The Highly Connected MOFs Constructed from Nonanuclear and Trinuclear Lanthanide-Carboxylate Clusters: Selective Gas Adsorption and Luminescent pH Sensing

The highly odd-numbered 15-connected nonanuclear [Ln₉(μ₃-O)₂­(μ₃-OH)₁₂­(O₂C−)₁₂­(HCO₂)₃] and 9-connected trinuclear [Ln₃(μ₃-O)­(O₂C−)₆­(HCO₂)₃] lanthanide-carboxylate clusters with triangular and linear carboxylate bridging ligands were synergistically combined into Ln-MOFs, [(CH₃)₂­NH₂]₃­{[Ln₉­(μ₃-O)₂­(μ₃-OH)₁₂­(H₂O)₆]­[Ln₃­(μ₃-O)­(H₂O)₃]­(HCO₂)₃­(BTB)₆}·(solvent)_<i>x</i> (abbreviated as <b>JXNU-3</b>, Ln = Gd, Tb, Er; BTB^3– = benzene-1,3,5-tris­(4-benzoate)), displaying a (3,9,15)-connected topological net. The <b>JXNU-3</b>(Tb) exhibits highly selective CO₂ adsorption capacity over CH₄ that resulted from the high localized charge density induced by the presence of the nonanuclear and trinuclear cluster units. In addition, <b>JXNU-3</b>(Tb) with high chemical stability and characteristic bright green color exhibits fluorescent pH sensing, which is pertinent to the different protonation levels of the carboxylate groups of the benzene-1,3,5-tris­(4-benzoate) ligand with varying pH

The Highly Connected MOFs Constructed from Nonanuclear and Trinuclear Lanthanide-Carboxylate Clusters: Selective Gas Adsorption and Luminescent pH Sensing

The highly odd-numbered 15-connected nonanuclear [Ln₉(μ₃-O)₂­(μ₃-OH)₁₂­(O₂C−)₁₂­(HCO₂)₃] and 9-connected trinuclear [Ln₃(μ₃-O)­(O₂C−)₆­(HCO₂)₃] lanthanide-carboxylate clusters with triangular and linear carboxylate bridging ligands were synergistically combined into Ln-MOFs, [(CH₃)₂­NH₂]₃­{[Ln₉­(μ₃-O)₂­(μ₃-OH)₁₂­(H₂O)₆]­[Ln₃­(μ₃-O)­(H₂O)₃]­(HCO₂)₃­(BTB)₆}·(solvent)_<i>x</i> (abbreviated as <b>JXNU-3</b>, Ln = Gd, Tb, Er; BTB^3– = benzene-1,3,5-tris­(4-benzoate)), displaying a (3,9,15)-connected topological net. The <b>JXNU-3</b>(Tb) exhibits highly selective CO₂ adsorption capacity over CH₄ that resulted from the high localized charge density induced by the presence of the nonanuclear and trinuclear cluster units. In addition, <b>JXNU-3</b>(Tb) with high chemical stability and characteristic bright green color exhibits fluorescent pH sensing, which is pertinent to the different protonation levels of the carboxylate groups of the benzene-1,3,5-tris­(4-benzoate) ligand with varying pH

Lanthanide-benzophenone-3,3′-disulfonyl-4,4′-dicarboxylate Frameworks: Temperature and 1‑Hydroxypyren Luminescence Sensing and Proton Conduction

