Synthesis and reactivity

22 Aug 2015

Antibacterial Reactivity of Ag(I) Cyanoximate Complexes

Submitted by Kari Young, Centre College
Evaluation Methods: 

We assessed student learning using formal reports, informal reports, and oral presentations. 

Evaluation Results: 

In general, students are able to prepare and characterize the complexes.  IR spectroscopy is especially useful in this lab because 1H NMR spectroscopy is not very diagnostic. One difficulty is removing excess solvent from the ligand, and we recommend using a mechanical vacuum pump after rotovapping. 

Some students are uncomfortable managing the amount of data this project generates when students share data for more than one compound. This project is a good opportunity to discuss using tables effectively.

Additionally, evaluating the "best" complex requires students to weigh a variety of parameters including heat stability and cost in addition to the antimicrobial activity.

Some students are also uncomfortable sharing data with their classmates or using others' data. This project provides a good opportunity to talk about the ways in which scientists collaborate.

Some but not all students report that they really enjoy the microbiology/biomedicine application.  

Description: 

In this experiment, students will synthesize and characterize one of three Ag(I) cyanoximate complexes as potential antimicrobial agents for use in dental implants. This experiment combines simple ligand synthesis, metalation and characterization, and a biomedical application. The complexes are both air and light stable. Students apply the Kirby-Bauer disk diffusion test, a common microbiology assay, to determine the antibacterial properties of their complexes. Students will also perform a simple cost analysis as part of the evaluation of the complexes.  This experiment was designed during the June 2015 “Improving Inorganic Chemistry Pedagogy” workshop funded by the Associated Colleges of the South.

Prerequisites: 
Learning Goals: 

A student should be able to:

  • Prepare one of a series of Ag(I) cyanoximate complexes and perform appropriate characterization of identity and purity
  • Measure antimicrobial activity in a semi-quantitative way using the Kirby-Bauer assay, including design and implementation of appropriate control experiments.
  • Evaluate a series of complexes as potential antimicrobials for dental applications based on the criteria of heat stability, water insolubility, and antibacterial activity.
  • Identify most cost effective complex.
Equipment needs: 

FT-IR spectrometer

NMR spectrometer

Melting point apparatus

Microbiology equipment

Implementation Notes: 

In this experiment, students connect organic synthesis, inorganic synthesis, and applications in microbiology in a multiweek experiment.

 

Students synthesize one of three possible derivatives of a cyanoxime ligand, coordinate Ag(I), and test the antimicrobial properties of their compound. The antimicrobial assay requires supplies not commonly found in a chemistry laboratory, and instructors are encouraged to collaborate with a colleage in microbiology.

 

This experiment has been tested several times since it was first developed in 2015. Additional notes were added in January 2020. We welcome others in the VIPEr community to help us test this experiment. If you do try it, please consider posting your comments or filling out our evalution survey:

 

Time Required: 
Four 3-hour lab sessions
2 Jul 2015
Description: 

Upper division literature discussion of a JACS paper on electrocatalysis.  This activity serves as an introductory look at the paper as a homework assignment to prepare the student for a more in depth class discussion.

Course Level: 
Corequisites: 
Learning Goals: 

Learning Objectives

  1. Identify the structure of a research article
  2. Summarize the motivation and major goals of a study.
  3. Recognize the central reaction and catalyst of a paper.
  4. Analyze a catalytic cycle.
  5. Explain how particular conclusions were determined based on experimental data.
  6. Recognize applications of the techniques presented in the paper.
Time Required: 
50 minutes
2 Jul 2015
Evaluation Methods: 
Options for assessment include: 
  • Students can complete the questions and submit their responses, which are then evaluated for clear understanding of the concepts. (Is the student able to describe clearly the chemistry in the paper?) 
  • Students can be evaluated for the quality of their contributions to in-class discussion. (Is it evident that the student has read the paper?)
  • Students can be asked follow up questions on a later exam. (Can the student recall and apply the principles discussed in the activity to a similar problem?) 
Evaluation Results: 

We have no results at this time for this newly created activity.  If you use this object in Fall 2015, please post comments to this LO so we can include your results!

