Über die Wirkung von Auxochromen in Flavyliumsalzen,II. 5,6-Benzo-flavyliumsalze

Analogously to the 7-hydroxyflavyliumion the 5,6-benzoflavyliumion affects auxochromes in 4′-position not as strongly as the flavylium ion. In the flavylium series the dimethyl-amino group e.g. causes a bathochromic effect of 137 nm; in the 5,6-benzoflavylium series however the bathochromic effect is only 109 nm. The absorption maxima of both series converge; in the case of the dimethylamino group the convergence amounts to 28 nm.