Dicarboxylate anions

Lipophilic N-tetrabenzylcylam, III, at pH 4-7 was found to be a good carrier for liquid membrane transport of dicarboxylate anions, such as o-phthalate, and of amino acid anions52). It was suggested that the diprotonated species, H2L2+, is an active carrier species for anions. 

Many workers have shown [3,19] that the gallery height in LDHs containing long chain aliphatic carboxylate, dicarboxylate, sulfonate or sulfate guests increases as the chain length increases. For the case of o, 6t)-dicarboxylate anions OOC(CH2)nCOO , the basal spacing shows a mean increase of 0.127 nm/CH2 from n = 3 to 12 as shown in Fig. 21 [213] for Mg/Al LDH... 

Fig. 21 Variation in basal spacing of a, -dicarboxylate anions OOC(CH2)nCOO", intercalated in Mg/Al LDH nanocrystals supported on silicon substrates. Reprinted with permission from [213]. Copyright American Chemical Society...

The enthalpy changes associated with exchange of chloride ions in a Zn2.2 A1 LDH by a variety of dicarboxylate anions (oxalate, succinate, adipate and tartrate) have been measured by microcalorimetry [222]. With the exception of tartrate, the exchange processes are endothermic and the enthalpies... 

Our first generation sapphyrin-sapphyrin dimer is represented by structure 15. In this system, two covalently connected anion binding sites are contained within the same overall recognition framework. It was thus expected that system 15 would act as an effective receptor for dicarboxylate anions under conditions where the corresponding monomeric systems (e.g. 3) would not. Indeed, this proved to be the case (vide infra). 

Our desire to generate a receptor for dicarboxylate anions came from an appreciation that di- and tricarboxylates play critical roles in numerous metabolic processes including, for instance, those associated with the citric acid and glyoxy-late cycles. They also play important roles in the generation of high-energy... 

Mass spectrometric studies were carried out as a first qualitative means of checking for dicarboxylate anion binding (see also Section 3). Here, mixtures of sapphyrin dimer 15 and several representative dicarboxylate anions, such as oxalate, 4-nitrophthalate, 5-nitroisophthalate and nitroterephthalate in methanol, were subjected to high resolution FAB mass spectrometric (HR FAB MS) analysis using FAB positive NBA matrix. In general, peaks for the putative complexes were seen, lending credence to the hypothesis that the dicarboxylate substrates in question were, in fact, being bound by 15 under the matrix desorption/gas phase conditions used to effect these mass spectrometric analyses. 

With the aim of binding dicarboxylic anions, Schmidtchen and coworkers synthesized receptor 16 by means of connecting two bicycloguanidinium building blocks with a naphthalene spacer [23]. Due to its flexible framework it binds dianions that range in size from carbonate up to p-phenylenbis(3-acrylate) with maximum association for malonate and 3-nitroisophthalate (K ss = 16500 M S 14500 M S respectively, in methanol) [24],... 

The reaction of alkyl isothiocyanates, RNCS, with diphenylphosphinic hydrazide (338) in benzene has been reported.308 The bis(diethylamino)[(methylthio)thiocarbon-yl]carbenium salts (339 X = I or BF4) display ambident reactivity and can react either at carbenium carbon (hard nucleophiles) or at the thiocarbonyl sulfur atom (soft nucleophiles).309 Electrochemically generated superoxide reacts with dithioic S,S -diesters (dicarbothiolates) (340 Ar = C5H3N or C6H4) to give the monocarboxylate anions in 100% yield before giving the dicarboxylate anions.310... 

Liu, S. Y., He, Y. B., Wu, J. L., et al., Calix[4]arenes containing thiourea and amide moieties neutral receptors towards alpha,omega-dicarboxylate anions. Org. Biomol. Chem. 2004, 2, 1582-1586. 

However, chiral recognition was the most common field of application of various chiral bis-porphyrinoids. Hence, Sessler s group prepared a series of bis-sapphyrins 67-69 for the chiral recognition of dicarboxylate anions via a combination of Coulombic attractions and hydrogen bonding [119]. While... 

A tetraamidinium functionalized, bowl-type cavitand (receptor 8) was developed by Diederich and Sebo [47]. This receptor was found to complex 1,3-dicarboxylate anions with good selectivity and a 1 2 binding stoichiometry both in CD3OD and D20, as revealed by standard Job plot analysis. In contrast, various nucleotide phosphates were found to be bound with a 1 1 stoichiometry in D20. In the case of the adenosine phosphates, the association constants increased as a function of nucleotide charge [i.e., the affinity order (K., M-1) was cAMP (1400) < AMP (10000)charged receptor (8) also showed moderate selectivity towards AMP (Ka = 10 000 M-1) over other nucleotide monophosphate anions, such as GMP (FCa = 5200 M-1), CMP (fCa = 3500 M-1), TMP (K l — 5900 M ), and UMP (Ka-3800M ) in D20 containing TRIS buffer (2.5 mM, pH 8.3). 

Fogg, A. M., Dunn, J. S., Shyu, S. G., Cary, D. R. and O Hare, D. (1998). Selective ion-exchange intercalation of isomeric dicarboxylate anions into the layered double hydroxide [LiAl2(OH)6)]Cl, H20. Chem. Mater. 10, 351. 

The next reaction occurs in the cytoplasm. Malate is transported to the cytoplasm by a dicarboxylate carrier which is specific for malate, succinate, and fumarate and which requires the entry of P, or one of these dicarboxylate anions. Cytoplasmic malate is then converted to oxaloacetate by cytoplasmic malate dehydrogenase ... 

Figure 5 Some coordination modes of (a) monocarboxylate anions, (b) dicarboxylate anions, (c) the carbonate anion, (d) the dianion of squaric acid, and (e) the dianion of croconic acid...

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