2D-Coordination polymers based on 1H-indazole4-carboxylic acid and transition metal ions: magnetic, luminescence and biological properties

We report the formation of five novel multifunctional coordination polymers based on 1H-indazole-4- carboxylic acid (HL). To the best of our knowledge, these complexes are the first examples of coordination compounds constructed with this interesting ligand. These materials were synthesized by solvothermal routes, possess different 2D-structures and show interesting magnetic properties due to the copper compound showing an unusual spin-canted effect while the anisotropic cobalt material behaves as a fieldinduced single molecule magnet. MTT assays performed on human embryonic kidney (HEK293) and mouse skin melanoma (B16-F10) cell lines indicated that the Cd-based compound was the only one exhibiting dose-dependent toxicity on B16-F10 cells, most likely due to the release of toxic Cd(II). Cadmium and zinc polymers exhibit interesting luminescence properties. The fact that zinc polymers did not exhibit inherent toxicity against both cancer and non-cancerous cells make this new family an excellent candidate for further investigation in the field of luminescent materials with biomedical applications.Junta de Andalucia FQM-394 FQM-1484Red Guipuzcoana de Ciencia, Tecnologia e Innovacion OF218/2018University of Basque Country GIU 17/13Basque Government IT1005-16Spanish Ministry of Science, Innovation and Universities (MCIU/AEI/FEDER, UE) PGC2018-102052-A-C22 PGC2018-102052-B-C21Junta de Andalucia FQM-394 FQM-1484European Union (EU)ESFGovernment of the Basque CountryFEDER/MCIU/AEI RYC-2016-21042 JdC-201

Dilution effect on the slow relaxation of a luminescent dysprosium Metal-Organic Framework based on 2,5-dihydroxyterephthalic acid

A new dysprosium based Metal-Organic Framework with {[Dy(dhbdc)(DMF)]·DMF} formula has been obtained from solvothermal reaction with 2,5-dihydroxyterephthalic acid ligand and dysprosium chloride. This coordination polymer has been characterized and its crystal structure has been solved by X-ray diffraction methods elucidating a three-dimensional network. Magnetic studies of this compound reveal the existence of weak antiferromagnetic interactions among the metal ions with θ value of −0.26 K. Dynamic ac magnetic susceptibility measurements were carried out under an external dc field of 1 kOe, highlighting that at high frequencies two relaxation processes can be observed. However, when studying the diamagnetically diluted analogue 1, a single relaxation process was detected highlighting the effect of the weak but not negligible exchange interactions. Finally, photoluminescence measurements were performed at different temperatures with the aim of getting a more representative characterization of the emissive performance of the material for potential applications in lighting and thermometry.Financial support was given by Junta de Andalucía (Spain) (project number FQM-394 and FQM-1484), University of the Basque Country (GIU 17/13), Gobierno Vasco/Eusko Jaurlaritza (IT1005-16) and the Spanish Ministry of Economy and Competitiveness (MCIU/AEI/FEDER, UE) (PGC2018-102052-A-C22, PGC2018-102052-B-C21 and CTQ-2015-64049-C3-3R). The authors thank for technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF). A.Z.-L. is grateful to the Government of the Basque Country for the predoctoral fellowshi

Influence of thermally induced structural transformations on the magnetic and luminescence properties of tartrate-based chiral lanthanide organic-frameworks

