Zirconium-Polycarboxylato Gel Systems as Substrates to Develop Advanced Fluorescence Sensing Devices.

This study presents the development of zirconium polycarboxylate gel systems as substrates for advanced fluorescence sensing devices. Zirconium-based metal-organic gels (MOGs) offer a promising alternative due to the robustness of the Zr-O bond, which provides enhanced chemical stability. In this work, zirconium polycarboxylate gels were synthesized using green solvents in a rapid room temperature method.

Chiral Supramolecular Proton Conductors: Harnessing Highly Charged Zirconium-Amino Acid Oxo-Clusters.

Incorporation of amino acid capping molecules (alanine (Ala), methionine (Met), phenylalanine (Phe), tryptophan (Trp), tyrosine (Tyr), and valine (Val)) in their zwitterionic form into archetypal [Zr(μ-O)(μ-OH)] clusters creates supramolecular frameworks in which the assembly of these highly charged discrete units with chloride counterions provides a unique combination of porosity, chirality, and proton conductivity. The supramolecular frameworks assembled from these cluster entities (i.e.

Drug-delivery and biological activity in colorectal cancer of a supramolecular porous material assembled from heptameric chromium-copper-adenine entities.

The therapeutic application of drugs often faces challenges due to non-specific distribution, inadequate dosification and degradation, which limits their efficacy. Two primary strategies are employed to overcome these issues: the use of derivatives of the active substances and incorporation of those into porous materials. The latter, involving materials such as zeolites, metal-organic frameworks (MOFs), and hydrogels, has shown promising results in protecting the active ingredients from degradation and enabling a controlled release.

Unravelling co-catalyst integration methods in Ti-based metal-organic gels for photocatalytic H production.

The synthesis, characterization and photocatalytic hydrogen evolution reaction (HER) performance of a series of metal-organic gels (MOGs) constructed from titanium(IV)-oxo clusters and dicarboxylato linkers (benzene-1,4-dicarboxylato and 2-aminobenzene-1,4-dicarboxylato) are described. All the MOGs exhibit a microstructure comprised of metal-organic nanoparticles intertwined into a highly meso-/macroporous structure, as demonstrated by cryogenic transmission electron microscopy and gas adsorption isotherms. Comprehensive chemical characterization enabled the estimation of the complex formula for these defective materials, which exhibit low crystallinity and linker vacancies.

Isoreticular Chemistry and Applications of Supramolecularly Assembled Copper-Adenine Porous Materials.

The useful concepts of reticular chemistry, rigid and predictable metal nodes together with strong and manageable covalent interactions between metal centers and organic linkers, have made the so-called metal-organic frameworks (MOFs) a flourishing area of enormous applicability. In this work, the extension of similar strategies to supramolecularly assembled metal-organic materials has allowed us to obtain a family of isoreticular compounds of the general formula [Cu(μ-adeninato-κ:κ)(μ-OH)(μ-OH)](OOC-R-COO)·HO (R: ethylene-, acetylene-, naphthalene-, or biphenyl-group) in which the rigid copper-adeninato entities and the organic dicarboxylate anions are held together not by covalent interactions but by a robust and flexible network of synergic hydrogen bonds and π-π stacking interactions based on well-known supramolecular synthons (SMOFs). All compounds are isoreticular, highly insoluble, and water-stable and show a porous crystalline structure with a topology containing a two-dimensional (2D) network of channels, whose dimensions and degree of porosity of the supramolecular network are tailored by the length of the dicarboxylate anion.

Thermochemical CO Reduction Catalyzed by Homometallic and Heterometallic Nanoparticles Generated from the Thermolysis of Supramolecularly Assembled Porous Metal-Adenine Precursors.

A family of unprecedented supramolecularly assembled porous metal-organic compounds (SMOFs), based on [CuM(μ-adeninato)(μ-OH)(μ-HO)] cations (M: Cu, Co, Ni, and Zn) and different dicarboxylate anions (fumarate, benzoate, and naphthalene-2,6-dicarboxylate), have been employed as precursors of catalysts for the thermocatalytic reduction of CO. The selected metal-organic cation allows us to tune the composition of the SMOFs and, therefore, the features and performance of the final homometallic and bimetallic catalysts. These catalysts were obtained by thermolysis at 600 °C under a N atmosphere and consist of big metal particles (10-20 μm) placed on the surface of the carbonaceous matrix and very tiny metal aggregates (<10 nm) within this carbonaceous matrix.

Magnetic sustentation as an adsorption characterization technique for paramagnetic metal-organic frameworks.

