Buckminsterfullerenes have been conjugated to CdSe nanocrystals by exchanging TOPO ligands on the CdSe nanocrystals with C
60-bound dithiocarbamate ligands. To improve solubility of the C
60-capped CdSe nanocrystals, a small molecular weight dithiocarbamate ligand was used as co-ligand in the ligand exchange reaction. The as synthesized (C
60)
8-CdSe conjugates were purified by dialysis against ethanol and characterized by
1H NMR, UV-vis and TEM. Photoelectrochemistry of a film cast from the (C
60)
8-CdSe conjugate revealed a significantly enhanced photocurrent compared with the film of CdSe-TOPO nanocrystals as well as that of C
60 alone, suggesting that our conjugation strategy is viable for efficient photo-induced charge separation, transport and collection.
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Buckminsterfullerenes have been conjugated to CdSe nanocrystals by exchanging TOPO ligands on the CdSe nanocrystals with C
60-bound dithiocarbamate ligands. To improve solubility of the C
60-capped CdSe nanocrystals, a small molecular weight dithiocarbamate ligand was used as co-ligand in the ligand exchange reaction. The as synthesized (C
60)
8-CdSe conjugates were purified by dialysis against ethanol and characterized by
1H NMR, UV-vis and TEM. Photoelectrochemistry of a film cast from the (C
60)
8-CdSe conjugate revealed a significantly enhanced photocurrent compared with the film of CdSe-TOPO nanocrystals as well as that of C
60 alone, suggesting that our conjugation strategy is viable for efficient photo-induced charge separation, transport and collection.
C
60 has been conjugated to PbSe by using the similar strategy to that of the C
60-CdSe nanoconjugate in Chapter 1. The as synthesized C
60-PbSe conjugates were characterized by H NMR, UV-Vis and TEM. The H NMR study shows that the dithiocarbamate ligands has stronger interaction with PbSe nanocrystals than that with CdSe nanocrystals. Photoelectrochemistry of a film cast from the C
60-PbSe nanoconjugate revealed a cathodic photocurrent, although the individual C
60 and PbSe nanocrystals generated anodic photocurrent respectively. The reversed polarity of the photocurrent suggesting the C
60 can serve as p-dopants to the PbSe nanocrystals through the surface transfer doping process.
A Cu(I)-assisted C
60-polymerization method has been developed for the seamless coating on nanosized objects of Cu
2O, forming novel Cu
2O-C
60 core-shell nanostructures. It is based on a reaction of C
60 and ethyl isocyanoacetate to form polymerized fulleropyrolines, catalyzed by and thus coated on the Cu
2O nanomaterials. Cu
2O nanoribbons and nanocubes were used in this work to demonstrate the nano-coating method. The Cu
2O-C
60 core-shell nanostructures were characterized comprehensively, revealing a uniform, covalently-polymerized C
60 shell that closely sheaths the Cu
2O nanostructures. Details of the Cu(I)-assisted C
60-polymerization process are proposed, which combines the solution chemistry and surface chemistry of C
60. The Cu
2O cores in the composite nanocubes could be removed, yielding monodispersed C
60 nanoboxes. Preliminary measurements demonstrated enhanced photocurrent of the Cu
2O-C
60 nanoribbons arrayed on Cu foil compared to that of the Cu
2O nanoribbons.
Two strategies have been explored for organic functionalizations of ZnO nanotetrapods via anchor groups of carboxylate and phosphonate. With these methods, oleyl chains were assembled on surfaces of the ZnO nanotetrapods, significantly enhancing their solubility in nonpolar solvents, such as chloroform and toluene. The surface functionalization strategies have been extended to electroactive and photoactive molecules such as protoporphyrin and C
60 on the ZnO nanotetrapods. The surface modified ZnO nanotetrapods were characterized comprehensively, revealing a uniform, covalently linked monolayer assembled on the surface. This work opens a broad perspective for the application of the organically functionalized nanotetrapods in optoelectronics and biomedicine.
Two-photon luminescence (TPL) spectra were measured to study the effect of protoporphyrin and C
60 to TPL properties of ZnO nanotetrapods. The results show that after modifying with protoporphyrin, the exciton emission of the ZnO nanotetrapods was red-shift for about 30 nm, which may be due to the surface charge transfer doping of protoporphyrin to ZnO nanotetrapods. After modified with C
60, the TPL spectrum of ZnO nanotetrapods was obviously enhanced to the exposure of laser with the intensity of 140 mW. The stable C
60-ZnO nanocomposites may have applications in the nonlinear optical devices.
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