Two isomers Ba5Mg4C54O48H114 and Pb5Mg4C54O48H114

There are reported two related structures of Ba5Mg4C54O48H114 (dodeca(aqua-6κ 3O,7κ 3O,8κ 3O,9κ 3O)-tris(μ2-propanoato-1:6κ 2O,1κO′)-tris(μ-propanoato-2:7κ 2O,2κO′-tris(μ-propanoato-3:8κ 2O,3κO′)-tris(μ-propanoato-4:9κ 2O,4κO′)-hexakis(μ3-propanoato-1:5κ 2O,2:5κ 2O′;1:5κ 2O,3:5κ 2O′;1:5κ 2O,4:5κ 2O′;2:5κ 2O,3:5κ 2O′;2:5κ 2O,4:5κ 2O′;3:5κ 2O,4:5κ 2O′)-pentabarium tetramagnesium), (I), and Pb5Mg4C54O48H114 (dodeca(aqua-1κ 3O,2κ 3O,3κ 3O,4κ 3O)-hexakis(μ3-propanoato-1:5κ 2O,2:5κ 2O′;1:5κ 2O,3:5κ 2O′;1:5 κ 2O,4:5κ 2O′;2:5κ 2O,3:5κ 2O′;2:5κ 2O,4:5κ 2O′;3:5κ 2O,4:5κ 2O′)tetramagnesium lead(II) tris(propanoato-κ 2O,O′)plumbate(II)), (II). The title structures are compositional isomers which crystallize in the same space group type. The structure of (I) comprises molecules with symmetry  4 ‾ 3 m $\overline{4}3m$ . The structure (II) comprises the complex cation {Pb(C3H5O2)6[Mg(H2O)3]4}4+ with the symmetry 4 ‾ 3 m $\overline{4}3m$ and four anions [tris(propanoato-κ 2O,O′)plumbate(II)]−, [Pb(C3H5O2)3]− , with 3m symmetry. The central cations Ba12+ and Pb12+ in (I) and in the cation {Pb(C3H5O2)6[Mg(H2O)3]4}4+ of the structure (II), respectively, have similar structural features which are comparable to the environment of the Ba2+ cation in BaCa2(C3H5O2)6 [Stadnicka, K. & Glazer, A. M. (1980). Acta Cryst. B36, 2977–2985]. The molecules in (I) and the ions in (II) are interconnected by Owater‒H⋯Opropanoate hydrogen bonds of a moderate strength. The ethyl chains are disordered which is common in propanoates. However, there are unprecedented features in the title structures: 1) The central atom Pb12+ is the first known example of a Pb2+ cation which is surrounded by six carboxylates in a bidentate bridging mode, i.e. by 12 oxygens. 2) The anion [tris(propanoato-κ 2O,O′)plumbate(II)]− has a constitution with unusually prominent stereochemical activity of the 6s 2 electron pair of the cation Pb2+ completing the coordination to the tetrahedral one. Thus, its formula can be expressed as [Pb[ψ−4t](C3H5O2)3]−. 3) In both title structures, there are propanoate molecules with disordered carboxylate oxygens.

Switching from Oxygen Quenching Resistance to Linear Response by Smart Luminescent Iridium(III)-Based Metal-Organic Frameworks

In this study, we utilize a photo-active Ir-metalloligand, Ir(C^N)₂(L) (C^N = 2-(2,4-difluorophenyl) pyridine, L = [2,2'-bipyridine]-5,5'-dicarboxylic acid), to assemble with CdX₂ under hydrothermal conditions, yielding highly emissive crystals of two-dimensional metal-organic frameworks (2D MOFs) (named Ir-Cd₂X_2, X = Cl, Br). The Ir-Cd₂X₂ MOFs exhibit μs-level phosphorescence lifetimes and more than 55% quantum yield (QY) at room temperature because of the rigid framework connected by Cd₂X₂ clusters. By immersing Ir-Cd₂X₂ in water solution for 5 min, a new MOF (Ir-Cd) was obtained, which is given a structure with hydrolyzed Cd-nodes by complete removal of halogen bridges as elucidated by single-crystal diffraction. Although the phosphorescence emission of pristine CdX₂ MOFs exhibits oxygen quenching resistance, the converted Ir-Cd MOF possesses sensitively oxygen-responsive ³MLCT properties, showing a K_SV value as high as 14.5 with strictly linear relation (R² = 0.995). This work differs from the traditional method for improving oxygen-sensing metrics by enhancing QY and phosphorescence lifetime in Ir complexes, while also demonstrating that the transformation in the surrounding coordination environment on adjacent metal centers can also constitute key factors for improved photoluminescence stability or responsive properties in Ir-based heteronuclear MOFs, providing clues for the development of either oxygen quenching blockers or sensors suitable for different occasions.

