Molecular and supramolecular recognition patterns in ternary copper(II) or zinc(II) complexes with selected rigid-planar chelators and a synthetic adenine-nucleoside

Dicopper(II)-EDTA Chelate as a Bicephalic Receptor Model for a Synthetic Adenine Nucleoside

“…In this context, significant advances have been made from crystal structures of a variety of ternary copper(II) complexes that bind acyclovir (acv) as coligand (see [ 12 ] and references therein). In these connections, we regard some metal complexes as receptors for the synthetic nucleoside N9-(2-hydroxyethyl)adenine (hereafter 9heade, Scheme 1 ), where the metal center is also linked to donor atoms of the coligands able to act as H-acceptors (O or Cl) atoms [ 13 , 14 , 15 , 16 ].…”

“…Interestingly, certain in vitro inhibitory effects of tumor cells to its 2′-phosphorilated form were reported [ 21 ], suggesting that such biological activities require the in vivo O-phosphorylation of its pseudo sugar -O(ol) H group. The structural knowledge of metal complexes with 9heade [ 13 , 14 , 15 , 16 ] strongly suggests that its preferred donor atom is N7 and that the N-basicity order for 9heade is N1 > N7 > N3 > >N6 (exocyclic) c. It is also clear that N7 is the preferred donor atom of 9heade, as supported by the crystal structures of various mixed-ligand complexes with Co(II) [ 15 ] Zn(II) [ 13 , 16 ], Cu(II) [ 13 ] or Cd(II) [ 14 ]. In addition, the bridging mode Cd 2 -µ-N1,N7(9heade) is documented for a Cd(II) coordination polymer [ 15 ].…”

Anion–Cation Recognition Pattern, Thermal Stability and DFT-Calculations in the Crystal Structure of H2dap[Cd(HEDTA)(H2O)] Salt (H2dap = H2(N3,N7)-2,6-Diaminopurinium Cation)

“…Nucleobase complexes with transition metals are continuously under investigation due to their applications as advanced functional materials, their biologic importance, structural diversity and use as molecular recognition models for nucleic acids [1][2][3][4][5][6]. The majority of structural information available in these systems is mainly dedicated to the adenine nucleobase [7][8][9][10][11][12][13][14][15][16] and a variety of N-alkylated derivatives as ligands [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. In contrast, available structural information in the Cambridge Structural Database (CSD) on metal complexes, co-crystals and salts with 2,6-diaminopurine (Hdap) nucleobase is much more limited, despite the fact that Hdap is an analog of adenine.…”

Novel Cd (II) Coordination Polymers Afforded with EDTA or Trans-1,2-Cdta Chelators and Imidazole, Adenine, or 9-(2-Hydroxyethyl) Adenine Coligands

“…For a long time, we have been interested in the investigation of molecular recognition modes between copper(II) chelates and amino-purine bases (such as adenine, 2-aminopurine, 2,6-diaminopurine, and hypoxanthine) [3][4][5][6][7][8][9][10][11][12][13]. Our work also includes deaza-and aza-purines and closely related N-heterocycles, related to at least one N atom in each five-or six-membered rings of the purine skeleton [5].…”

“…The main aim of this work was to extend the knowledge of mixed-ligand dinuclear Cu (II) complexes of the type (N-ligand)M(µ-EDTA)N(N-ligand) (such as NAMJOB [1] or PEZRES in CSD) to Cd (II), µ-EDTA, or µ-CDTA (where CDTA = trans-1,2-diaminocyclohexane-tetraacetate(4-) ion) as bridging-dinucleating chelators and imidazole (Him), adenine (Hade), or 9-(2-hydroxyethyl)adenine (9heade) as N-heterocyclic donor coligands. The following N-donor ligands were selected: the small heterocyclic fragment of adenine (Him), adenine itself (Hade), or the closely related synthetic nucleoside 9heade [13]. To this purpose, a series of syntheses were carried out maintaining a Cd (II):EDTA:CDTA ratio of 2:1:2 but different amounts of Him, Hade, or 9heade, from which the three reported polymers were crystallized.…”