Photo-Switchable Binding between a Photochromic Calix[4]Arene Derivative and Lanthanum Ions

The spectroscopic behavior of a photochromic compound 5, 11, 17, 23-tetra-tert-but yl-25, 27-bis (1’,3’,3’-trimethyl-6-nitrospiro-[2-H-1-benzopyran-2,2’-indoline]-8-methoxycarbonylmethoxy)-26,28-dihydroxycalix [4] arene (1) and its complex with lanthanum nitrate was described. Compound 1 has typical photochromic properties for its two spirobenzopyran groups. The complexation spectroscopic behavior has been investigated in anhydrous acetonitrile by UV-vis, fluorescence spectra and ESR spectra. The results obtained proved the formation of complexes and indicated that the spectroscopic behavior of the supramolecular system could be regulated by light. The system might be used as on-off switches.