A5050917541- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Magnetism in coordination complexes
- Metal-Catalyzed Oxygenation Mechanisms
- Crystallography and molecular interactions
- Metal-Organic Frameworks: Synthesis and Applications
- Lanthanide and Transition Metal Complexes
- Organic and Molecular Conductors Research
- Porphyrin and Phthalocyanine Chemistry
- Conducting polymers and applications
- MXene and MAX Phase Materials
- Magnetic and transport properties of perovskites and related materials
- Physics of Superconductivity and Magnetism
- Advanced NMR Techniques and Applications
- Electron Spin Resonance Studies
- Metal complexes synthesis and properties
- 2D Materials and Applications
- Electronic and Structural Properties of Oxides
- Perovskite Materials and Applications
- Quantum Dots Synthesis And Properties
- Quantum and electron transport phenomena
- Organometallic Complex Synthesis and Catalysis
- Covalent Organic Framework Applications
Northwestern University
2015-2019
Partial oxidation of an iron-tetrazolate metal-organic framework (MOF) upon exposure to ambient atmosphere yields a mixed-valence material with single-crystal conductivities tunable over 5 orders magnitude and exceeding 1 S/cm, the highest for three-dimensionally connected MOF. Variable-temperature conductivity measurements reveal small activation energy 160 meV. Electronic spectroscopy indicates population midgap states air corroborates intervalence charge transfer between Fe2+ Fe3+...
We report the magnetism and conductivity for a redox pair of iron-quinoid metal-organic frameworks (MOFs). The oxidized compound, (Me2NH2)2[Fe2L3]·2H2O·6DMF (LH2 = 2,5-dichloro-3,6-dihydroxo-1,4-benzoquinone) was previously shown to magnetically order below 80 K in its solvated form, with ordering temperature decreasing 26 upon desolvation. Here, we demonstrate this compound exhibit electrical values up σ 1.4(7) × 10-2 S/cm (Ea 0.26(1) cm-1) 1.0(3) 10-3 0.19(1) desolvated forms,...
We report the synthesis of a semiquinoid-bridged single-chain magnet, as generated through thermally induced metal-ligand electron transfer. Reaction FeCl3 with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (LH2) in presence (NMe4)Cl gave compound (NMe4)2[LFeCl2]. Together, variable-temperature X-ray diffraction, Mössbauer spectra, Raman and dc magnetic susceptibility reveal transition from chain containing (L2-)FeII units to one (L3-•)FeIII upon decreasing temperature, temperature T1/2 = 213...
Materials with switchable magnetic and electrical properties may enable future spintronic technologies, thus hold the potential to revolutionize how information is processed stored. While reversible switching of order or conductivity has been independently realized in materials, ability simultaneously switch both a single material presents formidable challenge. Here, we report 2D manganese benzoquinoid framework (Me4N)2[MnII2(L2-)3] (H2L = 2,5-dichloro-3,6-dihydroxo-1,4-benzoquinone), as...
The ability of tetraazalene radical bridging ligands to mediate exceptionally strong magnetic exchange coupling across a range transition metal complexes is demonstrated.
High-oxidation-state metal complexes with multiply bonded ligands are of great interest for both their reactivity as well fundamental bonding properties. This paper reports a combined spectroscopic and theoretical investigation into the effect apical ligand on spin-state preferences threefold symmetric iron(IV) tris(carbene) donor ligands. Specifically, singlet (S = 0) nitrido [{PhB(ImR)3}FeN], R tBu (1), Mes (mesityl, 2) related triplet 1) imido complexes, [{PhB(ImR)3}Fe(NR′)]+, Mes, R′...
Postsynthetic metal exchange represents a powerful synthetic method to generate metal–organic frameworks (MOFs) that are not accessible through direct synthesis, yet it is often hampered by slow reaction kinetics and incomplete exchange. While studies of reactions have primarily focused on the transmetalation process, transport exogenous ions into framework structure critical underexplored process. Here, we employ X-ray crystallography, electron microscopy, energy dispersive spectroscopy...
The paramagnetic cyano-bridged complex PhB(tBuIm)3Fe-NC-Mo(NtBuAr)3 (Ar = 3,5-Me2C6H3) is readily assembled from a new four-coordinate, high-spin (S 2) iron(II) monocyanide and the three-coordinate molybdenum(III) Mo(NtBuAr)3. X-ray diffraction IR spectroscopy reveal that delocalization of unpaired electron density into cyanide π* orbitals leads to reduction C-N bond order. Direct current (dc) magnetic susceptibility measurements, supported by electronic structure calculations, demonstrate...
Treatment of FeCl2(thf)1.5 with the pincer ligand bis(dicyclohexylphosphinomethyl)pyrrolide (CyPNP) in presence 2,2′-bipyridine (bipy) affords six-coordinate complex [FeCl(bipy)(CyPNP)]. The chloride exhibits spin-crossover behavior and serves as a starting point for series bipy-coordinated iron(II) compounds, including hydride species [FeH(bipy)(CyPNP)]. Chemical reduction [FeCl(bipy)(CyPNP)] generates new [Fe(bipy)(CyPNP)], which is found to be consistent structure featuring iron(I)...
Semiquinoid radical bridging ligands are capable of mediating exceptionally strong magnetic coupling between spin centers, a requirement for the design high-temperature materials. We demonstrate ability sulfur donors to provide much stronger relative their oxygen congeners in series dinuclear complexes. Employing chalcogen donor-based bis(bidentate) benzoquinoid ligands, complexes [(TPyA)2Cr2(RL4–)]2+ (OLH4 = 1,2,4,5-tetrahydroxybenzene, OSLH4 1,2-dithio-4,5-dihydroxybenzene, SLH4...
Structural phase transitions run in families of crystalline solids. Perovskites, for example, feature a remarkable number structural transformations that produce wealth exotic behaviors, including ferroelectricity, magnetoresistance, metal-insulator and superconductivity. In superatomic crystals other such materials assembled from programmable building blocks, offer pathways to new properties are both tunable switchable. Here we describe [Co6Te8(PEt3)6][C70]2, novel crystal with two separate...
Structural and spectroscopic characterization of the dimeric iron hydride complex [Ph2B(tBuIm)2FeH]2 reveals an unusual structure in which a tetrahedral iron(II) site (S = 2) is connected to square planar 1) by two bridging ligands. Magnetic susceptibility strong ferromagnetic coupling between centers, with constant J +110(12) cm–1, give S 3 ground state. High-frequency -field electron paramagnetic resonance (HFEPR) spectroscopy confirms this model. A qualitative molecular orbital analysis...