Nowadays, there are many reliable characterization techniques for the study of adsorption properties in gas phase. However, the techniques available for the study of adsorption processes in solution, rely on indirect characterization techniques that measure the adsorbate concentration remaining in solution. In this work, we present a sensing method based on the magnetic properties of metal-organic frameworks (MOFs) containing paramagnetic metal centres, which stands out for the rapidity, low cost and in situ direct measurement of the incorporated adsorbate within the porous material.

Copper(II) invigorated EHU-30 for continuous electroreduction of CO into value-added chemicals.

The doping of zirconium based EHU-30 and EHU-30-NH metal-organic frameworks with copper(II) yielded a homogeneous distribution of the dopant with a copper/zirconium ratio of 0.04-0.05.

The Chemistry of Zirconium/Carboxylate Clustering Process: Acidic Conditions to Promote Carboxylate-Unsaturated Octahedral Hexamers and Pentanuclear Species.

Clustering chemistry is a key point in the design and synthesis of the secondary building units that comprise metal-organic frameworks (MOFs) based on group IV metals. In this work, the first stages of the zirconium-carboxylate clustering process in alcohol/water mixtures are studied in detail using the monocarboxylic benzoic and hydroxybenzoic acids to avoid the polymerization. Mass spectroscopy measurements performed on the reactions revealed the presence of hexa- and pentanuclear species even at low pH values and also evidenced the acid-base nature and pH dependence of the transformation between both species.

Porous TiO thin film-based photocatalytic windows for an enhanced operation of optofluidic microreactors in CO conversion.

Using a photocatalytic window can simplify the design of an optofluidic microreactor, providing also a more straightforward operation. Therefore, the development of TiO coatings on glass substrates seems appealing, although they would imply a reduced accessible area compared with supported nanoparticle systems. Considering this potential drawback, we have developed an endurable photocatalytic window consisting on an inner protective SiO layer and an outer mesoporous anatase layer with enhanced surface area and nanoscopic crystallite size (9-16 nm) supported on a glass substrate.

Towards correlating dimensionality and topology in luminescent MOFs based on terephthalato and bispyridyl-like ligands.

Herein, we report on the synthesis, structural analysis, physicochemical characterization and photoluminescence performance of two ternary compounds based on dicarboxylate and bispyridyl-like ligands and metal ions of group 12, namely [Zn2(μ4-bdc)(μ-pbptz)(DMF)2(NO3)2]n (1-Zn) and {[Cd(μ3-bdc)(μ-pbptz)]·DMF}n (2-Cd) (where bdc = benzene-1,4-dicarboxylate, pbptz = 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine, and DMF = N,N-dimethylformamide). 1-Zn, consisting of a 2D-layered framework, can be considered as the lower-dimensional analogue of the previously reported {[Zn2(μ4-bdc)2(μ-pbptz)]·2DMF·3H2O}n 3D MOF (1'-Zn), which is shown to recrystallize into 1-Zn undergoing a kind of exfoliation. 2-Cd presents a 3D doubly interpenetrated framework whose porosity is reduced to approximately half of the available solvent-accessible voids contained in the non-interpenetrated homologue reported so far, {[Cd(μ3-bdc)(μ-pbptz)]·3DMF}n (2'-Cd).

Magnetic and Photoluminescent Sensors Based on Metal-Organic Frameworks Built up from 2-aminoisonicotinate.

In this work, three isostructural metal-organic frameworks based on first row transition metal ions and 2-aminoisonicotinate (2ain) ligands, namely, {[M(μ-2ain)]·DMF} [M = Co (1), Ni (2), Zn (3)], are evaluated for their sensing capacity of various solvents and metal ions by monitoring the modulation of their magnetic and photoluminescence properties. The crystal structure consists of an open diamond-like topological 3D framework that leaves huge voids, which allows crystallizing two-fold interpenetrated architecture that still retains large porosity. Magnetic measurements performed on 1 reveal the occurrence of field-induced spin-glass behaviour characterized by a frequency-independent relaxation.

Adenine nucleobase directed supramolecular architectures based on ferrimagnetic heptanuclear copper(II) entities and benzenecarboxylate anions.

Two planar organic anions, benzoate and benzene-1,4-dicarboxylate (terephthalate), have been selected as potential π-stacking intercalators among ferrimagnetic [Cu(μ-adeninato)(μ-OH)(μ-HO)] heptameric discrete entities. The resulting supramolecular architecture is highly dependent on the negative charge density distribution, mainly located in the carboxylate groups of the organic anions. In this sense, the benzoate anion, with just one carboxylate group, does not allow its intercalation between the adeninato ligands as it would imply a high steric hindrance among the heptameric entities.

[ZrO(OH)(benzene-1,4-dicarboxylato)]: a hexagonal polymorph of UiO-66.