This work reports on the synthesis and characterization of five enantiomeric pairs of isostructural 3D metal-organic frameworks (MOFs) with the general formula {[Ln2(μ4-tar)2(μ-tar)(H2O)2]·xH2O}n [where Ln(iii) = Tb (Tb-L and Tb-D), Dy (Dy-L and Dy-D), Ho (Ho-L and Ho-D), Er (Er-L and Er-D) and Tm (Tm-L and Tm-D); tar = tartrate (d- or l-) and x = 3 or 4 depending on the counterpart], which possess interesting luminescence and magnetic properties. These MOFs undergo progressive and reversible dehydration processes upon controlled heating yielding three crystalline phases (Ln-L′, Ln-L′′ and Ln-L′′′). Alternating current magnetic measurements on Tb, Dy and Er-based compounds exhibit field induced single-molecule magnet behavior dominated by QTM, which is partially suppressed when diluted on a Y-based matrix. Tartrate ligands show poor room temperature sensitization of Tb and Dy centers that is enhanced at low temperature (10 K), even enabling weak Tm-based emission. More interestingly, the dehydration modulates both magnetic and photoluminescence properties on the basis of both the distortions occurring in the coordination shells and a decrease of water molecules acting as quenchers, respectively, endowing these materials with potential humidity sensing capacity. Remarkably, the Tb-based MOF shows circularly polarized luminescence (CPL), being one of the examples of this very scarce family of CPL emitters reported so far. This journal i

Magneto-thermal properties and slow magnetic relaxation in Mn(II)Ln(III) complexes: Influence of magnetic coupling on the magneto-caloric effect

A family of Mn(II)Ln(III) dinuclear and tetranuclear complexes (Ln = Gd and Dy) has been prepared from the compartmental ligands N,N′-dimethyl-N,N′-bis(2-hydroxy-3-formyl-5-bromobenzyl)ethylenediamine (H2L1) and N,N′,N′′-trimethyl-N,N′′-bis(2-hydroxy-3-methoxy-5-methylbenzyl)diethylenetriamine (H2L2). The Mn(II)Gd(III) complexes exhibit antiferromagnetic interactions between Mn(II) and Gd(III) ions in most cases, which are supported by Density Functional Theory (DFT) calculations. Experimental magneto-structural correlations carried out for the reported complexes and other related complexes found in bibliography show that the highest ferromagnetic coupling constants are observed in di-μ-phenoxido bridged complexes, which is due to the planarity of the Mn–(μ-O)2–Gd bridging fragment and to the high Mn–O–Gd angles. The effect of these angles has been studied by DFT calculations performed on a di-μ-phenoxido doubly bridged model. The magneto-thermal properties of the Mn(II)Gd(III) based complexes have also been measured, concluding that the magnitude of the Magneto-Caloric Effect (MCE) is due to the strength rather than to the nature of the magnetic coupling. Moreover, when two Mn(II)Gd(III) dinuclear units are connected by two carbonato-bridging ligands the MCE is enhanced, obtaining a maximum magnetic entropy change of 36.4 Jkg−1 K−1 at ΔB = 7 T and T = 2.2 K. On the other hand, one of the dinuclear Mn(II)Dy(III) complexes displays Single-Molecule Magnet (SMM) behaviour with an energy barrier of 14.8 K under an applied external field of 1000 Oe.This work was supported by the Junta de Andalucía (FQM-195 and the Project I + D + i FEDER 2018, A-FQM-172-UGR), MICIU of Spain (Projects PGC2018-102052-B-C21 and RTI2018-098537-B-C22), the University of Granada, the University of The Basque Country UPV/EHU (GIU20/028) and the Gobierno de Aragón (E11 20R). We would like to thank the Centro de Supercomputación de la Universidad de Granada for computational resources. The authors acknowledge the technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF).Peer reviewe

Antiparasitic, anti-inflammatory and cytotoxic activities of 2D coordination polymers based on 1H-indazole-5-carboxylic acid

We report on the formation of two novel multifunctional isomorphous (4,4) square-grid 2D coordination polymers based on 1H-indazole-5-carboxylic acid. To the best of our knowledge, these complexes are the first examples of 2D-coordination polymers constructed with this novel ligand. We have analysed in detail the structural, magnetic and anti-parasitic properties of the resulting materials. In addition, the capability of inhibiting nitric oxide production from macrophage cells has been measured and was used as an indirect measure of the anti-inflammatory response. Finally, the photocatalytic activity was measured with a model pollutant, i.e. vanillic acid (phenolic compound), with the aim of further increasing the functionalities and applicability of the compounds