14 Jul 2014

The Synthesis and Characterization of a trans-Dioxorhenium(V) Complex

Lab Experiment

Submitted by Sibrina Collins, The Charles H. Wright of Museum of African American History

This experiment involves the preparation of a key starting reactant in high purity and yield for an ongoing research project, specifically for the development of potential photodynamic therapy (PDT) agents. The students synthesize [ReO2(py)4]Cl.2H2O using standard inorganic synthesis techniques. The students visualize the vibrations and electronic properties (e.g. molecular orbitals) of the compound using output files generated from density functional theory (DFT).

Microsoft Office document icon Experimental Details Handout241 KB
Learning Goals: 

A student will use spectroscopy (UV-vis, IR and 1H NMR) to show they have prepared the target compound.

A student will gain experience visualizing the molecular vibrations using output files generated from DFT.

A student will evaluate and analyze the experimental UV-vis spectra by comparing to the calculated DFT spectra.

A student will write a laboratory report in the format of the ACS journal, Inorganic Chemistry.

Equipment needs: 

CCD Array UV-vis Spectrophotometer, Thermo Scientific Nicolet 6700 FT-IR equipped with an ATR Sampler, Bruker 400 MHz NMR; GaussView software

Implementation Notes: 

The PDT agents I am developing that contain the [ReO2]+ core are based on the prototype, [ReO2(py)4]+(py = pyridine). This is a key reactant for my research efforts. The students enrolled in my inorganic chemistry laboratory synthesize this compound, as part of their curriculum. Thus, I am using classroom teaching as a means to enhance my research efforts. The students work in teams of 2-3 students to synthesize and characterize the compound.  The students are provided with the output of the DFT results to visual MOs and vibrations of the target molecule. I have included the calculated IR and UV-vis spectra in the powerpoint slide (CollinsSynthesis2014.pptx) for the instructors. The idea is for the students to compare their experimental data an compare it to the calculated data and discuss this in their report. I have also included a word document (Collins2014SupportingInformation.docx) that provides the coordinates (xyz) for the optimized geometry.

Time Required: 
Two three hour lab periods.
Evaluation Methods: 

One of the learning goals of this is to help the students develop effective writing skills. Thus, after completing the lab work, each student submits a laboratory report in the format of an ACS journal article. This experiment is worth 50 points, namely 35 points for the laboratory report, 10 points for notebook entries, and 5 points for their experimental plan(EP). The EP is their "ticket" for entry to the lab to complete the experiment.

Evaluation Results: 

I have created a rubric to evaluate the laboratory report. I make sure they adhere to formatting guidelines and sophistication of their ideas. I focus on how well they interpret their data. I tell them it is not my responsibility to explain their data! They have to tell a good story.  Approximately 40 students have prepared this compound over the course of two semesters (Spring 2013 and Fall 2013). In general, I have 2-3 "rock stars" per lab that write excellent/very good laboratory reports. Most students write lab reports that are considered good/very good.

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