Self-assembly directed synthesis of gold nanostructures

Gold nanocrystals are prepared in an aqueous medium consisting of an inclusion complex formed between β-cyclodextrin (β-CD) and 4-amino thiophenol (AT) by the reduction of HAuCl4 using NaBH4. The inclusion complex, β-CD/AT-IC is expected to play different roles in the preparation of Au nanocrystals. β-CD/AT-IC stabilizes the Au nanocrystals preventing agglomeration and provides self assembly environment for forming nanostructure around Au nanocrystals. Field emission scanning electron micrographs recorded with a lower resolution identify the nanotubular formation. Nanotubular structure is expected from the coalescence of self-assembled β-CD/AT-IC protected Au nanocrystals. Energy dispersed X-ray diffraction patterns of the nanotubes indicate the existence of Au nanocrystals inside the tubes. The molar ratio of the inclusion complex to HAuCl4 influences the size and distribution of Au nanocrystals within the nanotubular channels. Field emission transmission electron micrographs reveal the uniform distribution of Au nanocrystals. UV–vis spectra of the Au nanocrystals colloids reveal that the position and intensity of plasmon resonance peak of Au nanocrystals that are dependent on the molar ratio of the inclusion complex to HAuCl4.