The solubilities of C1C4im(+) and Tf2N(-) in nitric aqueous phases have been measured for several ligand types and concentrations (0.04 M tributylphosphine oxide, 0.05 M N,N'-dimethyl-N,N'-dibutylmalonamide, 0.10 M 1-methyl-3-[4-(dibutylphosphinoyl)butyl]-3H-imidazol-1-ium bis(trifluoromethylsulphonyl)imidate, and 1.1 M N,N-dihexyloctanamide). The data evidence a significant difference between the solubilities of the cations and anions of the ionic liquid as a consequence of several ion-exchange and/or ion-pairing mechanisms involving all ions present in the system as well as the protonation/nitric-extraction ability of the ligand.

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The conductometric sensor based on 25,27-di-(5-thio-octyloxy)calix[4]arene-crown-6 was developed for the quantitative analysis of ammonium. The calixarene was immobilized on the surface of the planar interdigitated electrodes by attachment of its dialkyl sulfide groups to the surface of the gold electrodes. The intrinsic ability of the calixarene to capture ammonium was studied in the conductometric measuring mode and by the electrochemical impedance spectroscopy. The developed sensor showed high selectivity to ammonium in the presence of mono-, di-, and trivalent cations. Selective and highly sensitive detection of ammonium resulted from the complexation between the ammonium ions and a crown-ether fragment of the upper rim of the 25,27-di-(5-thio-octyloxy)calix[4]arene-crown-6 macrocycle. The developed sensor had high signal repeatability. Its sensitivity was found to be satisfactory for the forthcoming sensor application in the water-sample analysis; the linear range was 0.01–1.5 mM and limit of detection 10 μM.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-016-1317-9) contains supplementary material, which is available to authorized users.

Calix[4]arenes bearing two or four methylenebisphosphonic acid groups at the macrocyclic upper rim have been studied with respect to their effects on fibrin polymerization. The most potent inhibitor proved to be calix[4]arene tetrakis‐methylene‐bis‐phosphonic acid (C‐192), in which case the maximum rate of fibrin polymerization in the fibrinogen + thrombin reaction decreased by 50% at concentrations of 0.52 × 10−6 m (IC50). At this concentration, the molar ratio of the compound to fibrinogen was 1.7 : 1. For the case of desAABB fibrin polymerization, the IC50 was 1.26 × 10−6 m at a molar ratio of C‐192 to fibrin monomer of 4 : 1. Dipropoxycalix[4]arene bis‐methylene‐bis‐phosphonic acid (C‐98) inhibited fibrin desAABB polymerization with an IC50 = 1.31 × 10−4 m. We hypothesized that C‐192 blocks fibrin formation by combining with polymerization site ‘A’ (Aα17–19), which ordinarily initiates protofibril formation in a ‘knob‐hole’ manner. This suggestion was confirmed by an HPLC assay, which showed a host–guest inclusion complex of C‐192 with the synthetic peptide Gly‐Pro‐Arg‐Pro, an analogue of site ‘A’. Further confirmation that the inhibitor was acting at the initial step of the reaction was obtained by electron microscopy, with no evidence of protofibril formation being evident. Calixarene C‐192 also doubled both the prothrombin time and the activated partial thromboplastin time in normal human blood plasma at concentrations of 7.13 × 10−5 m and 1.10 × 10−5 m, respectively. These experiments demonstrate that C‐192 is a specific inhibitor of fibrin polymerization and blood coagulation and can be used for the design of a new class of antithrombotic agents.