Copper(II) Complexes of N-Methylated Derivatives of ortho- and meta-Xylyl-Bridged Bis(1,4,7-triazacyclononane) Ligands: Synthesis, X-ray Structure and Reactivity as Artificial Nucleases

✍ Scribed by Matthew J. Belousoff; Bim Graham; Leone Spiccia

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 281 KB
• Volume: 2008
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.200800533

✦ Synopsis

Abstract

Two new binucleating ligands, 1,3‐bis[(4,7‐dimethyl‐1,4,7‐triazacyclononan‐1‐yl)methyl]benzene (L^memx^) and 1,2‐bis[(4,7‐dimethyl‐1,4,7‐triazacyclononan‐1‐yl)methyl]benzene(L^meox^), have been prepared from 1,4,7‐triazatricyclo[5.2.1.0^4,10^]decane and applied in the synthesis of the corresponding copper(II) complexes, Cu~2~(μ‐AcO)~2~(L^memx^)~2~·H~2~O (C~m~) and Cu~2~(η~2~‐AcO)~2~(L^meox^)~2~ (C~o~). The X‐ray crystal structures confirmed the dinuclear nature of the complexes, with pairs of copper(II) centres residing in distorted square‐pyramidal coordination environments. The nitrogen donors on the ligands occupy three facially disposed coordination sites about each copper(II) centre, with two acetate ligands completing the copper(II) coordination spheres. For C~m~, both acetate groups bridge the two metal centres, whilst in C~o~ each acetate chelates to a single metal centre. To assess their utility as simple nuclease mimics, the metal complexes were tested for their phosphate ester cleavage ability using the model phosphodiester, bis(4‐nitrophenyl)phosphate (BNPP). It was found that C~o~ exhibited the fastest rate of BNPP hydrolysis (k~obsd.~ = 2.4 × 10^–5^ s^–1^), this rate being five times faster than that of the Cu^II^ complex of the non‐methylated analogue. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)