33 research outputs found
Dicopper(II)-EDTA Chelate as a Bicephalic Receptor Model for a Synthetic Adenine Nucleoside
In the extensive field of metal ions, their interactions with nucleic acids, and their constituents,
the main aim of this work is to develop a metal chelate suitable to recognize two molecules of an adenine
nucleoside. For this purpose, the dinuclear chelate Cu2
(µ-EDTA) (ethylenediaminetetraacetate(4-) ion
(EDTA)) is chosen as a bicephalic receptor model for N9-(2-hydroxyethyl)adenine (9heade). A one-pot
synthesis is reported to obtain the compound [Cu2
(µ2
-EDTA)(9heade)2
(H2O)4
]·3H2O, which has been
characterized by single-crystal X-ray diffraction and various spectral, thermal, and magnetic methods.
The complex unit is a centro-symmetric molecule, where each Cu (II) center is chelated by a half-EDTA,
and is further surrounded by an N7-dentate 9heade nucleoside and two non-equivalent trans-O-aqua
molecules. The metal chelate-nucleoside molecular recognition is referred to as an efficient cooperation
between the Cu-N7(9heade) coordination bond and a (9heade)N6-H···O(carboxyl, EDTA) interligand
interaction. Theoretical calculations are also made to account for the relevance of this interaction. The
extreme weakness with which each water molecule binds to the metal center disturbs the thermal
stability and the infrared (FT-IR) and electron spin resonance (ESR) spectra of the compound.Agencia Estatal de Investigación, Ministerio de Ciencia,
Innovación y Universidades (MICIU) from SpainFEDER-EU (project nos.
PGC2018-102047-B-I00 and CTQ2017-85821-R)Junta de Andalucía (research group FQM-283)University of Granada (project ref. PPJIA2019-03
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)
We thank the Centre de Tecnologies de la Informació (CTI), Universitat de les Illes Balears for
computational facilities. We also thank all projects for financial support.The proton transfer between equimolar amounts of [Cd(H2EDTA)(H2O)] and
2,6-diaminopurine (Hdap) yielded crystals of the out-of-sphere metal complex H2(N3,N7)dap
[Cd(HEDTA)(H2O)]·H2O (1) that was studied by single-crystal X-ray diffraction, thermogravimetry,
FT-IR spectroscopy, density functional theory (DFT) and quantum theory of “atoms-in-molecules”
(QTAIM) methods. The crystal was mainly dominated by H-bonds, favored by the observed tautomer
of the 2,6-diaminopurinium(1+) cation. Each chelate anion was H-bonded to three neighboring
cations; two of them were also connected by a symmetry-related anti-parallel π,π-staking interaction.
Our results are in clear contrast with that previously reported for H2(N1,N9)ade [Cu(HEDTA)
(H2O)]·2H2O (EGOWIG in Cambridge Structural Database (CSD), Hade = adenine), in which H-bonds
and π,π-stacking played relevant roles in the anion–cation interaction and the recognition between
two pairs of ions, respectively. Factors contributing in such remarkable differences are discussed on
the basis of the additional presence of the exocyclic 2-amino group in 2,6-diaminopurinium(1+) ion.This research was funded by the Excellence Network ‘Metal Ions in Biological Systems’ MetalBio
CTQ2017-90802-REDT, the Research group FQM-283 (Junta de Andalucía) and MICIU/AEI of Spain (project
CTQ2017-85821-R FEDER funds)
Novel Cd (II) Coordination Polymers Afforded with EDTA or Trans-1,2-Cdta Chelators and Imidazole, Adenine, or 9-(2-Hydroxyethyl) Adenine Coligands
Three mixed-ligands of Cd(II) coordination polymers were unintentionally obtained: {[Cd(µ3-EDTA)(Him)·Cd(Him)(H2O)2]·H2O}n (1), {[Cd(µ4-CDTA)(Hade)·Cd(Hade)2]}n (2), and {[Cd(µ3-EDTA)(H2O)·Cd(H9heade)(H2O)]·2H2O}n (3), having imidazole (Him), adenine (Hade) or 9-(2-hydroxyethyl)adenine (9heade) as the N-heterocyclic coligands. Compounds 2 and 3 were obtained by working with an excess of corresponding N-heterocyclic coligands. The single-crystal X-ray diffraction structures and thermogravimetric analyses are reported. The chelate moieties in all three compounds exhibit hepta-coordinated Cd centers, whereas the non-chelated Cd center is five-coordinated in 1 and six-coordinated in 2 and 3. Him and Hade take part in the seven-coordinated chelate moieties in 1 and 2, respectively. In contrast, 9heade is unable to replace the aqua ligand of the chelate [Cd (EDTA) (H2O)] moiety in 3. The thermogravimetric analysis (TGA) behavior of [Cd (H2EDTA) (H2O)]·2H2O in 1 and 3 leads to a residue of CdO, whereas the N-rich compound 2 yields CdO·Cd(NO3)2 as a residue. Density functional theory (DFT) calculations along with molecular electrostatic potential (MEP) and quantum theory of atoms-in-molecules computations were performed in adenine (compound 2) and (2-hydroxyethyl)adenine (compound 3) to analyze how the strength of the H-bonding and π-stacking interactions, respectively, are affected by their coordination to the Cd-metal centerThis research was funded by the Excellence Network “Metal Ions in Biological Systems” MetalBio CTQ2017-90802-REDT, the Research group FQM-283 (Junta de Andalucía), and MICIU/AEI of Spain (project CTQ2017-85821-R FEDER funds)S
