  Low temperature magnetic properties were investigated on the gold nano
particles (GNP) with an average size of 11.5 nm, assembled with molecules of
ruthenium complex (Ru0) and phenylboronic acid (B0) by the proton nuclear
resonance (1H-NMR) and susceptibility measurements. The temperature dependence
of the NMR shift and the uniform susceptibility was described as the sum of the
Curie-Weiss term and a positive constant term. From the former, the average
number of Ru0 on each GNP was estimated to be 118, which is 23 % of the
calculation. The finite positive constant term shows a clear contrast with the
well-known fact that the bulk gold is diamagnetic. Finally, a disappearance of
the motional narrowing effect in the proton NMR spectra below 60 K indicates
that the wavering motion of Ru0 complexes on GNP at room temperature is frozen
at low temperatures.
