Frequency and time domain F ENDOR spectroscopy: role of nuclear dipolar couplings to determine distance distributions.

F electron-nuclear double resonance (ENDOR) spectroscopy is emerging as a method of choice to determine molecular distances in biomolecules in the angstrom to nanometer range. However, line broadening mechanisms in F ENDOR spectra can obscure the detected spin-dipolar coupling that encodes the distance information, thus limiting the resolution and accessible distance range. So far, the origin of these mechanisms has not been understood.

C=C Dissociative Imination of Styrenes by a Photogenerated Metallonitrene.

Photolysis of a platinum(II) azide complex in the presence of styrenes enables C=C double bond cleavage upon dissociative olefin imination to aldimido (Pt-N=CHPh) and formimido (Pt-N=CH) complexes as the main products. Spectroscopic and quantum chemical examinations support a mechanism that commences with the decay of the metallonitrene photoproduct (Pt-N) via bimolecular coupling and nitrogen loss as N. The resulting platinum(I) complex initiates a radical chain mechanism via a dinuclear radical-bridged species (Pt-CHCHPhN-Pt) as a direct precursor to C-C scission.

Pulsed EPR Methods in the Angstrom to Nanometre Scale Shed Light on the Conformational Flexibility of a Fluoride Riboswitch.

Riboswitches control gene regulation upon external stimuli such as environmental factors or ligand binding. The fluoride sensing riboswitch from Thermotoga petrophila is a complex regulatory RNA proposed to be involved in resistance to F cytotoxicity. The details of structure and dynamics underpinning the regulatory mechanism are currently debated.

Overhauser enhanced liquid state nuclear magnetic resonance spectroscopy in one and two dimensions.

Nuclear magnetic resonance (NMR) is fundamental in the natural sciences, from chemical analysis and structural biology, to medicine and physics. Despite its enormous achievements, one of its most severe limitations is the low sensitivity, which arises from the small population difference of nuclear spin states. Methods such as dissolution dynamic nuclear polarization and parahydrogen induced hyperpolarization can enhance the NMR signal by several orders of magnitude, however, their intrinsic limitations render multidimensional hyperpolarized liquid-state NMR a challenge.