Abstract
Carbon dioxide has received significant attention as a potential environmentally benign medium to replace hazardous organic compounds, but is a relatively poor solvent. The addition of siloxane substituents provides an attractive and inexpensive means to solubilize a wide variety of compounds in CO2. By synthesizing and testing a family of gem-diphosphonate ligands that have been rendered CO2-philic by incorporation of a number of related, discrete dimethylsiloxane oligomers, we show that small variations in substituents have a significant effect on the CO2-philicity of the ligand. To our knowledge, this is the first systematic study of the effect of siloxane substituent size, branching, and position on the affinity of a ligand for CO2. In addition, we present a general approach to the preparation of novel gem-diphosphonate ligands.
ACKNOWLEDGEMENTS
This work was funded by the Environmental Management Sciences Program of the Offices of Science and Environmental Management, U. S. Department of Energy, under grant number DE-FGO7-98ER14928 (Loyola), grant number FG07–98ER14924 (Notre Dame), and contract number DE-AC02–06CH11357 (Argonne). Mass spectrometry was provided by the Washington University Mass Spectrometry Resource, an NIH Research Resource (Grant No. P41RR00954).
∗Work performed under the auspices of the United States Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences, under contract number DE-AC02–06CH11357.
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