Oxalate Oxidase Model Studies – Substrate Reactivity

The synthesis and structure of [MnLCl]0.5H2O (1·0.5H2O, HL = 1‐benzyl‐4‐acetato‐1,4,7‐triazacyclononane) is reported. Complex 1 exists as a coordination polymer in the solid state, and the MnII center is bonded to three amine nitrogen atoms, one carboxylate oxygen atom, a chlorido ligand, and an adjacent carboxylate group in a chelating fashion to afford a seven‐coordinate center. The dissolution of 1 in acetonitrile containing excess oxalate (ox) ions results in a monomeric species. When mixtures of 1 and oxalate ions are exposed to oxygen under ambient conditions, a dark pink EPR‐silent species is generated. The pink species is believed to be [MnIII(ox)2]–, which results from the displacement of the ligand L– by an oxalate ion. The decomposition of this species ultimately results in the formation of 1 equiv. of CO2 per oxalate ion consumed, a HCO3– ion, and a MnII species. Further reaction of the resulting MnII species with excess oxalate in the presence of oxygen leads to additional oxalate degradation.MnLCl (HL = 1‐benzyl‐4‐acetato‐1,4,7‐triazacyclononane) is investigated as a structural and functional model for oxalate oxidase. MnLCl effects the catalytic degradation of oxalate ions under ambient conditions. MnLCl is converted to a light‐sensitive intermediate during catalysis. Analysis of the reaction mixture indicates that 1 equiv. of CO2 per oxalate ion is produced along with a HCO3– ion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110613/1/646_ftp.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/110613/2/ejic_201402835_sm_miscellaneous_information.pd

Thermally Induced Oxidation of [FeII(tacn)2](OTf)2 (tacn = 1,4,7‐triazacyclononane)

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141624/1/ejic201701190_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141624/2/ejic201701190-sup-0001-SupMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141624/3/ejic201701190.pd

Self-assembly of multiferroic core-shell particulate nanocomposites through DNA-DNA hybridization and magnetic field directed assembly of superstructures

Multiferroic composites of ferromagnetic and ferroelectric phases are of importance for studies on mechanical strain mediated coupling between the magnetic and electric subsystems. This work is on DNA-assisted self-assembly of superstructures of such composites with nanometer periodicity. The synthesis involved oligomeric DNA-functionalized ferroelectric and ferromagnetic nanoparticles, 600 nm BaTiO3 (BTO) and 200 nm NiFe2O4 (NFO), respectively. Mixing BTO and NFO particles, possessing complementary DNA sequences, resulted in the formation of ordered core-shell heteronanocomposites held together by DNA hybridization. The composites were imaged by scanning electron microscopy and scanning microwave microscopy. The presence of heteroassemblies along with core-shell architecture is clearly observed. The reversible nature of the DNA hybridization allows for restructuring the composites into mm-long linear chains and 2D-arrays in the presence of a static magnetic field and ring-like structures in a rotating-magnetic field. Strong magneto-electric (ME) coupling in as-assembled composites is evident from static magnetic field H induced polarization and low-frequency magnetoelectric voltage coefficient measurements. Upon annealing the nanocomposites at high temperatures, evidence for the formation of bulk composites with excellent cross-coupling between the electric and magnetic subsystems is obtained by H-induced polarization and low-frequency ME voltage coefficient. The ME coupling strength in the self-assembled composites is measured to be much stronger than in bulk composites with randomly distributed NFO and BTO prepared by direct mixing and sintering

A Structural Model for the Iron–Nitrosyl Adduct of Gentisate Dioxygenase

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146641/1/ejic201800992_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146641/2/ejic201800992-sup-0001-SupMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146641/3/ejic201800992.pd

Highest Recorded N–O Stretching Frequency for 6‑Coordinate {Fe-NO}⁷ Complexes: An Iron Nitrosyl Model for His₃ Active Sites

We report the synthesis, structure, and reactivity of [Fe­(T1Et4iPrIP)­(OTf)₂] [<b>1</b>; T1Et4iPrIP = tris­(1-ethyl-4-isopropylimidazolyl)­phosphine]. Compound <b>1</b> reacts reversibly with nitric oxide to afford [Fe­(T1Et4iPrIP)­(NO)­(THF)­(OTf)]­(OTf) (<b>2</b>), which is the first example of a 6-coordinate {FeNO}⁷ <i>S</i> = ³/₂ complex containing a linear Fe–N–O group. <b>2</b> exhibits the highest ν­(NO) for compounds in this class. Density functional theory studies reveal an enhanced degree of β-electron transfer from π*­(NO) to the Fe d orbitals accounting for the large stretching frequency

A Structural Model for the Iron–Nitrosyl Adduct of Gentisate Dioxygenase

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146641/1/ejic201800992_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146641/2/ejic201800992-sup-0001-SupMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146641/3/ejic201800992.pd