22 Aug 2015

Antibacterial Reactivity of Ag(I) Cyanoximate Complexes

Lab Experiment

Submitted by Kari Young, Centre College

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.

File Student Handout (updated 7-15-16)198.77 KB
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: 

We piloted this experiment during the 2015-2016 school year and have made some adjustments based on our experience.  We welcome others in the VIPEr community to help us test this!  If you do try this, please post your comments and/or consider filling out our evaluation survey http://goo.gl/forms/CrP5KJtDtursr5302


Students will synthesize and characterize one compound each, but are expected to pool data as a class for a comparative analysis.  The antimicrobial assay requires supplies not commonly found in a chemistry laboratory, and instructors are encouraged to collaborate with a colleague in microbiology.

Time Required: 
Four 3-hour lab sessions
Evaluation Methods: 

Instructors will most likely choose appropriate evaluation method, but instructions are included for the following options:

  1. Writing lab report

  2. Poster

  3. Oral presentation

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 report that they really enjoy the microbiology/biomedicine application. 

Creative Commons License: 
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