Porous matrix materials in optical sensing of gaseous oxygen

The review provides comparison of porous materials that act as a matrix for luminescent oxygen indicators. These include silica-gels, sol–gel materials based on silica and organically modified silica (Ormosils), aerogels, electrospun polymeric nanofibers, metal–organic frameworks, anodized alumina, and various other microstructured sensor matrices. The influence of material structure and composition on the efficiency of oxygen quenching and dynamic response times is compared and the advantages and disadvantages of the materials are summarized to give a guide for design and practical application of sensors with desired sensitivity and response time.

Glucose Sensing in Human Whole Blood Based on Near-Infrared Phosphors and Outlier Treatment with the Programming Language "R"

A near-infrared paper-based analytical device (NIR-PAD) for glucose detection in whole blood was based on iridium(III) metal complexes embedded in a three-dimensional (3D) enzyme gel. These complexes emit NIR luminescence, can avoid interference from the color of blood, and increase the sensitivity of sensing glucose. The glucose reaction behaviors of another two different iridium(III) and platinum(II) complexes were also tested. When the glucose solution was added to the device, the oxidation of glucose by glucose oxidase caused oxygen consumption and increased the intensity of the phosphorescence emission. To the best of our knowledge, this is the first time that data have been treated with the programming language "R", which uses Tukey's test to identify the outliers in the data and calculate a median for establishing a calibration curve, in order to improve the accuracy of NIR-PADs for sensing glucose. Compared with other published devices, NIR-PADs exhibit a wider linear range (1-30 mM, [relative emission intensity] = 0.0250[glucose] + 0.0451, and R 2 = 0.9984), a low detection limit (0.7 mM), a short response time (<2 s), and a small sample volume (2 μL). Finally, blood specimens were obtained from 19 patients enrolled in Taipei Veterans General Hospital under an approved IRB protocol (Taiwan; 2017-12-002CC). The sensors exhibited remarkable characteristics for glucose detection in comparison with other methods, including the clinical method in hospitals as well as those without blood sample pretreatment or a dilution factor. The above results confirm that NIR-PAD sensors can be put to practical use for glucose detection.

An Europium (III) Luminophore with Pressure-Sensing Units: Effective Back Energy Transfer in Coordination Polymers with Hexadentate Porous Stable Networks

A luminescent Eu^III coordination polymer with O₂ -sensing units under air, Eu^III -hcpt (hcpt: 2,3,6,7,10,11-hexakis(4-carboxy-phenyl)triphenylene), is reported. The hexadentate carboxylic acids in hcpt ligands play an important role in the formation of tight-packed three-dimensional networks in Eu^III -hcpt, giving hyper thermo-stable structures (decomposition temperature=420 °C). The three-dimensional porous network promotes bright luminescence (4f-4f emission quantum yield=70 %). The emission lifetime of Eu^III -hcpt under vacuum (0.86 ms) was twice as large as that under O₂ (0.48 ms, 1 atom:101.3 kPa). The Arrhenius analysis of the emission decay profile indicates that the back energy transfer (BEnT) from the emitting level of the europium(III) ion to the excited T₁ state of the hcpt ligand should be activated at room temperature. The gradual decrease of emission lifetime is caused by the BEnT process in Eu^III -hcpt. Finally, an advanced pressure-sensitive luminophore is demonstrated.

Coordination Polymers Based on Highly Emissive Ligands: Synthesis and Functional Properties

Coordination polymers are constructed from metal ions and bridging ligands, linking them into solid-state structures extending in one (1D), two (2D) or three dimensions (3D). Two- and three-dimensional coordination polymers with potential voids are often referred to as metal-organic frameworks (MOFs) or porous coordination polymers. Luminescence is an important property of coordination polymers, often playing a key role in their applications. Photophysical properties of the coordination polymers can be associated with intraligand, metal-centered, guest-centered, metal-to-ligand and ligand-to-metal electron transitions. In recent years, a rapid growth of publications devoted to luminescent or fluorescent coordination polymers can be observed. In this review the use of fluorescent ligands, namely, 4,4'-stilbenedicarboxylic acid, 1,3,4-oxadiazole, thiazole, 2,1,3-benzothiadiazole, terpyridine and carbazole derivatives, naphthalene diimides, 4,4',4''-nitrilotribenzoic acid, ruthenium(II) and iridium(III) complexes, boron-dipyrromethene (BODIPY) derivatives, porphyrins, for the construction of coordination polymers are surveyed. Applications of such coordination polymers based on their photophysical properties will be discussed. The review covers the literature published before April 2020.

