An Americium‐Containing Metal–Organic Framework: A Platform for Studying Transplutonium Elements

The synthesis, structure, and spectroscopic characterization of the first transplutonium metal–organic framework (MOF) is described. The preparation and structure of Am‐GWMOF‐6, [Am₂(C₆H₈O₄)₃(H₂O)₂][(C₁₀H₈N₂)], is analogous to that of the isostructural trivalent lanthanide‐only containing material GWMOF‐6. The presented MOF architecture is used as a platform to probe Am³⁺ coordination chemistry and guest‐enhanced luminescent emission, whereas the framework itself provides a means to monitor the effects of self‐irradiation upon crystallinity over time. Presented here is a discussion of these properties and the opportunities that MOFs provide in the structural and spectroscopic study of actinides.     

Two new isomeric zinc(II) metal–organic frameworks based on 1,5‐bis(2‐methyl‐1H‐imidazol‐1‐yl)pentane and 5‐methylisophthalate ligands

Many factors, such as temperature, solvent, the central metal atom and the type of coligands, may affect the nature of metal–organic frameworks (MOFs) and the framework formation in the self‐assembly process, which results in the complexity of these compounds and the uncertainty of their structures. Two new isomeric Zn^II metal–organic frameworks (MOFs) based on mixed ligands, namely, poly[[μ‐1,5‐bis(2‐methyl‐1H‐imidazol‐1‐yl)pentane‐κ²N ³:N ^3′](μ‐5‐methylisophthalato‐κ²O ¹:O ³)zinc(II)], [Zn(C₉H₆O₄)(C₁₃H₂₀N₄)]_n , (I), and poly[[μ‐1,5‐bis(2‐methyl‐1H‐imidazol‐1‐yl)pentane‐κ²N ³:N ^3′](μ₃‐5‐methylisophthalato‐κ³O ¹:O ^1′:O ³)(μ₃‐5‐methylisophthalato‐κ⁴O ¹:O ^1′:O ³,O ^3′)dizinc(II)], [Zn₂(C₉H₆O₄)₂(C₁₃H₂₀N₄)]_n , (II), have been synthesized under hydrothermal conditions and characterized by single‐crystal X‐ray diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis. Complex (I) displays a two‐dimensional layer net, while complex (II) exhibits a twofold interpenetrating three‐dimensional framework. Both complexes show high stability and good fluorescence in the solid state at room temperature.     

Systematic Investigation of High‐Sensitivity Luminescent Sensing for Polyoxometalates and Iron(III) by MOFs Assembled with a New Resorcin[4]arene‐Functionalized Tetracarboxylate

A new family of resorcin[4]arene‐based metal–organic frameworks (MOFs), namely, [Eu(HL)(DMF)(H₂O)₂] ? 3 H₂O ( 1 ), [Tb(HL)(DMF)(H₂O)₂] 3 H₂O ( 2 ), [Cd₄(L)₂(DMF)₄(H₂O)₂] 3 H₂O ( 3 ) and [Zn₃(HL)₂(H₂O)₂] 2 DMF ? 7 H₂O ( 4 ), have been constructed from a new resorcin[4]arene‐functionalized tetracarboxylic acid (H₄L=2,8,14,20‐tetra‐ethyl‐6,12,18,24‐tetra‐methoxy‐4,10,16,22‐tetra‐carboxy‐methoxy‐calix[4]arene). Isostructural 1 and 2 exhibit charming 1D motifs built with the cup‐like HL^3? anions and rare earth cations. Compounds 3 and 4 show a unique sandwich‐based 2D layer and a fascinating 3D framework, respectively. Remarkably, compounds 1 and 2 display intensive red and green emissions triggered by the efficient antenna effect of organic ligands under UV light. More importantly, systematic luminescence studies demonstrate that Ln‐MOFs 1 and 2 , as efficient multifunctional fluorescent materials, show highly selective and sensitive sensing of Fe³⁺, polyoxometalates (POMs), and acetone, which represents a rare example of a sensor for quantitatively detecting three different types of analytes. This is also an exceedingly rare example of Fe³⁺ and POMs detection in aqueous solutions employing resorcin[4]arene‐based luminescent Ln‐MOFs. Furthermore, the possible mechanism of the sensing properties is deduced.     

