title: Structural insights on the molecular recognition patterns between N(6)-substituted adenines and N-(aryl-methyl)iminodiacetate copper(II) chelates.
abstract: For a better understanding of the metal binding pattern of N(6)-substituted adenines, six novel ternary Cu(II) complexes have been structurally characterized by single crystal X-ray diffraction: [Cu(NBzIDA)(HCy5ade)(H2O)]·H2O (1), [Cu(NBzIDA)(HCy6ade)(H2O)]·H2O (2), [Cu(FurIDA)(HCy6ade)(H2O)]·H2O (3), [Cu(MEBIDA)(HBAP)(H2O)]·H2O (4), [Cu(FurIDA)(HBAP)]n (5) and {[Cu(NBzIDA)(HdimAP)]·H2O}n (6). In these compounds NBzIDA, FurIDA and MEBIDA are N-substituted iminodiacetates with a non-coordinating aryl-methyl pendant arm (benzyl in NBzIDA, p-tolyl in MEBIDA and furfuryl in FurIDA) whereas HBAP, HCy5ade, HCy6ade and HdimAP are N(6)-substituted adenine derivatives with a N-benzyl, N-cyclopentyl, N-cyclohexyl or two N-methyl groups, respectively. Regardless of the molecular (1-4) or polymeric (5-6) nature of the studied compounds, the Cu(II) centre exhibits a type 4+1 coordination where the tridentate IDA-like chelators adopt a mer-conformation. In 1-5 the N(6)-R-adenines use their most stable tautomer H(N9)adenine-like, and molecular recognition consists of the cooperation of the CuN3(purine) bond and the intra-molecular interligand N9H···O(coordinated carboxy) interaction. In contrast, N(6),N(6)-dimethyl-adenine shows the rare tautomer H(N3)dimAP in 6, so that the molecular recognition with the Cu(NBzIDA) chelate consist of the CuN9 bond and the N3H···O intra-molecular interligand interaction. Contrastingly to the cytokinin activity found in the free ligands HBAP (natural cytokinin), HCy5ade and HCy6ade, the corresponding Cu(II) ternary complexes did not show any activity.
authors.affiliation: Department of Inorganic Chemistry, Faculty of Pharmacy, Campus Cartuja, University of Granada, E-18071 Granada, Spain. Electronic address: adominguez@ugr.es.
authors.forename: Alicia
authors.initials: A
authors.lastname: Domínguez-Martín
authors.forename: Angel
authors.initials: A
authors.lastname: García-Raso
authors.forename: Catalina
authors.initials: C
authors.lastname: Cabot
authors.forename: Duane
authors.initials: D
authors.lastname: Choquesillo-Lazarte
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Pérez-Toro
authors.forename: Antonio
authors.initials: A
authors.lastname: Matilla-Hernández
authors.forename: Alfonso
authors.initials: A
authors.lastname: Castiñeiras
authors.forename: Juan
authors.initials: J
authors.lastname: Niclós-Gutiérrez
mesh_terms: D000085:Acetates / Q000737:chemistry*; D000225:Adenine / Q000737:chemistry*; D001681:Biological Assay; D002614:Chelating Agents / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D007098:Imino Acids / Q000737:chemistry*; D015394:Molecular Structure
chemical_list: D000085:Acetates; D002614:Chelating Agents; D056831:Coordination Complexes; D007098:Imino Acids; D003300:Copper; D000225:Adenine
keywords: Cytokinin activity bioassays; Iminodiacetate; Interligand interaction; Mixed-ligand copper(II) complexes; Molecular recognition; N6-substituted adenines