Description: 
The paper entitled “Electrochemical hydrogenation of a homogeneous nickel complex to form a surface adsorbed hydrogen-evolving species” explores the discovery, characterization and catalytic activity of a film that deposited on the electrode while studying a nickel complex under electrocatalytic conditions.
 
This literature discussion includes several sets of questions that address different aspects of the paper, as described in the implementation notes. Discussion questions cover the structure and electron configuration of the compounds used to form catalysts, their synthesis and reactivity, the formation and activity of the catalytic film, electrocatalysis using cyclic voltammetry, and the characterization of the catalytic film.  The list of questions is extensive, but we encourage you to review them and select the ones that will best fit the goals of your lesson. 
 
This learning object was developed at the 2015 NSF sponsored cCWCS VIPEr workshop at University of Washington where we were fortunate to hear Prof. Jillian Dempsey present this research. It is worth mentioning that the first author of this paper was an undergraduate student at UNC-CH. The Dempsey’s research lab focuses on developing new technology to support a solar energy economy through catalysis. 
 
Reference: Chem. Commun., 201551, 5290-5293 DOI: 10.1039/c4cc08662g
 
Several questions of the discussion focus on data found in the supporting information. 
Corequisites: 
Learning Goals: 
By completing this activity, the student will be able to:
  • Identify the difference between facial and meridional geometries.
  • Apply 18 electron counting rules to a transition metal complex.
  • Apply electrochemical concepts to describe qualitative features of a cyclic voltammogram trace.
  • Apply knowledge of redox chemistry to understand electrocatalysis.
  • Demonstrate an understanding of reduction and oxidation reactions as they relate to transition metal complexes.
  • Use retrosynthetic analysis to determine which starting materials are needed for a Schiff base product.
  • Understand what a hydrogenation reaction is and show what happens to a double bond when it is hydrogenated.
  • Understand the use of SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) images to characterize a film. 
  • Understand the use of XPS (X-ray Photoelectron Spectroscopy) and EDS (Electron Dispersion Spectroscopy) to elucidate the elemental composition of a film.
Implementation Notes: 
It may help to split this activity and assign portions to groups of students. Or it may be better to spread the questions out over several weeks of the course, as relevant topics present themselves in the course content. For reference, the questions are split into groups below. You may also choose to eliminate certain groups of questions if they do not align with the covered content of your course. Also, a suggested exam question is included separately.
 
Questions 1-3. The structure and electronic configuration of two octahedral nickel(II) complexes. Includes basic concepts on coordination chemistry like isomerism, coordination geometry, oxidation state, and the 18 electron rule.
 
Questions 4-9. Synthesis and reactions of the organic ligands coordinated to nickel. Includes imine chemistry and the concepts of hydrogenation, hybridization, and aromaticity.
 
Questions 10-15. Electrochemical deposition of a film and its catalytic activity to produce hydrogen. Electrocatalysis and hydrogen evolution. Includes topics of cyclic voltammetry, overpotential, reversible and irreversible reductions. 
 
Questions 16-17. Discussion of methods used in the paper: CV, imaging (SEM and TEM) and spectroscopic techniques (XPS and EDS) and how XPS was used to characterize the film . Question 16 is particularly amenable to division among groups of students.
 
Suggestions for exam questions (faculty handout only). The provided exam question would be used to assess students after they have completed the in-class discussion. If very specific details about the mechanism behind the voltammetric response are desired then students may benefit from access to a clean version of the paper during the exam, 
 
This activity has not yet been tested. If the in-class discussion is to fit within 50 minutes, then several questions need to be left out of the discussion, though the students still need to do them to prepare for the discussion. Also, closely related questions can be addressed together. For example, questions 1, 2, and 6 are primarily intended to review concepts that the students need to answer questions 3, 4-5,  and 7-8. Question 9 deals with organic retrosynthetic analysis and is not essential for the questions that follow. Questions 10-13 deal with the heart of the paper, and questions 14-17 deal with controls and characterization of the system. The instructor's priorities should determine whether only the most critical questions (such as 3-5, 7-8, 10-13, and perhaps 14 and 15) are each briefly discussed in one fifty class period, or if at least half of two class periods are used for a more extensive discussion.
 