Luminescence Tuning and White‐Light Emission of Co‐doped Ln–Cd–Organic Frameworks

Four new three‐dimensional isostructural lanthanide–cadmium metal–organic frameworks (Ln–Cd MOFs), [LnCd₂(imdc)₂(Ac)(H₂O)₂]?H₂O (Ln=Pr ( 1 ), Eu ( 2 ), Gd ( 3 ), and Tb ( 4 ); H₃imdc=4,5‐imidazoledicarboxylic acid; Ac=acetate), have been synthesized under hydrothermal conditions and characterized by IR, elemental analyses, inductively coupled plasma (ICP) analysis, and X‐ray diffraction. Single‐crystal X‐ray diffraction shows that two Ln^III ions are surrounded by four Cd^II ions to form a heteronuclear building block. The blocks are further linked to form 3D Ln–Cd MOFs by the bridging imdc^3? ligand. Furthermore, the left‐ and right‐handed helices array alternatively in the lattice. Eu–Cd and Tb–Cd MOFs can emit characteristic red light with the Eu^III ion and green light with the Tb^III ion, respectively, while both Gd–Cd and Pr–Cd MOFs generate blue emission when they are excited. Different concentrations of Eu³⁺ and Tb³⁺ ions were co‐doped into Gd–Cd/Pr–Cd MOFs, and tunable luminescence from yellow to white was achieved. White‐light emission was obtained successfully by adjusting the excitation wavelength or the co‐doping ratio of the co‐doped Gd–Cd and Pr–Cd MOFs. These results show that the relative emission intensity of white light for Gd–Cd:Eu³⁺,Tb³⁺ MOFs is stronger than that of Pr–Cd:Eu³⁺,Tb³⁺ MOFs, which implies that the Gd complex is a better matrix than the Pr complex to obtain white‐light emission materials.     

Highly Selective Detection of 2,4,6‐Trinitrophenol and Cu2+ Ions Based on a Fluorescent Cadmium–Pamoate Metal–Organic Framework

A luminescent cadmium–pamoate metal–organic framework, [Cd₂(PAM)₂(dpe)₂(H₂O)₂]?0.5(dpe) ( 1 ), has been synthesized under hydrothermal conditions by using π‐electron‐rich ligands 4,4′‐methylenebis(3‐hydroxy‐2‐naphthalenecarboxylic acid) (H₂PAM) and 1,2‐di(4‐pyridyl)ethylene (dpe). Its structure is composed of both mononuclear and dinuclear Cd^II building units, which are linked by the PAM and dpe ligands, resulting in a (4,8)‐connected 3D framework. The π‐conjugated dpe guests are located in a 1D channel of 1 . The strong emission of 1 could be quenched efficiently by trace amounts of 2,4,6‐trinitrophenol (TNP), even in the presence of other competing analogues such as 4‐nitrophenol, 2,6‐dinitrotoluene, 2,4‐dinitrotoluene, nitrobenzene, 1,3‐dinitrobenzene, hydroquinone, dimethylbenzene, and bromobenzene. The high sensitivity and selectivity of the fluorescence response of 1 to TNP shows that this framework could be used as an excellent sensor for identifying and quantifying TNP. In the same manner, 1 also exhibits superior selectivity and sensitivity towards Cu²⁺ compared with other metal ions such as Zn²⁺, Mn²⁺, Mg²⁺, K⁺, Na⁺, Ni²⁺, Co²⁺, and Ca²⁺. This is the first MOF that can serve as a dual functional fluorescent sensor for selectively detecting trace amounts of TNP and Cu²⁺.     

