Synthesis and reactivity

7 Apr 2019

Encapsulation of Small Molecule Guests by a Self-Assembling Superstructure

Submitted by Shirley Lin, United States Naval Academy
Evaluation Methods: 

I have not yet implemented this LO. As with other literature discussions, instructors could collect the completed worksheets (by an individual student or in groups of students) for evaluation.

Evaluation Results: 

I have not yet implemented this LO so there are currently no evaluation results to share.

Description: 

This literature discussion focuses upon two journal articles by the Rebek group on the synthesis and host-guest chemistry observed with the "tennis ball." 

Corequisites: 
Learning Goals: 

After completing this literature discussion, students will be able to:

  • provide examples of supramolecular systems in nature that use reversible, weak noncovalent interactions 
  • define terms in supramolecular chemistry such as host, guest, and self-complementary
  • identify the number and location of hydrogen bonds within the "tennis ball" assembly
  • draw common organic reaction mechanisms for the synthesis of the "tennis ball" subunits
  • describe the physical and spectroscopic/spectrometric techniques used to provide evidence for assembly of a host-guest system
  • explain the observed thermodynamic parameters that are important for encapsulation of small molecule guests by the "tennis ball"
Implementation Notes: 

This LO could be used at the end of a traditional 2-semester organic chemistry sequence as an introduction to organic supramolecular systems, as an organic chemistry example within a discussion about inorganic supramolecular chemistry, or in an upper-division elective course about supramolecular chemistry. The LO topic, the "tennis ball," has a published laboratory experiment in J. Chem. Educ. (found here). Time permitting, instructors could have students read the article and complete the literature discussion before executing the experiment in the lab.

As usual, instructors may wish to mix-and-match questions to suit their learning goals.

Time Required: 
depends upon implementation; minimum of 20-30 minutes for the literature discussion if students read an d answer questions outside of class
26 Mar 2019

Redox-switch polymerization catalysis

Submitted by Chip Nataro, Lafayette College
Evaluation Methods: 

I am really unsure at this point. I may use the 1FLO version of this as a series of exam quesitons, or I may have the students work on this literature discussion in class. Either way, I am excited to see what they will do with it.

Description: 

This is the full literature discussion based on a communicaiton (J. Am. Chem. Soc. 2011133, 9278). This paper describes a redox-switch yttrium catalyst that is an active catalyst for the polymerization of L-lactide in the reduced form and inactive in the oxidized form. The catalyst contains a ferrocene-based ligand that serves as the redox active site in the catalyst. This full literature discussion is an extension of the one figure literature discussion that is listed below. In addition to presenting all of the same questions as that learning object, this includes interpretation of the XANES spectra presented in the paper. It also asks the students to identify the monomer and polymer in the reaction of interest. A possible extension of this learning object would be to have students examine and take measurements from the crystal structure presented in the paper in order to support the apparently low electron count on the yttrium catalyst. The Covalent Bond Classification system for counting electrons is used in this learning object.

Corequisites: 
Course Level: 
Learning Goals: 

A student should be able to apply their knowledge to 

  1. describe and interpret a plot of conversion vs. time
  2. count electrons and determine valence states in organometallic compounds
  3. determine if an organometallic compound is an oxidizing or reducing agent
  4. decipher a first-order kinetic plot
  5. interpret XANES spectra to determine the valence of iron in the catalyst
Subdiscipline: 
22 Mar 2019

1FLO: Redox-switch polymerization catalysis

Submitted by Chip Nataro, Lafayette College
Evaluation Methods: 

I am really unsure at this point. I could certainly see this being used as a series of exam questions or have students take a few minutes to think about the questions individually and then have them share with a small group and present their thoughts in class. This is actively interpreting a figure from the literature with almost no context. As such, it is certainly going to be indicative of their understanding of other ideas and concepts.

Description: 

This is what I hope will be a new classification of learning object called a one figure learning object (1FLO). The purpose is to take a single figure from a paper and present students with a series of questions related to interpreting the figure. This literature discussion is based on a paper (J. Am. Chem. Soc. 2011, 133, 9278) from Paula Diaconescu's lab in which a yttrium polymerization catalyst with a ferrocene-based ligand can effectively be rendered active or inactive depeneding on the valence state of the ligand. The figure chosen from the paper shows the conversion of the monomer (L-lactide) to polymer over the course of time. During the reaction, the valence state of the ligand is changed and the rate of polymerization is significantly impacted. While the purpose of this LO was to limit consideration to a single figure, there is so much to mine from this communication that a companion literature discussion was developed to go into more of the details that were presented. Certainly this 1FLO can stand alone or be used in conjunction with the companion literature discussion. The Covalent Bond Classification system for counting electrons is used in this learning object.

