Contribución al estudio de la hidrolisis de quelatos 1:1 de ácidos aminotricarboxílicos con iones trivalentes lantánidos

La hidrólisis alcalina de disoluciones equimolares de los ácidos (H3A) nitrilotriacético (ANT), D, L-a-alanina-N, N-bis (carboximetil) (AiMNT), 2-metil a-alanina-N, N-bis (carboximetil) (ADNT) o alanin-N, N-bis (carboximetil) con un nitrato trivalente lantánido o de itrio [1 = 0,1 mol X dm-3 (KN03)] se pone de manifiesto en las curvas de valoración potenciométrica frente a KOH 0,1 mol X dm-3, a 25° C y atmósfera de N2• La hidrólisis representa el consumo de entre 1 y 1,5 equivalentes de base/ion-gramo de lantánido, en desacuerdo con lo descrito en la bibliografía para el 'caso del ANT. Este comportamiento se explica por la contribución de diversos procesos asociados a la hidrólisis de los quelatos 1: 1 [Ln A(HP)x] a hidroxocomplejos con OH/Ln>1. La tendencia a la hidrólisis crece al avanzar en la serie lantánida , con cierta irreguaridad, lo que se explica por la influencia de las 'características cristalquímicas de los iones y por la posible disminución en una unidad del número de moléculas de agua coordinadas en quelatos 1: 1 de los elementos centrales de la serie.The alkaline hydrolysis of eqimolar solutions of (H3A) nitrilotriacetic acid (NTA), N, N-bis (carboxymethyl)-D, L-a-alanine (MNTA). N, N-bis (carboxymethyl)-2-methyl-a-alanine (DNTA) or N, N-bis (carboxymethyl)--alanine (NPDA) with a nitrate of trivalent lanthanide or yttrium ions [1 = 0.1 mol X dm-3 (KNOa )] is shown by potentiometric titration curves against KOH 0,1 mol X X dm a at 25° e, under N2 atmosfere. From 1 to 1.5 equivalents of base/ lanthanide g-ion were consummed in the hydrolysis, in disagreement with previous data reported for the NTA case. This behavoir is explained the contribution of several processes associated to the hydrolysis of the 1: 1: che late [LnA(Hp)x], to give hydroxo-complexes with OH/Ln > 1. Tendency towards hydrolysis increase with certain irregularities throught the lanthanide series; this fact is explained on the basis of the influence of the crystallochemicaI characteristics of the lanthanicte ions and also by the possible decrease of one unit in the number of coordinated wated molecules in the 1: 1 chelates of the central elements of the series

Aportaciones a la síntesis de tres análogos del ácido nitrilotriacético derivados de alaninas

Se aislan y estudian los factores relativos a la preparación de los ácidos D, L-α-alanin -N,N -bis (carboximetil), 2-metil-α-alanin-N,N-bis (carboximetil) y β-alanin-N,N-bis(carboximetil) por condensación de cloro acetato con la correspondiente alanina, en medio alcalino. Los rendimientos, comparables con los anteriormente publicados, se explican en base a dificultades en la condensación y a diferencias observadas en la solubilidad de estos productos. Asimismo, se aporta por primera vez la síntesis de sus clorhidratos y se incluyen diversos datos para la caracterización de los ácidos.In this work we have studied and discussed the factors related to the preparation of the acids D, L-alanine-N N-bis(carboxymethyl), 2-methyl-aalanine-N,N-bisC'carboxymethyl) y B-alanine-N,N-bisCcarboxymethyl) through condensation of chloroacetate with the corresponding alanine in alkaline medium. Similar yields as published earlier, are discussed and explained on the basis of difficulties in the condensation process and observed differencies in the solubility of these products. By first time, the isolation of their hydrochlorides is provided and several data for the chara,cterization of the acids are included

Estabilidad de los complejos de algunos ácidos aminotricarboxílicos con iones Iantanido (III). Parte I. Estudio potenciométrico y conductimétrico

Extracto en parte de la Tesis Doctoral de J. Niclós Gutiérrez, Universidad de Granada, 1980. Presentado en parte a la XVIII Reunión Bienal Real Soco Esp. Fís. Quím. (Simpo. Quím: Coord.), Comunicación científica 22.3, Colegio Universitario de Burgos, Burgos, 1980

H(N3)dap (Hdap = 2,6-Diaminopurine) Recognition by Cu2(EGTA): Structure, Physical Properties, and Density Functional Theory Calculations of [Cu4( -EGTA)2( -H(N3)dap)2(H2O)2] 7H2O