A self‐penetrated three‐dimensional zinc(II) coordination framework based on 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoic acid and 1,3‐bis[(imidazol‐1‐yl)methyl]benzene ligands: synthesis,structure and properties

With the rapid development of metal–organic frameworks (MOFs), a variety of MOFs and their derivatives have been synthesized and reported in recent years. Commonly, multifunctional aromatic polycarboxylic acids and nitrogen‐containing ligands are employed to construct MOFs with fascinating structures. 4,4′,4′′‐(1,3,5‐Triazine‐2,4,6‐triyl)tribenzoic acid (H₃TATB) and the bidentate nitrogen‐containing ligand 1,3‐bis[(imidazol‐1‐yl)methyl]benzene (bib) were selected to prepare a novel Zn^II‐MOF under solvothermal conditions, namely poly[[tris{μ‐1,3‐bis[(imidazol‐1‐yl)methyl]benzene}bis[μ₃‐4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoato]trizinc(II)] dimethylformamide disolvate trihydrate], {[Zn₃(C₂₄H₁₂N₃O₆)₂(C₁₄H₁₄N₄)₃]·2C₃H₇NO·3H₂O}_n ( 1 ). The structure of 1 was characterized by single‐crystal X‐ray diffraction, IR spectroscopy and powder X‐ray diffraction. The properties of 1 were investigated by thermogravimetric and fluorescence analysis. Single‐crystal X‐ray diffraction shows that 1 belongs to the monoclinic space group Pc. The asymmetric unit contains three crystallographically independent Zn^II centres, two 4,4′,4′′‐(1,3,5‐triazine‐2,4,6‐triyl)tribenzoate (TATB^3?) anions, three complete bib ligands, one and a half free dimethylformamide molecules and three guest water molecules. Each Zn^II centre is four‐coordinated and displays a distorted tetrahedral coordination geometry. The Zn^II centres are connected by TATB^3? anions to form an angled ladder chain with large windows. Simultaneously, the bib ligands link Zn^II centres to give a helical Zn–bib–Zn chain. Furthermore, adjacent ladders are bridged by Zn–bib–Zn chains to form a fascinating three‐dimensional self‐penetrated framework with the short Schläfli symbol 6⁵·7·8¹³·9·10. In addition, the luminescence properties of 1 in the solid state and the fluorescence sensing of metal ions in suspension were studied. Significantly, compound 1 shows potential application as a fluorescent sensor with sensing properties for Zr⁴⁺ and Cu²⁺ ions.     

Selective Sensing of Fe3+ and Al3+ Ions and Detection of 2,4,6‐Trinitrophenol by a Water‐Stable Terbium‐Based Metal–Organic Framework

A water‐stable luminescent terbium‐based metal–organic framework (MOF), {[Tb(L₁)_1.5(H₂O)] ? 3 H₂O}_n (Tb‐MOF), with rod‐shaped secondary building units (SBUs) and honeycomb‐type tubular channels has been synthesized and structurally characterized by single‐crystal X‐ray diffraction. The high green emission intensity and the microporous nature of the Tb‐MOF indicate that it can potentially be used as a luminescent sensor. In this work, we show that Tb‐MOF can selectively sense Fe³⁺ and Al³⁺ ions from mixed metal ions in water through different detection mechanisms. In addition, it also exhibits high sensitivity for 2,4,6‐trinitrophenol (TNP) in the presence of other nitro aromatic compounds in aqueous solution by luminescence quenching experiments.     

