Molecular recognition of nucleobases via simultaneous first- and second-sphere coordination

• Published in: Journal of the American Chemical Society 1993-07, Vol.115 (15), p.7031-7032
• Main Authors: Kickham, James E, Loeb, Stephen J, Murphy, Shannon L
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Cell receptors; Cell structures and functions; Fundamental and applied biological sciences. Psychology; Miscellaneous; Molecular and cellular biology
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja00068a094

The interaction of transition-metal complexes with nucleobases has been studied extensively with emphasis on the development of antitumor agents, reagents for molecular biology, and regulators of gene expression. Concurrently, major advances have been made in designing synthetic receptors for nucleobases by optimizing noncovalent host-guest interactions. Herein, we describe a new approach to designing receptors for the nucleobases. A series of macrocyclic metal complexes has been prepared which bind to a substrate via simultaneous first- and second-sphere coordination. This is accomplished by sigma -donation to a transition metal (Pd) and noncovalent bonding (hydrogen bonds, pi - pi stacking) to peripheral receptor sites on the ligand. Although the combination of metal coordination, hydrogen bonding, and pi - pi stacking interactions is common to each nucleobase, the relative placement of these binding sites is different for each and acts as a source of discrimination. Although very few complexes have been characterized which show evidence of simultaneous first- and second-sphere coordination, this type of multiple-point binding has been demonstrated in both the binding of urea and barbiturates to a salicylaldimine-bound UO sub(2) super(2+) moiety and the recognition of amino acids employing Rh and Zn porphyrin complexes.