A Robust Framework Based on Polymeric Octamolybdate Anions and Copper(II) Complexes of Tetradentate N-donor Ligands

Dissem, Nour; Artetxe, Beñat; Felices, Leire San; Lezama, Luis; Haddad, Amor; Gutiérrez‐Zorrilla, Juan M.

doi:10.3390/cryst8010020

Cited by 10 publications

(13 citation statements)

References 64 publications

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“…200°C. This thermal behavior has been observed for other polyoxometalates ions with organic moieties (Iyer et al, 2014 ; Sánchez-Lombardo et al, 2014 ; Martin-Caballero et al, 2016 ; Dissem et al, 2018 ). Considering that the melting point of Metformin hydrochloride is 224°C (Benmessaoud et al, 2016 ), we can assign the endothermic peaks observed in the DTA thermogram in a temperature range of 190–210°C, to the melting of Metforminium cations (HMetf) present in Compound 2 .…”

Section: Resultssupporting

confidence: 65%

Decavanadate Salts of Cytosine and Metformin: A Combined Experimental-Theoretical Study of Potential Metallodrugs Against Diabetes and Cancer

et al. 2018

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Cytosine, a DNA and RNA building-block, and Metformin, the most widely prescribed drug for the treatment of Type 2 Diabetes mellitus were made to react separately with ammonium or sodium metavanadates in acidic aqueous solutions to obtain two polyoxovanadate salts with a 6:1 ratio of cation-anion. Thus, compounds [HCyt]6[V10O28]·4H2O, 1 and [HMetf]6[V10O28]·6H2O, 2 (where HCyt = Cytosinium cation, [C4H6N3O]+ and HMetf = Metforminium cation, [C4H12N5]+) were obtained and characterized by elemental analysis, single crystal X-ray diffraction, vibrational spectroscopy (IR and Raman), solution 51V-NMR, thermogravimetric analysis (TGA-DTGA), as well as, theoretical methods. Both compounds crystallized in Pfalsemml-overline1¯ space group with Z' = 1/2, where the anionic charge of the centrosymmetric ion [V10O28]6− is balanced by six Cytosinium and six Metforminium counterions, respectively. Compound 1 is stabilized by π-π stacking interactions coming from the aromatic rings of HCyt cations, as denoted by close contacts of 3.63 Å. On the other hand, guanidinium moieties from the non-planar HMetf in Compound 2 interact with decavanadate μ2-O atoms via N−H···O hydrogen bonds. The vibrational spectroscopic data of both IR and Raman spectra show that the dominant bands in the 1000-450 cm−1 range are due to the symmetric and asymmetric ν(V−O) vibrational modes. In solution, 51V-NMR experiments of both compounds show that polyoxovanadate species are progressively transformed into the monomeric, dimeric and tetrameric oxovanadates. The thermal stability behavior suggests a similar molecular mechanism regarding the loss of water molecules and the decomposition of the organic counterions. Yet, no changes were observed in the TGA range of 540–580°C due to the stability of the [V10O28]6− fragment. Dispersion-corrected density functional theory (DFT-D) calculations were carried out to model the compounds in aqueous phase using a polarized continuum model calculation. Optimized structures were obtained and the main non-covalent interactions were characterized. Biological activities of these compounds are also under investigation. The combination of two therapeutic agents opens up a window toward the generation of potential metalopharmaceuticals with new and exciting pharmacological properties.

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Section: Resultssupporting

confidence: 65%

Decavanadate Salts of Cytosine and Metformin: A Combined Experimental-Theoretical Study of Potential Metallodrugs Against Diabetes and Cancer

et al. 2018

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“…In fact, we have always observed the trans-III form in all of our previous POM-Cu(cyclam) hybrid systems. [37][38][39][40] The crystal packing of compounds 1-Ln displays intrinsic layered nature and contains covalent 2-dimensional hybrid assemblies parallel to the (1-10) plane in which each dimeric POT is linked to four neighboring analogues along the [111] and [001] directions through the Cu1B and Cu1C moieties, respectively. Such connectivity follows a staggered brickwork grid pattern with rectangular intralamellar cavities of dimensions about 7.9 × 23.0 Å (Figure 3).…”

