Direct cationic binding

Imazato and co-workers [29,30] prepared a novel monomer, methacryloyloxydodecyl pyrimidinium bromide (MDPB). A water-soluble homopolymer of MDPB and copolymer of MDPB with acrylamide were also synthesised and the bactericidal activity against oral streptococci was studied. The mechanism of action of these quaternary compounds is assumed to be due to direct cationic binding to cell wall components, which results in disruption of the cell wall membrane, and subsequently results in leakage of critical cell contents and cell death. 

Gustowski, D. A., Gatto, V. J., Mallen, J., Echegoyen, L., Gokel, G. W., Direct correlation of cation binding strengths to Hammett parameters in substituted TV-benzylaza-15-crown-5 lariat ether and A 7V-dibenzyl-4,13-diaza-18-crown-6 BiBLE derivatives. J. Am. Chem. Soc. 1987, 52, 5172-5176. 

Nevertheless, pendant arm derivatives of [9]aneN3 and other polyaza-macrocycles have garnered great interest in recent years for their use in many different chemical applications such as catalysis [24-30], selective cation binding [30-32], surfactants [33, 34], mimicry of enzymes and siderophores [35-39], tumor-directed radioisotope carriers, and use in magnetic resonance imaging reagents [40],... 

The scope of the tether-directed remote functionalization has been expanded from Cgo to the higher fullerene C70, and the described reactions are completely regioselective, featuring, in the case of C70, the kinetically disfavored addition pattern. The crown ether is a real template, since it can be readily removed by transesterification, giving a much-improved access to certain bis-adducts that are not accessible by the direct route. Cation-binding studies by CV reveal that cyclophane-type crown ethers derived from C60 and C70 form stable complexes with metal cations, and a perturbation of the fullerene reduction potentials occurs because the cation is tightly held close to the fullerene surface. This conclusion is of great importance for future developments of fullerene-based electrochemical ion sensors. 

Van Huysse, J.W., Jewell, E.A., Lingrel, J.B. (1993). Site-directed mutagenesis of a predicted cation binding site of Na,K-ATPase. Biochemistry 32, 819-826. 

Numerous studies have been performed on the dynamic generation from DCLs of either molecular receptors for substrates or substrates for receptors [35-39, 46]. Work in our group has been directed in particular towards the influence of physical and chemical stimuli on the behavior of DCLs, as for instance in the case of the constitutional dynamic reorganization exerted by temperature and protonation on imine libraries [45], the induction of liquid crystal properties by an electric field acting on a dynamic library [47], or component selection induced by cation binding in a folded dynamer chain [48] (see also below). 

---