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Show 162 THE EFFECT OF TRAPPED SOLVENT ON MAGNETIC MATERIAL'S PHYSICAL PROPERTIES Zach Fox (Joel S. Miller) Department of Chemistry University of Utah research posters on the hill spring 2012 Acetone, CH3CN [TCNE]·- Introduction Physical Effects of Solvent in Organic-Based Magnets Zach Fox (Dr. Joel S. Miller) Department of Chemistry Dr. Joel S. Miller Focus of this Poster Synthetic and Experimental Method Magnets used in everyday devices today almost exclusively consist of traditional metal or metal-oxide magnets. These can be expensive to manufacture, requiring extremely high temperatures. Organic-based magnets are synthesized under mild conditions but lack the magnetic density traditional magnets have. Despite this weakness, organic-based magnets also allow magnetic properties to be customized through changes in the organic ligands which normally only requires a small change in the synthetic method. Zach Fox Though similar iron containing compounds have been solved before, the lose of solvent under ambient conditions causes the structure to disorder quickly. By controlling the removal of any bound or trapped solvent a crystal structure of the stable dried product may be able to be solved. The drying process is monitored through infrared spectrum taken immediately after the product is collected and again after the drying process is finished. Drying Methods Drying tube methods: Slow low temperature: under vacuum at 30 °C for at least 3 days, up to a week Fast high temperature: under vacuum at 60 °C overnight TGA assisted drying: Temperature is slowly ramped up from 15 - 150 °C under ambient pressure. Effluent gasses are analyzed with mass spectrometer for solvent. Infrared Analysis Analysis is done focusing of the cyano region (2000 - 2500 cm-1) of the infrared spectrum because both product and solvent have cyanide groups, allowing them both to be easily monitored. Previous group members were able to obtain crystal structures from undried products, but the dry products have always been amorphous. If drying is done is such a way as to avoid changing the compound itself, a dried crystal structure could be solved. IR comparisons -Undried product -Dried product -3 day drying time -7 day drying time The spectrum on the left corresponds to a product that has been dried using the slow drying tube method for 3 days resulting in significant solvent removal. On the right, a different batch of product was dried using the same method for a week, resulting in more complete solvent removal. The product peaks show a shift to slighly higher energy upon drying. In order to show the slight difference in spectra with different drying times, the two dried spectra are overlayed. The acetonitrile peaks were not entirely removed after the 3 days of drying. After drying for 1 week, the compounds are still amorphous. AC Susceptibility measurements show both the wet and dry compound to be magnetically active at very low temperatures, but the dried compound's response in c'' indicates a permanent magnetic moment that was not observed in the undried sample. Magnetic Data The Miller Research Group AC Susceptibility, AC Susceptibility, AC Susceptibility, AC Susceptibility, Dried Undried Dried Sample Comparison Sample Dried 3 Days Sample Dried 7 Days Ongoing Research IR monitoring during the long drying process to optimize the process Implementation of other drying techniques Use acetone as a solvent in the Mn compound and compare to the Fe compound previously made in the group Solving crystal structure of dried material requiring the proper drying technique Full magnetic investigation of crystalline material CN CN NC NC TCNE = Jack DaSilva Endrit Shurdha Jordan Arthur Josh Bell Andrew Simonson Amber McConnell Chris Kareis Royce Davidson Casey Hawkins Lan Vo Kevin Siegel Ashley Dunn Dr. Joel S. Miller Organic-based magnets are being studied in order to expand the utility of magnets in modern devises. Advantages of the organic-based magnet include synthesis under less energy intensive conditions and enable greater versatility through changes to organic components of the structure. Studying the properties of these magnets could someday lead to cheaper and highly specialized magnets with a broader range of physical properties than today's alloy magnets. For example, magnets could be made transparent or flexible, or adapted specifical-ly for quantum computing. A family of metallopolymers built around octacyanobutadiendiide has been previously synthesized with the general formula MII[C4(CN)8](acetone)x, (MII=Fe, Mn). The acetone is weakly bound and can leave the structure at ambient conditions. The result of solvent "drying" is an amorphous solid that magnetically orders. Magnetic measurements of AC susceptibility show manganese contain-ing compounds to have an ordering temperature of ~60 K while iron orders at ~80 K. In order to raise the ordering temperature, a more controlled method of solvent removal is explored. Freshly synthesized material is monitored throughout the drying process with IR spectroscopy and magnetic properties mea-surements. These measurements determine which methodology is most likely to provide stable crystalline product for which a structure could be determined. Along with attempts to remove the solvent from the material, substitution of the coordinated solvent is also studied. The substitution of acetone with acetoni-trile would possibly yield a more stable crystalline product, or products that respond better to a particular drying method. This project provides a better understanding of the relationship between trapped solvent and the magnetic and structural properties of this family of molecule-based magnets. |