coupling product of azulene with its isoelectronic isomer naphthalene, have been synthesized. The optical properties of A-N and its single crystal structure were studied. The results show that the azulene contained molecules exhibit unique properties and may be applicable to novel molecular devices.This paper consists of three parts as follows:First, a series of azulene contained molecular diodes were designed, and the key structure 2,6-positions modified azulene was obtained. Based on theoretical computation,2,6-positions modified azulene can be applicable to novel molecular diodes. Different active functional groups or conjugated units were attached to the 2, 6-positions of azulene to control the molecular orientation in self-assembled monolayers. The synthesis of 2,6-modified azulene laid good foundation for the further molecular diode synthesis.Second, the compound 2-(naphthalen-2-yl)azulene (A-N) was synthesized via the Suzuki coupling reaction. The optical properties and theoretical calculation suggest that the A-N have strong electron delocalization, and the aromatic delocalization energy of azulene is lower than benzene, thiophene, naphthalene and other aromatics. The single crystal structure analysis of A-N shows that it crystallizes with two reasonably similar molecules in the asymmetric unit. The crystal structure exhibits two sets of parallel layers, with a typical edge-to-face herringbone packing arrangement. The structure is stabilized by an extensive series of weak C-H…πinteractions. All the special characters argue that azulene and its derivatives may have good potential applications in various areas of molecular electronic materials. Third, the synthesis of a series of OPE molecular wires was carried out. The synthesis of biphenyl and its methyl derivatives contained OPE molecular wires was carried out as part of the work towards investigating single molecular conductance in our group.