Corequisites: 
Subdiscipline: 
Learning Goals: 

A student should be able to apply their knowledge to

  1. describe and interpret a plot of conversion vs. time
  2. count electrons and determine valence states in organometallic compounds
  3. determine if an organometallic compound is an oxidizing or reducing agent
  4. decipher a first-order kinetic plot
Course Level: 
Implementation Notes: 

I have yet to use this but I anticipate doing so in the fall. I hope it works as well as I think it can. It is such a simple plot and yet it is so rich in chemistry. I have a feeling I am going to have a very hard time containing myself to just this LO and not using the companion full Literature Discussion.

Time Required: 
Unknown but I think it could be as short as 15 minutes
28 Jan 2019
Evaluation Methods: 

Concepts covered during literature discussions will be included among exam materials.

Evaluation Results: 

N/A

Description: 

This Guided Literature Discussion was assigned as a course project, and is the result of work originated by students Joie Games and Benjamin Melzer.  It is based on the article “Next-Generation Water-Soluble Homogeneous Catalysts for Conversion of Glycerol to Lactic Acid” by Matthew Finn, J. August Ridenour, Jacob Heltzel, Christopher Cahill, and Adelina Voutchkova-Kostal in Organometallics 2018 37 (9), 1400-1409. It includes a Reading Guide that will direct students to specific sections of the paper that were emphasized in the discussion.  This article reports a systematic study of a series of homogeneous catalysts for the conversion of glycerol to lactic acid.

Course Level: 
Corequisites: 
Learning Goals: 

After reading and discussing this article, a student should be able to…

-       Apply the CBC electron-counting method to homogeneous catalysts.

-       Understand the effect of metal and/or metal oxidation state on catalyst activity.

-       Understand the effect of ligand and/or ligand charge on catalyst activity.

-       Understand the differences between microwave and conventional heating.

Implementation Notes: 

I am planning on assigning this LO as a graded in-class group discussion. Students will be given a copy of the article, reading guide, and discussion questions one week in advance. On the day of the discussion, students will be assigned in groups of 2-3. They will then have one lecture period to answer the questions in writing as a group. A portion of their grade (20%) is dedicated to literature discussions (4-6 over the course of the semester). The grading rubric involves 3 possible ratings for each question/answer: “excellent”, “acceptable”, or “needs work”. [This article is among the free-access ACS Editors’ Choice.]

Time Required: 
1 lecture period, with materials given one week in advance
28 Jan 2019
Evaluation Methods: 

A portion of their grade (20%) is dedicated to literature discussions (4-6 over the course of the semester). The grading rubric involves 3 possible ratings for each question/answer: “excellent”, “acceptable”, or “needs work”.

Concepts covered during literature discussions will be included among exam materials.

Evaluation Results: 

N/A

Description: 

This Guided Literature Discussion was assigned as a course project, and is the result of work originated by students Christopher Lasterand Patrick Wilson.  It is based on the article “Deca-Arylsamarocene: An Unusually Inert Sm(II) Sandwich Complex” by Niels J. C. van Velzen and Sjoerd Harder in Organometallics 201837, 2263−2271. It includes a Reading Guide that will direct students to specific sections of the paper that were emphasized in the discussion.  This article presents a study of the reactivity of bulky CpAr-Et/iPrSm complexes that is contrasted to the more well-known Cp*2Sm.

Course Level: 
Corequisites: 
Learning Goals: 

After reading and discussing this article, a student should be able to…

-      Be more familiar with the chemistry of sandwich samarocene complexes.

-      Understand how bulky ligands affect structure and reactivity in a sandwich complex.

-      Apply the CBC method to identify ligand functions and metal valence number/ligand bond number.

-       Understand how XRD bond distances can help determine a ligand charge.

Implementation Notes: 

I am planning on assigning this LO as a graded in-class group discussion. Students will be given a copy of the article, reading guide, and discussion questions one week in advance. On the day of the discussion, students will be assigned in groups of 2-3. They will then have one lecture period to answer the questions in writing as a group.  [This article is among the free-access ACS Editors’ Choice.]

Time Required: 
1 lecture period, with materials given one week in advance

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