A novel octanuclear nickel(II)–molybdenum(VI) heterometallic cluster based on the salicylhydroxamate ligand

Salicylhydroxamic acid (H₃shi) is known for its strong coordination ability and multiple coordination modes, and can easily coordinate to metal cations to form compounds with five‐ or six‐membered rings, as well as mono‐, di‐ and multinuclear compounds with interesting structures having potential applications in organic chemistry, coordination chemistry, and the materials and biological sciences. A novel octanuclear nickel(II)–molybdenum(VI) heterometallic cluster based on the salicylhydroxamate ligand, namely di‐μ₃‐acetato‐di‐μ₂‐acetato‐di‐μ₃‐hydroxido‐di‐μ₃‐oxido‐tetraoxidooctakis(pyridine‐κN)bis(μ₅‐salicylhydroxamato)hexanickel(II)dimolybdenum(VI) monohydrate, [Mo₂Ni₆(C₇H₄NO₃)₂(C₂H₃O₂)₄O₅(OH)₂(C₅H₅N)₈]·H₂O, (I), was synthesized by the reaction of sodium molybdate, nickel acetate and salicylhydroxamic acid in a dimethylformamide/pyridine/methanol solution at room temperature. The salicylhydroxamate(3−) (shi³⁻), acetate and oxide ligands adopt complicated coordination modes and link six Ni^II and two Mo^VI cations into the octanuclear heterometallic cluster. All of the metal cations exhibit octahedral coordination geometries and are connected to each other through the sharing of corners, edges or planes. The heterometallic clusters are further connected to form two‐dimensional supramolecular layers through weak C—H…O hydrogen bonds. Studies of the magnetic properties of the title compound reveal antiferromagnetic interactions between the Ni^II cations.     

A lithium‐organic framework as a fluorescent sensor for detecting aluminum (III) ion

Due to the low coordination number and the relatively weak coordination ability, it is a great challenge to introduce Li⁺ into the construction of metal–organic frameworks (MOFs). Here, one Li‐based metal–organic framework (Li‐MOF), [Li₄L(DMF)₂]_n ( HNU‐31 ), is constructed by the assembly of LiNO₃ and 5‐(bis(4‐carboxybenzyl)amino)isophthalic acid (H₄L) ligand, which possesses a 3D framework, and can be serve as a luminescent sensor for detecting Al³⁺ ion with the detection limit of 4 × 10^?6 M.     

Cationic,neutral and anionic metal(II) complexes derived from 4‐oxo‐4H‐pyran‐2,6‐dicarboxylic acid (chelidonic acid)

The structures of five metal complexes containing the 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate dianion illustrate the remarkable coordinating versatility of this ligand and the great structural diversity of its complexes. In tetraaquaberyllium 4‐oxo‐4H‐pyran‐2,6‐dicarboxylate, [Be(H₂O)₄](C₇H₂O₆), (I), the ions are linked by eight independent O—H...O hydrogen bonds to form a three‐dimensional hydrogen‐bonded framework structure. Each of the ions in hydrazinium(2+) diaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)calcate, (N₂H₆)[Ca(C₇H₂O₆)₂(H₂O)₂], (II), lies on a twofold rotation axis in the space group P2/c; the anions form hydrogen‐bonded sheets which are linked into a three‐dimensional framework by the cations. In bis(μ‐4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)bis[tetraaquamanganese(II)] tetrahydrate, [Mn₂(C₇H₂O₆)₂(H₂O)₈]·4H₂O, (III), the metal ions and the organic ligands form a cyclic centrosymmetric Mn₂(C₇H₂O₆)₂ unit, and these units are linked into a complex three‐dimensional framework structure containing 12 independent O—H...O hydrogen bonds. There are two independent Cu^II ions in tetraaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)copper(II), [Cu(C₇H₂O₆)(H₂O)₄], (IV), and both lie on centres of inversion in the space group P; the metal ions and the organic ligands form a one‐dimensional coordination polymer, and the polymer chains are linked into a three‐dimensional framework containing eight independent O—H...O hydrogen bonds. Diaqua(4‐oxo‐4H‐pyran‐2,6‐dicarboxylato)cadmium monohydrate, [Cd(C₇H₂O₆)(H₂O)₂]·H₂O, (V), forms a three‐dimensional coordination polymer in which the organic ligand is coordinated to four different Cd sites, and this polymer is interwoven with a complex three‐dimensional framework built from O—H...O hydrogen bonds.     

