Nucleic acids absorption band assignments

Since the nucleic acid bases are aromatic compounds (see Chapter 3), the analogy with benzene has led several authors to correlate the absorption spectra (which also determine CD) of these two series. The region between 200 and 300 nm shows four absorption bands in benzene and other aromatic compounds. The names B2u (around 265 to 285 nm) and Biu (around 230 to 260 nm) have been assigned. These bands are tt-tt bands and are polarized in the plane of the base. Below 220 nm, benzene possesses a doubly... 

---