Anion receptors acyclic

While interesting neutral alternatives to the unsaturated expanded porphyrin derivatives, calix[n] pyrroles (n = 4, 5, 6, 8) are relatively limited in their scope for anion binding because of the constraints of the cavity size. Nevertheless pyrroles linked by an sp3 hybridised carbon atom are of considerable interest because of their resemblance to the anti-cancer agents the prodigiosins (Section 4.2.4), moreover pyrrole anion-receptor chemistry is synthetically versatile and hence a range of acyclic pyrroles and hybrid amidopyrroles such as 4.50-4.52 have been developed, particularly by the groups of... 

CYCLIC AND ACYCLIC AMIDOPYRROLE CONTAINING ANION RECEPTORS... 

The general poor solubility of these macrocyclic polycobalticinium systems coupled with their lability to ester hydrolysis has very recently led us to a new synthetic strategy which utilizes the stable amide linkage to construct novel acyclic cobalticinium anion receptors (132). 

Beer PD et al (1992) Acyclic redox responsive anion receptors containing amide linked cobalticinium moieties. J Chem Soc Chem Commun 270-272... 

Gale, P.A. (2006) Structural and molecular recognition studies with acyclic anion receptors. Accounts of Chemical Research, 39, 465-475. 

We recently incorporated the ruthenium(II) bipyridyl moiety into acyclic, macrocyclic, and lower rim caUx[4Jarene structural frameworks to produce a new class of anion receptor capable of optical and electrochemical sensing (226, 253. 254). Stability constant determinations in DMSO using H NMR titration techniques demonstrated that these acyclic receptors (131 and 132) form strong complexes with chloride and dihydrogen phosphate anions (stronger than with analogous monopositive cobaltocenium based receptors). The ruthenium ion is dipositive and hence the electrostatic interactions are particularly favorable. The 4,4 -substituted ruthenium bipyridyls were observed to bind anions more... 

The development of new anion receptors based on organic frameworks continues to attract considerable research effort [1-4]. A wide variety of systems have been published in the last 15 years with both macrocyclic and acyclic... 

Y. Ito, Y Lee, E. Lee, M. Water-supported organized structures based on wedge-shaped amphiphilic derivatives of dip5rrolyldiketone horon complexes. Phys. Chem. Chem. Phys. 2011, 13, 3843-3850. (f) Maeda, H. Terashima, Y. Solvent-dependent supramolecu-lar assemblies of rr-conjugated anion-responsive acyclic oligopyrroles. Chem. Commun. 2011, 47, 7620-7622. (g) Maeda, H. Kinoshita, K. Naritani, K. Bando, Y. Self-sorting self-complementary assemhlies of rr-conjugated acyclic anion receptors. Chem. Commun. 

Modifications at a boron unit, substitution by diols and aryl moieties, have also been reported (a) Maeda, H. Fujii, Y Mihashi, Y. Diol-substituted boron complexes of dipyrrolyldiketones as anion receptors and covalently linked pivotal dimers. Chem. Commun. 2008, 4285-4287. (b) Maeda, H. Takayama, M. Kobayashi, K. Shinmori, H. Modification at a boron unit tuning electronic and optical properties of ir-conjugated acyclic anion receptors. Org. Biomol. Chem. 2010, 8, 4308-4315. (c) Maeda, H. Bando, Y Shimomura, K. Yamada, L Naito, M. Nobusawa, K. Tsumatori, H. Kawai, T. Chemical-stimuli-controllable circularly polarized luminescence from anion-responsive... 

A number of these complexes have been used as anion receptors (492,1470,1471). These include cychc (350) and acyclic (351) dithiocarba-mate-based anion receptors (Fig. 190) incorporating thiourea and amide hydrogen-bond donor groups (1470). The NMR titrations with 351 in DMSO-tf resulted in significant downshield shifts, particularly for the amide protons, while UV-vis titrations with both 350 and 351 in DMSO show that 350... 

ArmentroutPB (1999) Gas-Phase Organometallic Chemistry. 4 1-45 Astruc D, Daniel M-C, Ruiz J (2006) Metallodendritic Exo-Receptors for the Redox Recognition of Oxo-Anions and Halides. 20 121-148 Aubert C, Fensterbank L, Gandon V, MalacriaM (2006) Complex Polycyclic Molecules from Acyclic Precursors via Transition Metal-Catalyzed Cascade Reactions. 19 259-294... 

Cation-anion cotransport was effected by an optically active macrotricyclic cryp-tand that carried simultaneously an alkali cation and a mandelate anion and displayed weak chiroselectivity [4.23a], as did also the transport of mandelate by an optically active acyclic ammonium cation [6.39]. Employing together a cation and an anion carrier should give rise to synergetic transport with double selection by facilitating the flow of both components of a salt (see the electron-cation symport below). Selective transport of amino acids is effected by a convergent dicarboxylic acid receptor [4.24b]. 

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