All chemicals were purchased from commercial producers and most were used without further purification. Electronic absorption spectra was measured on a HP-8453 UV-vis spectrophotometer. Infrared spectroscopy were measured from 4000 to 500 as KBr pellets on a ThermoScientific Nicolet iS5 spectrometer.
Purification of Acetate Metals. Both acetate metals were purified through crystallization. The crystallization of the copper (II) acetate monhydrate was uneventful and resulted in a 28.1 percent yield.
The crystallization of zinc (II) acetate dihydrate was done in two separate experiments. For the first experiment, needle-like zinc (II) acetate dihydrate crystals were formed with a 73.33 percent yield while in the second experiment, polygonal zinc (II) acetate dihydrate crystals were formed with a 39.86 percent yield. The difference between the crystals formed in the first experiment and the second experiment is probably due to the different amounts of water contained in the crystal lattices of each experiment.
2-methylthio-N-(3-pyridinylmethyl) acetamide (3-HLSMe) ligand and 2-methylthio-N-(4-pyridinylmethyl) acetamide (4-HLSMe) ligand synthesis. For both ligand syntheses, (methylthio) acetic acid, triethylamine, EDC-HCl, and HoBt were dissolved in dichloromethane (CH2Cl2). Both solutions were then cooled to 0 degrees Celsius and stirred. 3-amino pyridine, the characterizer of the 3-HLSMe, was then added to the solution in order to synthesize the 3-HLSMe ligand. 4-amino pyridine, the characterizer of the 4-HLSMe, was added to another solution to synthesize the 4-HLSMe ligand. This solution was stirred vigorously for one hour at 0 degrees Celsius. The solution was warmed to room temperature and stirred overnight.
Both crude ligands were washed with CH2Cl2 and a sodium carbonate solution to remove urea and other contaminants. Both ligand syntheses were run through a silica gel column, using a mixture of ethyl acetate and methanol in a 95 to 5 ratio as the eluent. For the 3-HLSMe ligand synthesis, it was determined that the ligand came out of the column in fractions three, four, and five using thin layer chromatography (TLC). For the 4-HLSMe ligand synthesis, it was attempted to determine in which fraction the ligand came out using TLC. Unfortunately, the ligand came out in such low concentrations that it did not appear on the TLC paper. All thirteen fractions containing the mix of ethyl acetate and methanol as an eluent were then poured into one round-bottom flask and all of the eluent was rota-vaporized off. After the eluent had been rota-vaporized off, the 4-HLSMe ligand appeared as a yellow, oily substance in the flask.
Creating the coordination complex experiments. In these experiments, copper (II) acetate monohydrate and zinc (II) acetate dihydrate were each combined with the 3-HLSMe ligand and the 4-HLSMe ligand. These experiments were begun by dissolving the metal acetates and each ligand into methanol. A ligand solution was then added to a metal acetate solution, resulting in a total of four experiments. The copper (II) acetate monohydrate and zinc (II) acetate dihydrate solutions mixed with the 3-HLSMe ligand were first left to supersaturate and then put into an ether diffusion to grow crystals. The copper (II) acetate monohydrate and zinc (II) acetate dihydrate solutions mixed with the 4-HLSMe ligand were left to supersaturate. Unfortunately, due to time constraints, the solutions did not have enough time to crystallized. Instead, all of the solutions were rota-vaporized in order to evaporate the solvent. Acetonitrile was added to each solution to create 10 mM solutions. These solutions were then put through an infrared spectroscopy (IR) and a UV-vis spectroscopy in an attempt to determine whether some form of a complex was created.