Achievement of intrinsic white light emission by hybridization-deformable haloplumbates with rigid luminescent naphthalene motifs

The combination of red emissions stemming from deformable haloplumbates and blue emissions originating from luminescent naphthalene motifs give rise to intrinsic single-component white-light emitters.

Functional metal–organic frameworks as effective sensors of gases and volatile compounds

This review summarizes the recent advances of metal organic framework (MOF) based sensing of gases and volatile compounds.

Paper-based microfluidic devices based on 3D network polymer hydrogel for the determination of glucose in human whole blood

In this study, optical microfluidic paper analytical devices (μPADs) for glucose detection from whole blood samples with a small sample volume (2 μL) have been developed on a single paper. In the proposed method, a mushroom-shaped analytical device contains a sample inlet zone and a detection zone. When blood is dripped onto the inlet region of a μPAD, the plasma diffuses to the detection region. The detection region is implanted with a metallic three-dimensional (3D) polymer hydrogel vehicle. The gel vehicle consists of a copper complex that responds to oxygen changes and glucose oxidase (GOx) immobilized inside the gel as a bioactivity preservative. The phosphorescence of the copper complex is enhanced by oxygen consumed by detection of glucose with a limit of detection (S/N = 3) of 0.44 mM, and the total analysis of the sample is completed within 1 min. The validity of the proposed research is demonstrated using control samples and real-world whole blood samples of glucose concentrations ranging from 3 to 200 mM, and the detection results are shown to be in agreement with those obtained using a glucometer. Attaining a simple device for analysing glucose in human whole blood without any pretreatment procedures and having a broad sensing range while consuming a small sample volume remain challenging; thus, our new analytical device is of great interest.

Synthesis, Structural Characterization and Ligand-Enhanced Photo-Induced Color-Changing Behavior of Two Hydrogen-Bonded Ho(III)-Squarate Supramolecular Compounds

Two coordination polymers (CPs) with chemical formulas, [Ho2(C4O4)2(C2O4)(H2O)8]·4H2O (1) and [Ho(C4O4)1.5(H2O)3] (2), (C4O42- = dianion of squaric acid, C2O42- = oxalate), have been synthesized and their structures were determined by single-crystal X-ray diffractometer (XRD). In compound 1, the coordination environment of Ho(III) ion is eight-coordinate bonded to eight oxygen atoms from two squarate, one oxalate ligands and four water molecules. The squarates and oxalates both act as bridging ligands with 1,2-bis-monodentate and bis-chelating coordination modes, respectively, connecting the Ho(III) ions to form a one-dimensional (1D) ladder-like framework. Adjacent ladders are interlinked via O-HO hydrogen bonding interaction to form a hydrogen-bonded two-dimensional (2D) layered framework and then arranged orderly in an AAA manner to construct its three-dimensional (3D) supramolecular architecture. In compound 2, the coordination geometry of Ho(III) is square-antiprismatic eight coordinate bonded to eight oxygen atoms from five squarate ligands and three water molecules. The squarates act as bridging ligands with two coordination modes, 1,2,3-trismonodentate and 1,2-bis-monodentate, connecting the Ho(III) ions to form a 2D bi-layered framework. Adjacent 2D frameworks are then parallel stacked in an AAA manner to construct its 3D supramolecular architecture. Hydrogen bonding interactions between the squarate ligands and coordinated water molecules in 1 and 2 both play important roles on the construction of their 3D supramolecular assembly. Compounds 1 and 2 both show remarkable ligand-enhanced photo-induced color-changing behavior, with their pink crystals immediately turning to yellow crystals under UV light illumination.

A Lead Carboxylate-Azolate Metal-Organic Framework Based on Hexanuclear Clusters: Luminescence and Accelerating the Thermal Decomposition of Ammonium Perchlorate

A lead carboxylate-azolate framework, [Pb₃ (μ₄ -O)(L)₂ (H₂ O)] ⋅ 2H₂ O (1), has been constructed from the reaction of 2-methyl-4-(1H-tetrazol-5-yl) benzoic acid (H₂ L) and Pb(NO₃ )₂ under solvothermal conditions. Compound 1 contains an unprecedented hexanuclear cluster [Pb₆ (μ₄ -O)₂ (COO)₄ (CN₄ )₂ ], which as an 8-connected node is connected by 3-connected L linkers to give rise to a three-dimensional framework with an uncommon (3,8)-connected tfz-d; UO₃ topology. Framework 1 possesses strong solid-state yellow luminescence (563 nm), which stems from ligand-to-metal charge transfer (LMCT), however, the removal of water molecules in 1 lead to the significant luminescent decrease of the sample. Importantly, in the presence of 1, the thermal decomposition of ammonium perchlorate is significantly accelerated.

