Spectroscopic reporter group

Since new carbonyl compounds of Ti, Zr, and Hf and their accompanying chemistry are appearing at a steady rate in the literature, it seems appropriate at this time to bring this rapidly growing area into perspective. In this review we will endeavor to categorize all reported group 4B metal carbonyls including their synthesis, formation,1 structure, spectroscopic... 

In a spectroscopic study designed to elucidate the mechanism of the allosteric transition in ATCase, hybrid enzyme molecules were formed containing (in addition to regulatory subunits) three native catalytic subunits, and three modified catalytic subunits. The modified catalytic subunits contained the nitrotyrosine reporter group and a modified lysine that precluded substrate binding. Why was this modified lysine necessary to the experiment ... 

The C5 position of dU has been used to attach a variety of labels or reporter groups, in particular fluorophores ° (see section 3.5). The pyrene-modified analogue (39) has been used to detect RNA bulge conformations in the HIV-TAR RNA sequence where the fluorescence is greatly enhanced,and as a donor for the red emitter nile red (40) when the two dyes are adjacent in duplex DNA the result is white light that is emitted upon excitation of (39). A zinc-porphyrin complex has been added to C5 of dU for use in electron transfer. Norbornene has been attached via an alkyne linker for post-synthetic modification with nitrile oxides in a copper-free Click reaction, " and various dienes have been attached for Diels-Alder tagging of DNA. The photoaffinity tag (41) has been incorporated into DNA adjacent to a damaged DNA base (8-oxo-dG or thymine dimer) such that when exposed to repair systems, the repair enzyme is trapped by the diazirine for mass spectroscopic characterisation. ... 

Although the nature of the general polar effect suggested by Kamernitzsky and Akhrem " to account for axial attack in unhindered ketones is not clear, several groups have reported electrostatic interactions affect the course of borohydride reductions. Thus the keto acid (5a) is not reduced by boro-hydride but its ester (5b) is reduced rapidly further, the reduction of the ester (6b) takes place much more rapidly than that of the acid (6a). Spectroscopic data eliminate the possibility that in (5a) there is an interaction between the acid and ketone groups (e.g. formation of a lactol). The results have been attributed to a direct repulsion by the carboxylate ion as the borohydride ion approaches. " By contrast, House and co-workers observed no electrostatic effect on the stereochemistry of reduction of the keto acid (7). However, in this compound the acid group may occupy conformations in which it does not shield the ketone. Henbest reported that substituting chlorine... 

The isolation of four terpenes from the bitter principles of Ginkgo by Furukawa in 19326 marked an important advance in the quest for the identification of the active constituents of Ginkgo extracts. A second major milestone was reached in 1967 when Nakanishi and his group reported their extensive and brilliant studies which permitted the structures of these compounds to be fully defined.4 On the basis of spectroscopic data and chemical reactivity... 

Spectroscopic analysis of Pu5+ and Pu6+ halides is in its initial stages. No low-temperature single-crystal spectra have been reported. A 25°C mull spectrum of the compound Rb2PuF7 was described earlier (37), and is now supplemented by the results for CsPuFg (31) PuF gas-phase spectra have been reported by several different groups at ANL (38-39). 

The acid-base interaction in group 13-stibine and -bismuthine adducts seems to be very weak as is indicated by mass spectroscopic studies, which never showed the molecular ion peak but only the respective Lewis acid and Lewis base fragments. The extreme lability in the gas phase may also account for the fact that there are only very few reports on thermodynamic data of group 13-stibine or bismuthine adducts in the literature. Therefore, multinuclear NMR spectroscopy and single crystal X-ray diffraction are the most important analytical tools for the characterization of such adducts. 

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