Membrane-Permeant, Bioactivatable Coumarin Derivatives for In-Cell Labelling.

The delivery of small molecule fluorophores with minimal compartmentalization is currently one of the most critical technical problems in intracellular labelling. Here we introduce sulfonated and phosphonated coumarin dyes, demonstrate rapid cell entry via a prodrug approach, and show a lack of interaction with membranes, organelles, or other compartments. The dyes show no specific localization and are evenly distributed in the cells. Our fluorogenic, clickable phosphonate derivatives successfully tagged model targets in intact cells and the increase in brightness upon click reaction was around 60-fold.

Structure, magnetism and colour in simple bis(phosphine)nickel(II) dihalide complexes: an experimental and theoretical investigation.

The complex [1,2-bis(di-tert-butylphosphanyl)ethane-κ(2)P,P']diiodidonickel(II), [NiI2(C18H40P2] or (dtbpe-κ(2)P)NiI2, [dtbpe is 1,2-bis(di-tert-butylphosphanyl)ethane], is bright blue-green in the solid state and in solution, but, contrary to the structure predicted for a blue or green nickel(II) bis(phosphine) complex, it is found to be close to square planar in the solid state. The solution structure is deduced to be similar, because the optical spectra measured in solution and in the solid state contain similar absorptions. In solution at room temperature, no (31)P{(1)H} NMR resonance is observed, but the very small solid-state magnetic moment at temperatures down to 4 K indicates that the weak paramagnetism of this nickel(II) complex can be ascribed to temperature independent paramagnetism, and that the complex has no unpaired electrons. The red [1,2-bis(di-tert-butylphosphanyl)ethane-κ(2)P,P']dichloridonickel(II), [NiCl2(C18H40P2] or (dtbpe-κ(2)P)NiCl2, is very close to square planar and very weakly paramagnetic in the solid state and in solution, while the maroon [1,2-bis(di-tert-butylphosphanyl)ethane-κ(2)P,P']dibromidonickel(II), [NiBr2(C18H40P2] or (dtbpe-κ(2)P)NiBr2, is isostructural with the diiodide in the solid state, and displays paramagnetism intermediate between that of the dichloride and the diiodide in the solid state and in solution. Density functional calculations demonstrate that distortion from an ideal square plane for these complexes occurs on a flat potential energy surface. The calculations reproduce the observed structures and colours, and explain the trends observed for these and similar complexes. Although theoretical investigation identified magnetic-dipole-allowed excitations that are characteristic for temperature-independent paramagnetism (TIP), theory predicts the molecules to be diamagnetic.

Perils and promise of online exams.

As academic staff scrambled into emergency remote teaching during COVID-19 restrictions, we also had to move in-person exams online without compromising integrity. This disruption caused us to think carefully about how chemistry is assessed, because 'business as usual' was no longer possible - and at some institutions, there are no plans for in-person exams to return.

Visualization of Ectopic Serine Protease Activity by Förster Resonance Energy Transfer-Based Reporters.

Channel-activating proteases (CAPs) play a fundamental role in the regulation of sodium transport across epithelial tissues mainly via cleavage-mediated fine-tuning of the activity of the epithelial sodium channel (ENaC). Hyperactivity of CAPs and subsequently increased ENaC activity have been associated with various diseases, including cystic fibrosis (CF). To date, there is only a limited number of tools available to investigate CAP activity. Here, we developed ratiometric, peptide-based Förster resonance energy transfer (FRET) reporters useful to visualize and quantify the activity of ectopic serine proteases including the CAPs prostasin and matriptase in human and murine samples in a temporally and spatially resolved manner. Lipidated varieties were inserted into the outer leaflet of the plasma membrane to detect enzyme activity on the surface of individual cells, that is, close to the protease substrates. The FRET reporters (termed CAPRee) selectively detected the activity of ectopic serine proteases such as CAPs in solution and on the surface of human and murine cells. We found increased CAP activity on the surface of cells with a genetic background of CF. The new reporters will contribute to a better understanding of ectopic serine protease activity and their regulation under physiological and pathophysiological conditions.

Tris[4,4,4-trifluoro-1-(2-thien-yl)butane-1,3-dionato]aluminium(III)-tris-[4,4,4-trifluoro-1-(2-thien-yl)butane-1,3-dion-ato]iron(III) (3/1).

In the title compound, [Al(C(8)H(4)F(3)O(2)S)(3)](3)[Fe(C(8)H(4)F(3)O(2)S)(3)], the metal centre is statistically occupied by Al(III) and Fe(III) cations in a 3:1 ratio. The metal centre is within an octa-hedral O(6) donor set defined by three chelating substituted acetoacetonate anions. The ligands are arranged around the periphery of the mol-ecule with a mer geometry of the S atoms.

Di-µ-iodido-bis-[(diethyl ether-κO)(η-1,3-di-tert-butyl-cyclo-penta-dien-yl)ytterbium(II)].

The half-sandwich title compound, [Yb(2)(C(13)H(21))(2)I(2)(C(4)H(10)O)(2)], crystallizes as a centrosymmetric dimer. The Yb atom is coordinated in a three-legged piano-stool geometry by a cyclo-penta-dienyl ring, two I anions and the O atom of a diethyl ether mol-ecule. The central Yb(2)I(2) core is an approximate square.

[P,P-Di-tert-butyl-N-trimethylsilyl-P-(trimethylsilylamino)phosphine imidato-kappa2N,N']bis(pyridine-kappaN)lithium(I).

In the title compound, [Li(C(14)H(36)N(2)PSi(2))(C(5)H(5)N)(2)], the bulky chelating monoanionic P,P-di-tert-butyl-N-trimethylsilyl-P-(trimethylsilylamino)phosphine imidate ligand and two pyridine ligands bind to Li in a pseudo-tetrahedral arrangement with twofold symmetry. The Li-N(phosphine) distance is 2.048 (5) A, while the Li.P distance is 2.520 (6) A.