The Knoevenagel condensation using quinine as an organocatalyst under solvent-free conditions

An organocatalytic Knoevenagel condensation has been developed for the synthesis of electrophilic alkenes using natural quinine under green reaction conditions.

Phosphorescence emission and fine structures observed respectively under ambient conditions and at ca. 55 K in a coordination polymer of lead(ii)-thiophenedicarboxylate

Under solvothermal conditions, a robust Pb²⁺-based coordination polymer (CP), [Pb(TDC)]_n (1), where H₂TDC is thiophenedicarboxylic acid, has been achieved.

Lead-carboxylate/polyiodide hybrids constructed from halogen bonding and asymmetric viologen: structures, visible-light-driven photocatalytic properties and enhanced photocurrent responses

Two lead-carboxylate/polyiodide hybrids constructed from halogen bonding and asymmetric viologen have been synthesized, which exhibit efficient photocatalytic degeneration performances.

Dual emissions and thermochromic luminescences of isomorphic chiral twofold interpenetrated 3-D nets built from I1O2 type hybrid inorganic–organic frameworks of [NH2(CH3)2]3[Pb2X3(BDC)2] (X = Br, I)

Two pairs of isomorphic chiral twofold interpenetrated 3-D nets were built from I¹O² type hybrid inorganic–organic frameworks and show dual emissions and thermochromism.

Synthesis, characterization, second and third order non-linear optical properties and luminescence properties of 1,10-phenanthroline-2,9-di(carboxaldehyde phenylhydrazone) and its transition metal complexes

The requirement for materials which exhibit good second and third order non-linear optical properties and also for materials which could sense metals in trace quantities has kindled renewed investigations. Organometallics and coordination compounds show a lot of promise as new NLO materials combining the variety of organic moieties with the strength and variable oxidation states of metals. Especially ligands which selectively detect industrial pollutants like Cd and biologically significant metals like Zn are necessary. In the current work the ligand 1,10-phenanthroline-2,9-di(carboxaldehyde phenylhydrazone) (L) and its Ni2+, Co2+, Fe2+, Zn2+, Cd2+ and Ir3+ complexes were synthesized. These were characterized by UV-Vis, FT-IR, 1H NMR, MS and CHN microanalysis techniques. The complexes were shown to have the formula [ML]2+. The second and third order NLO of the ligand and its complexes were recorded These new compounds were found to have same order of third order nonlinear optical susceptibility as that of CS2 and their second hyperpolarizability was an order of magnitude greater than that of C60. Furthermore the ligand also displays selective luminescence sensing of metals ions Fe2+ and Ir3+ even in the presence of other metal ions.

Mixed-Lanthanide Porous Coordination Polymers Showing Range-Tunable Ratiometric Luminescence for O2 Sensing

Luminescent porous coordination polymers (PCPs) are emerging as attractive oxygen-sensing materials, but they are mostly based on single-wavelength luminometry. Here, we report a special mixed-lanthanide strategy for self-referenced ratiometric oxygen sensing. A series of isostructural, pure-lanthanide, or mixed-lanthanide PCPs, MCF-53(Tb/Eu_x), were synthesized by solvothermal reactions. Single-crystal X-ray diffraction revealed that MCF-53(Tb/Eu_x) is composed of complicated two-dimensional coordination networks, which interdigitate to form a three-dimensional supramolecular structure retaining one-dimensional ultra-micropores. MCF-53(Tb/Eu_x) can undergo multiple single-crystal to single-crystal structural transformations upon desorption/adsorption of coordinative and lattice guest molecules, and the lanthanide metal ions are partially exposed on the pore surface at the guest-free state. Tb(III) ions are not luminescent and only act as separators between Eu(III) ions, and the Tb(III)/Eu(III) mixing ratio can tune the relative emission intensities, luminescence lifetimes of the Eu(III) phosphorescence, and the ligand fluorescence, giving rise to not only ratiometric photoluminescence oxygen sensing but also tunable emission-color-changing ranges.

Intense greenish phosphorescence emission under ambient conditions in a two-dimensional lead(ii) coordination polymer with a 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate ligand

A new 2D Pb²⁺-based coordination polymer emits intense greenish phosphorescence in the solid state under ambient conditions with a quantum yield of 1.5% and a phosphorescence lifetime of 4.17 ms.

