N,N,O and N,O,N Meridional cis Coordination of Two Guanines to Copper(II) by d(CGCGCG)2.

Many research groups study the generation of supramolecular n-dimensional arrays by combining metals with DNA building blocks. Most of the time, the natural nucleobases are modified to obtain higher-affinity metal binding sites. Using unmodified nucleobases avoids a potentially difficult synthesis; however, they have the possible disadvantage of a less defined and/or weaker coordination mode of the metal.

Mono- and dinuclear metal complexes containing the 1,5,9-triazacyclododecane ([12]aneN3) unit and their interaction with DNA.

The ability of mononucleating and dinucleating macrocylic polyamines and their novel nickel, copper and zinc complexes to induce the left-handed form of poly d(GC) was evaluated. The influence of the nuclearity, the presence or absence of metals ions, the linker length in the case of dinucleating ligands and the metal ion was determined. Almost all dinuclear metal complexes efficiently induced Z-DNA, the zinc ones being the least and the copper ones the most efficient ones.

When two metal centres are needed instead of one: exclusive induction of Z-DNA by dinuclear metal complexes.

The B- to Z-DNA transition was very efficiently induced by dinuclear nickel and copper complexes based on the 1,3-bis(1,5,9-triazacyclododecyl) propane ligand but not by the corresponding mononuclear complexes. This dramatically different behaviour is explained by the formation of a macrochelate of the dinuclear complexes to the DNA.

The synthesis of 1,2-bis(1,5,9-triazacyclododecyl)ethane: a showcase for the importance of the linker length within bis(alkylating) reagents.

The synthesis of 1,2-bis(1,5,9-triazacyclododecyl)ethane (1) showcases how different bis(alkylating) reagents change the reaction from an intra- to an intermolecular pathway. The isolation of the intermediate hexahydro-3a,6a-ethano-1H,4H,7H,9bH-9a-aza-3a,6a-diazoniaphenalene-3a,6a-diium (2) explained why initially the synthesis of 1 was not possible. Both isomers of 2 were found in solution.

Structural analysis of Cu(II) ligation to the 5'-GMP nucleotide by pulse EPR spectroscopy.

Simple copper salts are known to denature poly d(GC). On the other hand, copper complexes of substituted 1,4,7,10,13-pentaazacyclohexadecane-14,16-dione are able to convert the right-handed B form of the same DNA sequence to the corresponding left-handed Z form. A research program was started in order to understand why Cu(II) as an aquated ion melts DNA and induces the conformational change to Z-DNA in the form of an azamacrocyclic complex.