 
The activity uses some figures from the paper itself. The paper was published under a Creative Commons Attribution-NonCommercial 3.0 Unported (CC BY-NC 3.0) license as described below:
 
Time Required: 
Untested. A selection of key questions could be discussed in one 50 minute session (see implementation notes). Otherwise, the activity could take over 90 minutes.
29 Jun 2015

Synthesis of Aspirin- A Lewis Acid Approach

Submitted by Kathleen Field, WGU
Evaluation Methods: 

Data sheet for intro level courses along with supplemental questions.  

Lab Reports and supplemental questions for uppper classes.  

 

 

Description: 

This is the procedure for a Fe(III) catalyzed synthesis of aspirin, an alternative to the traditionally sulfuric acid catalyzed synthesis of aspirin.  The prep compares and contrasts the Bronsted acid catalyzed esterification reaction with a Lewis acid iron (III) catalyzed pathway.  This can be used in different courses at different levels, but is it written for a general/intro level chemistry course.    

Prerequisites: 
Learning Goals: 

Intro Chemistry

  • Students will be able to compare and contrast Lewis Acids/Bases with Bronsted Acids/Bases
  • Students will be able to calculate the moles of each reactant, the aspirin product, and the percent yield of product.  
  • Students will be able to determine the limiting reagent and calculate amount of excess material

Organic Chemistry

  • Students will characterize aspirin using melting point determination, IR and NMR spectroscopy and be able to distinguish the different structural elements between the starting material (salicylic acid) and the product (aspirin)
  • Students will be able to differentiate between the Fe(III) catalyzed mechanism and the sulfuric acid catalyzed esterification mechanism

Inorganic Chemistry/upper level

  • Students should be able to relate experimental observations (color) to the d-orbital splitting of Fe(III) complexes
  • Students will be able to draw plausible intermediates and propose a mechanism for the iron catalyzed reaction in relation to the observed reaction colors
Equipment needs: 

Erlenmeyer Flasks, Hot Plate, Balance, Vacuum Filtration, NMR and IR spectroscopy

Chemicals: Acetic Anhydride, FeCl3, Salicylic Acid, Water

Implementation Notes: 

Some notes have been included in the uploaded instructor notes.  

We are interested to submit this to the Journal of Chemical Education, so we (the authors) would be very interested in examining any student data that anyone receives if using the procedure as written in addition to any modifications to the procedure for both general/intro level classes and upper level classes/labs.  

Time Required: 
1-3hr class for intro class, 4 hour class for organic, or longer for upper level classes.
13 Jun 2015

Palladium-catalyzed couplings: Literature examples

Submitted by Martin A. Walker, SUNY Potsdam
Description: 

Examples taken from the literature for the six palladium-catalyzed coupling reactions used in organic chemistry.

Corequisites: 
Topics Covered: 
Course Level: 
Learning Goals: 

Students will be able to classify a palladium-catalyzed reaction.

Students will be able to describe how palladium-catalyzed reactions may be used in organic synthesis.

Subdiscipline: 
Implementation Notes: 

I use these during my Advanced Organic lecture to show examples of how these reactions work in practice.  They could also be useful in an organometallics course.

Time Required: 
10-25 minutes
Evaluation
Evaluation Methods: 

Done much later, by exam or homework

Evaluation Results: 

This is lecture support material, and it is not directly assessed at the time. 

12 Jun 2015

Materials Project

Submitted by Barbara Reisner, James Madison University
Description: 

The Materials Project is part of the Materials Genome Initiative that uses high-througput computing to uncover the properties of inorganic materials.

It's possible to search for materials and their properties

It employs high-throughput computation approaches and IT to create a system that can be used to predict properties and construct phase diagrams andPourbaix diagrams.

Prerequisites: 
Corequisites: 
10 Jun 2015

Beautiful Chemistry

Submitted by Adam R. Johnson, Harvey Mudd College
Description: 

This is just a cool little website I just happened to stumble upon today while looking for something else at the RSC site. It comes from China, and it is pretty!

