Two macrocyclic squares (one with four Pd 21 corners, the other with four Pte+ corners) were synthesized according to literature methods."2 The charge-transfer complexes which formed when each were mixed with a bis(thiol)hydroquinone were then studied by UV-VIS, NMR, and IR spectroscopy. The UV-VIS data obtained indicated a stoichiometric relationship of I mole of molecular square to 2 moles of dithiol and a very large binding constant. Further evidence for the association between each macrocyclic square and the dithiol was observed in the NMR spectrum by the shifting of the proton resonances on the bipyridine unit of the molecular square and in the IR spectra by the changes in the aromatic ring absorptions of the dithiol and the bipyridine ring absorptions of the square.A monolayer formed on gold from a dilute solution of the dithiol in ethanol and a monolayer formed from a dilute solution of a 6:1 ratio of molecular square to dithiol were each observed by infrared grazing angle spectroscopy. The spectrum of the dithiol monolayer indicated that the aromatic ring was oriented perpendicular to the gold surface. The infrared spectrum of the square/dithiol monolayer showed the presence of triflate absorptions and methyl stretches, suggesting the square was attached via a catanane formation. Furthermore, the spectral data indicated that upon formation of the catanane, the aromatic ring of the dithiol and the bipyridine rings of the square were oriented parallel to the gold surface. / Department of Chemistry

We plan to study the attachment of a cationic tetranuclear palladium II-based macrocyclic square onto a planar gold surface or a gold nanoparticle. To understand the possible mechanisms of attachment of inorganic molecular square to gold we will see if certain related salts can cause an induced aggregation of nanoparticles.The replacement of the surface-passivated citrate layer on the gold nanoparticles can be characterized by infrared spectroscopy and shifts in the surface plasmon resonance band. Consequently, if it can bond gold nanoparticles via electrostatic interactions, then it may be possible that the square can attach to a planar gold surface by a similar mechanism.Infrared spectra of the aggregated nanoparticles will be compared to those obtained using the attachment of molecular square on a planar gold surface. By comparing.infrared spectra it may be possible to determine by what mechanism the square is attaching to gold. / Department of Chemistry