| Summary: | 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.
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