Luminescent coordination polymers (CPs) are known for their unique abilities to provide tunable emission processes originated at the interplay between their infinite inorganic and organic ...constituents combined in endless ways, thus yielding smart molecule‐scaled materials to be processed as photodevices, sensors, optical storage systems or even logic gates. Nonetheless, most of these applications demand the occurrence of persistent luminescence to prevent background interference with the fluorescence signal. This is the reason why attention has been recently shifted to CPs exhibiting long‐lasting phosphorescence (CP‐LLPs), which imbues these crystalline solids with a long‐lived emission that is traceable by the human eye. The large interest awakened by these materials opposes with their difficulty to being achieved compared to dominant fluorescent CPs, probably derived from their challenging design. In this microreview we give an overview of the CP‐LLPs reported so far with the aim of deciphering some hints that enable this behavior while their potential applications are also discussed.
CP‐LLPs are luminescent materials exhibiting persistent emissions that last for several seconds. Accompanied by a brief description of reported CP‐LLPs, this review provides some hints towards their rational design and discusses their potential applications.
Siloxanes and silanols containing Si–H units are important building blocks for the synthesis of functionalized siloxane materials, and their synthesis is a current challenge. Herein, we report the ...selective synthesis of hydrosilanols, hydrosiloxanes, and silanodiols depending on the nature of the catalysts and the silane used. Two neutral ({MClSiMe2(o-C6H4PPh2)2}; M = Rh, Ir) and two cationic ({MSiMe2(o-C6H4PPh2)2(NCMe)}BArF 4; M = Rh, Ir) have been synthesized and their catalytic behavior toward hydrolysis of secondary silanes has been described. Using the iridium complexes as precatalysts and diphenylsilane as a substrate, the product obtained is diphenylsilanediol. When rhodium complexes are used as precatalysts, it is possible to selectively obtain silanediol, hydrosilanol, and hydrosiloxane depending on the catalysts (neutral or cationic) and the silane substituents.
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, ...Cu3(μ3-CNip)2(μ-H2O)2(μ3-OH)2 n (1), {Co3(μ4-CNip)3(DMF)4·∼2DMF} n (2), Cd(μ4-CNip) (DMF) n (3), {Ln2(μ4-CNip)(μ3-CNip)2(DMF)4·∼DMF·H2O} n (4-Ln) (with LnIII = Tb, Dy, and Er), {Gd6(μ3-CNip)5(μ4-CNip)3(μ-form)2(H2O) (DMF)10·∼3DMF·3H2O} n (5), {Zn32(μ4-CNip)12(μ-CNip)12(μ4-O)8(H2O)24·∼12DMF} n (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 N2 adsorption measurements at 77 K. Magnetic direct current (dc) susceptibility data on compounds 1, 2, and 5 were measured. Moreover, compounds 2, 4-Dy, 4-Er, and 5 show slow magnetic relaxation, from which it is worth highlighting the effective energy barrier of 44 K at zero dc field for the dysprosium counterpart. Compound 5 also deserves to be mentioned given the few 3D Gd-organic frameworks reported examples. Photophysical properties were also accomplished at different temperatures, confirming both the fluorescent emission of 5-cyanoisophthalate ligands when coordinated to cadmium ions in 3 and their capacity to sensitize the long-lived fluorescence of the selected lanthanide ions in 4-Ln. Broken symmetry and time-dependent density functional theory computational calculations support the experimental luminescence and magnetic properties.
In this work a family of multidimensional (2‐(1H‐tetrazol‐5‐yl)ethyl) amino acid coordination compounds have been synthesized and thoroughly characterized. For this purpose, glycine, valine, ...phenylalanine and tyrosine have been selected as starting amino acids and Mn2+, Zn2+ and Cd2+ as metallic nodes. From one side, for Mn2+ based dimer magnetic resonance imaging studies have been conducted, prompted by the number and disposition of the coordinated water molecules and taking into consideration the promising future of manganese‐based coordination compounds as bio‐compatible substitutes to conventional Gd based contrast agents. From another side, d10 block metal‐based complexes allowed exploring photoluminescence properties derived by in situ synthesized ligands. Finally, amino acid preserved structural chirality allowed us to examine chiroptical properties, particularly focusing on circularly polarized luminescence.
A family of multidimensional coordination compounds have been synthesized based on glycine, valine, phenylalanine and tyrosine. Magnetic resonance imaging studies and chiroptical properties have been explored.
