Spectroscopic and Other Physical Measurements

A review, in Russian, on the molecular and crystal structure of nucleosides and their derivatives includes much data on conformations and intramolecular interactions.  

FAB mass spectrometry of nucleosides, nucleotides and oligonucleotides has been reviewed the spectra of the major nucleosides of RNA and DNA have been reported in both positive-and 

Three-bond coupling constants (C-6,H-1 and C-2,H-1 ) in the C-n.m.r. spectra of pyrimidine nucleosides were used to obtain information on the glycosidic bond conformation in conjunction with X-ray results, a four-state conformational model was proposed consisting of an equilibrium between two syn and two anti conforma-16 2 

The stacking interaction between tryptophan and uracil was studied in the model compound (59) intramolecular stacking in 

Raman spectra of nine crystals containing guanosine moieties have been reported useful correlations were obtained with the conformations previously established by X-ray studies.The temperature-dependent CD spectra of a- and P-5-substituted-2 -deoxy-uridines indicate an increase in the proportion of syn isomer in changing from aqueous to ethanolic solution. 68 preferred 

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In a paper from this laboratory it was shown that x-ray data collection can be substantially sped up without loss of significant information Q). With a Nicolet P2i diffractometer we collect 12,000 to 14,000 to scan reflections in 24 h. Presumably, newer diffractometers can work at higher speeds. If crystals of reasonable quality are available, a 50-atom (non-H) structure should therefore be determined in less than 24 h. Once the crystal structure has been established, spectroscopic and other physical measurements can be planned and executed in a more rational manner than can be done with unknown samples. An x-ray structure determination should therefore normally be the first analytical procedure performed on a newly synthesized compound. 

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