The Ultraviolet Spectra of Flavones and Flavonols

Abstract

The methanol spectra of flavones and flavonols exhibit two major absorption peaks in the region 240 -- 400 nm1. These two peaks are commonly referred to as Band I (usually 300 -- 380 nm, Table V-1 records the $λ$maxvalues for Band I for all flavones and flavonols examined in the present investigation), and Band II (usually 240 -- 280 nm). Band I is considered to be associated with absorption due to the B-ring cinnamoyl system, and Band II with absorption involving the A-ring benzoyl system (see III) [1].