Detailed structural characterization and photoluminescence properties of four new metal–organic frameworks (MOFs) based on zinc(II) or cadmium(II) metal ions, di- or tricarboxylic aromatic ligands, ...and bipyridyl-like elongated ancillary linkers, namely, {Zn2(μ4-bdc)2(μ-pbptz)·2DMF·3H2O} n (1), {Cd(μ3-bdc)(μ-pbptz)·3DMF} n (2), {Cd3(μ5-btc)2(μ-pbptz)·2DMF} n (3), and {Zn2(μ-dhbdc)2(μ-pbptz)(DMF)4·2DMF·H2O} n (4) (where bdc = benzene-1,4-dicarboxylato, btc = benzene-1,3,5-tricarboxylato, dhbdc = 2,5-dihydroxobenzene-1,4-dicarboxylato, pbptz = 3,6-bis(4-pyridyl)-1,2,4,5-tetrazine, DMF = N,N-dimethylformamide) are reported. The occurrence of large accessible volumes and structural and topological diversity are a constant for crystal structures of these compounds, which is a result of the connectivity established among the metal-carboxylato building units formed in each case. Three-dimensional (3D) pcu frameworks of compounds 1 and 2 are built from the linkage of dimeric cores (established by the coordination of dicarboxylato bdc ligands) into two-dimensional networks that are further joined together by ancillary ligands, whereas the novel jcr7 topological 3D framework is achieved in 3 owing to the presence of the tricarboxylic btc ligand. Two-dimensional layers are generated in 4 given the bidentate coordination of both dhbdc and pbptz ligands. Interestingly, most crystal structures (3D frameworks of 1, 2, and 3) exhibit open architectures containing large solvent-occupied void systems that account for high relative void volumes. A deep analysis of the photophysical properties has been also accomplished for all compounds, confirming an overall blue emission under UV excitation in the steady state. Compound 3 is characterized with a strong phosphorescent emission that lasts a few seconds and is observed by the naked eye, which constitutes an infrequent photoluminescent behavior for metal–organic materials.
This work reports on the preparation and optical characterization of two metal–organic frameworks (MOFs) based on strontium ions and 2-amino-1,4-benzenedicarboxylate (NH2-bdc) ligand: i.e., ...Sr(NH2-bdc)(DMF) n (1) and {Sr(NH2-bdc)(Form)·H2O} n (2) (where DMF = dimethylformamide and Form = formamide). Compound 1 has a 3D architecture built up from the linkage established by NH2-bdc among metal–carboxylate rods, leaving significant microchannels that are largely occupied by DMF molecules coordinated to strontium centers. The solvent molecules play a crucial role in the photoluminescence (PL) properties, which has been deeply characterized by diffuse reflectance and variable-temperature emission. Interestingly, both materials present intriguing photoluminescence (PL) properties involving intense short-lived and long-lasting phosphorescence (LLP), though the latter is especially remarkable for compound 2 with a lifetime of 815 ms at low temperature. Conversely, the strong PL shown by 1 may be successfully exploited due to both its luminescent thermochromism observed in the RT to 10 K range and its solvent-dependent PL sensing capacity, imbuing this material with potential activity as a PL thermometer as well as a toluene detector in water solutions.
Pesticides are agrochemical compounds used to kill pests (insects, rodents, fungi, or unwanted plants), which are key to meet the world food demand. Regrettably, some important issues associated with ...their widespread/extensive use (contamination, bioaccumulation, and development of pest resistances) demand a reduction in the amount of pesticide applied in crop protection. Among the novel technologies used to combat the deterioration of our environment, metal–organic frameworks (MOFs) have emerged as innovative and promising materials in agroindustry since they possess several features (high porosity, functionalizable cavities, ecofriendly composition, etc.) that make them excellent candidates for the controlled release of pesticides. Moving toward a sustainable development, in this work, we originally describe the use of pesticides as building blocks for the MOF construction, leading to a new type of agricultural applied MOFs (or AgroMOFs). Particularly, we have prepared a novel 2D-MOF (namely, GR-MOF-7) based on the herbicide glufosinate and the widely used antibacterial and fungicide Cu2+. GR-MOF-7 crystallizes attaining a monoclinic P21/c space group, and the asymmetric unit is composed of one independent Cu2+ ion and one molecule of the Glu2– ligand. Considering the significant antibacterial activity of Cu-based compounds in agriculture, the potential combined bactericidal and herbicidal effect of GR-MOF-7 was investigated. GR-MOF-7 shows an important antibacterial activity against Staphylococcus aureus and Escherichia coli (involved in agricultural animal infections), improving the results obtained with its individual or even physical mixed precursors glufosinate and Cu(NO3)2. It is also an effective pesticide against germination and plant growth of the weed Raphanus sativus, an invasive species in berries and vines crops, demonstrating that the construction of MOFs based on herbicide and antibacterial/antifungal units is a promising strategy to achieve multifunctional agrochemicals. To the best of our knowledge, this first report on the synthesis of an MOF based on agrochemicals (what we have named AgroMOF) opens new ways on the safe and efficient MOF application in agriculture.
