Novel Fluorescence Probes Based on 2,6-Donor−Acceptor-Substituted Anthracene Derivatives

[reaction: see text] The fluorescence properties of selected derivatives of 6-methoxyanthracene-2-carboxylic acid were studied. The corresponding ester and oxazoline derivatives exhibit a moderate solvatochromism, which is caused by the donor-acceptor interplay. The fluorescence band shift and intensity of oxazoline 1f may be reversibly modulated by protonation or complexation with silver ions; thus, the oxazoline heterocycle serves as a useful substituent with switchable acceptor strength.