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Macrochelation, Cyclometallation and G‐Quartet Formation: N 3 ‐ and C 8 ‐Bound Pd II Complexes of Adenine and Guanine
Author(s) -
Price Clayton,
Shipman Michelle A.,
Rees Nicholas H.,
Elsegood Mark R. J.,
Edwards Andrew J.,
Clegg William,
Houlton Andrew
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010316)7:6<1194::aid-chem1194>3.0.co;2-3
Subject(s) - chemistry , alkyl , denticity , medicinal chemistry , reactivity (psychology) , stereochemistry , ethylenediamine , guanine , ligand (biochemistry) , nucleobase , metal , crystal structure , diamine , crystallography , polymer chemistry , organic chemistry , nucleotide , dna , receptor , medicine , biochemistry , pathology , gene , alternative medicine
The reactions of Pd II ions with a series of chelate‐tethered derivatives of adenine and guanine have been studied and reveal a difference in the reactivity of the purine bases. Reactions of [PdCl 2 (MeCN) 2 ] and A‐alkyl‐enH⋅Cl (alkyl=propyl or ethyl, A=adenine, en=ethylenediamine) yield the monocationic species [PdCl(A‐ N3 ‐Et‐en)] + ( 1 ) and [PdCl(A‐ N3 ‐Pr‐en)] + ( 2 ). Both involve co‐ordination at the minor groove site N3 of the nucleobase as confirmed by single‐crystal X‐ray analysis. Reactions with the analogous G‐alkyl‐enH⋅Cl derivatives (G=guanine, alkyl=ethyl or propyl) were more complex with a mixture of species being observed. For G‐Et‐en⋅HCl a product was isolated which was identified as [PdCl(G‐ C8 ‐Et‐en)] + ( 3 ). This compound contains a biomolecular metal–carbon bond involving C8 of the purine base. Crystallography of a product obtained from reaction of G‐Pr‐enH⋅Cl and [Pd(MeCN) 4 ][NO 3 ] 2 reveals an octacationic tetrameric complex ( 4 ), in which each ligand acts to bridge two metal ions through a combination of a tridentate binding mode involving the diamine and N3 and monodentate coordination at N7.