Interaction between the DNA Model Base 9-Ethylguanine and a Group of Ruthenium Polypyridyl Complexes:  Kinetics and Conformational Temperature Dependence

• Published in: Inorganic chemistry 2007-08, Vol.46 (16), p.6715-6722
• Main Authors: Corral, Eva, Hotze, Anna C. G, Magistrato, Alessandra, Reedijk, Jan
• Format: Article
• Language: English
• Subjects: Chemistry - methods; Crystallography, X-Ray; DNA - chemistry; Guanine - analogs & derivatives; Guanine - chemistry; Kinetics; Magnetic Resonance Spectroscopy - methods; Models, Chemical; Models, Molecular; Molecular Conformation; Pyridines - chemistry; Ruthenium - chemistry; Software; Temperature; Time Factors
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic070092u

The binding capability of three ruthenium polypyridyl compounds of structural formula [Ru(apy)(tpy)L n -](ClO4)(2- n ) [1a − c; apy = 2,2‘-azobis(pyridine), tpy = 2,2‘:6‘,2‘ ‘-terpyridine, L = Cl, H2O, CH3CN] to a fragment of DNA was studied. The interaction between each of these complexes and the DNA model base 9-ethylguanine (9-EtGua) was followed by means of 1H NMR studies. Density functional theory calculations were carried out to explore the preferential ways of coordination between the ruthenium complexes and guanine. The ruthenium−9-EtGua adduct formed was isolated and fully characterized using different techniques. A variable-temperature 1H NMR experiment was carried out that showed that while the 9-EtGua fragment was rotating fast at high temperature, a loss of symmetry was suffered by the model base adduct as the temperature was lowered, indicating restricted rotation of the guanine residue.