We have made significant progress during the first year of support for this project.  Four undergraduate students, three of whom belong to under-represented ethnic groups, have participated in research funded by the PRF.  Due to the availability of student support funds at Chicago State University, only one student was supported financially by this grant.  Two poster presentations on research supported by this grant were delivered by students at the National ACS meeting held in Chicago in the Spring of 2007 and one manuscript is currently under review.  Their participation in the conference was supported by this grant.  As summarized below, this research has expanded to include a collaborative study on the oxidation of disilver complexes and has opened up a new avenue of research involving electrochemistry in unusual solvents. 

We have completed the first aim of the proposed research, namely synthesizing several tricopper complexes and identifying the most promising molecules for an in-depth electrochemical investigation.  Research from Stack's group (Mirica and Stack, Inorg. Chem. 2005, 44, 2131) has shown that the synthesis of a family of Cu_xO_x complexes is sensitive to the types of counterions present in solution.  We have synthesized the reported Cu₂O₂ and Cu₃O₃ complexes and have conducted preliminary electrochemical investigations on them.  Adsorption of reduction products is the primary challenge in obtaining quantitative electrochemical data.  Our present task is to survey a variety of electrochemical conditions and identify the best medium in which to continue the investigation.

Synthesis of one of the proposed tricopper complexes involved a disilver intermediate that we proposed would be worthwhile to study electrochemically.  While engaged in this work, we established a collaboration with Chuan He, at the University of Chicago, who is studying the catalytic activity of disilver complexes.  Our continued collaborative efforts should yield an interesting story on the factors that allow for generation of stable Ag(II) containing species.  A Chicago State student presented a poster at the Chicago National ACS meeting entitled, “Electrochemistry of disilver complexes” which summarized our progress in this area.

While working on the proposed research, we have begun to explore electrochemistry in a new family of solvents, deep eutectic solvents (DES).   A DES is typically formed between a hydrogen bond donor and choline chloride (Abbott et al. J. Am. Chem. Soc. 2004, 126, 9142).  These tunable solvents with negligible vapor pressure have appreciable viscosities which hamper traditional electrochemical investigations.  We therefore studied electrochemical processes in the solvents using scanning electrochemical microscopy (SECM).  SECM utilizes a microelectrode positioned above a second electrode to obtain mechanistic information.  The high resistance and low diffusivities of deep eutectic solvents do not impede electrochemistry at closely spaced microelectrodes, making SECM an ideal technique for investigations in these solvents.  Our work has shown that DES formed between choline chloride and either malonic acid or trifluoroacetamide display non-newtonian behavior which adds a complexity to SECM experiments that has not been addressed previously.  We modified the current steady-state SECM theories to include an electrode-velocity term.  This, in turn, allowed us to simulate the observed response of microelectrode as it approaches an insulating substrate at varying velocities.  A poster presentation on this work was delivered by a student researcher at the Chicago National ACS meeting.  A manuscript describing this work has been submitted to the Journal of Physical Chemistry.

During the upcoming year, we will continue to make progress in the above three areas.  We expect that both the multicopper and disilver electrochemistry studies will result in manuscripts within the year.  Research is currently underway on the study of interfacial electrochemistry in deep eutectic solvents an its implication in energy and electron transfer.