Interaction of (amine)M(II) complexes (amine=dien, en; M=Pd, Pt) with purine nucleoside 2′-, 3′- and 5′-monophosphates—the role of the phosphate site for specific metal fragment–nucleotide recognition by macrochelation
作者:W. Wirth、J. Blotevogel-Baltronat、U. Kleinkes、W.S. Sheldrick
DOI:10.1016/s0020-1693(02)00921-0
日期:2002.11
The pH-dependent interaction of [Pd(dien)(H2O)](2+) with adenosine and guanosine 2'- and 3-monophosphates at molar ratios R = 1 and 3 has been studied by potentiometric and NMR techniques. The absence of additional intramolecular stabilisation of the N7 coordination mode by (amine)N-(HO)-O-...(phosphate) hydrogen bonding, as for 5'-AMp(2-) or 5'-GMp(3-), leads to reversal of the intrinsic binding ratio log [beta(BM1)/beta(M7B)] in favour of N1 coordination for mononuclear (dien)Pd(II) complexes of the purine 2'- and 3'-nucleotides. Outer-sphere kappa(2)N7,O(phosphate) macrochelation is also responsible for the formation of a specific mu-N1,N7 bridged cyclic tetramer [(en)Pd(5'- GMP)}(4)](4-) in the pH range 5.5-9.5. Both inner- and outer-sphere kappa(2)N3,O(phosphate) macrochelation lead at R = 3 to a dramatic enhancement of (en)Pd(II) binding to N3 of 2'-GMp(3-) in comparison to 3- or 5'-GMp(3-) . Reaction of [Pt(dien)}(2)(2'-GMP-mu-N1,N7)](+) with [Pt(en)(H2O)(2)](2+) affords both types of macrochelate at approximately 1:1 ratio, namely [Pt(dien)}(2)(2'-GMP-mu(3)-N1,N3,N7,O(P))Pt(en)}(3+) and [Pt(dien)}(2)(2'-GMP-mu(3)-N1,N3,N7)Pt(en)H2O)}](3+) with respectively direct (en)Pt-O(phosphate) and outer-sphere (amine)N-(HO)-O-...(phosphate) hydrogen bonding. Following HPLC separation, these trinuclear products could be characterised by NMR and FAB-MS. (C) 2002 Elsevier Science B.V. All rights reserved.