New Insights on Anion Recognition by Isomers of a Calix Pyrrole Derivative

摘要: Two isomeric structures of meso-tetramethyltetrakis(3-hydroxyphenyl)calix[4]pyrrole, 4-alphaalpha betabeta and 4-alphabeta alphabeta, have been isolated characterized by 1H NMR in different solvents (CD3CN, CD3OD, DMSO-d6) at 298 K. Standard Gibbs energies solution derived from solubility data various were used to calculate the transfer energy, delta(t)G(o), these ligands using acetonitrile as reference solvent. These results are consistent with studies media that show chemical shift changes observed resonances NH OH protons ligands. Solvate formation was when isomers exposed saturated atmosphere N,N-dimethylformamide, dimethyl sulfoxide propylene carbonate. Anion interaction involving alphabeta investigated CD3CN while complex composition assessed through conductance measurements. Significant differences affinity for anions well fluoride complexes. Thus shows selectivity H2PO4(-) its isomer is selective anion. Again altered anion complexed (1:1 complex) relative same The latter an enhanced hosting ability this two taken up per unit ligand. thermodynamics complexation discussed, compared those calix[4]pyrrole It shown interact one interacts This paper demonstrates first time enthalpy parameter may be a suitable reporter number hydrogen bonds formed derivatives dihydrogen phosphate acetonitrile. In moving unable enter most anions, except fluoride, which 1:2 (ligand:anion) demonstrated. rather versatile behavior receptors explained on basis evidence solvation effects. investigations highlight importance medium effect stability reflect inherent nature solvent highly significant involvement process.