Polímeros de coordinación conmutables de hierro(II) para aplicaciones multifuncionales

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, leída el 21-02-2022In recent years, interest in coordination polymers (CPs) has grown rapidly with the demand for new materials that exhibit improved properties, are more cost-effective or can combine several desired properties. This particular development has been driven by crystal engineering, which entails the self-assembly of organic ligands and metal ions with specific functionality and directionality. This enables the design and synthesis of new molecules with targeted properties. Accordingly, a wide variety of CPs with potential applications in catalysis,1 gas sorption,2 luminescence,3 drug delivery,4 sensing,5 magnetism6 and anion exchange7 have been reported. Among them, the family of spin crossover materials (SCO) and coordination polymers exhibiting electrical properties hasgarnered considerable attention.The SCO effect occurs when the metal ion in coordination compounds undergoes a reversible and reproducible spin transition between the low spin (LS) and high spin (HS) electronic states, under the influence of external stimuli, such as temperature, pressure, light, magnetic field and the absorption/desorption of guest molecules...En los últimos años, el interés por los polímeros de coordinación (CPs por sus siglas en inglés) ha crecido rápidamente con la demanda de nuevos materiales que presenten mejores propiedades, sean más rentables o puedan combinar varias propiedades deseadas. Este desarrollo ha sido impulsado por la ingeniería cristalina, que implica el autoensamblaje de ligandos orgánicos e iones metálicos con una funcionalidad y direccionalidad específicas. Esto permite el diseño y la síntesis de nuevas moléculas con propiedades específicas. En consecuencia, se ha publicado una amplia variedad de CPs con aplicaciones potenciales en catálisis,1 absorción de gases,2 luminiscencia,3administración de fármacos,4 detección de moléculas,5 magnetismo6 e intercambio aniónico.7 Entre ellos, la familia de materiales de transición de espín (SCO por sus siglas en inglés) y los polímeros de coordinación que presentan propiedades eléctricas han recibido una atención considerable. El efecto SCO se produce cuando el ion metálico de los compuestos de coordinación experimenta una transición de espín reversible y reproducible entre los estados electrónicos de bajo espín (LS) y de alto espín (HS), bajo la influencia de estímulos externos, como la temperatura, la presión, la luz, el campo magnético y la absorción/desorción de moléculas huésped...Fac. de Ciencias QuímicasTRUEunpu

Switchable iron(II) coordination polymers for multifunctional applications

In recent years, interest in coordination polymers (CPs) has grown rapidly with the demand for new materials that exhibit improved properties, are more cost-effective or can combine several desired properties. This particular development has been driven by crystal engineering, which entails the self-assembly of organic ligands and metal ions with specific functionality and directionality. This enables the design and synthesis of new molecules with targeted properties. Accordingly, a wide variety of CPs with potential applications in catalysis,1 gas sorption,2 luminescence,3 drug delivery,4 sensing,5 magnetism6 and anion exchange7 have been reported. Among them, the family of spin crossover materials (SCO) and coordination polymers exhibiting electrical properties hasgarnered considerable attention.The SCO effect occurs when the metal ion in coordination compounds undergoes a reversible and reproducible spin transition between the low spin (LS) and high spin (HS) electronic states, under the influence of external stimuli, such as temperature, pressure, light, magnetic field and the absorption/desorption of guest molecules..

Tunable Proton Conductivity and Color in a Nonporous Coordination Polymer via Lattice Accommodation to Small Molecules

International audienc

Water Soluble Iron-Based Coordination Trimers as Synergistic Adjuvants for Pancreatic Cancer

International audiencePancreatic cancer is a usually fatal disease that needs innovative therapeutic approaches since the current treatments are poorly effective. In this study, based on cell lines, triazole-based coordination trimers made with soluble Fe(II) in an aqueous media were explored for the first time as adjuvant agents for the treatment of this condition. These coordination complexes were effective at relatively high concentrations and led to an increase in reactive oxygen species (ROS) in two pancreatic cancer cell lines, PANC-1 and BXPC-3, and this effect was accompanied by a significant reduction in cell viability in the presence of gemcitabine (GEM). Importantly, the tested compounds enhanced the effect of GEM, an approved drug for pancreatic cancer, through apoptosis induction and downregulation of the mTOR pathway. Although further evaluation in animal-based models of pancreatic cancer is needed, these results open novel avenues for exploring these iron-based materials in biomedicine in general and in pancreatic cancer treatment

Concomitant Thermochromic and Phase-Change Effect in a Switchable Spin Crossover Material for Efficient PassiveControl of Day and Night Temperature Fluctuations

