Synthesis and properties of potassium salts of per-O-carboxymethyl-calix[4]pyrogallols and their complexes with Cu2+, Fe3+, and La3+

Abstract

Synthesis of water soluble potassium salts of carboxymethyl derivatives of calix[4]pyrogallols and dodeca(carboxylatomethyl)tetramethylcalix[4]pyrogallol (L) complexes with transition metal ions (Cu 2+ , Fe 3+ , La 3+ ) is described. Their structures in the solid state and in solution were characterized by NMR spectroscopy, ESR, and IR spectroscopy. Calix[4]pyrogallol dodecacarboxylates exist in the rccc configuration. Calix[4]pyrogallol with methyl substituents at the lower rim in a wide range concentrations exists in water predominantly in the dimeric form. The obtained polynuclear transition metal complexes possess less symmetric structure than potassium salt of calix[4]pyrogallol (K 12 L). All studied complexes contain water mol ecules bound by rather strong hydrogen bonds. At room temperature the Fe 4 L complex is characterized by the environment of the Fe 3+ ions close to octahedral. The absence of signals in the ESR spectrum of the Cu 6 L complex indicates the strong antiferromagnetic interaction Cu 2+ -Cu 2+ .

Modulating the Inclusive and Coordinating Ability of Thiacalix[4]arene and Its Antenna Effect on Yb3-Luminescence via Upper-Rim Substitution+

“…The self-diffusion coefficient for the thiacalix[4]arene H4L(3) under the complex formation with Lu 3+ becomes lower by 14% ( Table 1 ). According to the literature data, the decrease of D s by ~25% testifies to the dimerization of the molecules in the solutions [ 46 , 47 , 48 ]. Therefore, the less pronounced decrease in self-diffusion coefficients D s of ligands H 4 L( 2 , 3 ) under the complex formation with Lu 3+ versus La 3+ ions indicates the greater contribution of the monomeric forms.…”

Effect of the formation of capsules of tetra(propyl) pyrogallol[4]arene on the host-guest interaction with neurotransmitters

“…Pyrogallol [4]arenes represent a class of macrocyclic phenolic compounds obtained from the condensation reaction of pyrogallol with several aldehydes in acidic solutions 18 , and they can be modified with various substituents on the upper rim in order to provide specific functionality and selectivity [19][20][21][22] . Pyrogallol [4]arenes have attracted great interest in the field of supramolecular chemistry due to the ease of forming capsules [23][24][25] with different types of reagents such as water 26 , zinc complex 27 , magnesium cations 28 and ammonium salts 29 .…”