Highly effective yet simple transmembrane anion transporters based upon ortho-phenylenediamine bis-ureas

Abstract

Simple, highly fluorinated receptors are shown to function as highly effective transmembrane anion antiporters with the most active transporters rivalling the transport efficacy of natural anion transporter prodigiosin for bicarbonate.

Anthracene Bisureas as Powerful and Accessible Anion Carriers

“…All the anthracene bisureas were found to mediate chloride transport, with activities measurable at transporter to lipid loadings as low as 1:250k (1.6 n m overall in the aqueous suspension) (Figure b). Consistent with previous observations, the electron‐deficient aryl termini N , F , and F2 promoted faster transport than unsubstituted P . The most powerful variant was the nitrophenyl bisurea 7ON , for which [ I ] was measured as 2100 s −1 .…”

“…This is remarkable when one compares the accessibility of the anthracene system with that of the decalins. The affinities are also higher than receptors based upon other simple scaffolds, for example, 3 – 6 , where binding constants measured under the same conditions do not typically exceed 10 3 m −1 . The affinities are only modestly influenced by the electronic effects exerted by the terminal aryl groups, although unsubstituted bisurea 7OP was found to be the weakest chloride receptor as anticipated.…”

“…It is more difficult to compare the transporters with systems from other groups, but the dose‐response data for 7ON (Figure ) allows the estimation of an EC 50, 270 s , a measure which is widely used by other laboratories. The EC 50, 270 s value calculated for 7ON is 0.0003 mol %, the lowest reported to date for chloride–nitrate exchange, and even lower than that of the natural anionophore prodigiosin …”

“…Previous work has shown that electron‐withdrawing terminal groups favor binding and transport in (thio)urea‐based anionophores. 4‐Nitrophenyl N , 4‐trifluoromethylphenyl F , and 3,5‐bis(trifluoromethyl)phenyl ( F2 ) (Figure ) are especially well‐known and effective . We therefore targeted anthracene‐based bisureas bearing these substituents ( 7ON , 7OF , and 7OF2 ; Figure ), with unsubstituted bisurea 7OP and the bisthiourea 7SF2 included for comparison purposes.…”

Repositioning Chloride Transmembrane Transporters: Transport of Organic Ion Pairs

“…[11,12] The exact mechanism by which these neurotransmitters are transported in vivo is not yet fully elucidated but seems to involve the transport of Cl À as well as of Na + and K + . [16][17][18] These calix [6]arenes are thus promising candidates for the transport of primary ammonium chloride contact ion pairs.Asmany of the effective Cl À carriers reported to date bear multiple urea or thiourea groups, [19][20][21][22][23][24] we decided to evaluate the potential of calix [6]arene tris(thio)ureas 1-4 ( Figure 1a)f or the transmembrane transport of RNH 3 Cl ion pairs. [16][17][18] These calix [6]arenes are thus promising candidates for the transport of primary ammonium chloride contact ion pairs.Asmany of the effective Cl À carriers reported to date bear multiple urea or thiourea groups, [19][20][21][22][23][24] we decided to evaluate the potential of calix [6]arene tris(thio)ureas 1-4 ( Figure 1a)f or the transmembrane transport of RNH 3 Cl ion pairs.…”