Section: Crystal Structure Of Compounds 1-lnmentioning

confidence: 99%

Thermostructural Behavior in a Series of Lanthanide-Containing Polyoxotungstate Hybrids with Copper(II) Complexes of the Tetraazamacrocycle Cyclam: A Single-Crystal-to-Single-Crystal Transformation Study

et al. 2019

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The series of fourteen isostructural [Cu(cyclam)]2[{Cu(cyclam)}4{(α-GeW11O39)Ln(H2O)(OAc)}2]•18H2O (1-Ln, Ln = La to Lu; cyclam = 1,4,8,11-tetraazacyclotetradecane) polyoxometalate-based hybrids reported herein represent: (i) the first example of a 2-dimensional covalent hybrid lattice involving the [{(α-XW11O39)Ln(H2O)(OAc)}2] narchetype; and (ii) the first structural characterization of such dimeric polyoxotungste for Ln = La and Pr, as well as for the combination of X = Ge and Ln = Ce, Nd, Sm or Lu. Compounds 1-Ln have been characterized by elemental analyses, infrared spectroscopy and thermogravimetry, and their thermo-structural behavior has been monitored by powder and single-crystal X-ray diffraction. The title compounds undergo two single-crystal-to-single-crystal transformations triggered by thermal dehydration to lead to the [{Cu(cyclam)}6{(α-GeW11O39)Ln(H2O)(OAc)}2]•4H2O intermediate (2-Ln, Ln = Eu, Er) and [Cu(cyclam)]0.5[{Cu(cyclam)}5.5{(α-GeW11O39)Ln(OAc)}2] (3-Ln, Ln = Ce, Eu) final anhydrous phases, the latter evidencing a coordinatively unsaturated derivative of the dimeric archetype for the first time. These transitions involve formation and disruption of Cu-OPOM bonds that result in different {Cu(cyclam)} 2+ moieties grafting at and releasing from Keggin surfaces, which reduces the dimensionality of 1-Ln to 1-dimensional covalent assemblies for 2-Ln and 3-Ln. While all 3-Ln phases rehydrate fully upon exposure to air for 24 h, the kinetics governing the crystal transitions back toward 1-Ln through 2-Ln depend on the nature of Ln. Under ambient moisture, the anhydrous structures fully revert back to the parent framework for Ln = La-to-Sm, while the Eu-to-Lu-containing samples afford mixtures of 1-Ln and 2-Ln and require immersion in water for the structural reversion to be completed. Single-crystal X-ray diffraction analyses on the rehydrated 1R-Ln samples (Ln = Ce, Eu and Er) support these observations.

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“…An additional example of a hybrid framework based on POM clusters and {Cu(cyclam)} 2+ metal-organic moieties showing robustness towards dehydration has been reported recently, namely [{Cu(cyclam)} 2 (Mo 8 O 26 )]Á1.5H 2 O (Dissem et al, 2018). The dehydration process into the [{Cu(cyclam)} 2 -(Mo 8 O 26 )] anhydrous phase does not proceed through an SCSC transformation in a strict sense, but through an SC-tocrystal transition, as the release of hydration water molecules from the parent compound has been found to result in nonmerohedral twinning and, hence, the single-crystal integrity is lost through the process.…”

Section: When Solvent Molecules Are Just Fillersmentioning

confidence: 99%

Single-crystal-to-single-crystal transformations triggered by dehydration in polyoxometalate-based compounds

Reinoso¹,

Artetxe²,

Gutiérrez‐Zorrilla³

2018

Acta Crystallogr C Struct Chem

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Single‐crystal‐to‐single‐crystal transformations are solid‐state phase transitions between different crystalline states in which the crystal integrity and the long‐range structural order are retained through the whole transformation process. Such a phenomenon constitutes the structural response that some compounds afford when being exposed to a given external stimulus (temperature, pressure, light, etc.) and, therefore, its study has become a relevant focus of interest within crystal engineering because it allows for monitoring how certain properties (colour, magnetism, luminescence, porosity) of the stimuli‐responsive material are modified as the structure evolves into the activated form. A range of organic, inorganic and hybrid systems have been found to undergo such phase transitions, but these examples only include a small number of compounds that incorporate polyoxometalate anions, among which the removal of guest solvent molecules (dehydration) stands out as the most common external stimulus able to induce the occurrence of a single‐crystal‐to‐single‐crystal transformation. This feature article compiles the examples of dehydration‐triggered single‐crystal‐to‐single‐crystal transformation studies that have been reported to date for polyoxometalate‐based compounds and reviews some of their most relevant structural aspects.

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A Robust Framework Based on Polymeric Octamolybdate Anions and Copper(II) Complexes of Tetradentate N-donor Ligands

Abstract: (1a) with potentially accessible micropores as demonstrated by single-crystal X-ray diffraction measurements. Electron paramagnetic resonance spectroscopy analysis of 1 has also been assessed.

Cited by 10 publications

References 64 publications

Decavanadate Salts of Cytosine and Metformin: A Combined Experimental-Theoretical Study of Potential Metallodrugs Against Diabetes and Cancer

Decavanadate Salts of Cytosine and Metformin: A Combined Experimental-Theoretical Study of Potential Metallodrugs Against Diabetes and Cancer

Thermostructural Behavior in a Series of Lanthanide-Containing Polyoxotungstate Hybrids with Copper(II) Complexes of the Tetraazamacrocycle Cyclam: A Single-Crystal-to-Single-Crystal Transformation Study

Single-crystal-to-single-crystal transformations triggered by dehydration in polyoxometalate-based compounds

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