Weak Interactions in Cocrystals of Isoniazid with Glycolic and Mandelic Acids
This research was funded by the Network of Excellence “Metallic Ions in Biological
Systems” CTQ2017-90802-REDT [Ministerio de Economía y Competitividad (Spain) and European
Regional Development Fund (EU)], and the Xunta de Galicia (Spain) [Rede de Excelencia MetalBIO
ED431D 2017/01].Acknowledgments: We thank the “Centre de Tecnologies de la Informació” (CTI) at the Univeritat
de les Illes Baleares for computational facilities.This work deals with the preparation of pyridine-3-carbohydrazide (isoniazid, inh) cocrystals
with two -hydroxycarboxylic acids. The interaction of glycolic acid (H2ga) or d,l-mandelic
acid (H2ma) resulted in the formation of cocrystals or salts of composition (inh) (H2ga) (1) and
[Hinh]+[Hma]– (H2ma) (2) when reacted with isoniazid. An N0-(propan-2-ylidene)isonicotinic hydrazide
hemihydrate, (pinh) 1/2(H2O) (3), was also prepared by condensation of isoniazid with
acetone in the presence of glycolic acid. These prepared compounds were well characterized by
elemental analysis, and spectroscopic methods, and their three-dimensional molecular structure
was determined by single crystal X-ray crystallography. Hydrogen bonds involving the carboxylic
acid occur consistently with the pyridine ring N atom of the isoniazid and its derivatives. The
remaining hydrogen-bonding sites on the isoniazid backbone vary based on the steric influences
of the derivative group. These are contrasted in each of the molecular systems. Finally, Hirshfeld
surface analysis and Density-functional theory (DFT) calculations (including NCIplot and QTAIM
analyses) have been performed to further characterize and rationalize the non-covalent interactions.Network of Excellence “Metallic Ions in Biological Systems” CTQ2017-90802-REDT [Ministerio de Economía y Competitividad (Spain) and European Regional Development Fund (EU)]Xunta de Galicia (Spain) [Rede de Excelencia MetalBIO ED431D 2017/01
Outstanding bioinorganic contributions from the International Symposium on Metal Complexes, Pavia, Italy, 2014 (ISMEC2014)
Solid State Structures of Cadmium Complexes with Relevance for Biological Systems
This chapter provides a review of the literature on structural information from crystal structures determined by X-ray diffractometry of cadmium(II) complexes containing ligands of potential biological interest. These ligands fall into three broad classes, (i) those containing N-donors such as purine or pyrimidine bases and derivatives of adenine, guanine or cytosine, (ii) those containing carboxylate groups such as α-amino acids, in particular the twenty essential ones, the water soluble vitamins (B-complex) or the polycarboxylates of EDTA type ligands, and (iii) S-donors such as thiols/thiolates or dithiocarbamates. A crystal and molecular structural analysis has been carried out for some representative complexes of these ligands, specifically addressing the coordination mode of ligands, the coordination environment of cadmium and, in some significant cases, the intermolecular interactions.Ministerio de Ciencia e Innovación | Ref. MAT2010-15594Xunta de Galicia | Ref. INCITE08PXIB203128PRXunta de Galicia | Ref. 10TMT314002P
H-Bonds, π-Stacking and (Water)O-H/π Interactions in (µ4-EDTA)Bis(Imidazole) Dicopper(II) Dihydrate
We synthesized and studied the polymeric compound {[Cu2
(µ4
-EDTA)(Him)2
] 2H2O}n
(1). The single-crystal structure is reported along with an in depth characterization of its thermal
stability (TGA), spectral properties (FT-IR, Vis-UV and RSE), and magnetic behavior. The crystal
consists of infinite 2D-networks built by centrosymmetric dinuclear motifs, constructed by means of
a bridging anti,syn-carboxylate group from each asymmetric unit. Each layer guides Him ligands
toward their external faces. They are connected by intermolecular (Him)N-H···O(carboxylate) bonds
and antiparallel π–π stacking between symmetry related pairs of Him ligands, and then pillared in a
3D-network with parallel channels, where disordered water molecules are guested. About half of
the labile water is lost from these channels over a wide temperature range (r.t. to 210 ◦C) before the
other one, most strongly retained by the cooperating action of (water)O1-H(1A)···O(carboxylate) and
(water) O1-H(1B)···π(Him) interactions. The latter is lost when organic ligands start to burn. ESR
spectra and magnetic measurements indicated that symmetry related Cu(II) centers connected by the
bridging carboxylate groups behave magnetically not equivalently, enabling an exchange interaction
larger than their individual Zeeman energies.MICINN of Spain (project PGC2018-102047-B-I00)MICIU/AEI of Spain (project CTQ2017-
85821-R FEDER)Research groups FQM-283FQM-243 (Junta de Andalucía, Spain