This collection includes new and/or updated lab experiments useful for online/distance learning. To be included in this collection, data should be provided for others to use in their new virtual laboratory courses. This collection was prepared as part of my response to the COVID-19 pandemic.
Students are generally asked to write a full lab report including an abstract, brief introduction, experimental and results/discussion. I will likely not ask them to do that in this virtual lab. However, they will be asked to determine the value for n for the various [Ni(en)x] solutions as well as questions 1 and 2 from Angelici's book. In addition, I typically ask them to do some literature searching questions, but I am not sure if they will have access to SciFinder so I may have to bypass that or provide them the original papers I have them look at. Links to those papers are included.
I'll use this in a few weeks and see how it goes.
This is the classic Job's Method experiment from "Synthesis and Technique in Inorganic Chemistry" 2nd Ed. (1977 or 1986 pp 108-114) by R. J. Angelici. There are slight changes from the experiment published in the book but they just include running solutions with ethylenediamine mole fractions of 0.67 and 0.75, so details will not be provided. What is provided are a series of pictures and videos showing the experiment being performed. Also included are the raw files of the absorbance spectra in EXCEL. It is not perfect but given the situation many of us are facing at the time this is published, it is better than nothing.Note that this lab was updated on 4/4/2020. The previous data was terrible. New solutions using a fresh bottle of ethylenediamine were prepared. The two solutions mentioned previously were also included. The data is much better. The worked up data has also been included in the instructor only files.
My apologies to my coauthors who spent way too much time looking over the original data set and trying to make sense of it. Their thoughts and insight led to this update. My sincere apologies to anyone else that scuffled over the original data.
A student should get an appreciation for what doing this lab would be like by watching videos. In addition, the student will analyze the data provided and determine the species present in solutions containing various mole fractions of ethylenediamine and Ni(II).
Like most everyone at this time this is going to be a trial by fire.
I did not grade this activity.
Three students out of 14 explicitly mentioned that this activity was helpful on the free response section of the course evaluations.
This LO is an in-class assignment to prepare students for literature readings involving catalytic cycles in which multiple protons and electrons are transferred. Students practice assigning oxidation states to complexes with aquo, oxo, superoxo, and hydroperoxo ligands then use this information to analyze a proposed water oxidation mechanism from the literature.
Students are asked to add in the substrates and products entering and leaving the catalytic cycle. While this is, at its heart, a stoichiometry excercise, it helps calibrate students for the level of attention to detail needed to effectively engage with reading about multi-electron catalytic mechanisms.
After completing this activity:
A student should be able to assign formal oxidation states to monometallic complexes with aquo, oxo, hyrdoperoxo, and superoxo ligands
A student should be able to apply their knowledge of formal oxidation states to the analysis of a proposed mechanism of a catalytic water oxidation reaction
I used this activity during a lab lecture before an inorganic laboratory experiment in which students would be preparing and testing the Ru-based OEC mimic.
I began the class period with a brief review of L/X type ligands and formal oxidation states.
Students then worked in groups to complete this activity.
Other implementation options:
While I used this activity as part of a lab lecture it could also be used in a lecture setting or as part of a problem set.
It could also be modified for use as an equation balancing excercise in a majors or honors general chemistry course.
assessment of students will be preformed by grading their answers to the questions in the activity.
This is a 1 Figure lit discussion (1FLO) based on a Figure from a 2015 JACS article on synthesizing conductive MOFs. This LO introduces students to Metal-Organic Frameworks and focuses on characterization techniques and spectroscopy.
As a result of completing this activity, students will be able to...
- define what metal-organic Frameworks and Post-synthetic Modifications are
- understand MOF terminology and notation
- discover how mass transport and electron mobility effect conductivity
- calculate energies of electronic transitions in electron volts
- make connections betweeen diagrams and material sturctures
- compare optical and microscopy techniques
- discover the concept of photocurrect and how it could be used in different applications
Students should be able to complete the activity without any prior knowledge of MOFs, although some introduction to MOFs and UV-vis absorption spectroscopy would be nice.
Students completed this activity in small groups, then turned in individual worksheets. Student learning and performance were assessed through 1) in-class group discussion after they had worked on the activity in small groups, and 2) grading the individual worksheets. Participation was most important in the small-group portion.
In general, students really enjoyed this exercise and felt that it was helpful for visualizing metal-organic frameworks (particularly the extended 3D structure). They also generally felt that it was helpful in visualizing the bonding sites of metal vertices, particularly for thinking about how that influences potential reactivity. We used Mercury as a visualization software for this discussion, and the majority of students felt very comfortable using Mercury and looking at cifs on their own after this activity.
The biggest challenge for students seemed to be in relating the 3D structure in the cif to the images and chemicals formulas in the article. They also tended to need some hints about question 5 – to think about what information Mössbauer can provide about oxidation state of the metal, or that you can tell whether or not there are two distinct iron environments. In our class, we do brief units on X-ray crystallography including how to use and interpret cifs, and Mössbauer spectroscopy before this literature discussion. If those topics are not already addressed in a particular class it might be helpful to add them in or directly address those topics for the students as an introduction to the literature discussion.
This literature discussion explores the physical structures, electronic structures, and spectroscopic characterization of several porphyrin-based metal-organic frameworks through discussion of “Iron and Porphyrin Metal−Organic Frameworks: Insight into Structural Diversity, Stability, and Porosity,” Fateeva et al. Cryst. Growth Des. 2015, 15, 1819-1826, http://dx.doi.org/doi:10.1021/cg501855k. The activity gives students experience visualizing and interpreting MOF structures, and gives students exposure to some of the methods used to characterize MOFs.
Students will be able to:
- Interpret and describe the bonding and structural characteristics of MOFs
- Apply knowledge of ligand field strength to electronic structure of MOFs
- Analyze X-ray crystallographic data to gain information about structural characteristics of MOFs
- Interpret Mössbauer spectra to gain information about electronic structure of MOFs
This literature discussion was designed for use in an advanced (upper-level) inorganic chemistry course, but could be used in a foundational inorganic course if students have already been introduced to d-splitting diagrams and are given some coverage of Mössbauer spectroscopy and X-ray crystallography. When covering MOFs in class, students frequently expressed that visualizing and understanding the bonding sites and extended 3D structures was very challenging. So, this literature discussion was developed specifically to address that. Students completed this activity in small groups. It is very helpful to advise students ahead of time to bring laptops (or instructor should have some available) and to have the cifs from the paper downloaded and ready to go. We used Mercury as a visualization software for this activity. This activity can easily be completed in one class period. It is also helpful if students have been provided with the article ahead of time and encouraged to look it over – otherwise the most time-consuming part of this activity was allowing time for students to examine the MOF structure images in the paper before being able to discuss and answer the questions with their groups.
Note on visualization of MOFs using Mercury: To answer the discussion questions, we used the ‘stick’ or the ‘ball and stick’ style. We also used the default packing scheme (0.4x0.4x0.4) and the 1x1x1 packing scheme. The packing scheme can be changed by selecting Packing/Slicing… in the Calculate menu. I also had students view the 3x3x3 packing scheme – while this is not necessary to answer the discussion questions, it was interesting for students to be able to visualize the extended structure of the MOFs.