Zhao, Jiang-Lin Wu, Chong Zeng, Xi Rahman, Shofiur Georghiou, P.E. Elsegood, Mark Warwick, Thomas G. Redshaw, Carl Teat, Simon J. Yamato, Takehiko Thiacalix[4]arene derivatives bearing imidazole units: a ditopic hard/soft receptor for Na+ and K+/Ag+ with an allosteric effect and a reusable extractant for dichromate anions Two novel receptors 5,11,17,23-tetra-tert-butyl-25,27-bis[(ethoxycarbonyl)methoxy]-26,28-bis-[1-methyl-(imidazole)meth-oxy]-2,8,14,20-tetra-thiacalix[4]arene (L1) and 5,11,17,23-tetra-tert-butyl-25,27-bis-[(benzyl)methoxy]-26,28-bis-[1-methyl-(imidazole)-methoxy]-2,8,14,20-tetrathiacalix[4]arene (L2) possessing imidazole moieties based on thiacalix[4]arene in the 1,3-alternate conformation have been synthesized and characterized. The crystal structures of L1 and L2 have been determined. The binding behaviour towards Li+, Na+, K+ and Ag+ ions has been examined by 1H NMR titration experiments in (CDCl3/CD3CN; 10:1, v/v) solution. The exclusive formation of mononuclear complexes of L1 with metal cations is of particular interest revealing a negative allosteric effect in the thiacalix[4]arene family. Liquid-liquid extraction experiments indicate that synthesized L2 can be utilized as an efficient reusable extractant for dichromate anion by controlling the pH of the aqueous solution. Thiacalix[4]arene;Imidazole;Allosteric effect;Dichromate;Chemical Sciences not elsewhere classified 2016-06-22
    https://repository.lboro.ac.uk/articles/journal_contribution/Thiacalix_4_arene_derivatives_bearing_imidazole_units_a_ditopic_hard_soft_receptor_for_Na_and_K_Ag_with_an_allosteric_effect_and_a_reusable_extractant_for_dichromate_anions/9390938