Powerful Bipodal Anion Transporters Based on Scaffolds That Contain Different Chalcogens

Abstract

A new family of bipodal anion transporters based on chalcogen‐containing scaffolds has been designed and synthesized. Though structurally related to the well‐studied tripodal anionophores, these molecules are simpler with only two anion‐binding sites. However, the activities remain high. Anion transport could be facilitated by the new transporter at an exceptionally low loading of transporter/lipid ratio of 1:500000. This impressive efficiency is comparable with the most active one from the tren‐based tripodal series. To investigate influences from different scaffolds and substituent groups, lipophilicity, anion‐binding property, and transport activity of each molecule were studied. It was found that the bridge atom has a major impact on transport activities mainly as a result of anion‐binding differences. The results also suggest that chalcogen can act as a key structural modulator to develop highly effective anion transporters and optimize their activities.

Anthracene Bisureas as Powerful and Accessible Anion Carriers

“…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.…”

“…This is remarkable when one compares the accessibilityo ft he anthracenes ystem with that of the decalins.T he affinities are also higher than receptors based upon other simple scaffolds, for example, 3-6,w here binding constants measured under the same conditions do not typically exceed1 0 3 m À1 . [23][24][25][26][27][28]50] The affinitiesa re only modestly influenced by the electronic effects exertedb yt he terminal aryl groups, although unsubstituted bisurea 7OP was found to be the weakest chloride receptor as anticipated. In the case of bisthiourea 7SF2,a nalysis indicated much weakerb inding, with K a,1:1 = 130 m À1 .T his finding runs counter to normal expectation, given that thioureas are more acidic than ureas.…”

“…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.…”

“…To express their activity,i ti sg enerally necessaryt oi ncorporate them in the bilayer during membrane production. Meanwhile [a] C. M. Dias other,s impler scaffolds also yield powerful anionophores (e.g., 3-6, [23][24][25][26][27][28]50] Figure 1), but none seem able to match the activities of the cholapod and trans-decalin families.…”

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.…”