Cleavage of an RNA analog by Zn(II) macrocyclic catalysts appended with a methyl or an acridine group

Cleavage of a RNA analog containing uridine by a bifunctional dinuclear Zn(II) catalyst

“…First, the small 0.5 pK a unit difference in the first two pK a values shows that the two Zn(II) centers behave nearly independently [11], indicative of the absence of the bridging OH unit that is found in complexes related to Zn 2 (L4) (see Scheme 2). Second, the pK a values of the first two Zn(II) water ligands in Zn 2 (L1) (7.34 and 7.82) are low compared to those of Zn(L2) (pK a = 8.11), but similar to analogous Zn(II) macrocyclic complexes of L2 that have N-alkyl groups [34,35]. Finally, the presence of a third water ligand ionization shows that at least one Zn(II) center in Zn 2 (L1) forms a six-coordinate species in solution that presumably has four macrocycle donor groups and two hydroxide ligands.…”

“…Dinuclear Zn(II) complexes may differ because the two Zn(II) centers may be sufficiently close to induce interactions between the two uridines, as shown here by the moderately stronger binding of the second uridine. In addition, we have shown that the N-methylated analog of Zn(L2) has a lower water ligand pK a than the unsubstituted analog (pK a of 7.3 compared to 7.7), but uridine binding constants for the two complexes are nearly identical [34]. This shows that alkylation of the macrocyclic amine ligand of the Zn(II) complex does not improve uridine binding compared to the parent complex.…”

Macrocycles embedding phenothiazine or similar nitrogen and/or sulphur containing heterocycles

“…These results are similar to those recorded for 98b, but somewhat different to those recorded in similar experiments run with 99a,b when, at low temperature, a clear separation of the signals belonging to the protons of the two types of bridges could not be obtained. Despite the specific investigations by NMR techniques (ROESY, Some other macrocyclic systems having pendant arms decorated with acridine, acridone or phenazine units were also investigated [99][100][101].…”

Men in science

“…Hierfür eignen sich DNA‐Interkalatoren, die sich durch N‐Funktionalisierung an das Cyclengerüst anbringen lassen. Acridinsubstituierte ZnII‐Cyclen‐Komplexe binden aufgrund ihrer Wechselwirkung mit den Thyminbasen an DNA (Abbildung 3 D);8 deren analoge Oxacyclenkomplexe können RNA‐Modellverbindungen spalten 9. RNA ist allerdings aufgrund ihrer geringeren Stabilität leichter zu spalten als DNA 2…”