High-field (high-frequency) EPR spectroscopy and structural characterization of a novel manganese(III) corrole

The X-ray structure, magnetic susceptibility, and high-field (high-frequency) EPR spectrum of manganese 5,10,15-tris(pentafluorophenyl) corrole unambiguously establish that the complex contains an isolated, slightly rhombic, manganese(III) center

Bis(tetraphenylphosphonium) tetra­cyanido­nitridochromate(V) dihydrate

In the title compound, (C24H20P)2[Cr(CN)4(N)]·2H2O, the complex anion exhibits a square-based pyramidal geometry around the central CrV atom, which is coordinated by a nitride ligand in the apical position and by four cyanide ligands in the equatorial plane. The chromium atom is located 0.4493 (13) Å out of the plane formed by the ligating C atoms of the cyanide ligands. The water mol­ecules of crystallization form inter­molecular O—H⋯N hydrogen bonds to the N atoms of two cyanide ligands of neighbouring complex anions, forming an infinite hydrogen-bonded chain parallel to [011] of water mol­ecules and [Cr(N)(CN)4]2− anions. The terminal nitride ligands are not engaged in inter­molecular inter­actions

Imposing high-symmetry and tuneable geometry on lanthanide centres with chelating Pt and Pd metalloligands

Exploitation of HSAB preferences allows for high-yield, one-pot syntheses of lanthanide complexes chelated by two Pd or Pt metalloligands, [MII(SAc)4]2− (SAc− = thioacetate, M = Pd, Pt). The resulting complexes with 8 oxygen donors surrounding the lanthanides can be isolated in crystallographically tetragonal environments as either [NEt4]+ (space group: P4/mcc) or [PPh4]+ (space group: P4/n) salts. In the case of M = Pt, the complete series of lanthanide complexes has been structurally characterized as the [NEt4]+ salts (except for Ln = Pm), while the [PPh4]+ salts have been structurally characterized for Ln = Gd–Er, Y. For M = Pd, selected lanthanide complexes have been structurally characterized as both salts. The only significant structural difference between salts of the two counter ions is the resulting twist angle connecting tetragonal prismatic and tetragonal anti-prismatic configurations, with the [PPh4]+ salts approaching ideal D4d symmetry very closely (φ = 44.52–44.61°) while the [NEt4]+ salts exhibit intermediate twist angles in the interval φ = 17.28–27.41°, the twist increasing as the complete 4f series is traversed. Static magnetic properties for the latter half of the lanthanide series are found to agree well in the high temperature limit with the expected Curie behavior. Perpendicular and parallel mode EPR spectroscopy on randomly oriented powder samples and single crystals of the Gd complexes with respectively Pd- and Pt-based metalloligands demonstrate the nature of the platinum metal to strongly affect the spectra. Consistent parametrization of all of the EPR spectra reveals the main difference to stem from a large difference in the magnitude of the leading axial term, B02, this being almost four times larger for the Pt-based complexes as compared to the Pd analogues, indicating a direct Pt(5dz2)–Ln interaction and an arguable coordination number of 10 rather than 8. The parametrization of the EPR spectra also confirms that off-diagonal operators are associated with non-zero parameters for the [NEt4]+ salts, while only contributing minimally for the [PPh4]+ salts in which lanthanide coordination approximates D4d point group symmetry closely.LHD acknowledges support from NSF-CCT EMT 08-517. (08-517 - NSF-CCT EMT

Mechanical traits of isolated nuclei inspected via force spectroscopy

The larger stiffness of the nuclei when compared to the rest of the cell imposes a key restriction to cell deformability and their capability to traverse interstices. In contrast, cancerous cells have been reported to exhibit larger and poorly-defined nuclear shapes. Upon probing the mechanical properties of these abnormal nuclei, membrane rigidities were found to be below that of normal nuclei. A plausible explanation is an altered distribution of the nuclear chromatin. This argument is in line with the increased migration capabilities of invasive nuclei and their enhanced adaptability to the abnormal forces these cells experiment. As a response to mechanical stresses, the normal function of the nuclei is altered and can induce changes such as gene expression alteration in the cell. Despite the obvious relevance of the nuclear mechanical traits, few works report data directly acquired on nuclear membranes without any participation from the plasma membrane, which is bound to induce alterations that may disrupt results yielded by high sensitivity tests such as those performed using optical tweezers. In the present work, optical tweezers are used alongside force spectroscopy to test the mechanical traits of isolated nuclear membranes. Membranes’ Young moduli and, therefore, stiffnesses are calculated by performing indentation/retraction cycles inducing gentle deformation on the membranes using an optically trapped microbead. Nuclear membrane responses are studied as a function of the frequency with which cycles were performed to highlight possible dependency on the time lapse over which the perturbation is applied. Additionally, drastic pushing of the trapped bead against the membranes and pulling motions were performed to trigger more dramatic mechanical responses from the nuclei. During those perturbations, maximum indentation depth and maximum tension could be measured from simultaneously acquired confocal microscopy images.Ayudas para la recualificación del Sistema Universitario español modalidad Margarita Salas. NextGenerationEU (UE) & Ministerio de Universidades, Gobierno de España. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech