A series of alkaline earth, transition, and post-transition metal salen, M(salo-R), coordination complexes are being investigated as potential subterranean fluid-flow tracer molecules. Resonance Raman (rRaman) spectroscopy is an invaluable probe for chromophoric transition metal centers in polydentate metal-salen complexes, due to the electron rich nature of the ligands’ secondary coordination sphere. This study was especially sensitive to rRaman spectroscopy due to this innate aromatic property of the salen ligand, and is highly sensitive to electronic transitions, thus allowing for detection of multiple metal-salen complexes in the same sample at low concentrations. For accurate long-term fluid flow rate determinations, it is necessary to measure low levels of concentration of metal-salen tracer molecules, whether in aqueous or hydrocarbon systems. Solution based rRaman spectroscopic methods have proven to be especially useful, since the molecules generally displayed similar excitation wavelengths with distinct and characteristic emission spectra. This is critical as it allows for single scan detection of multiple metal-salen complexes in a single mixture. Elution kinetics testing in both hydrocarbon and aqueous solvent systems will be presented. Additional results are focused on subsurface solution behavior of hydrocarbon and aqueous soluble metal-salen complexes through molecular modeling, including DFT calculations.<br/>

Solution behavior and resonance Raman spectroscopic investigation of modified salen-type subterranean fluid flow tracers

254th National Meeting (2017)

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