Reactions inwater between the Cu2( -EGTA) chelate (EGTA= ethylene-bis(oxyethyleneimino) tetraacetate(4-) ion) and Hdap in molar ratios 1:1 and 1:2 yield only blue crystals of the ternary compound [Cu4( -EGTA)2( -H(N3)dap)2(H2O)2] 7H2O (1), which has been studied via single-crystal X-ray diffraction and various physical methods (thermal stability, spectral and magnetic properties), as well as DFT theoretical calculations. In the crystal, uncoordinated water is disordered. The tetranuclear complex molecule also has some irrelevant disorder in an EGTA-ethylene moiety. In the complex molecule, both bridging organic molecules act as binucleating ligands. There are two distorted five- and two six-coordinated Cu(II) centers. Each half of EGTA acts as a tripodal tetradentate Cu(II) chelator, with a mer-NO2 + O(ether, distal) conformation. Hdap exhibits the tautomer H(N3)dap, with the dissociable H-atom on its less basic N-heterocyclic atom. These features favor the efficient cooperation between Cu-N7 or Cu-N9 bonds with appropriate O-EGTA atoms, as N6-H O or N3-H O interligand interactions, respectively. The bridging role of both organics determines the tetranuclear dimensionality of the complex. In this crystal, such molecules associate in zig-zag chains built by alternating – interactions between the five- or six-atom rings of Hdap ligands of adjacent molecules. DFT theoretical calculations (using two different theoretical models and characterized by the quantum theory of “atoms in molecules”) reveal the importance of these – interactions between Hdap ligands, as well as those corresponding to the referred hydrogen bonds in the contributed tetranuclear moleculeMICIU/AEI of Spain project PID2020-115637GB-I00 FEDER, MICINN of Spain project PGC2018-102047-B-I00Project B-FQM-478-UGR20 (FEDER-Universidad de Granada, Spain)FQM-283 (Junta de Andalucía, Spain

The Copper(II)-Thiodiacetate (tda) Chelate as Efficient Receptor of N9-(2-Hydroxyethyl)Adenine (9heade): Synthesis, Molecular and Crystal Structures, Physical Properties and DFT Calculations of [Cu(tda)(9heade)(H2O)]·2H2O

This research was funded by MICIU/AEI of Spain project PID2020-115637GB-I00 FEDER, MICINN of Spain project PGC2018-102047-B-I00, Project B-FQM-478-UGR20 (FEDER-Universidad de Granada, Spain). Funds and instrumental support of research group FQM-283 (Junta de Andalucia, Spain) are also acknowledged.Supplementary Materials: The following supporting information can be downloaded at: https://www. mdpi.com/article/10.3390/molecules28155830/s1Considering that Cu(tda) chelate (tda: dithioacetate) is a receptor for adenine and related 6-aminopurines, this study reports on the synthesis, molecular and crystal structures, thermal stability, spectral properties and DFT calculations related to [Cu(tda)(9heade)(H2O)]& BULL;2H(2)O (1) [9heade: N9-(2-hydroxyethyl)adenine]. Concerning the molecular recognition of (metal chelate)-(adenine synthetic nucleoside), 1 represents an unprecedented metal binding pattern (MBP) for 9heade. However, unprecedentedly, the Cu(tda)-9heade molecular recognition in 1 is essentially featured in the Cu-N1(9heade) bond, without any N6-HMIDLINE HORIZONTAL ELLIPSISO(carboxyl tda) interligand interaction. Nevertheless, N1 being the most basic donor for N9-substituted adenines, this Cu-N1 bond is now assisted by an O2-water-mediated interaction (N6-HMIDLINE HORIZONTAL ELLIPSISO2 and O2MIDLINE HORIZONTAL ELLIPSISCu weak contact). Also, in the crystal packing, the O-H(ol) of 9heade interacts with its own adenine moiety as a result of an O3-water-mediated interaction (O(ol)-HMIDLINE HORIZONTAL ELLIPSISO3 plus O3-H36MIDLINE HORIZONTAL ELLIPSIS & pi;(adenine moiety)). Both water-mediated interactions seem to be responsible for serious alterations in the physical properties of crystalline or grounded samples. Density functional theory calculations were used to evaluate the interactions energetically. Moreover, the quantum theory of atoms-in-molecules (QTAIM), in combination with the noncovalent interaction plot (NCIPlot), was used to analyze the interactions and rationalize the existence and relative importance of hydrogen bonding, chalcogen bonding and & pi;-stacking interactions. The novelty of this work resides in the discovery of a novel binding mode for N9-(2-hydroxyethyl)adenine. Moreover, the investigation of the important role of water in the solid state of 1 is also relevant, along with the chalcogen bonding interactions demonstrated by the density functional theory (DFT) study.MICIU/AEI of Spain project PID2020-115637GB-I00MICINN of Spain project (FEDER-Universidad de Granada, Spain) PGC2018-102047-B-I00, B-FQM-478-UGR20Junta de Andalucí

