Synthesis and biological activity studies of Schiff base ligand transition
metal complexes
Nathan Riggsbee, Amanda Koch, A...
of 1

Nathan poster ACS 2014 v2

Published on: Mar 3, 2016
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Transcripts - Nathan poster ACS 2014 v2

  • 1. Synthesis and biological activity studies of Schiff base ligand transition metal complexes Nathan Riggsbee, Amanda Koch, Amanda J. Crook. Department of Chemistry, Tennessee Technological University, Cookeville, TN 38505, United States Abstract Schiff bases are common ligands in coordination chemistry. The transition metal complexes of these ligands, especially those of platinum and palladium, have been shown in literature to have antitumor activity. This research proposes the synthesis and characterization of a class of Schiff base ligands similar to the acetylacetonate (acac) ligands. These acac transition metal complexes were synthesized using cobalt (II) and copper (II). These metal complexes were then tested for anti-proliferative activity against seven microbes, including four bacteria strains, two yeast strains, and one mold strain. The minimum inhibitory concentration (MIC) was determined for the metal complexes. These complexes were expected to show biological activity with different microorganisms. Introduction Schiff-Base metalloid ligands are compounds that have a functional group that contains a carbon-nitrogen double bond, where the nitrogen is also bonded to an aryl or alkyl group[1]. These compounds are used often in coordination chemistry and biochemistry[1]. Ligands are microscopic molecules that are found outside of the cellular membrane of an organism that have the ability to enter the membrane of the cell through various active and passive pathways, and have a reaction with the intracellular receptors of the cell. The advantage of the Schiff-Base ligands is that a compound can be created that allows control over certain processes occurring within the cell. This allows the potential use of these metalloid compounds as a means to treat various cancers and tumors. Oxindolime copper (II) and zinc (II) complexes are known to inhibit the activity of certain DNA topoisomerase enzymes in humans, and can be used for cancer treatment [2]. This project focused on transition metal complexes that are synthesized by using acetylacetonate (acac) ligands. The copper (II) acac ligand synthesized can be used to catalyze coupling and carbene transfer reactions [3] and the cobalt (II) acac ligand can be used as an NMR shift reagent [4]. Acknowledgements We would like to acknowledge Ed Lisic for use of space and supplies, and for help in starting this project. References [1] IUPAC, Compendium of Chemical Terminology, 2nd Ed. (1997) [2] R. Pankajavilli, et.al. Thermal stability of organo-chromium or chromium organic complexes and vapor pressure measurements on tris(2,4-pentanedionato)chromium(III) and hexacarbonyl chromium(0) by TG-based transpiration method. Chemical Engineering Science 57 (2002) 3603- 3610. [3] E. J. Parish, S. Li "Copper(I) Acetylacetonate" in Encyclopedia of Reagents for Organic Synthesis. (2004) [4] H.M. Goff, et. al. “Synthesis, Charactersization, and Use of a Cobalt(II) Complex as an NMR Shift Reagent”. J Chem Ed. 59 (5), (1982) [5] “Synthesis of Metal Acetylacetonate Complexes. zyxel- nsa210.lilu2.ch/MyWeb/public/.../sintesi_acetiacetonati.doc. Accessed September 2013. Discussion The synthesis of the Cu(acac)2 and the Co(acac)2 complexes were both successful and gave reasonable percent yields. Both products were successfully recrystallized. The bacterial studies showed that both compounds had little to no effect on all of the cultures of bacteria and fungi. Finally, the UV-Vis spectra revealed that the Cu(acac)2 ligand and the Co(acac)2 complexes had a λmax of 632 nm and 491 nm, respectively. Experimental Synthesis of the Co(acac)2 and Cu(acac)2 complexes were conducted and the products were recrystallized via published literature methods [4,5]. Bacterial studies were conducted by placing the bacteria listed in Tables 1 and 2 in a Thioglycollate broth which was then inoculated with a solution containing the Co(acac)2 and Cu(acac)2. The concentration used decreased in each trial by a factor of two. The resulting mixture was incubated, and was then tested for bacteria that survived the metal complex inoculation. UV-Vis spectral data was collected by preparing solutions that gave an absorbance reading in the range of 0.1-1 absorbance units. The wavelength of maximum absorbance was determined in the wavelength range of 400-800 nm.. [Co(Acac)2(OH)2] 100 mg Conc 1 2 3 4 5 6 7 8 9 10 Bact control ug/mL 250.0 125.0 62.5 31.25 15.625 7.8125 3.906 1.953 0.9766 0.4883 Microrg Sacchromyces cerevisiae + + + + + + + + + + + Aspergillus niger + + + + + + + + + + + Candida albicans + + + + + + + + + + + Pseudomonas aeruginosa + + + + + + + + + + + Escherichia coli + + + + + + + + + + + Bacillus subtilis + + + + + + + + + + + Staphylococcus aureus + + + + + + + + + + + [Cu(Acac)2] 50mg Conc 1 2 3 4 5 6 7 8 9 10 Bact control ug/mL 125.0 62.5 31.3 15.63 7.8125 3.9063 1.953 0.977 0.4883 0.2441 Microrg Sacchromyces cerevisiae + + + + + + + + + + + Aspergillus niger + + + + + + + + + + + Candida albicans + + + + + + + + + + + Pseudomonas aeruginosa + + + + + + + + + + + Escherichia coli + + + + + + + + + + + Bacillus subtilis + + + + + + + + + + + Staphylococcus aureus + + + + + + + + + + + Table 2: MIC data for Cu(acac)2 Figure 2: Determination of λmax of Cu(acac)2 Figure 1: General synthesis of acetylacetonate metal complexes Results (a) (b) (c) (d) Figure 4: (a) Cu(acac)2 precipitate, (b): Co(acac)2 precipitate, (c): Cu(acac)2-methanol solution, (d): Co(acac)2 synthesis Figure 3: Determination of λmax of Co(acac)2 Table 1: MIC data for Co(acac)2

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