Design And Synthesis Of Molecules Based On Trithiasumanene With Photophysical Properties

Organic materials have been widely applied in various organic electronic devices such as organic light-emitting diodes,organic photovoltaic cells,organic field-effect transistors,and molecular switches.In comparison to inorganic materials,the organic ones shows advantages in low-cost,easy fabrication,light weight,and large-area production.It has been well documented that the oxidation of thienyl sulfur into its S,S-dioxide form would result in two significant variations on the electronic properties of the resulting materials:(i)conversion of the p-type semiconductors into the n-type ones by increasing the electron affinity;(ii)enhancement of photoluminescence efficiency in solid state,which is beneficial to high performance OLEDs and optically pumped lasers.In the present thesis,we reported the design and synthesis of novel organic functional molecules derived from the electron-rich and bowl-shaped molecule trithiasumanene.We have investigated the chemical reactivity of this compound,and carried out the selective oxidation of it to prepare the donor-acceptor type system.The electronic and/or photophysical properties of the resulting molecules and corresponding solids are evaluated.The contents of this thesis are as following.In Chapter 1,we firstly made a brief introduction about the design and classification of organic semiconductors.Then,we focus on the recent progress of thiophene S,S-dioxides based organic functional materials.Finally,we introduced our strategies on molecule design,synthesis and assembly.In Chapter 2,we reported the investigation of the reactivity of trithiasumanene.Trithiasumanene is an electro-rich molecule with high rain string to show a bowl-shaped conformation.According to its structural and electronic feature,the selective oxidation of sumanene was performed as following:(1)the thienyl sulfur was converted to thiophene S,S-dioxides by employing hydrogen peroxide(H2O2)as the oxidant;(2)one of the flank benzene rings is opened upon oxidation by Oxone(potassium peroxymonosulfate).The driving force for the ring-opening oxidation is mainly attributed to the electron rich feature of trithiasumanene since both butoxy groups and sulfur bridges are electron-donating units,yet the ring strain would be also taken into account as the curved-system decreases the aromaticity.On the basis of this ring-opening reaction,a "molecular surgery" type functionalization of trithiasumanene leads to the creation of a series of unprecedented donor-acceptor type[5-6-7]-fused polyheterocycles,which can be employed to prepare multiple-ring fused conjugated polyheterocycles by means of convenient functional group transformation.In Chapter 3,we reported the solid state structures and photophysical properties of oxidation derivatives of trithiasumanene,as well as their assembly.The ring-opening products of the trithiasumanene show the almost planar conjugated?-system.The absorption and emission bands of these compounds show the distinct red-shifts as compared with triathiasumanene,which is due to the co-existence of electron-donating and-withdrawing groups,say the D-A type structure to lowering the HOMO-LUMO energy gap.Moreover,the emission bands of these compounds show the obvious red-shifts as the polarity of the solvents increases,that is the positive solvatochromism.When the trithiasumanene is oxidize to corresponding S,S-dioxide,the absorption band also shows red-shift.This compound can form the D-A type co-crystal with HBT(2,3,6,7,10,11-hexabutoxytriphenylene)in the molar ratio of 1:1.Crystallographic studies indicated that the S,S-dioxide of trithiasumanene possess planar ?-conjugated system.The co-crystal crystallizes in the non-centrosymmetric space group,which is also proved by the solid state CD spectra.Compared with both single components,the co-crystals show the clearly red-sifted emission,indicating the existence of the intermolecular electronic transition between two components.Theoretical investigation indicates that the HOMO and LUMO orbitals are mainly on the HBT and trithiasumanene S,S-dioxides,respectively.