Complexation with Cations

Even though all studies revealed a different complexation behavior of the drugs on the one hand and the metal ions on the other hand, it can be stated that fluoroquinolones should not be co-administered with antacid or multivitamin drugs in order to avoid the complexation and, as a result, a decreased antimicrobial activity. 

A L Thakkar, L G Tensmeyer, R B Hermann, W L Wilham, Chem Commun, 524-525 (1970) 

J Nishijo, I Yonetani, K Tagahara, Y Suzuta, E Iwamoto, Chem Pharm Bull 34. 4451-4456(1986) 

G Mendoza-Diaz, K H Pannell, Inorg Chim Acta 152, 77-79 (1988) 

J Shimada, K Shiba, T Oguma, H Miwa, Y Yoshimura, T Nishikawa, Y Okabayashi, T Kitagawa, S Yamamoto, Antimicrob Agents Chemother36, 1219-1224 (1992) 

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These can be prepared by electrolytic oxidation of chlorates(V) or by neutralisation of the acid with metals. Many chlorates(VII) are very soluble in water and indeed barium and magnesium chlorates-(VII) form hydrates of such low vapour pressure that they can be used as desiccants. The chlorate(VII) ion shows the least tendency of any negative ion to behave as a ligand, i.e. to form complexes with cations, and hence solutions of chlorates (VII) are used when it is desired to avoid complex formation in solution. 

Many different types of foaming agents are used, but nonionic surfactants are the most common, eg, ethoxylated fatty alcohols, fatty acid alkanolamides, fatty amine oxides, nonylphenol ethoxylates, and octylphenol ethoxylates, to name a few (see Alkylphenols). Anionic surfactants can be used, but with caution, due to potential complexing with cationic polymers commonly used in mousses. 

Molecular Interactions. Various polysaccharides readily associate with other substances, including bile acids and cholesterol, proteins, small organic molecules, inorganic salts, and ions. Anionic polysaccharides form salts and chelate complexes with cations some neutral polysaccharides form complexes with inorganic salts and some interactions are stmcture specific. Starch amylose and the linear branches of amylopectin form inclusion complexes with several classes of polar molecules, including fatty acids, glycerides, alcohols, esters, ketones, and iodine/iodide. The absorbed molecule occupies the cavity of the amylose helix, which has the capacity to expand somewhat to accommodate larger molecules. The starch—Hpid complex is important in food systems. Whether similar inclusion complexes can form with any of the dietary fiber components is not known. 

Hilgenfeld, R., Saenger, W. Structural Chemistry of Natural and Synthetic Ionophores and their Complexes with Cations, in Topics in Current Chemistry (ed. Boschke, F. L.), p. 8, Berlin—Heidelberg—New York, Springer 1982... 

In this review, recent development of active transport of ions accross the liquid membranes using the synthetic ionophores such as crown ethers and other acyclic ligands, which selectively complex with cations based on the ion-dipole interaction, was surveyed,... 

Structural chemistry of natural and synthetic ionophores and their complexes with cations. R. Hil-genfeld and W. Saenger, Top. Curr. Chem., 1982,101,1-82 (346). 

It is expected, therefore, that the cyclic hexamer also exhibits a characteristic tendency to complex with cations. In fact, the addition of an acetonitrile solution of metal thiocyanates to a solution of the cyclic hexamer in the same solvent shifted the carbonyl absorption to a lower wave number46,52 The shift values depended upon the kind of metal ions present, and the largest shift value of 40 cm-1 was observed for barium thiocyanate (molar ratio of Ba2+/hexamer = 10). In addition to the shift of the carbonyl absorption, the intensities of the C—O-C stretching vibrations around 1200 cm-1 varied appreciably. 

Recently the use of another bifunctional reagent, glutaraldehyde, has been described for the stabilization of DNA complexes with cationic peptide CWK18 [104]. The authors of this paper, however, limited the study to the protective effects toward nuclease degradation. 

Ring systems intermediate between phthalocyanines and naphthalocyanines are known 263,264 (51) is such a compound. They are most simply called benzonaphthoporphyrazines, and various zinc(II) complexes with cationic (A--m e t hy 1 pyridini um-3-oxy) substituents have Amax in the range 680-750 nm in solution or in Cremophor micelles, and show promise in bioassays in vivo.264... 

Label Aq represents each possible surface complex, including protonated and deprotonated sites (e.g., >(w)FeO- and >(w)FeOH ) and complexes with cations and anions (>(w)FeOZn+ and >(w)FeP04-, for example). The molalities of the uncomplexed and complexed sites, respectively, are mp and mq. 

Tb clarify the effect of addition of a cationic HC surfactant on phase separation behavior in the mixed monolayers of anionic HC and FC surfactants polyion complexed with cationic polymers, the mixed monolayers containing three amphiphilic components complexed with PVA were transferred on various substrate plates and studied by AFM, FFM, SSPM, and SIMS. As a cationic surfactant, ODTMAC was examined. 

The sizes of the phase separated HC islands in the mixed monolayers of HC and FC anionic amphiphiles polyion complexed with cationic polymers were increased by addition of a HC cationic amphiphile. The HC islands sat on the FC sea in a structure of on-top in a two story monolayer in the same way as two-component amphiphile systems. By SSPM and conventional and SNOAM fluorescence microscopies, the cationic HC amphiphile was found to dissolve preferentially into the HC islands, although it also dissolved partially in the FC sea phase. 

Both the absolute and the relative values of the association constants of crown-ether complexes with cations are dependent on the type of solvent used. 

Letard JF, Lapouyade R, Rettig W (1993) Synthesis and photophysical study of 4-(N-monoaza-15-crown-5) stilbenes forming TICT states and their complexation with cations. Pure Appl Chem 65 1705-1712... 

It is important to notice that a change in lifetime is not a necessary result of a change in fluorescence intensity. For instance, the Ca2+ probe Fluo-3 displays a large increase in intensity on binding Ca2+, but there is no change in lifetime. This is because the Ca-free form of the probe is effectively nonfluorescent, and its emission does not contribute to the lifetime measurement. In order to obtain a change in lifetime, the probe must display detectable emission from both the free and cation-bound forms. Then the lifetime reflects the fraction of the probe complexed with cations. Of course, this consideration does not apply to collisional quenching, when the intensity decay of the entire ensemble of fluorophores is decreased by diffusive encounters with the quencher. 

Therefore, the efficiency of an activator depends on its acidity which decreases pulp pH, and its bonding ability with cations which forms soluble stable complexes with cations at the p5nite surface. In other words, a better activator should have a lower pATa value(stronger acidity) and a greater Ag value (stronger affinity). A combination of these factors defines the activity index Ai as follows ... 

Since the chelating ligand forms a strong complex with cations it is conceivable that this complex formation would lead to slow transfer of the ion into a cathode material ... 

Ligand An electron donor. Ligands form ion complexes with cations (i.e., electron acceptors). 

We have purified natural double-strand DNA from salmon testes, in which anionic DNA complexes with cationic proteins of protamine. After mincing salmon testes, the homogenized solution was treated with protease in order... 

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