A Tetranuclear Cu^II-Based 2D Aggregate with an Unprecedented Tetradentate μ₄-N1,N3,N7,N9-Adeninate Nucleobase

Abstract

A unique tetranuclear Cu(II)-based 2D aggregate containing 26-membered Cu(II)ade macrocycles, [Cu(4)(DMF)(6)(mu(4)-ade)(2)(mu(2)-Cl)(2)Cl(4)](n) (1; Hade = adenine, DMF = N,N-dimethylformamide), was isolated by the reaction of CuCl(2) and Hade in a mixed DMF-methanol medium and structurally characterized by X-ray crystallography, elemental analysis, Fourier transform infrared, fluorescence spectroscopy, and thermogravimetry-differential thermal analysis techniques. Unexpectedly, the adeninate in 1 represents an unprecedented tetradentate mu(4)-N1,N3,N7,N9-bridging mode, which significantly contributes to both the aggregate of four Cu(II) cores within the subunit and the extension of the 2D covalent framework. Additionally, 1 displays the intense Hade-based fluorescence emission in solution at room temperature.

Cu(II)–N6-Alkyladenine Complexes: Synthesis, X-ray Characterization and Magnetic Properties

“…The N 6 -adenine derivatives were prepared by the 1:1 condensation of 6-chloropurine with the corresponding amine (ethylamine, butylamine or isobutylamine) in n-butanol/triethylamine following the literature method (see Scheme 1). For the synthesis of the complexes, CuCl 2 •2H 2 O and HL n in a 2:1 molar ratio in HCl 2M, were reacted under reflux for 4 h, yielding, by slow evaporation of the solution over several weeks, the corresponding complex in a moderate yield (40-55%).…”

“…Moreover, coordination compounds involving nucleobases have interesting potential applications as advanced functional materials [3][4][5]. In particular, adenine (6-aminopurine) presents many binding possibilities using the endocyclic N 1 , N 3 , N 7 , N 9 or exocyclic N 6 atoms as coordination sites [6,7], giving rise to a great number of possibilities. Furthermore, upon the formation of the metal−adenine complex, the remaining non-coordinated N-atoms' donor sites are good hydrogen bond acceptors, thus conferring the ability to form supramolecular assemblies [8,9].…”

“…To the best of our knowledge, the solid state structure of dinuclear Cu(II) complexes through the N 3 and N 9 bridging mode using N 1 -protonated adeninium nucleobase is not available in the literature. In this manuscript we report the synthesis and X-ray characterization of three new dinuclear copper(II) complexes, [Cu(µ-HL 1 ) 2 (µ-Cl) 2 Cl 2 ]Cl 2 (1), [Cu(µ-HL 2 ) 2 (µ-Cl) 2 Cl 2 ]Cl 2 (2) and [Cu(µ-HL 3 ) 2 (µ-Cl) 2 Cl 2 ]Cl 2 (3), where HL 1 , HL 2 , and HL 3 are N 6 -propyladeninium, N 6 -butyladeninium, and HL 3 = N 6 -isobutyladeninium, respectively. Complexes 1-3 exhibit a coplanar arrangement of both N 6 -alkyladeninium moieties and both copper atoms are five-coordinated (N 2 Cl 3 donor set).…”

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.…”

Synthesis, X‐ray characterization and density functional theory studies of N6‐benzyl‐N6‐methyladenine–M(II) complexes (M = Zn, Cd): The prominent role of π–π, C–H···π and anion–π interactions

“…Moreover, adenine and its derivatives are notable nitrogen donor ligands for the generation of transition metal complexes . The reason is that there are many binding possibilities (endocyclic N1, N3, N7, N9 and exocyclic N6 atoms) as coordination sites . This provides a great number of possibilities and combinations to generate multinuclear complexes and assemblies.…”