Binding of Cd2+ to Self-Assembled Bilayers Bearing Pyridine Terminal Groups: Attenuated Total Reflection Fourier Transform Infrared Spectroscopic Studies.

Date Published:



Various aspects of the adsorption of Cd2+ on self-assembled monolayers (SAMs) of 4-heptadecylpyridine (HDpy) and 4'-tridecyl-4-Me-2,2'-bipyridine (TMbipy) supported on an octadecylsilane (ODS)-modified Ge prism were examd. both ex situ (dry) and in situ (in the presence of aq. solns.) using attenuated total reflection FTIR spectroscopy. In direct analogy with the behavior found for a variety of genuine pyridine (py) and bipyridine (bipy) metal ion complexes, Cd2+ binding to both SAMs led to shifts in the skeletal vibrational modes of the corresponding uncoordinated ligands in the region 1650-1400 cm-1, toward higher energies. Anal. of spectra acquired ex situ for HDpy/ODS/Ge and TMbipy/ODS/Ge before and after exposure to 0.1 mM [Cd2+] yielded values for the fraction of uncoordinated py, θ(pyun), and uncoordinated bipy, θ(bipyun), of ∼0.5 and ∼0.1, resp. The features attributed to the pyun groups for spectra collected for HDpy/ODS/Ge in situ and ex situ are virtually identical, making it possible to isolate by graphical means the most prominent band of pyco centered at ∼1615 cm-1 for HDpy/ODS/Ge collected in situ. The resulting bands for pure pyco and pyun in situ were then used to deconvolute spectra recorded in situ for HPpy/ODS/Ge in contact with Cd2+-contg. solns. in the range 10 nM < [Cd2+] < 0.1 mM, from which information regarding the adsorption isotherm was obtained. [on SciFinder(R)]


CAPLUS AN 2004:321624(Journal)