New star-shaped mesophase & phosphorescence emitting materials: synthesis, mesomorphic behavior, and photophysical properties

• Main Authors: Yueh-Ju Wang, 王月汝
• Other Authors: 賴重光
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/79515940394507688733

博士 === 國立中央大學 === 化學研究所 === 95 === Part I: In this thesis, a new type of organic mesogenic materials is prepared and studied, in which a non planar structure, triphenylamine (TPA) is applied as core group and weak interaction such as H-bondings and/or π-π interaction was used to induce the mesogens. Also, their interesting mesomorphic behavior, optical properties and electrochemical properties resulted from core TPA were investigated. The phase behavior of these mesogenic compounds was characterized and studied by differential scanning calorimetry, polarized optical microscopy and powder XRD diffraction. The mesophase observed by all compounds were found to be side dependent. Compounds appended with one, two or three side chains exhibited lameller columnar (ColL) phases, and compounds with four or six side chains formed hexagonal columnar (Colh) phases. The formation of the mesophase, lamellar or columnar mesophases was probably induced by H-bonding formed between -CH2NH groups. Introductionof H-bonding and dipole was attributed for the better mesomorphic behavior. Also π-πinteraction was found important in the formation of the mesophases. The optical and electrochemical properties was studied by UV-vis, photoluminescence and cyclic voltammetry (CV). All compounds derived from TPA showed good reversible redox behavior, and the substituents on the nitrogen atom and/or the numbers of the terminal alkoxy chains showed an apparent effect on the physical properties. Part II: A new family of Iridium(III) complexes derived from oxadiazole and thiodiazole derivatives as ligands was prepared and their potential applications as light emitting materials was also studied. By choosing a variety of electrondonor and electron withdrawing groups, an increase/decrease in molecular resonance length or/and changing different monodentate ligand, a quite wide range of emitting wavelengths observed by these luminescence materials were obtained. A few single crystal structures of iridium(III) complexes were also resolved and analyzed. The replacement of oxygen atom by sulfur atom in chromophore a red shift about 28-68 nm in the emitting wavelength was found. Both The relative energy on the HOMO and LUMO orbitals was changed by electron-donor or electron-withdrawing group. On the other hand, the LUMO can also be adjusted by resonance lengths. By using those methods mentioned above, red emitting and green emitting materials were prepared in this thesis. The physical properties studied by UV-Vis, photoluminescence and cyclic voltammetry were also studied and discussed.