METAL-ION COMPLEXATION AND ELECTRON-DONOR PROPERTIES OF DIOCTADECYLDITHIOCARBAMATE IN MONOLAYERS AT THE GAS WATER INTERFACE AND IN ORGANIZED MONOLAYER SYSTEMS

Dioctadecyldithiocarbamate (DOTC), incorporated in monolayers and orga nized monolayer assemblies, forms complexes with metal ions present in an adjacent aqueous phase. Surface pressure/area, surface potential/a rea isotherms, and surface enhanced UV-vis reflection spectroscopy at the gas/water interface have been used for the characterization and in vestigation of the DOTC-metal ion complexation. The formation of DOTC- metal complexes leads to changes in the area per molecule and the surf ace potential of the DOTC monolayers as well as to either a shift or t he appearance of a new band in the UV-vis reflection and absorption sp ectra. Complexation data for mono-, bi-, and trivalent metals ions are presented. In the multilayer assemblies on solid substrates, the comp lexation was monitored using UV-vis absorption spectroscopy. Metal com plex forming properties of DOTC should serve as the basis for the deve lopment of metal ion sensors. DOTC monolayers have been found to be st able even on acidic subphases in contrast to the behavior of short cha in derivatives of dithiocarbamate in aqueous solution. In addition to the metal ion complexation properties, DOTC exhibits pH dependent elec tron donor properties at the gas/water interface and in monolayer asse mblies. In mixed monolayers of DOTC and an amphiphilic electron accept or tetracyanoquinodimethane (C18TCNQ) we have observed the formation o f ionic charge transfer (CT) complexes.