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

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.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 center.Excellence Network "Metal Ions in Biological Systems" MetalBio CTQ2017-90802-REDTJunta de Andalucia FQM-283MICIU /AEI of Spain CTQ2017-85821-

Synthesis, Structural Characterisation, and Electrochemical Properties of Copper(II) Complexes with Functionalized Thiosemicarbazones Derived from 5-Acetylbarbituric Acid

The reaction between 5-acetylbarbituric acid and 4-dimethylthiosemicarbazide or 4- hexamethyleneiminyl thiosemicarbazide produces 5-acetylbarbituric-4-dimethylthiosemicarbazone (H2AcbDM) and 5-acetylbarbituric-4N-hexamethyleneiminyl thiosemicarbazone (H2Acbhexim). Eight new complexes with different copper(II) salts have been prepared and characterized using elemental analysis, molar conductance, UV–Vis, ESI-HRMS, FT-IR, magnetic moment, EPR, and cyclic voltammetry. In addition, three-dimensional molecular structures of [Cu(HAcbDM)(H2O)2](NO3)·H2O (3a), [Cu(HAcbDM)(H2O)2]ClO4 (4), and [Cu(HAcbHexim)Cl] (6) were determined by single crystal X-ray crystallography, and an analysis of their supramolecular structure was carried out. The H-bonded assemblies were further studied energetically using DFT calculations and MEP surface and QTAIM analyses. In these complexes, the thiosemicarbazone coordinates to the metal ion in an ONS-tridentate manner, in the O-enolate/S-thione form. The electrochemical behavior of the thiosemicarbazones and their copper(II) complexes has been investigated at room temperature using the cyclic voltammetry technique in DMFA. The Cu(II)/Cu(I) redox system was found to be consistent with the quasi-reversible diffusion-controlled process.Consellería de Cultura, Educación, Formación Profesional e Universidades, Xunta de Galicia (Spain), GPC GI-2197 (ED481B- 2022-068 2023/19

Aproximación al cálculo de las constantes de disociación de ácidos aminotricarboxílicos: determinación de los valores de pKa del ácido nitrilotripropiónico

Se propone una aproximación para el cálculo de los valores de pK de ácidos aminotricarboxílicos, por la que pK0 pK1 y pK2 se determinan por tratamiento de mínimos cuadrados y, después, pK3 se obtiene algebraicamente. Se ilustra la utilidad de esta aproximación por su aplicación al cálculo de los pKa del ácido nitrilotripropiónico.An approximation to evaluate the pK. values of aminotricarboxylic acids is proposed. By least square treatements, the values of pK o' pK \ and pK 2 are obtained; then, pK 3 is found by algebraic ca\culations. The evaluation of pK. of nitrilotripropionic acid used to ilustrate the utility of the above approximation

Aproximación al cálculo de los constantes de disociación de ácidos aminotricarboxílicos: determinación de los valores de pKa del ácido nitrilotripropiónico

Se propone una aproximación para el cálculo de los valores de pKa de ácidos aminotricarboxílicos, por la que pKo, pK1 y pK2 se determinan por tratamiento de mínimos cuadrados y, después, pK3 se obtiene algebráicamente. Se ilustra la utilidad de esta aproximación por su aplicación al cálculo de los pKa del ácido nitrilotripropiónico.An approximation to evaluate the pK. values of aminotricarboxylic acids is proposed. By least square treatements, the values of pKo, pKI and pK2 are obtained; then, pK3 is found by algebraic calculations. The evaluations of pKo of nitrilotripropionic acid is used to ilustrate the utility of the aboye approximation

Towards the Development of Novel Diclofenac Multicomponent Pharmaceutical Solids

Multicomponent pharmaceutical materials offer new opportunities to address drug physicochemical issues and to obtain improved drug formulation, especially on oral administration drugs. This work reports three new multicomponent pharmaceutical crystals of the non-steroidal antiinflammatory drug diclofenac and the nucleobases adenine, cytosine, and isocytosine. They have been synthesized by mechanochemical methods and been characterized in-depth in solid-state by powder and single crystal X-ray diffraction, as well as other techniques such as thermal analyses and infrared spectroscopy. Stability and solubility tests were also performed on these materials. This work aimed to evaluate the physicochemical properties of these solid forms, which revealed thermal stability improvement. Dissociation of the new phases was observed in water, though. This fact is consistent with the reported observed layered structures and BFDH morphology calculations.Spanish Agencia Estatal de Investigacion of the Ministerio de Ciencia, Innovacion y Universidades (MICIU)European Commission PGC2018-102047-B-I00FEDER-Universidad de Granada, Spain B-FQM-478-UGR2