  This mini review focuses on conductance measurements through molecular
junctions containing few tens of molecules, which are fabricated along two
approaches: (i) conducting atomic force microscope contacting a self-assembled
monolayers on metal surface, and (ii) tiny molecular junctions made of metal
nanodot (diameter < 10 nm), covered by fewer than 100 molecules and contacted
by a conducting atomic force microscope. In particular, this latter approach
has allowed to obtain new results or to revisit previous ones, which are
reviewed here: (i) how the electron transport properties of molecular junctions
are modified by mechanical constraint, (ii) the role of intermolecular
interactions on the shape of conductance histograms of molecular junctions, and
(iii) the demonstration that a molecular diode can operate in the microwave
regime up to 18 GHz.