[EN] The increasing environmental protection demand has prompted thedevelopment of passive thermal regulation systems that reduce temperaturefluctuations in buildings. Here, it is demonstrated that the heat generated bythe sun can trigger a spin crossover (SCO) in a molecule-base material,resulting in a concomitant color variation (from pink to white) and a phasetransition. This leads to a cooling effect with respect to other thermochromicmaterials. In addition, when the material is cooled, a dampening of thetemperature decrease is produced. Therefore, these materials can potentiallybe implemented for passive temperature control in buildings. Furthermore,SCO materials are remarkably stable upon cycling and highly versatile, whichallows for the design of compounds with properties tailored for the desiredclimatic conditions and comfortable temperature.The authors thank Hector Guerrero for his very valuable expertise andcriticisms. J.S.C. thanks funds from the Spanish MINECO through National Research Project (CTQ2016-80635-P), the Spanish MICIU (C AIREPID2019-111479GB-I00) the Ramon y Cajal Research program (RYC-2014-16866), the Comunidad de Madrid (PEJD-2017-PRE/IND-4037), andthe NANOMAGCOST (P2018/NMT-4321). IMDEA Nanociencia acknowl-edges support from the “Severo Ochoa” Programme for Centres of Excel-lence in R&D (MINECO, Grant SEV-2016-0686). MAG thanks the SpanishMinisterio de Ciencia e Innovación (PID2020-114192RB-C41). A.E. thanksthe Comunidad de Madrid I+D+i grant program (Atracción de Talentoproject 2018-T1/IND-1005) and the AECC project Ideas Semilla 2019.Peer reviewe

Passive control of temperature fluctuations through a sunlight-induced spin transition in a molecule-based material

The increasing environmental protection demand has prompted the development of passive thermal regulation systems that reduce temperature fluctuations in buildings. Here, we demonstrate that the heat generated by the sun can trigger a spin transition in a spin-crossover (SCO) material, resulting in a color change. This leads to a cooling effect in respect to other similar materials, due to an increase in light reflection. In addition, when the material is cooled, a dampening of the temperature decrease is produced. Therefore, these materials could potentially be implemented for passive temperature control in buildings. Furthermore, SCO materials are remarkably stable upon cycling and highly versatile, which allows for the design of compounds with properties tailored for the desired climatic conditions and comfort temperature

A switchable iron-based coordination polymer toward reversible acetonitrile electro-optical readout.

Efficient and low cost detection of harmful volatile organic compounds (VOCs) is a major health and environmental need in industrialized societies. For this, tailor-made porous coordination polymers are emerging as promising molecular sensing materials thanks to their responsivity to a wide variety of external stimuli and could be used to complement conventional sensors. Here, a non-porous crystalline 1D Fe(ii) coordination polymer acting as a porous acetonitrile host is presented. The desorption of interstitial acetonitrile is accompanied by magneto-structural transitions easily detectable in the optical and electronic properties of the material. This structural switch and therefore its (opto)electronic readout are reversible under exposure of the crystal to acetonitrile vapor. This simple and robust iron-based coordination polymer could be ideally suited for the construction of multifunctional sensor devices for volatile acetonitrile and potentially for other organic compounds

Spin Crossover-assisted modulation of electron transport in a single crystal 3D metal-organic framework

Molecule-based spin crossover (SCO) materials display likely one of the most spectacular switchable processes. The SCO involves reversible changes in their physicochemical properties (i.e. optical, magnetic, electronic, and elastic) that are coupled with the spin-state change under an external perturbation (i.e. temperature, light, magnetic field, or the inclusion/release of analytes). Although very promising for their future integration into electronic devices, most SCO compounds show two major drawbacks: (i) their intrinsic low conductance and (ii) the unclear mechanism connecting the spin-state change and the electrical conductivity. Herein, we report the controlled single-crystal-to-single-crystal temperature-induced transformation in a robust metal–organic framework, [Fe2(H0.67bdt)3]·9H2O (1), being bdt2– = 1,4-benzeneditetrazolate, exhibiting a dynamic spin-state change concomitant with an increment in the anisotropic electrical conductance. Compound 1 remains intact during the SCO process even after approximately a 15% volume reduction. The experimental findings are rationalized by analyzing the electronic delocalization of the frontier states by means of density-functional theory calculations. The results point to a correlation between the spin-state of the iron and the electronic conductivity of the 3D structure. In addition, the reversibility of the process is proved

Spin Crossover-Assisted Modulation of Electron Transport in a Single-Crystal 3D Metal−Organic Framework

Molecule-based spin crossover (SCO) materials display likely one of the most spectacular switchable processes. The SCO involves reversible changes in their physicochemical properties (i.e. optical, magnetic, electronic, and elastic) that are coupled with the spin-state change under an external perturbation (i.e. temperature, light, magnetic field, or the inclusion/release of analytes). Although very promising for their future integration into electronic devices, most SCO compounds show two major drawbacks: (i) their intrinsic low conductance and (ii) the unclear mechanism connecting the spin-state change and the electrical conductivity. Herein, we report the controlled single-crystal-to-single-crystal temperature-induced transformation in a robust metal–organic framework, [Fe2(H0.67bdt)3]·9H2O (1), being bdt2– = 1,4-benzeneditetrazolate, exhibiting a dynamic spin-state change concomitant with an increment in the anisotropic electrical conductance. Compound 1 remains intact during the SCO process even after approximately a 15% volume reduction. The experimental findings are rationalized by analyzing the electronic delocalization of the frontier states by means of density-functional theory calculations. The results point to a correlation between the spin-state of the iron and the electronic conductivity of the 3D structure. In addition, the reversibility of the process is proved