A zinc(II) metal–organic framework with a novel topology formed from 4,4′,4′′‐nitrilotribenzoate and 4,4′‐bipyridine ligands

A metal–organic framework with a novel topology, poly[sesqui(μ₂‐4,4′‐bipyridine)bis(dimethylformamide)bis(μ₄‐4,4′,4′′‐nitrilotribenzoato)trizinc(II)], [Zn₃(C₂₁H₁₂NO₆)₂(C₁₀H₈N₂)_1.5(C₃H₇NO)₂]_n, was obtained by the solvothermal method using 4,4′,4′′‐nitrilotribenzoic acid and 4,4′‐bipyridine (bipy). The structure, determined by single‐crystal X‐ray diffraction analysis, possesses three kinds of crystallographically independent Zn^II cations, as well as binuclear Zn₂(COO)₄(bipy)₂ paddle‐wheel clusters, and can be reduced to a novel topology of a (3,3,6)‐connected 3‐nodal net, with the Schläfli symbol {5.6²}₄{5².6}₄{5⁸.8⁷} according to the topological analysis.     

Mononuclear and dinuclear bromide–nitrite cadmium(II) complexes with related 1,4‐diazabicyclo[2.2.2]octane ligands

The title compounds, di‐μ‐bromido‐bis[bromido(1‐carboxymethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane‐κN⁴)(nitrito‐κ²O,O′)cadmium(II)] dihydrate, [Cd₂Br₄(C₈H₁₅N₂O₂)₂(NO₂)₂]·2H₂O, (I), and aquabromido(1‐cyanomethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane‐κN⁴)bis(nitrito‐κ²O,O′)cadmium(II) monohydrate, [CdBr(C₈H₁₄N₃)(NO₂)₂(H₂O)]·H₂O, (II), are two‐dimensional hydrogen‐bonded metal–organic hybrid complexes. In (I), the complex is situated on a centre of inversion so that each symmetry‐related Cd^II atom is coordinated by two bridging Br atoms, one monodentate Br atom, one chelating nitrite ligand and one organic ligand, yielding a significantly distorted octahedral geometry. The combination of O—H...O and O—H...Br hydrogen bonds produces centrosymmetric R₆⁶(16) ring motifs, resulting in two‐dimensional layers parallel to the ab plane. In contrast, the complex molecule in (II) is mononuclear, with the Cd^II atom seven‐coordinated by two bidentate nitrite groups, one N atom from the organic ligand, one monodentate Br atom and a water O atom in a distorted pentagonal–bipyramidal environment. The combination of O—H...O and O—H...Br hydrogen bonds produces R₅⁴(14) and R₃³(8) rings which lead to two‐dimensional layers parallel to the ac plane.     

pH‐Dependent Proton Conducting Behavior in a Metal–Organic Framework Material

A porous metal–organic framework (MOF), [Ni₂(dobdc)(H₂O)₂]?6 H₂O (Ni₂(dobdc) or Ni‐MOF‐74; dobdc^4?=2,5‐dioxido‐1,4‐benzenedicarboxylate) with hexagonal channels was synthesized using a microwave‐assisted solvothermal reaction. Soaking Ni₂(dobdc) in sulfuric acid solutions at different pH values afforded new proton‐conducting frameworks, H⁺@Ni₂(dobdc). At pH 1.8, the acidified MOF shows proton conductivity of 2.2×10^?2 S cm^?1 at 80 °C and 95 % relative humidity (RH), approaching the highest values reported for MOFs. Proton conduction occurs via the Grotthuss mechanism with a significantly low activation energy as compared to other proton‐conducting MOFs. Protonated water clusters within the pores of H⁺@Ni₂(dobdc) play an important role in the conduction process.     

