AbstractPartially acetalisized poly(vinyl alcohol)s with degrees of acetalization between 39 and 60% were prepared by reaction of poly(vinyl alcohol) with 9‐isobutyl‐3‐carbazolealdehyde(5a)or 3‐formyl‐9‐((S)‐2‐methylbutyl)carbazole(5b). Complex formation constants and ε‐values of the charge‐transfer complexes with ethylenetetracarbonitrile, 2,5‐cyclohexadien‐1, 4‐diylidenedimalonodinitrile, 2,4,5,7‐tetranitro‐9‐fluorenone, and 2,4,7‐trinitro‐9‐fluorenone were determined. Circular dicroism measurements of the optically active CT‐comple