Tomoaki Nishino

Understanding electron transfer (ET) from a single molecule to another single molecule holds essential importance to realize bottom-up molecular devices in which constituent molecules are self-assembled via noncovalent interactions between each other. However, rather little is currently known about the ET properties at the single-molecule interface. Here we employ molecular tips to quantify the ET through a H-bond between single molecules. We found that a H-bond conducts electrons better than a

Carboxyl-terminated single-walled carbon nanotubes (SWNTs) were successfully immobilized from solution phases onto the apexes of gold tips for scanning tunneling microscopy (STM). Gold STM tips were first modified with self-assembled monolayers of 4-mercaptobenzoic acid, and its carboxyl groups were used to anchor carboxylated SWNTs through Zn2+ ion-bridged coordination. These SWNT tips gave high-resolution STM images of a diether monolayer formed on the graphite surface. In addition and more im

A fullerene molecular tip was used to detect electron tunneling from a single porphyrin molecule. Electron tunneling was found to occur locally from an electron-donating moiety of the porphyrin to the fullerene through charge-transfer interaction between them. In addition, electron tunneling within the single fullerene–porphyrin pair exhibited rectifying behavior in which electrons can be driven only at the direction from the porphyrin to the fullerene. It is demonstrated that localized electron

This chapter contains sections titled: Introduction Scanning Tunneling Microscopy Atomic Force Microscopy Conclusion References

Gold tips modified with self-assembled monolayers were used for the scanning tunneling microscopy (STM) observation of monolayers of dihexadecyl ether and 1,11-bis(hexadecyloxy)undecane physisorbed onto highly ordered pyrolytic graphite. The ether oxygens gave dark lines in STM images measured with unmodified and thiophenol-modified tips. In contrast, they appeared as bright lines in images observed with tips modified with 4-mercaptobenzoic acid, allowing the selective recognition of ether oxyge

Molecular tips were used to investigate electron transfer through metal-coordination bonds between single molecules. Coordination of a single metal ion to two carboxylate-terminated thiolate molecules formed a sandwich-type single molecular junction. It was found that a favorable charge transfer is induced through such molecular junctions. The electron transfer facilitated by metal coordination was utilized to implement conductance switching in a molecular junction of a head-to-head pyridine dim

The single-molecule conductance of DNA was found to increase by over four fold upon intercalation, while the conductance nearly unaltered upon groove-binding. These effects are interpreted on the basis of the electronic interaction of the DNA-binding molecules with the stacked DNA bases.

A DNA molecule was utilized as a probe tip to achieve single-molecule genetic diagnoses. Hybridization of the probe and target DNAs resulted in electron tunneling along the emergent double-stranded DNA. Simple stationary monitoring of the tunneling current leads to single-molecule DNA detection and discovery of base mismatches and methylation.

Single-stranded DNA was utilized as a probe tip for single-molecule DNA detection. Hybridization of the DNA tip and target DNA induces electron tunneling through the resulting DNA duplex. It is demonstrated that the DNA tip allows not only genetic detection but also discovery of single-nucleotide polymorphisms at the single-molecule level.

Chiral surfaces attract increasing interest due to their vital role in a variety of scientific fields, such as chiral separation and heterogeneous enantioselective catalysis. The most urgent issue in research on such two-dimensional chirality is a lack of methodologies that recognize molecular chirality on a surface. Here we show that the chiral molecular tips enable for the first time discrimination of enantiomers on a single-molecule basis. The chiral selectivity is attributed to favorable che

Herein, we report on the kinetic investigation for the breakdown of single-molecule junctions.

Scanning tunneling microscopy tips were functionalized with a boronic acid derivative. In combination with a similarly modified substrate, the molecular tip forms a supramolecular complex selectively with a glucose molecule. The conductance of the resulting single complex allows one to achieve the specific single-molecule detection of glucose.

We describe herein the concept, principle, and experimental results of molecular tips for chemically selective scanning tunneling microscopy. It has been shown that molecular tips allow chemically selective imaging to recognize particular functional groups or chemical species on the basis of the hydrogen bond, metal coordination, and charge-transfer interactions between the sample and tip molecules. The selectivity can be tailored upon designing functional groups of the tip molecules. Furthermor