Potentiometric response of amino-calix[4]resorcinarenes modified membranes towards neutral nitrophenols

Polymeric Liquid Membrane Electrodes Incorporated with Undecylcalix[4]-Resorcinarene for Screening of Neutral Forms of Diaminobenzene Isomers

“…The crucial parameters governing this process for nitrogen containing macrocycles as well for oxygen ones, are the differences between acidity and basicity of molecules (both hosts and guests) involved in time of the intermolecular recognition at the polymer/water interface. PVC membranes incorporated with the macrocycles possessing NH groups were able to generate the anionic potentiometric signal after stimulation with neutral forms of phenolic compounds [18]. However, in the case of membranes incorporated with host possessing OH groups, as described in this report, cationic potentiometric responses were observed upon stimulation with uncharged diaminobenzene isomers.…”

“…The consideration of the previously reported potentiometric results concerned with use of calix [4]pyrrole, corrole [15,17], macrocyclic amines [11], amino-calix [4]resorcinarene [18] and results presented here lead to the main conclusion that the ability for potential generation by the mem- branes modified with neutral macrocyclic host molecules is not limited to nitrogen-containing compounds and is a more general phenomenon. The crucial parameters governing this process for nitrogen containing macrocycles as well for oxygen ones, are the differences between acidity and basicity of molecules (both hosts and guests) involved in time of the intermolecular recognition at the polymer/water interface.…”

“…Whereas for membranes incorporated with macrocycles containing OH phenolic groups, the proton is transferred in the opposite direction: from the surface of aqueous layer to surface of organic one. The excellent example of the changing direction of transfer of protons between organic (membrane) and aqueous phase by changing the functional groups (OH and NH) in host and guest molecules are the anionic responses of amino-calix [4]resorcinarene-ISE stimulated with neutral forms of phenol derivatives [18] and cationic responses of UDC [4]Rene-ISE stimulated with uncharged diaminobenzene isomers reported here.…”

“…The generation of potentiometric anionic signal by neutral molecules was previously described only for ionophores containing nitrogen atom in their structure [11][12][13][14][15][16][17][18]. These membranes generated the anionic potential responses upon stimulation with uncharged guest molecules containing phenolic OH groups in their structures.…”

“…The results reported there showed that not only membrane modified with quaternary ammonium salts and lipophilic polyamines, but also those based on calix [4]pyrrole [13][14][15][16], corrole [17], and amino-calix [4] resorcinarenes [18] are able to generate anionic potentiometric responses after stimulation by undissociated form of phenol derivatives.…”