title: Metal-modified nucleobase sextet: joining four linear metal fragments (trans-a2PtII) and six model nucleobases to an exceedingly stable entity.
abstract: Crosslinking of three different model nucleobases (9-ethyladenine, 9-EtA; 9-ethylguanine, 9-EtGH; 1-methyluracil, 1-MeU) by two linear trans-aPtII (a = NH3 or CH3NH2) entities leads to a flat metal-modified base triplet, trans,trans-[(NH3)2Pt(1-MeU-N3)(mu-9-EtA-N7,N1)Pt(CH3NH2)2(9-EtGH-N7)]3+ (4b). Upon hemideprotonation of the 9-ethylguanine base at the N1 position. 4b spontaneously dimerizes to the metalated nucleobase sextet 5, [(4b)(triple bond)(4b-H)]5+. In this dimeric structure a neutral and an anionic guanine ligand, which are complementary to each other, are joined through three H bonds and additionally by two H bonds between guanine and uracil nucleobases. Four additional interbase H bonds maintain the approximate coplanarity of all six bases. The two base triplets form an exceedingly stable entity (KD = 500 +/- 150 M(-1) in DMSO), which is unprecedented in nucleobase chemistry. The precursor of 4b and several related complexes are described and their structures and solution properties are reported.
authors.affiliation: Fachbereich Chemie, Universität Dortmund, Germany.
authors.forename: R K
authors.initials: RK
authors.lastname: Sigel
authors.forename: S M
authors.initials: SM
authors.lastname: Thompson
authors.forename: E
authors.initials: E
authors.lastname: Freisinger
authors.forename: F
authors.initials: F
authors.lastname: Glahé
authors.forename: B
authors.initials: B
authors.lastname: Lippert
mesh_terms: D020029:Base Pairing; D002945:Cisplatin / Q000737:chemistry*; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009694:Nucleic Acid Precursors / Q000737:chemistry*; D009944:Organoplatinum Compounds / Q000138:chemical synthesis*; D010984:Platinum; D011687:Purines / Q000737:chemistry; D011743:Pyrimidines / Q000737:chemistry
chemical_list: D009694:Nucleic Acid Precursors; D009944:Organoplatinum Compounds; D011687:Purines; D011743:Pyrimidines; C034697:transplatin; D010984:Platinum; D002945:Cisplatin