Anion receptors tris

The respective association constants of the latter anion to free 376 is only 10 M 1 while for the self-assembled complex it is equal to 2.5 104 M 1 [39]. Kubik and Goddard obtained a cyclic pseudopeptide ditopic receptor 378 for the simultaneous complexation of cations and anions [40]. Simultaneous encapsulation of N03 and PF6 ions by a highly charged (+12) anion receptor 379 was achieved by Schnebeck and coworkers [41]. By coordinating of 2,4,6-tris[(4-pyridyl)methylsulfa nyl]-l,3,5-triazine 380 with Ag, Hong and coworkers obtained nanosized tubes (Fig.7.8.1) that could host solvent and anionic molecules [42]. 

Anzenbacher, P., Jr. Try, A.C. Miyaji, H. Jursikova, K. Lynch, V.M. Marquez, M. Sessler, J.L. Fluorinated calix[4]pyrrole and dipyrrolylquinoxaline neutral anion receptors with augmented affinities and enhanced selectivities. J. Am. Chem. Soc. 2000, 122, 10268-10272, and references therein. 

In 1993, Reinhoudt and co-workers described the synthesis and binding properties of a series of tris-amides and tris-sulfonamides based upon the tren skeleton [11]. These receptors proved to be selective for phosphate in acetonitrile solution and demonstrated, arguably for the first time, that anion receptor systems need not be difficult to make but rather that simple organic compounds could function as very effective receptors. Stability constants were calculated by conductivity experiments and showed that receptor If bound dihydrogenphosphate with the highest affinity (14200 M ) in acetonitrile presumably due to the preorganization of the receptor via Jt-Jt interactions between the naphthyl groups. 

The first synthetic amide-based anion receptor 1 was reported in 1986 by Pascal Jr. and coworkers.This neutral cyclophane-type receptor was synthesized by reaction of l,3,5- m-(bromomethyl)benzene with three equivalents of cystearnine to form a triamine which was then clipped with one equivalent of the tris-acid chloride of 1,3,5-benzenetriacetic acid. The receptor contains three amide NH groups chat may be directed into the center of... 

X. Sun, H. S. Lee, S. Lee, X. Q. Yang, J. McBreen, Electrochem. Solid-State Lett. 1998, 1, 239-240. A novel lithium battery electrolyte based on Uthium fluoride and a tris(pentafluorophenyl) borane anion receptor in DME. 

Nieto, S., P6rez, ] , Riera, V., Miguel, D. and Alvarez, C., Cationic fac-tris(pyrazole) complexes as anion receptors, Chem. Commun., 2005,546-548. 

Anzenbacher P, Try AC, Miyaji H, Jursicova K, Lynch VM, Marquez M, Sessler J (2000) Fluorinated cahx[4]pyrrole and dipyrrolylquinoxahne. Neutral anion receptors with augmented affinities and enhanced selectivities. J Am Chem Soc 2000(122) 10268-10272... 

Lee YM, Seo JE, Choi N-S, Park J-K (2005) Influence of tris(pentafluorophenyl) borane as an anion receptor on ionic conductivity of LiClQ4-based electrol3rie for lithium batteries. Electrochim Acta 50 2843-2848. doi 10.1016/j.electacta.2004.11.058... 

Xie B, Lee HS, Li H, Yang XQ, McBreen J, Chen LQ (2008) New electrolytes using Li20 or Li202 oxides and tris(pentafluorophenyl)borane as boron based anion receptor for lithium batteries. Electrochem Commun 10 1195-1197. doi 10.1016/j.elecom.2008.05.043... 

Fig. 2 Bis- and tris(iodoperfluoroarene) anion receptors 2a-3c. Association constants with Bu4isrCP (acetone, 295 K) are listed...

Gillis EAL, Demireva M, Sarwar MG, Chudzinski MG, Taylor MS, Williams ER, Pridgen TD (2013) Structure and energetics of gas phase halogen-bonding in mono-, bi- and tri-dentate anion receptors as studied by BIRD. Phys Chem Chem Phys 15 7638... 

Another concept for anion receptors comprises bases on boron. It is possible to obtain highly conducting liF solutions in nonaqueous solvents hy means of boron additives, such as tris(pentafluorophenyl)borane (TPFPB) (see Figure 17.15) [423, 424], Solubihty of LiF can be increased by 6 orders of magnitude up to 1 mol- solutions. This observation can be exclusively attributed to Equation 17.27 Moreover, 1 molL solutions of LiF and boron-based anion receptors show good electrochemical stabiHty up to 5 V vs Li. Therefore, full battery systems... 

Figure 17.15 Structure of the anion receptor and Lewis acid tris(pentafluorophenyl)borane (TPFPB).

The open channel has in most cases a selective permeability, allowing a restricted class of ions to flow,for example Na+, K+, Ca++ or Cl- and, accordingly, these channels are called Na+-channels, K+-channels, Ca -channels and Cr-channels. In contrast, cation-permeable channels with little selectivity reject all anions but discriminate little among small cations. Little is known about the structures and functions of these non-selective cation channels [1], and so far only one of them, the nicotinic acetylcholine receptor (nAChR, see Nicotinic Receptors), has been characterized in depth [2, 3]. The nAChR is a ligand-gated channel (see below) that does not select well among cations the channel is even permeable to choline, glycine ethylester and tris buffer cations. A number of other plasma... 

Scheme 28. Modification of a tris(pyrazolyl)hydroborato ligand to a receptor for binding anions.

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