Since its discovery in 2008, the paradigmatic UiO-66 has behaved as the germ that has prompted the chemistry of group-4 metal based metal-organic frameworks, all of them featuring outstanding thermal and chemical stability. Herein we present the first polymorph of UiO-66 and the key conditions that led to its formation.

Synthesis of heterometallic metal-organic frameworks and their performance as electrocatalyst for CO reduction.

Herein we report the solventless synthesis and doping of the benchmark HKUST-1(Cu) as a facile route to afford heterometallic metal-organic frameworks (MOFs) having proficient behavior as electrocatalytic materials in the reduction of carbon dioxide. Zn(ii), Ru(iii) and Pd(ii) were selected as doping metals (M) with the aim of partially replacing the Cu(ii) atoms of the pristine structure to afford HKUST-1(Cu,M) type materials. Apart from the high yield and good crystallinity of the obtained materials, the extremely high reagent concentration that the reaction conditions imply makes it feasible to control dopant loading in all cases.

Designing Multifunctional 5-Cyanoisophthalate-Based Coordination Polymers as Single-Molecule Magnets, Adsorbents, and Luminescent Materials.

Detailed structural, magnetic, and photoluminescence characterization of a family of new compounds based on 5-cyanoisophthalate (CNip) ligand and several transition metal or lanthanide ions, namely, [Cu(μ-CNip)(μ-HO)(μ-OH)] (1), {[Co(μ-CNip)(DMF)]·∼2DMF} (2), [Cd(μ-CNip) (DMF)] (3), {[Ln(μ-CNip)(μ-CNip)(DMF)]·∼DMF·HO} (4-Ln) (with Ln = Tb, Dy, and Er), {[Gd(μ-CNip)(μ-CNip)(μ-form)(HO) (DMF)]·∼3DMF·3HO} (5), {[Zn(μ-CNip)(μ-CNip)(μ-O)(HO)]·∼12DMF} (6) (where DMF = dimethylformamide, form = formate), is reported. The large structural diversity found in the system may be explained mainly in terms of the coordination characteristics that are inherent to the employed metal ions, the coordination versatility of the dicarboxylic ligand and the synthetic conditions. Interestingly, some crystal structures (three-dimensional (3D) frameworks of 4-Ln and 5 and 3D network of 6) exhibit open architectures containing large solvent-occupied void systems, among which 5 reveals permanent porosity as confirmed by N adsorption measurements at 77 K.

3D Magnetically Ordered Open Supramolecular Architectures Based on Ferrimagnetic Cu/Adenine/Hydroxide Heptameric Wheels.

The present work provides two new examples of supramolecular metal-organic frameworks consisting of three-dimensional extended noncovalent assemblies of wheel-shaped heptanuclear [Cu7(μ-H2O)6(μ3-OH)6(μ-adeninato-κN3:κN9)6](2+) entities. The heptanuclear entity consists of a central [Cu(OH)6](4-) core connected to six additional copper(II) metal centers in a radial and planar arrangement through the hydroxides. It generates a wheel-shaped entity in which water molecules and μ-κN3:κN9 adeninato ligands bridge the peripheral copper atoms.

The crystal structure of a new polymorph of hexa-aqua-nickel(II) bis-(6-oxo-1,6-di-hydro-pyridine-3-carboxyl-ate).

In a new polymorph of the title salt, [Ni(H2O)6](C6H4NO3)2, the metal atom of the cationic complex lies on a symmetry centre and is coordinated by six water mol-ecules to provide a quite regular octa-hedral coordination environment. These cations inter-act with 6-oxo-1,6-di-hydro-pyridine-3-carboxyl-ate anions through electrostatic inter-actions and by means of O-H⋯O and N-H⋯O hydrogen bonds involving the carboxyl-ate, keto and protonated imine groups of the anion, and the coordinating water mol-ecules from the cationic complex entity to generate a supra-molecular three-dimensional architecture. The previously reported polymorph of this compound presents a network of hydrogen bonds, in which the organic anions establish mutual hydrogen-bonding inter-actions involving their keto and protonated imine groups.

Aerogels of 1D Coordination Polymers: From a Non-Porous Metal-Organic Crystal Structure to a Highly Porous Material.

The processing of an originally non-porous 1D coordination polymer as monolithic gel, xerogel and aerogel is reported as an alternative method to obtain novel metal-organic porous materials, conceptually different to conventional crystalline porous coordination polymer (PCPs) or metal-organic frameworks (MOFs). Although the work herein reported is focused upon a particular kind of coordination polymer ([M(μ-ox)(4-apy)₂], M: Co(II), Ni(II)), the results are of interest in the field of porous materials and of MOFs, as the employed synthetic approach implies that any coordination polymer could be processable as a mesoporous material. The polymerization conditions were fixed to obtain stiff gels at the synthesis stage.

