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Recent interest in potassium-doped p-terphenyl has been fueled by reports of superconductivity at Tc values surprisingly high for organic compounds. Despite these interesting properties, studies of the structure–function relationships within these materials have been scarce. Here, we isolate a phase-pure crystal of potassium-doped p-terphenyl: [K(222)]2[p-terphenyl3]. Emerging antiferromagnetism in the anisotropic structure is studied in depth by magnetometry and electron spin resonance. Combining these experimental results with density functional theory calculations, we describe the antiferromagnetic coupling in this system that occurs in all 3 crystallographic directions. The strongest coupling was found along the ends of the terphenyls, where the additional electron on neighboring p-terphenyls antiferromagnetically couple. This delocalized bonding interaction is reminiscent of the doubly degenerate resonance structure depiction of polyacetylene. These findings hint toward magnetic fluctuation-induced superconductivity in potassium-doped p-terphenyl, which has a close analogy with high Tc cuprate superconductors. The new approach described here is very versatile as shown by the preparation of two additional salts through systematic changing of the building blocks., C.N. thanks Sheldon and Dorothea Buckler for their generous support. Support for this research was provided by the Center for Precision Assembly of Superstratic and Superatomic Solids, an NSF MRSEC (award numbers DMR-1420634 and DMR-2011738), and the Air Force Office of Scientific Research (award number FA9550-18-1-0020). R.H.S. acknowledges support from the Columbia Nano Initiative Postdoctoral Fellowship. X.R. acknowledges support from the NSF CAREER award (NSF DMR-1751949). A.K.B. is supported by the Arnold O. Beckman Fellowship in Chemical Sciences. I.S. is supported by the National Science Foundation under award number CHE-1807654. Single-crystal X-ray diffraction was performed at the Shared Materials Characterization Laboratory at Columbia University, maintained using funding from Columbia University for which we are grateful. Work in Lausanne was supported by the Swiss National Science Foundation. Work in Spain was supported by MICIU (Spain) through Grants PGC2018-096955-B-C44 and PGC2018-093863-B-C22 and Generalitat de Catalunya (2017SGR1506 and 2017SGR1289). E.C. acknowledges support from the Spanish MINECO through the Severo Ochoa Centers of Excellence Program (SEV-2015-0496) and P.A. from the Maria de Maeztu Units of Excellence Program (MDM-2017-0767). S.C. was supported by FONDECYT (Chile) through project 11107163.

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2019, Tutores: Montserrat Corbella i Cordomí, Beltzane Garcia i Cirera, In order to mimic the active site of the Mn-catalase enzyme, the syntheses of three manganese(II) (1-3) and four manganese(III) (4-7) compounds have been studied, and the effect that an Ionic Liquid (1-Butyl-3-methylimidazolium Chloride, BmimCl) and another chloride salt (Bu4NCl) had caused on the syntheses. For manganese(II) compounds, stoichiometric amounts of Mn(2-NO2C6H4COO)2 (previously synthesized) and 2,2'-bipyridine were used, and different reaction conditions (solvent and presence of BmimCl or Bu4NCl in solution) were tested. The dinuclear compounds obtained 1 and 2 have general formula [{Mn(bpy)(2-NO2C6H4COO)(L1)}(μ-2-NO2C6H4COO)2{Mn(bpy)(2-NO2C6H4COO)(L2)}], where for 1 L1 = EtOH, L2 = H2O and for 2 L1 = L2 = H2O. Analogous compounds had been synthesized by the research group previously. Compound 3 [Mn(bpy)(H2O)2(2-NO2C6H4COO)2]n could be a more complex system that will need to be studied in more detail. Manganese(III) compounds were obtained from the comproportionation reaction between a manganese(II) salt (nitrate or perchlorate) and Bu4NMnO4. The reaction conditions were also modified by adding BmimCl or Bu4NCl to the solutions, which led to the obtention of surprising compounds. Dinuclear compounds 4 and 7 (general formula [{Mn(H2O)(bpy)}2 (μ-2-NO2C6H4COO)2(μ-O)](X)2, where X = NO3- (4) or ClO4- (7)) had already been obtained as well by the research group. The mixed-valence compounds [Mn(bpy)Cl2(H2O)2] [{Mn(bpy)Cl}(μ-2-NO2C6H4COO)(μ-O)2{Mn(bpy)(H2O)}] (5) and [Mn(bpy)2Cl2][{Mn(bpy)(H2O)}2 (μ-2-NO2C6H4COO)2(μ-O)]Cl3(ClO4) (6) were only obtained by adding BmimCl or Bu4NCl to the solutions. These could also be more complex systems. In this work, any crystal of good quality for X-ray diffraction has been obtained. However, the different compounds were characterized by IR spectroscopy, conductivity measurements, study of the magnetic behaviour and EPR spectroscopy. The molecular formulas of compounds 1-7 have been proposed from these studies.Finally, an attempt to measure the catalase activity of the manganese(III) compounds 4-7 was performed, by the volumetric measurement of the O2 evolved by the reaction of disproportion of H2O2. The compounds were poorly active, and the results have not been included in the memory.

Aquest mateix article està publicat a l'edició en alemany de la revista 'Angewandte Chemie' ISSN 0044-8249, EISSN 1521-3757), 2015, vol. 127, núm. 14, p. 4431–4435 http://dx.doi.org/10.1002/ange.201411995 FeIII-hypohalite complexes have been implicated in a wide range of important enzyme-catalyzed halogenation reactions including the biosynthesis of natural products and antibiotics and post-translational modification of proteins. The absence of spectroscopic data on such species precludes their identification. Herein, we report the generation and spectroscopic characterization of nonheme FeIII-hypohalite intermediates of possible relevance to iron halogenases. We show that FeIII-OCl polypyridylamine complexes can be sufficiently stable at room temperature to be characterized by UV/Vis absorption, resonance Raman and EPR spectroscopies, and cryo-ESIMS. DFT methods rationalize the pathways to the formation of the FeIII-OCl, and ultimately FeIV=O, species and provide indirect evidence for a short-lived FeII-OCl intermediate. The species observed and the pathways involved offer insight into and, importantly, a spectroscopic database for the investigation of iron halogenases Financial support comes from the European Research Council (ERC-2011-StG-279549 to W.R.B.; ERC-2009-StG-239910 to M.C.), the Netherlands Fund for Technology and Science STW (11059, to W.R.B.) the Ministry of Education, Culture and Science (Gravity program 024.001.035 to A.D. and W.R.B.) and the Ubbo Emmius Fund of the University of Groningen (A.D.). The BBSRC is thanked for a studentship to M.G.Q. and COST action CM1003 “Biological oxidation reactions—mechanism and design of new catalyst” for funding of a short-term scientific mission to A.D. and D.A. The National (UK) Service of Computational Chemistry Software is acknowledged for providing CPU time (S.P.d.V.)

High-sensitivity electron paramagnetic resonance experiments have been carried out in fresh and stressed Mn12 acetate single crystals for frequencies ranging from 40 GHz up to 110 GHz. The high number of crystal dislocations formed in the stressing process introduces a E(Sx2-Sy2) transverse anisotropy term in the spin Hamiltonian. From the behavior of the resonant absorptions on the applied transverse magnetic field we have obtained an average value for E=22 mK, corresponding to a concentration of dislocations per unit cell of c=10-3.