One-Dimensional Array of Au Nanoparticles Fixed on Nanofibers of Organogelators by the Langmuir−Blodgett Method

Abstract

The Langmuir-Blodgett (LB) method was applied to low molecular weight organogelator N-[N-(6-hydroxyhexyl)-3-carbamoylpropyl]-3,4,5-tris(dodecyloxy)benzamide (1) to form molecular-assembly fibers on a solid substrate. Molecule 1 formed a stable monolayer up to 40 mN/m at the air-water interface. The monolayer was transferred onto a mica surface at 35 mN/m. In the transferred film, fibrous structures with typical dimensions of 1.2 nm (height) × 50-100 nm (width) × 5-10 µm (length) were observed by atomic force microscopy. These structures were ordered in specific directions, reflecting the C 6 surface crystal symmetry of mica. Lateral modulation frictional force microscope measurements revealed that the fibrous structures had high crystallinity and that the surface groups were hydrophilic. These results enabled us to construct functional fibers by introducing functional units into the hydrophilic part of molecule 1. N-[N-(6-Aminohexyl)-3-carbamoylpropyl]-3,4,5-tris(dodecyloxy)benzamide hydrochloride (2) has an ammonium moiety instead of the terminal alcohol moiety of 1. By adding 2 to 1, we introduced adsorption sites for Au nanoparticles on the surface of the fibrous structure. By casting a Au nanoparticle suspension onto this fibrous structure, we successfully constructed Au nanoparticle arrays in which Au nanoparticles were adsorbed on a mixed fibrous structure of 1 and 2 on mica substrates.

Fullerene Nanowires: Self‐Assembled Structures of a Low‐Molecular‐Weight Organogelator Fabricated by the Langmuir–Blodgett Method

“…ADT forms stable orgnanogels at room temperature with, for example, CCl 4 . [17] Figure 3a shows IR spectra for solutions of ADT in CCl 4 (1-10 mm) and the ADT gel. Once the 10 mm solution was cooled to 277 K, gelation occurred and the gel was stable at room temperature.…”

“…ADT, compound 4, and N-triphenylmethylpyrrolidine-C 60 were prepared according to previously reported methods. [17,19] All reagents and solvents were purchased from commercial suppliers and were used as provided. Compounds were characterized by 1 H NMR spectroscopy, mass spectroscopy and elemental analysis.…”

“…[16] In our investigations on LB films of organogelators, we recently reported the fabrication of nanofiber structures of a derivative of 3,4,5-tris(dodecyloxy)benzamide (ADT) on a solid substrate. [17] The molecule has an amphiphilic property in addition to gelation ability, which allows application of the LB method. In the LB films, fibrous structures with a height of 1.2 nm and a width of 50-100 nm were observed.…”

“…An excellent technique for immobilization of self‐assembled nanostructures on solid substrates is the LB method 14. Although the LB method has been used to prepare two‐dimensional molecularly thin films, quasi‐one‐dimensional nanostructures have often been observed in LB monolayers,15–17 for example, when molecules exhibit strong anisotropic intermolecular interactions. We have reported the formation of nanowires based on an amphiphilic bis(tetrathiafulvalene)‐substituted macrocycle on a mica substrate using the LB method.…”

“…As a result of one‐dimensional π–π stacking and intermolecular S⋅⋅⋅S interaction between the tetrathiafulvalene moieties, nanowire structures were formed in the LB films 16. In our investigations on LB films of organogelators, we recently reported the fabrication of nanofiber structures of a derivative of 3,4,5‐tris(dodecyloxy)benzamide (ADT) on a solid substrate 17. The molecule has an amphiphilic property in addition to gelation ability, which allows application of the LB method.…”