Zn(2+)-selective switch of duplex to hairpin DNA.

DNA sequences that undergo large changes in secondary structure upon binding of small molecules are the basis for molecular switches. Here we report a Zn(2+) complex that promotes the conversion of a fully complementary DNA double helix into DNA hairpins. The conformational switch is promoted by an isolated Zn(2+) complex or by free ZnCl2 and a macrocyclic ligand.

Bifunctional Zn(II) complexes for recognition of non-canonical thymines in DNA bulges and G-quadruplexes.

Six Zn(II) complexes of derivatives of 1,4,7,10-tetraazacyclododecane (cyclen) were studied for binding to DNA sequences containing non-canonical thymines, including a hairpin with a single thymine bulge (T-bulge) and a G-quadruplex (H-telo) containing thymine loops. The cyclen-based macrocycles contained pendents with either two fused rings to give planar groups including quinolinone (QMC), coumarin (MCC) and quinoline (CQC) derivatives or a non-planar dansyl group (DSC). Macrocyclic complexes with three fused rings including an anthraquinone pendent (ATQ) were also studied.