| Liquid crystals are intermediate mesophases between highly ordered crystals and disordered isotropic liquids.Due to the ?-? stacking interaction of the aromatic core,the discotic liquid crystal molecules are easy to assemble into a one-dimensional columnar structure,and further self-assembled to form various two-dimensional columnar mesophases.Because of the onedimensional charge transport property along the aromatic column axis,it is widely used in various organic semiconductor optoelectronic devices.Gold nanorods(GNRs),as typical anisotropic nanoparticles,have excellent photothermal effects and shape-controlled plasma resonance properties.The next generation of multifunctional nanomaterials requires metal materials that are monodisperse,controllable in size and shape,and therefore are particularly important for the assembly of nanoparticles.The discotic liquid crystal is characterized by both order and fluidity,and is a potential candidate for mediating self-assembly of nanoparticles.There are some reported examples of discotic liquid crystal and gold nanorod composites in the literature.However,due to the obstacle in direct functionalization of GNRs with ligands of triphenylene,it is difficult to study the effect of directly linked triphenylene with various short spacers on the assembly of gold nanorods.In this thesis,we first realized the covalent linkage of S-Au bond by the method of mixed phase ligand-exchange,and synthesized the organic-inorganic composite materials directly covalently functionalized by discotic mesogens.The composite material can achieve parallel arrangement under the joint effect of the magnetic dipole moment interaction of the gold nanorods and the ?-? interaction of the surface-attached triphenylene discotic mesogen ligands.And when the spacer is short,three-dimensional(3D)vertical standing and side-by-side alignment occurs.When the spacer length is 4-12 methylene,as the spacer grows,the 2D parallel assembly can be formed,with the longest one ranged up to the ?m level.Most importantly,the distance between the parallel rows of gold nanorods can be precisely controlled by just adjusting the spacer length of the triphenylene ligands.Furthermore,we studied the effect of GNRs on the charge-carrier mobility properties of discotic liquid crystals H4TP and H6TP doped by the TPC2-S-GNRs and TPC12-S-GNRs composites.The doped complex samples still exhibited good liquid crystal phase behaviors.By shearing the sample at liquid crystalline phase,it was found that the fully symmetric discotic liquid crystals can well realize the macroscopic alignment of the doped GNRs with the alignment efficiency reaching 92%.By evaluating the carrier mobility properties of the doped complex discotic liquid crystal samples with TOF,most of the samples exhibited higher hole mobility than pure H4TP/H6TP due to the addition of GNRs,with H4TP+1 wt%TPC2-S-GNRs showing the highest hole mobility of 3.737×10-2cm2V-1s-1,which is 1 to 2 orders of magnitude higher than that of the ordinary small molecule,and the hole mobility of the long spacer length mixed sample TPC12-S-GNRs is even greater than that of the short one doped complex system. |
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