Films pyrimidine bases

Spectral data (Amax and AE, and e x 10 3) for the pyrimidine bases investigated in a few representative papers are collected in Table XXVIII. The absorption bands are denoted by the capital letters A, B, C, etc. In Table XXVIII we have listed the results of the vacuum ultraviolet measurements by Yamada and Fukutome428 (cf. also ref. 429), who measured the spectra of sublimed films of cytosine, thymine, uracil (and also of guanine and adenine) down to 120 nm at room temperature. Several remarkable absorption peaks were found below 190 nm in addition to the already known ones near 260 and 200 nm. A weak absorption at 230-240 nm in cytosine was not indicated in the sublimed films of the molecule,428 but was visible in the stretched polyvinyl alcohol film spectrum.432 Crewe et al.i3° studied the interactions of fast electrons with the five nucleic acid bases and measured the energy-loss spectra of 20 keV electrons transmitted through thin films of these bases. These last data are also listed in Table XXVIII for comparison with the other spectral findings. 

There has been considerable interest in recent years in the formation of condensed films of purine and pyrimidine bases at the solid-liquid interface. It is well recognised that non-covalent affinities between base pairs play a prevalent role in determining nucleic acid conformation and functionality. Likewise, there has been interest in the role of substrate and non-covalent intermolecular interactions in the configuration of ordered monolayers of purine and pyrimidine bases. There is also more general interest in the interaction of bases with metal surfaces and metal complexes. In the latter case it is noted that the biological role of nucleic acids and certain nucleotides are dependent on metal ions, particularly Mg, Ca, Zn, Mn, Cu and Ni. " Also certain metal complexes, notably of platinum, have the anti-tumour activity, which is linked to their ability to bind to bases on DNA. On a different note, the possibility that purine-pyrimidine arrays assembled on naturally occurring mineral surfaces might act as possible templates for biomolecular assembly has been discussed by Sowerby et al. 

Ekind and coworkers pyrimidine-based hyperbranched and aromatic pol3dmides were tested as hydrogen peroxide-selective membrane in the presence of interferents. It was found that the pol3dmide films can be applicable to amperometric sensing of hydrogen peroxide in the presence of the mentioned elecboactive and non-elecboactive interferents[23-24]. 

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