(e, 3e) test on e-e correlations in helium

The angular variations of the five-fold differential cross section obtained by using different wave functions of helium are compared with experimental data. It is found that in the coplanar geometry two kinematical arrangements, (i) equal energy sharing between the two ejected electrons with one of them ejected along the momentum transfer direction and the other along varying direction and (ii) the Bethe ridge condition with fixed sum of ejected electron energies and varying angle between them, are very sensitive to e-e correlations contained in the target wave function. This comparison has been used to show that open-shell class of wave functions better incorporate e-e correlations than the closed-shell class.     

Simultaneous Detection of Carbon Monoxide and Viscosity Changes in Cells

A new family of robust, non-toxic, water-compatible ruthenium(II) vinyl probes allows the rapid, selective and sensitive detection of endogenous carbon monoxide (CO) in live mammalian cells under normoxic and hypoxic conditions. Uniquely, these probes incorporate a viscosity-sensitive BODIPY fluorophore that allows the measurement of microscopic viscosity in live cells via fluorescence lifetime imaging microscopy (FLIM) while also monitoring CO levels. This is the first example of a probe that can simultaneously detect CO alongside small viscosity changes in organelles of live cells.     

Hydrocarbon radiolysis in the presence of carboranes(12) 3. Formation of product hydrocarbons

Conclusions A study has been made of the effect of o-carborane on hydrocarbon formation in the radiolysis of n-heptane. The introduction of o-carborane into the n-heptane system reduced the yield of intermediate and dimeric hydrocarbon products. The inhibiting effect of o-carborane traces back to its electron-acceptor activity and its ability to deactivate the excited n-heptane molecule.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1507–1510, July, 1977.The authors would like to thank V. A. Brattsev for advice on matters of technique.     

Radiolysis of hydrocarbons in the presence of carboranes (12)

Conclusions A study has been made of the effect of o-,.m-, and p-carboranes on the formation of hydrogen in the radiolysis of n-heptane; it has been shown that the carboranes not only function as electron acceptors in such processes but also deactivate the excited solvent molecules. Rate constant ratios for the competing reactions have been estimated.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 328–331, February, 1977.     

Monitoring the effect of ultrafast deactivation of the electronic excited states of DNA bases and polynucleotides following 267 nm laser excitation using picosecond time-resolved infrared spectroscopy

In this paper we demonstrate the use of picosecond time-resolved infrared spectroscopy (ps-TRIR) to monitor the early structural dynamics of DNA bases and polydeoxynucleotides following UV excitation in solution.     

Organoboron Compounds 351. Study of the thermal reactions of tetraalkyldiboranes by NMR methods

Conclusions The methods of¹¹B NMR spectroscopy have been used to demonstrate that the 1,1,2-trial-kyldiboranes are the principal products from the disproportionation of the lower tetraalkyl-diboranes (tetraethyl-, tetra-n-propyl-, tetra-n-butyl-, and tetraisobutyldiboranes) at temperatures in excess of 70C, the 1,1- and 1,2-dialkyldiboranes being formed in considerably smaller amounts. The general direction of the disproportionation reaction is not affected by a change in the size of the alkyl radical, or by the replacement of a bridging hydrogen by a deuterium atom. The amount of trialkylboranes in the equilibrium mixture increases with increasing size of the radical, and the rate of the disproportionation reaction falls off when the bridging hydrogen is replaced by a deuterium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 314–318, February, 1979.The authors would like to thank V. S. Bogdanov who obtained and interpreted the NMR spectra.     

Fluorescence lifetime imaging of molecular rotors to map microviscosity in cells

Fluorescence liftime imaging （FLIM） of modified hydrophobic bodipy dyes that act as fluorescent molecular rotors shows that the fluorescence lifetime of these probes is a function of the microviscosity of their environment. Incubating cells with these dyes, we find a punctate and continuous distribution of the dye in cells. The viscosity value obtained in what appears to be endocytotic vesicles in living cells is around 100 times higher than that of water and of cellular cytoplasm.Time-resolved fluorescence anisotropy measurements also yield rotational correlation times consistent with large microviscosity values. In this way, we successfully develop a practical and versatile approach to map the microviscosity in cells based on imaging fluorescent molecular rotors.     

Cationic helicenes as selective G4 DNA binders and optical probes for cellular imaging

The important role that G-quadruplex DNA (G4 DNA) structures play in regulating biological processes is becoming widely recognised. These structures have also been proposed to be attractive drug targets. Therefore, there has been significant interest in developing small molecules that can selectively bind to G4 DNA over other topologies. In this paper we investigate the interaction between DNA and helical compounds (helicenes) based on a central carbocation trisubstituted with aromatic rings. We show that the non-planar structure of these helicenes results in a significantly reduced affinity for dsDNA when compared to their planar analogues, whilst maintaining a high affinity for G4 DNA. Additionally, the right- and left-handed enantiomers of one of these helicenes recognise the chiral DNA environments of G4 and dsDNA differently. We show that upon DNA binding the helicenes display a fluorescence switch-on effect, which we have successfully used for cellular imaging in live and fixed U2OS cells, staining mitochondria and the nucleus, respectively.

G-quadruplex DNA (G4 DNA) structures are selectively recognised by helical optical probes.