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Structure formation and self-assembly of physisorbed and chemisorbed organic monolayers will be described on electrified solid–liquid interfaces employing in-situ scanning tunneling microscopy (STM) and surface-enhanced infrared spectroscopy (SEIRAS) in combination with electrochemical techniques. We present first a case study on self-assembly by directional hydrogen bonding and its interplay with the electrode potential choosing aromatic carboxylic acids, with an emphasis on 1,3,5-benzene-tricarboxylic acid (TMA). Structure and electrical characteristics of chemisorbed organic monolayers involving the formation of covalent bonds with the substrate surface will be discussed for a series of 4-methyl-4'-(n-mercaptoalkyl)biphenyls on Au(111) electrodes. In an attempt to explore single molecule properties, such as charge transport and redox-mediated tunneling, we subsequently introduce an STM-based technique to construct symmetric and asymmetric metal/(single) molecule/metal junctions. Employing α,ω-alkanedithiols and redox-active derivatives of viologens we demonstrate novel transport and single molecule electrochemical studies, which bear unique novel perspectives for fundamental as well as applied investigations. [ABSTRACT FROM AUTHOR]

Measuring the electronic transport properties of single molecules and molecular nanostructures is an interesting and challenging new frontier from both a fundamental as well as technological perspective. Conducting atomic force microscopy (C-AFM) represents an attractive line of approach given its ability to position a sharp electrical probe with nanometer-scale precision and a controlled nano-Newton-range force. Moreover, the combination of AFM imaging and C-AFM electrical characterization enables investigation of the relationship between structure and function in molecular architectures. The aim of the present review is twofold: (1) to introduce the C-AFM method, alongside a discussion of experimental practices, capabilities and limitations, and (2) to provide an overview of the application of C-AFM to different types of molecular systems. These include alkane-based and oligomer-based self-assembled monolayers, molecular crystals, conducting polymer films, molecular wires (e.g. carbon nanotubes), and electrically active biomolecules. We will also discuss C-AFM approaches that allow single molecule measurements as well as other recent developments. [ABSTRACT FROM AUTHOR]