Enhancing luminescence properties of lanthanide(III)/pyrimidine-4,6-dicarboxylato system by solvent-free approach.

The solvent-free melt reactions between lanthanide(iii) nitrates and pyrimidine-4,6-dicarboxylic acid (H2pmdc) led to three-dimensional (3D) coordination polymers with formula [Ln(μ4-pmdc)(NO3)(H2O)]n () [Ln(iii) = La, Ce, Pr, Nd, Sm, and Eu] and {[Ln(μ4-pmdc)(NO3)(H2O)]·H2O}n () [Ln(iii) = Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu]. The crystal structure of compounds is built up from the junction of centrosymmetric Ln(iii)-pmdc dimers, where pmdc ligand adopts an unusual μ4-κ(2)N,O:κ(2)N',O':κ(2)O,O'':κO''' coordination mode, rendering a metal coordination number of 10. The smaller ionic radii of the second half of the series prevents the latter coordination mode in , giving rise to a framework based on triangular shaped motifs.

Porous M(II)/pyrimidine-4,6-dicarboxylato neutral frameworks: synthetic influence on the adsorption capacity and evaluation of CO2-adsorbent interactions.

The understanding of the factors that affect the real pore-network structure for a given bulk material due to different synthetic procedures is essential to develop the material with the best adsorption properties. In this work, we have deeply studied the influence of the crystallinity degree over the adsorption capacity on three new isostructural MOFs with the formula {[CdM(μ4-pmdc)2(H2O)2]⋅solv}n (in which, pmdc = pyrimidine-4,6-dicarboxylate; solv = corresponding solvent; M(II) = Cd (1), Mn (2), Zn (3)). Compared with other methods, the solvent-free synthesis stands as the most effective route because, apart from enabling the preparation of the heterometallic compounds 2 and 3, it also renders the adsorbents with the highest performance, which is indeed close to the expected one derived from Grand Canonical Monte Carlo (GCMC) calculations.

Synthetic control to achieve lanthanide(III)/pyrimidine-4,6-dicarboxylate compounds by preventing oxalate formation: structural, magnetic, and luminescent properties.

Control over the synthetic conditions in many metal/diazinedicarboxylato systems is crucial to prevent oxalate formation, since dicarboxylato ligands easily undergo degradation in the presence of metal salts. We report here an efficient route to obtain oxalato-free compounds for the lanthanide/pyrimidine-4,6-dicarboxylato (pmdc) system on the basis of the reaction temperature and nonacidic pH or oxygen free atmosphere. Two different crystal architectures have been obtained: {[Ln(μ-pmdc)(1.

Improving the performance of a poorly adsorbing porous material: template mediated addition of microporosity to a crystalline submicroporous MOF.

The presence of butanoic acid excess in the reaction media employed for the synthesis of a MOF with formula [Cu(2)(μ(3)-ade)(2)(μ(2)-OOC(CH(2))(2)CH(3))(2)](n) (ade: adeninate) leads to the formation of micelles that exert a template effect and provide a pronounced increase of its microporosity, doubling the intrinsic adsorption capacity of the pristine crystal network.

Lanthanide(III)/pyrimidine-4,6-dicarboxylate/oxalate extended frameworks: a detailed study based on the lanthanide contraction and temperature effects.

Detailed structural, magnetic, and luminescence studies of six different crystalline phases obtained in the lanthanide/pyrimidine-4,6-dicarboxylate/oxalate system have been afforded: {[Ln(μ-pmdc)(μ-ox)(0.5)(H(2)O)(2)]·3H(2)O}(n) (1-Ln), {[Ln(μ-pmdc)(μ-ox)(0.5)(H(2)O)(3)]·2H(2)O}(n) (2-Ln), {[Ln(μ(3)-pmdc)(μ-ox)(0.

Open-framework copper adeninate compounds with three-dimensional microchannels tailored by aliphatic monocarboxylic acids.

A series of isostructural copper(II) coordination polymers containing the nucleobase adenine and different monocarboxylic acids as bridging ligands, [Cu(2)(μ(3)-ade)(2)(μ(2)-OOC(CH(2))(n)CH(3))(2)]·xH(2)O (n from 0 to 5), have been prepared. Single-crystal X-ray analysis of acetate (n = 0) and butanoate (n = 2) compounds shows a covalent three-dimensional network in which the copper(II) centers are bridged by μ-N3,N7,N9-adeninato and μ-O,O'-carboxylato ligands, with crystallization water molecules trapped in the pores, which are decorated by the Watson-Crick faces of the adenine. The tunable permanent porosity of guest-free compounds was confirmed by gas adsorption measurements.