Fluorescence properties of p-tert-butyldihomooxacalix[4]arene derivatives and the effect of anion complexation

The intrinsic electronic absorption and fluorescence properties of several multifluorophoric dihomooxacalix[4]arenes are studied. The contributions of phenyl and/or benzyl groups (lower rim) and p-tert-butylphenyl ethers (upper rim) to the absorption and fluorescence are established. Fluorescence titrations were undertaken to investigate the calixarene complexes with nitrate and hydrogen sulfate. A comparison with UV-Vis titrations in the same concentration range showed that similar values for the association constants are obtained by both techniques. Fluorescence is thus demonstrated to be a good method for the determination of calixarene–anion association constants.