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Organic Ligand Design for Use in Spin Crossover Materials

Title: Organic Ligand Design for Use in Spin Crossover Materials.

Inaccessible until Sep 27, 2020 due to copyright restrictions.

Name(s): Hrudka, Jeremy James, author
Shatruk, Mykhailo, professor directing dissertation
Hill, S. (Stephen Olof), university representative
Dalal, Naresh S., committee member
Kennemur, Justin Glenn, committee member
Florida State University, degree granting institution
College of Arts and Sciences, degree granting college
Department of Chemistry and Biochemistry, degree granting department
Type of Resource: text
Genre: Text
Doctoral Thesis
Issuance: monographic
Date Issued: 2017
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource (144 pages)
Language(s): English
Abstract/Description: Spin crossover (SCO) is a physical phenomenon whereby certain transition metal ions exhibit a change in magnetic state under the influence of external stimuli such as temperature, pressure, or light. SCO is most commonly observed in complexes of the Fe(II) cation when an intermediate-strength ligand field is achieved, most commonly with six coordinating nitrogen atoms. New organic molecules synthesized in this work belong to the 2,2’-bisimidazole (bim) family of ligands and are sought to induce SCO in a variety of Fe(II) complexes. Several novel bim derivatives were targeted to afford different functionality. Their synthesis required careful reaction optimization studies, which were conducted on a small scale and analyzed primarily using 1H-NMR spectroscopy. After optimizing and scaling up the ligand synthesis, the resulting purified bim derivatives were reacted with various Fe(II) salts to furnish mononuclear complexes, which were characterized by single crystal x-ray diffraction and SQUID magnetometry, as well as high-resolution mass spectrometry and elemental analysis. Both homoleptic and heteroleptic complexes of newly obtained bim derivatives were synthesized. In the case of homoleptic complexes, a range of SCO behaviors was observed, with spin transitions taking place at significantly different temperatures and with varying degree of abruptness. These differences can be explained by intricate structure-property relationships uncovered by the complimentary results provided by single-crystal x-ray diffraction and magnetic measurements. Various heteroleptic Fe(II) complexes containing a bim-type ligand and a tetradentate “capping” ligand were also synthesized and characterized for potential SCO behavior. The tetradentate capping ligands used included N4-donating ligands, leading to the typical N6 coordination environments, as well as N2S2-donating ligands, leading to the N4S2 coordination, which is more exotic among known SCO complexes. The spin-state energetics in these complexes was also assessed with electronic structure calculations at the density-functional level of theory. Insight into forecasting SCO behavior in homoleptic complexes of bidentate ligands was achieved via data-mining of the Cambridge Structural Database. This analysis led to an empirical rule, which uses the N-N chelating distance in bidentate ligands to predict the spin-state of the Fe(II) complex. This empirical rule was backed by DFT calculations. The combination of experimental design and theoretical investigations into novel Fe(II) SCO complexes with functionalized bisimidazole-type ligands, as presented in this Thesis, advances the knowledge of spin-state switching in transition metal complexes and inches towards more applied studies of functionalized SCO materials.
Identifier: FSU_FALL2017_Hrudka_fsu_0071E_14255 (IID)
Submitted Note: A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of Philosophy.
Degree Awarded: Fall Semester 2017.
Date of Defense: November 9, 2017.
Bibliography Note: Includes bibliographical references.
Advisory Committee: Michael Shatruk, Professor Directing Dissertation; Stephen Hill, University Representative; Naresh Dalal, Committee Member; Justin Kennemur, Committee Member.
Subject(s): Chemistry
Persistent Link to This Record:
Owner Institution: FSU

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Hrudka, J. J. (2017). Organic Ligand Design for Use in Spin Crossover Materials. Retrieved from