New aluminium scorpionate based complexes have been prepared and used for the synthesis of cyclic carbonates from epoxides and carbon dioxide. Bimetallic aluminium(heteroscorpionate) complexes 9–14 ...were synthesised in very high yields. The single‐crystal X‐ray structures of 12 and 13 confirm an asymmetric κ2‐NO‐μ‐O arrangement in a dinuclear molecular disposition. These bimetallic aluminium complexes were investigated as catalysts for the synthesis of cyclic carbonates from epoxides and carbon dioxide in the presence of ammonium salts. Under the optimal reaction conditions, complex 9 in combination with tetrabutylammonium bromide acts as a very efficient catalyst system for the conversion of both monosubstituted and internal epoxides into the corresponding cyclic carbonates showing broad substrate scope. Complex 9 and tetrabutylammonium bromide is the second most efficient aluminium‐based catalyst system for the reaction of internal epoxides with carbon dioxide. A kinetic study has been carried out and showed that the reactions were first order in complex 9 and tetrabutylammonium bromide concentrations. Based on the kinetic study, a catalytic cycle is proposed.
Mild conditions: A combination of a bimetallic aluminium(scorpionate) complex and tetrabutylammonium bromide catalyses the formation of cyclic carbonates from terminal and internal epoxides and carbon dioxide under mild reaction conditions.
Herein, we describe and study a new family of isostructural multifunctional metal–organic frameworks (MOFs) with the formula {Ln5L6(OH)3(DMF)3·5H2O} n (where (H2L) is 3-amino-4-hydroxybenzoic acid ...ligand) for magnetism and photoluminescence. Interestingly, three of the materials (Dy-, Er-, and Yb-based MOFs) present single-molecule magnet (SMM) behavior derived from the magnetic anisotropy of the lanthanide ions as a consequence of the adequate electronic distribution of the coordination environment. Additionally, photoluminescence properties of the ligand in combination with Eu and Tb counterparts were studied, including the heterometallic Eu–Tb mixed MOF that shows potential as ratiometric luminescent thermometers. Finally, the porous nature of the framework allowed showing the CO2 sorption capacity.
Herein, the synthesis and study of bifunctional coordination polymers (CPs) with both magnetic and photoluminescence properties, derived from a heterometallic environment, are reported. As a starting ...point, three isostructural monometallic CPs with the formula M(μ‐2ani)2n (MII=Mn (1Mn), Co (3Co) and Ni (4Ni); 2ani=2‐aminonicotinate), crystallise as chiral 2D‐layered structures stacked by means of supramolecular interactions. These compounds show high thermal stability in the solid state (above 350 °C), despite which, in aqueous solution, compound 1Mn is shown to partially transform into a novel 1D chain CP with the formula Mn(2ani)2(μ‐H2O)2n (2Mn). A study of the direct current (dc) magnetic properties of 1Mn, 3Co and 4Ni reveals a spin‐canted structure derived from antisymmetric antiferromagnetic weak exchanges along the chiral network (as confirmed by DFT calculations) and magnetic anisotropy of the ions, in such a way that long‐range ordering is observed with variable magnitude for the spin carriers. Moreover, compounds 3Co and 4Ni show no frequency‐dependent alternating current (ac) susceptibility curves under zero dc field; this is characteristic behaviour of a glassy state that may be partially supressed for 3Co by applying an external dc field. To overcome long‐range magnetic ordering, CoII ions are diluted in a diamagnetic ZnII‐based matrix, which enables single‐molecule magnet behaviour. Interestingly, this strategy allows a bifunctional CoxZn1−x2ani material, which is imbued with a strong photoluminescent emitting capacity, as characterised by an intense blue light followed by a green afterglow, to be obtained.
Behavioural changes: The combination of 2‐aminonicotinic acid and 3d ions gives rise to a chiral 2D layered structure, showing intriguing long‐range weak ferromagnetic ordering, mainly in the case of the CoII counterpart. Long‐range ordering is suppressed by magnetically diluting the sample into a ZnII‐based homologue, in such a way that the resulting material behaves as a bifunctional single‐ion magnet and long‐lasting phosphor.
