PECULIARITIES OF STRUCTURE AND SPECTRAL-LUMINESCENT PROPERTIES OF CARBOXYMETHOXY-SUBSTITUTED CALIX[4]ARENES AND THEIR COMPLEXES WITH LANTHANIDES

Abstract

Spectral-luminescent properties of a variety of carboxymethoxy-substituted p-tert-butyl-calix[4]arenes and their complexes with lanthanides (Nd, Er, Yb) that exhibit the 4f-luminescence in the IR-spectrum region have been investigated. The effect of substitution of hydrogen phenolic atoms by carboxymethoxy groups on the stability and spectral-luminescent characteristics of both the ligands and lanthanide complexes was analyzed. Thus, based on the combination of the results obtained by means of elemental analysis, mass spectrometry, IR and 1H NMR spectroscopy, and taking into account the data of pH-metric titration, spectrophotometric and luminescence measurements, it can be concluded that lanthanide ions form neutral complexes of 1:1 ratio with L1H4 - L4H4. This is explained by the presence of mobile hydrogen atoms of phenol and/or carboxyl groups in the molecules of these ligands. An increase in the number of donor substituents leads to changes in the number of solvent molecules in the series L3H4 < L1H4 < L2H4 < L4H4 from 0.8 to 2.4 for neodymium complexes, from 1.2 to 2.2 - for ytterbium complexes. Both the quantum yield and lifetime of the 4f-luminescence of the neodymium and ytterbium complexes and also the luminescence intensity of the erbium-containing compounds change in the same order.