Self-assembled monolayers (SAMs) of 1,1′-disubstituted ferrocene derivatives, i.e., 1,1′-bis(11-mercaptoundecyl)ferrocene (1) and 1-decyl-1′-(11-mercaptoundecyl)ferrocene (2), on a gold surface were prepared, and their structural and electrochemical properties were characterized by reflection-absorption infrared spectroscopy (RAIRS), ellipsometry, cyclic voltammetry (CV), and subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS). From the RAIR spectral features, both molecules, 1 and 2, were found to chemisorb on gold as thiolates after deprotonation. The peak positions of the methylene stretching modes indicated that the alkyl chains of 1 and 2 assume disordered structures on the gold surface. The thicknesses of the monolayers 1 and 2 on gold were determined by ellipsometry to be 2.27 ( 0.10 and 2.30 ( 0.10 nm, respectively. In the CV experiments, symmetric redox peaks were identified at ca. 0.32 and 0.30 V versus saturated calomel electrode (SCE) for the SAMs of 1 and 2, respectively. The surface coverage values determined from the CV of 1 and 2 were 3.4 × 10 -10 and 3.2 × 10 -10 mol/cm 2 , respectively. Both SAMs at full-coverage limits were stable in neutral (0.2 M NaClO4) as well as in acidic (0.2 M HClO4) medium, suggesting that hardly any decomposition of the ferricinium cation occurred for the SAMs prepared from disubstituted ferrocene derivatives. In particular, the SAMs of 1 were stable irrespective of the surface coverage, displaying the bonding capability of dithiols to gold; the submonolayer of 2 was slightly unstable in neutral medium. The SNIFTIR spectral data suggested that the alkyl chain of the two SAMs takes a more upright orientation when the ferrocene moiety is oxidized to a ferricinium cation.

[Ru([D 14 ]-ph 2 phen)]Cl 2 (2b) (where bpy ) 2,2′-bipyridine, ph 2 phen ) 4,7-diphenyl-1,10-phenanthroline) the emission at 520 nm persisted for times beyond 200 ps. Our original assignment was that the longerlived emission from the deuterated complexes was from the same excited state as the short luminescence lifetime for the non-deuterated complex. We now believe this to be in error. This new conclusion stems from our continuing investigations which, although confirming that both deuterated and nondeuterated ruthenium complexes give ultrafast luminescence (on 4 ps time scales), reveal that the observation of the longer-lived emission for the deuterated ruthenium complex prepared by other synthetic routes cannot be confirmed in every case.Due to the susceptibility of luminescence measurements to interference from artifacts such as sample impurities, we originally undertook extensive investigations involving the study of the free ligand and the corresponding Fe(II) and Os(II) complexes, both perprotio and perdeuterio, as well as multiple purification steps of the complexes, with several independently prepared batches of samples. While we are presently unable to explain the source of the long-lived emission, it is certain that free ligand is not responsible. It is also certain that the observation of the longer-lived emission is linked directly to the deuteriation process but not specifically to the deuterated complexes themselves.