Complexation nucleobases

Here, the spacer may not be a simple building element but an appropriate aromatic moiety. In that case, the host enjoys simultaneously the possibility of Watson-Crick and Hoogsteen H-bonding and of aromatic stacking with the complexed nucleobase. For example, the 2,7-naphthalene compounds depicted below (X = NH, O) were shown to transport adenine... 

Nucleobases, including 9-methyl-, 9-ethyl-, 1,9-dimethyl-guanine and 2-amino-6-methoxy-9-methylpurine, form complexes of the type Au(N)Cl3 when reacted with [AuCU] in water at pH 3—4. Binding of a AuCh unit to the N (7) position of the purine ring was confirmed by X-ray crystallography [26]. 

There is an extensive number of nucleobase complexes that contain multiple metal ions (75). In some cases the binding sites are in close proximity and there is the possibility for metal-metal interactions. Figures 23 and 24 illustrate various binding modes involving the N,0-donor sites which can potentially give rise to such phenomena. 

There have been few reports of purine derivatives1 that contain metal-carbon nucleobase binding (75), and those that have been described are often polymetalated (84). Quite recently mononuclear complexes of adenine and guanine have been prepared that contain... 

This same di-platinum complex 31 has generated perhaps the largest discrete metal-nucleobase assembly characterized to date a sextet... 

Base-pairing interactions have been realized in metal complexes by extending ligand functionalization to include two complementary nucleobases (136). Sequential alkylation of 1,2-dithioethane using 2-chloroethyl-9-adenine and 3-chloropropyl-l-thymine yields the AT-... 

A dinuclear complex of Pd11 was obtained by the reactions of Pd(bpm)(H20)2]2+ (bpm = bis (pyridine-2-yl)methane) with model nucleobases as constituents of DNA.534... 

It is assumed that tholins also played an important role in the PAH world hypothesis. The PAH world could have existed as a pre-RNA world on the primeval Earth. It is suggested that PAHs can undergo stacking, thus forming structures to which nucleobases are chemically bound (to OH functions which are formed by photochemical derivatisation of the PAHs). The PAH stacks replace the more complex phosphate-D-ribose-phosphate chains in the nucleic acids (Ehrenfreund et al., 2006). 

The nature of the target to be attacked by any drug obviously depends on the specific application. Many cytotoxic metal complexes target DNA because of its importance in replication and cell viability. Coordination compounds offer many binding modes to polynucleotides, including outer-sphere noncovalent binding, metal coordination to nucleobase and phosphate backbone... 

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