Windmill Co4{Co4(μ4‐O)} with 16 Divergent Branches Forming a Family of Metal–Organic Frameworks: Organic Metrics Control Topology,Gas Sorption,and Magnetism

A series of highly connected metal–organic frameworks (MOFs), [Co₈(O)(OH)₄(H₂O)₄(ina)₈](NO₃)₂ ? 2 C₂H₅OH ? 4 H₂O ( 1 ), [Co₈(O)(OH)₄(H₂O)₄(pba)₈](NO₃)₂ ? 8 C₂H₅OH ? 28 H₂O ( 2 ), and [Co₈(O)(OH)₄(H₂O)₄(pbba)₈](NO₃)₂ ? guest ( 3 ), in which ina=isonicotinate, pba=4‐pyridylbenzoate, and pbba=4‐(pyridine‐4‐yl)phenylbenzoate, is reported. These MOFs contain a new secondary building unit (SBU), with a square Co₄(μ₄‐O) central unit having the rare μ₄‐O^2? motif, which is decorated by the other four peripheral cobalt atoms through μ₃‐OH in a windmill‐like shape. This SBU holds 16 divergent connecting organic ligands, pyridyl‐carboxylates, to form three different frameworks. The high porosity of desolvated 2 is shown by the efficient gas absorption of N₂, CO₂, CH₄, and H₂. In addition, 1 and 2 exhibit unusual canted antiferromagnetic behavior with spin‐glass‐like relaxation, with blocking temperatures that are fairly high, 20 K ( 1 ) and 10 K ( 2 ), for cobalt materials. The relationship between the metal clusters and linkers has been studied, in which the size and rotational degrees of freedom of the ligands are found to control the topology, gas sorption, and magnetic properties.     

Reversible Solvatomagnetic Switching in a Spongelike Manganese(II)–Copper(II) 3D Open Framework with a Pillared Square/Octagonal Layer Architecture

The concept of “molecular magnetic sponges” was introduced for the first time in 1999 by the creative imagination of the late Olivier Kahn. It refers to the exotic spongelike behavior of certain molecule‐based materials that undergo a dramatic change of their magnetic properties upon reversible dehydration/rehydration processes. Here we report a unique example of a manganese(II)–copper(II) mixed‐metal–organic framework of formula [Na(H₂O)₄]₄[Mn₄{Cu₂(mpba)₂(H₂O)₄}₃]? 56.5 H₂O ( 1 ) (mpba=N,N′‐1,3‐phenylenebis(oxamate)). Compound 1 possesses a 3D Mn^II₄Cu^II₆ pillared layer structure with mixed square and octagonal pores of approximate dimensions 1.2×1.2 nm and 2.1×3.0 nm, respectively, hosting a large amount of crystallization H₂O molecules and hydrated Na^I countercations as guests. It reversibly switches from a crystalline hydrated phase with long‐range ferromagnetic ordering at a rather high critical temperature (T_c) of 22.5 K to an amorphous dehydrated phase with T_c as low as 2.3 K, which is accompanied by a breathing‐type dynamic effect involving a large crystal volume (ca. 45 %) and color changes after water desorption/adsorption. The combination of both the open‐framework structure and the spongelike optical, mechanical, and magnetic switching behavior in this new class of oxamato‐based porous magnets offers fascinating possibilities in designing multifunctional materials for host–guest molecular sensing.     

