The NIMS-MANA car is a binaphthyl dimer. Naphtyl compounds are composed by two aromatic cycles and are known for their smell. Here, each naphthyl are the paddles of the Nims-Mana car.
Although limited, naphthyl planes of binaphthyl can be fluctuated around the connected bond. This fluctuation is expected to work for a caterpillar-motion. Although one binaphthyl can produce a basic motion, we installed two binaphthyls due to the limitation of sublimation conditions.
We took very simple strategy; only one step to go.
To a mixture of (R)-(+)-1,1'-bi(2-naphthol) (1.00 g, 3.49 mmol) and CsCO3 (2.84 g, 8.73 mmol) in dry acetone (100 mL) was added 1,2,4,5-tetrakis(bromomethyl)benzene (715 mg, 1.59 mmol) and the mixture was refluxed overnight. The mixture was extracted with CH2Cl2 (2 x 200 mL) and concentrated in vacuo. The crude material was purified by silica gel column chromatography (eluent: CH2Cl2/Hexane) to give pure binaphthyl dimer (410 mg, 37%). The compound was further purified by sublimation (< 300 °C) for the STM experiments.
To be submitted
Our nano-car has softness. This is a different characteristic compared with other cars. Our molecule has "hinges", which consist of binaphthyl structures. The hinges worked with good control at the air water interface, as we recently reported (Angew. Chem. Int. Ed. 2015, 54, 8988.). We have not tried on the gold surface, and I will cross my fingers.
We took the strategy, simple is the best.
Before we decided to submit this binaphthyl dimer as a nanocar, we tried several kinds of candidates. Some of them decomposed during sublimation, and some of them we gave up due to too low sublimation temperature. Also fancy substituents were not suitable for sublimation. Finally, we found the simple molecule with a certain molecular weight is suitable as a nanocar.
Anxious and excited.
Although softness is important and studied in molecular sciences, little known in nano-world. Behavior of a soft single molecule on the solid gold surface, which is used in nano car race, is not well known. One interest is to know how the softness of molecule affect on the motion of the molecule.
At the same time, since little is known about the softness in nano-world, our team can suffer from many risks, which is my anxiety.
We are interested in chirality-based motion.
Chirality of molecular structure can affect the chirality of motion.
Since our molecule has chirality (helical chirality based on binaphthyl structure), I expect our molecule to move in right- or left-hand.
This race will help us to understand relation between molecular motion and molecular structure. This knowledge may help us to control nano-machine made of some molecules in future.