Cottrell College Science Awards - 2015
Bismuth (III)-Chiral Anion Complexes: Creating an Environmentally-Friendly, Versatile, Chiral Catalyst
Bismuth is a heavy metal most people encounter in the commercial antacid concoction Pepto-Bismol. In its pure form bismuth has some of the same properties as lead, but it is slightly less dense and virtually nontoxic.
Recently chemists began looking at bismuth’s potential as an environmentally friendly catalyst for use in drug manufacturing. A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
Rebecca Lyn K.C. LaLonde, assistant professor of chemistry at Reed College, has received a Cottrell College Science Award from Research Corporation for Science Advancement to explore new ways to create “enantioselective” bismuth catalysts. This means they are catalysts that are good at producing molecules that have the same atoms but that can be mirror images one another. The chemical term “chirality” also covers these mirror-image molecules.
Enantioselectivity/chirality is a desirable quality in the molecules a catalyst helps to create because although they have the same atoms, mirror-image molecules can behave quite differently in a living organism such as a human.
Specifically, LaLonde and her colleagues hope to develop “dual Lewis acid-chiral anion catalysis.” Basically, a “Lewis acid” is an electron-deficient substance, such as a hydrogen atom that has lost its single electron (H+), that can accept a pair of nonbonding electrons. An “anion” is an atom or molecule with a net negative charge.
“If successful,” she said, “this new mode of reactivity will allow us to develop novel methods that harness the environmental-friendliness of bismuth while attaining the high enantioselectivity currently accessible by the use of rare and/or toxic metals.”