Two new NiII and ZnII metal–organic frameworks of glutarate and 1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene ligands: syntheses,structures and luminescence sensing properties

Two new metal–organic frameworks (MOFs), namely, three‐dimensional poly[diaquabis{μ₂‐1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene}bis(μ₂‐glutarato)dinickel(II)] monohydrate], {[Ni₂(C₅H₆O₄)₂(C₁₆H₁₈N₄)₂(H₂O)₂]·H₂O}_n or {[Ni₂(Glu)₂(1,4‐mbix)₂(H₂O)₂]·H₂O}_n, ( I ), and two‐dimensional poly[[{μ₂‐1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene}(μ₂‐glutarato)zinc(II)] tetrahydrate], {[Zn(C₅H₆O₄)(C₁₆H₁₈N₄)]·4H₂O}_n or {[Zn(Glu)(1,4‐mbix)]·4H₂O}_n ( II ), have been synthesized hydrothermally using glutarate (Glu^2?) mixed with 1,4‐bis[(2‐methyl‐1H‐imidazol‐1‐yl)methyl]benzene (1,4‐mbix), and characterized by single‐crystal X‐ray diffraction, IR and UV–Vis spectroscopy, powder X‐ray diffraction, and thermogravimetric and photoluminescence analyses. Ni^II MOF ( I ) shows a 4‐connected 3D framework with point symbol 6⁶, but is not a typical dia network. Zn^II MOF ( II ) displays a two‐dimensional 4⁴‐ sql network with one‐dimensional water chains penetrating the grids along the c direction. The solid‐state photoluminescence analysis of ( II ) was performed at room temperature and the MOF exhibits highly selective sensing toward Fe³⁺ and Cr₂O₇^2? ions in aqueous solution.     

Syntheses and structures of two novel fluorescent metal–organic frameworks generated from a tridentate donor–acceptor motif ligand

The tridentate organic ligand 4,4′,4′′‐(4,4,8,8,12,12‐hexamethyl‐8,12‐dihydro‐4H‐benzo[9,1]quinolizino[3,4,5,6,7‐defg]acridine‐2,6,10‐triyl)tribenzoic acid ( H₃L ) has been synthesized (as the methanol 1.25‐solvate, C₄₈H₃₉NO₆·1.25CH₃OH). As a donor–acceptor motif molecule, H₃L possess strong intramolecular charge transfer (ICT) fluorescence. Through hydrogen bonds, H₃L molecules construct a two‐dimensional (2D) network, which pack together into three‐dimensional (3D) networks with an ABC stacking pattern in the crystalline state. Based on H₃L and M(NO₃)₂ salts (M = Cd and Zn) under solvothermal conditions, two metal–organic frameworks (MOFs), namely, catena‐poly[[triaquacadmium(II)]‐μ‐10‐(4‐carboxyphenyl)‐4,4′‐(4,4,8,8,12,12‐hexamethyl‐8,12‐dihydro‐4H‐benzo[9,1]quinolizino[3,4,5,6,7‐defg]acridine‐2,6‐diyl)dibenzoato], [Cd(C₄₈H₃₇NO₆)(H₂O)₃]_n, I , and poly[[μ₃‐4,4′,4′′‐(4,4,8,8,12,12‐hexamethyl‐8,12‐dihydro‐4H‐benzo[9,1]quinolizino[3,4,5,6,7‐defg]acridine‐2,6,10‐triyl)tribenzoato](μ₃‐hydroxido)zinc(II)], [Zn₂(C₄₈H₃₆NO₆)(OH)]_n, II , were synthesized. Single‐crystal analysis revealed that both MOFs adopt a 3D structure. In I , partly deprotonated HL ^2? behaves as a bidentate ligand to link a Cd^II ion to form a one‐dimensional chain. In the solid state of I , the existence of weak interactions, such as O—H…O hydrogen bonds and π–π interactions, plays an essential role in aligning 2D nets and 3D networks with AB packing patterns for I . The deprotonated ligand L ^3? in II is utilized as a tridentate building block to bind Zn^II ions to construct 3D networks, where unusual Zn₄O₁₄ clusters act as connection nodes. As a donor–acceptor molecule, H₃L exhibits fluorescence with a photoluminescence quantum yield (PLQY) of 70% in the solid state. In comparison, the PL of both MOFs is red‐shifted with even higher PLQYs of 79 and 85% for I and II , respectively.     

