Supramolecular Signatures of Adenine-Containing Organostannoxane Assemblies

Abstract

The reactions of 3-(N9-adeninyl) propanoic acid (LH) with various di- and triorganotin oxides have been investigated. Thus, the reaction of di-tert-butyltin oxide (t-Bu2SnO)3 in a 3:1 ratio afforded the dinuclear derivative [t-Bu2Sn(μ-OH)L]2· 7H2O (1). A similar reaction involving bis(tri-n-butyltin)oxide, (n-Bu3Sn)2O, in a 2:1 ratio afforded the one-dimensional (1D) coordination polymer [n-Bu3SnL·0.33H2O] n (2). Similarly the reaction with (n-Bu2SnO)n in a 2:1 ratio afforded the tetranuclear [n-Bu2Sn 2(μ3-O)(μ-OH)L]2 (3). On the other hand, a similar reaction in a 1:1 ratio also gave the tetranuclear product [n-Bu 2Sn2(μ3-O)L2]2 (4). The molecular structure of 1reveals a central dinuclear Sn2O 2 motif where the two tin centers are bridged by two μ-OH groups. Each tin is bound with a monodentate carboxylate group; the Cî - O unit of these carboxylates is involved in an intramolecular hydrogen bonding with the bridging OH unit. The supramolecular structure of 1 reveals the formation of a 1D zigzag chain mediated by intermolecular hydrogen bonding interaction through the Watson-Crick or the Hoogsteen faces. 2 is a 1D coordination polymer formed by the successive bridging of triorganotin units by the carboxylate ligand L. The supramolecular structure of 2 reveals that two 1D coordination polymers interact to generate novel adenine homotrimers formed as a result of alternating Watson-Crick-Watson-Crick and Hoogsteen-Watson-Crick interactions. The molecular structures of 3 and 4 reveal them to be tetranuclear possessing a ladder-like structure. The essential difference between their molecular structures is that in 4 there are four carboxylate ligands, while in 3 there are only two. Both of these complexes reveal intramolecular and intermolecular hydrogen bonding and π···π stacking interactions. The nematicidal activity of 1-3 was examined against Caenorhabditis elegans. Compound 2 was found to be highly active, effecting a high mortality even at very low concentrations such as 25 or 10 ppm.