Lanthanide coordination polymer probe for time-gated luminescence sensing of pH in undiluted human serum

Lanthanide coordination polymers (LCPs) have emerged as fascinating materials because of their specific structure and properties. In this work, utilizing hydrosoluble biomolecule of guanosine-5'-monophosphate (GMP) as bridging linker, lanthanide terbium ions (Tb³⁺) as metal nodes, and silver ions (Ag⁺) as sensitizers, we synthesized a pH responsive luminescent lanthanide CP probe of Tb/GMP/Ag. The probe possesses high luminescence due to the sensitization of Ag⁺; While in alkaline solutions, Ag⁺ in Tb/GMP/Ag immediately binds to OH^-, forming Ag₂O precipitation and resulting in a distinct fluorescence quenching of Tb/GMP/Ag. This probe displays high selectivity for OH^- and a broader pH detection range of 7.5-13.0. In addition, based on the high anti-interference ability in serum, we applied Tb/GMP/Ag to measure pH in undiluted human serum samples, yielding satisfactory results.

Photoluminescent Metal-Organic Frameworks for Gas Sensing

Luminescence of porous coordination polymers (PCPs) or metal-organic frameworks (MOFs) is sensitive to the type and concentration of chemical species in the surrounding environment, because these materials combine the advantages of the highly regular porous structures and various luminescence mechanisms, as well as diversified host-guest interactions. In the past few years, luminescent MOFs have attracted more and more attention for chemical sensing of gas-phase analytes, including common gases and vapors of solids/liquids. While liquid-phase and gas-phase luminescence sensing by MOFs share similar mechanisms such as host-guest electron and/or energy transfer, exiplex formation, and guest-perturbing of excited-state energy level and radiation pathways, via various types of host-guest interactions, gas-phase sensing has its unique advantages and challenges, such as easy utilization of encapsulated guest luminophores and difficulty for accurate measurement of the intensity change. This review summarizes recent progresses by using luminescent MOFs as reusable sensing materials for detection of gases and vapors of solids/liquids especially for O₂, highlighting various strategies for improving the sensitivity, selectivity, stability, and accuracy, reducing the materials cost, and developing related devices.

Chemical Sensors Based on Metal-Organic Frameworks

Metal-organic frameworks (MOFs) as chemical sensors have developed rapidly in recent years. There have been many papers concerning this field and interest is still growing. The reason is that the specific merits of MOFs can be utilized to enhance sensitivity and selectivity by various energy/charge transfers occurring among different ligands, ligand, and metal centers, such as from ligands to metal centers or metal centers to ligands, as well as from MOF skeletons to guest species. This review intends to provide an update on recent progress in various applications of different MOF-based sensors on the basis of their luminescent and electrochemical responses towards small molecules, gas molecules, ions (cations and anions), pH, humidity, temperature, and biomolecules. MOF-based sensors function by utilizing different mechanisms, including luminescent responses of "turn-on" and "turn-off", as well as electrochemical responses.

Ionic Self-Assembly and Red-Phosphorescence Properties of a Charged Platinum(II) 8-Quinolinol Complex Associated with Ammonium-Based Amphiphiles

A series of ionic associates based on the platinum(II) chelate of 5-sulfo-8-quinolinol, [Pt(qS)2](2-), and ammonium-based amphiphiles is described. At variance with the prototypical neutral complex Pt(q)2 (q=8-quinolinol), these dianionic fluorophores, functionalized at the periphery with sulfonate groups, can be associated by the ionic self-assembly approach with various ammonium cations, such as (H2n+1Cn)2Me2N(+) (n=12, 16, 18) or complex ammonium cations carrying three Cn carbon chains (n=12, 14, 16) and an additional amide group. Investigations of their luminescence properties in solution, in the solid state, and, when possible, in thin films revealed that the phosphorescence properties in condensed phases are directly correlated to intermolecular interactions between the luminescent [Pt(qS)2](2-) centers. Of particular interest is also the formation of a columnar liquid-crystalline phase around room temperature (between -25 and +180 °C), as well as the very good film-forming ability of some of these fluorophores from organic solvents.

Molecular tectonics: heterometallic (Ir,Cu) grid-type coordination networks based on cyclometallated Ir(III) chiral metallatectons

A chiral-at-metal Ir(III) organometallic metallatecton was synthesised as a racemic mixture and as enantiopure complexes and combined with Cu(II) to afford a heterobimetallic (Ir,Cu) grid-type 2D coordination network.