A EuIII‐MOF with Bis(2‐carboxyethyl)isocyanurate for Luminescence Sensing of Fe3+ and SCN– Ions

The water‐stable 3D lanthanide‐organic framework (Ln‐MOF) {[Eu(bci)(H₂O)] · 2H₂O}_n ( 1 ) [H₂bci = bis(2‐carboxyethyl)isocyanurate] was synthesized under hydrothermal conditions. Compound 1 ‐ Eu exhibits a 3D open‐framework connected by Eu–(μ‐O)₂–Eu chains and bci ligands. Meanwhile, 1 ‐ Eu exhibits highly efficient luminescent sensing for environmentally relevant Fe³⁺ and SCN^– ions through luminescence quenching. These results indicated that it could be utilized as a multi‐responsive luminescence sensor.     

A Terbium Metal–Organic Framework for Highly Selective and Sensitive Luminescence Sensing of Hg2+ Ions in Aqueous Solution

A series of isomorphic lanthanide metal–organic frameworks (MOFs) Ln(TATAB)?(DMF)₄(H₂O)(MeOH)_0.5 (LnTATAB, Ln=Eu, Tb, Sm, Dy, Gd; H₃TATAB=4,4′,4′′‐s‐triazine‐1,3,5‐triyltri‐p‐aminobenzoic acid) have been solvothermally synthesized and structurally characterized. Among these MOFs, TbTATAB exhibits good water stability and a high fluorescence quantum yield. Because mercury ions (Hg²⁺) have a high affinity to nitrogen atoms, and the space between multiple nitrogen atoms from triazine and imino groups is suitable for interacting with Hg²⁺ ions, TbTATAB shows highly selective and sensitive detection of Hg²⁺ in aqueous solution with a detection limit of 4.4 nm . Furthermore, it was successfully applied to detect Hg²⁺ ions in natural water samples.     

A ladder coordination polymer based on Ca2+ and (4,5‐dicyano‐1,2‐phenylene)bis(phosphonic acid): crystal structure and solution‐state NMR study

The preparation of coordination polymers (CPs) based on either transition metal centres or rare‐earth cations has grown considerably in recent decades. The different coordination chemistry of these metals allied to the use of a large variety of organic linkers has led to an amazing structural diversity. Most of these compounds are based on carboxylic acids or nitrogen‐containing ligands. More recently, a wide range of molecules containing phosphonic acid groups have been reported. For the particular case of Ca²⁺‐based CPs, some interesting functional materials have been reported. A novel one‐dimensional Ca²⁺‐based coordination polymer with a new organic linker, namely poly[[diaqua[μ₄‐(4,5‐dicyano‐1,2‐phenylene)bis(phosphonato)][μ₃‐(4,5‐dicyano‐1,2‐phenylene)bis(phosphonato)]dicalcium(II)] tetrahydrate], {[Ca₂(C₈H₄N₂O₆P₂)₂(H₂O)₂]·4H₂O}_n, has been prepared at ambient temperature. The crystal structure features one‐dimensional ladder‐like _∞¹[Ca₂(H₂cpp)₂(H₂O)₂] polymers [H₂cpp is (4,5‐dicyano‐1,2‐phenylene)bis(phosphonate)], which are created by two distinct coordination modes of the anionic H₂cpp²⁻ cyanophosphonate organic linkers: while one molecule is only bound to Ca²⁺ cations via the phosphonate groups, the other establishes an extra single connection via a cyano group. Ladders close pack with water molecules through an extensive network of strong and highly directional O—H…O and O—H…N hydrogen bonds; the observed donor–acceptor distances range from 2.499 (5) to 3.004 (6) Å and the interaction angles were found in the range 135–178°. One water molecule was found to be disordered over three distinct crystallographic positions. A detailed solution‐state NMR study of the organic linker is also provided.