Prerequisites: 
Corequisites: 
Learning Goals: 

Students will see the beauty of chemistry and chemical apparatus.

Subdiscipline: 
Course Level: 
10 Jun 2015

Sheila's Safety Net

Submitted by Sheila Smith, University of Michigan- Dearborn

Collection of Safety LOs from VIPEr

Prerequisites: 
Corequisites: 
10 Jun 2015
Description: 

 

The resources on this website will help students learn concepts in materials chemistry, solid state chemistry, and nanoscience. The website provides links to

  • a video lab manual,
  • a cineplex of demonstrations,
  • kits that can be used for extended structures, and
  • interactive structures of solid state materials, Au nanoparticles and forms of carbon.

There videos and resources have applications across the chemistry curriculum. Many materials are inorganic. This is a great resource for people looking for ways to incorporate the new CPT guideline to discuss macromolecular, supramolecular, mesoscale and nanoscale systems within the framework of their existing curriculum.

Prerequisites: 
Corequisites: 
11 Feb 2015

In-Class Review Questions for Metal Carbonyl Complexes

Submitted by Christian R. Goldsmith, Auburn University
Evaluation Methods: 

Mostly, I am looking for a good discussion of the material. Smaller classes and ones with students who are not accustomed to group exercises may require more prompting to work together.

Certainly, students who provide more correct answers to the questions demonstrate that they understand the material to a higher degree.

Evaluation Results: 

I have found that most students handle the material very well. Most of their predictions (80-90%) are correct and require minimal input from myself.

With respect to the electron counting, some students have difficulty with the nitride ligand and the metal-metal bond.

Students have the most difficulty gauging the electron-donating/withdrawing abilities of the different phosphine and carbonyl ligands. They usually need to be told that Cp- ligands are electron donating relative to carbonyls. The students in my classes have had very little experience with Hammett relationships and do not have a good feel for what substituents are electron-donating and electron-withdrawing. Those with a third semester of organic chemistry would be anticipated to handle this portion more easily.

Students normally correlate the IR stretching frequencies of the carbonyl ligands to the preferred mode of reactivity without any problems.

Description: 

The slides provide review questions for a senior-level treatment of the spectroscopy and reactivity of metal carbonyl complexes. These are intended to be dispersed through one to three class periods.

The first slide is a review of electron counting and the 18-electron rule.

The second slide quizzes the students on the relationship between the electron-density of the metal center and the strength of the C-O bonds in the carbonyl ligands. It is intended to be given after a discussion of how IR can be used to assess the strength of M-C and C-O bonds in the compounds.

The third slide has students make predictions about the acidity of metal carbonyl hydride complexes. For the most part, this is a review of concepts that students would have encountered in general and organic chemistry. The last question brings in hard soft acid base theory and forces students to think about the nature of the M-H bond. I present this after a discussion of metal carbonyl reactivity, specifically their reduction to metal carbonylates and subsequent protonation to metal carbonyl hydrides.

The fourth slide can be used to link the spectroscopic characteristics of the metal carbonyl complex to its reactivity. I present these questions after a discussion of how the electron density of the metal center biases the compounds towards reactivity with electrophiles or nucleophiles.

Learning Goals: 

The goal is to allow students to apply the knowledge that they have just learned about metal carbonyl complexes. The students will specifically correlate the spectroscopic characteristics of these compounds to their reactivity. One overarching theme that can be stressed throughout the lecture is that the electronic characters of the metal ion and ligands greatly influence not only the IR stretching frequencies of the carbonyl ligands but also their reactivities.

Equipment needs: 

Besides a projector and a computer, there are no special equipment needs. A blackboard or white board may facilitate discussion of the answers.

Subdiscipline: 
Course Level: 
Corequisites: 
Implementation Notes: 

I typically have the students begin each exercise by working individually. Upon arriving at their independent answers, I have the students share them. First, they discuss their answers with one or two partners. Afterwards, the groups share their answers with the class. I will then supplement their answers by noting things that they may have missed.

Throughout the discussion period, I will walk amongst the students to gauge how they are doing with the exercise. If they appear lost or are on the completely wrong track, I'll offer a hint to help them out.

Time Required: 
5-15 min per slide

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