The benzophenone-3,3′-disulfonyl-4,4′-dicarboxylic acid (H₄–BODSDC) ligand and compounds, {(H₃O)­[Ln­(BODSDC)­(H₂O)₂]}_<i>n</i> (Ln = Tb­(<b>1</b>), Eu­(<b>2</b>), and Gd­(<b>3</b>)), were synthesized and structurally characterized. The lanthanide centers are bridged by the carboxylate groups of BODSDC^4– ligands to give a one-dimensional (1D) chain. The 1D chains are connected by the BODSDC^4– ligands to yield a three-dimensional (3D) structure featuring 1D channels. The lanthanide ions are efficiently sensitized by the BODSDC^4– ligand with an appropriate triplet excited state to generate characteristic Tb­(III) and Eu­(III) emissions in Tb­(<b>1</b>) and Eu­(<b>2</b>), respectively. Thus the binary compound, {(H₃O)­[Tb_0.93Eu_0.07(BODSDC)­(H₂O)₂]}_<i>n</i> (abbreviated as Tb_0.93Eu_0.07-BODSDC), was achieved for use as a ratiometric temperature sensor. The ratio values of Tb­(III) emission at 544 nm (<i>I</i>_Tb) and Eu­(III) emission at 616 nm (<i>I</i>_Eu) for Tb_0.93Eu_0.07-BODSDC linearly vary with temperature over a wide range, which indicates that the Tb_0.93Eu_0.07-BODSDC is a thermometer for ratiometric fluorescence sensing of temperature. Additionally, Tb­(<b>1</b>) is a fluorescent probe for detecting 1-hydroxypyrene (1-HP) by luminescence quenching. The uncoordinated sulfonate oxygens exposed on the channel surfaces serve as the binding sites for 1-HP. Finally, the enrichment of the solvent water molecules in the channels decorated by high-density hydrophilic sulfonate groups resulted in a high proton conductivity for Tb­(<b>1</b>)

A Water-Stable Anionic Metal–Organic Framework Constructed from Columnar Zinc-Adeninate Units for Highly Selective Light Hydrocarbon Separation and Efficient Separation of Organic Dyes

A metal–organic framework (MOF), {(Me₂NH₂)₂[Zn₆(μ₄-O)­(ad)₄(BPDC)₄]}_<i>n</i> (<b>JXNU-4</b>; ad^– = adeninate), with an anionic three-dimensional (3D) framework constructed from one-dimensional (1D) columnar [Zn₆(ad)₄(μ₄-O)]_<i>n</i> secondary building units (SBUs) and 4,4′-biphenyldicarboxylate (BPDC^2–) ligand, was prepared. The anionic 3D framework has 1D square channels with an aperture of about 9.8 Å and exhibits a carboxylate-O-decorated pore environment. The microporous nature of <b>JXNU-4</b> was established by the N₂ adsorption data, which gives Langmuir and Brumauer–Emmett–Teller surface areas of 1800 and 1250 m² g^–1, respectively. Noticeably, <b>JXNU-4</b> shows potential as a separation agent for the selective removal of propane and ethane from natural gas with high selectivities of 144 for C₃H₈/CH₄ (5:95) and 14.6 for C₂H₆/CH₄ (5:95), respectively. Most importantly, <b>JXNU-4</b> shows an aqueous-phase adsorption of a positively charged ion of methylene blue selectively over a negatively charged ion of resorufin, which is pertinent to the anionic nature of the framework, and provides a size-exclusive sieving of methylene blue over other positively charged ions of Janus Green B and ethyl violet, which is relevant to its pore structure, enabling the efficient aqueous-phase separation of organic dyes

A Water-Stable Anionic Metal–Organic Framework Constructed from Columnar Zinc-Adeninate Units for Highly Selective Light Hydrocarbon Separation and Efficient Separation of Organic Dyes

A metal–organic framework (MOF), {(Me₂NH₂)₂[Zn₆(μ₄-O)­(ad)₄(BPDC)₄]}_<i>n</i> (<b>JXNU-4</b>; ad^– = adeninate), with an anionic three-dimensional (3D) framework constructed from one-dimensional (1D) columnar [Zn₆(ad)₄(μ₄-O)]_<i>n</i> secondary building units (SBUs) and 4,4′-biphenyldicarboxylate (BPDC^2–) ligand, was prepared. The anionic 3D framework has 1D square channels with an aperture of about 9.8 Å and exhibits a carboxylate-O-decorated pore environment. The microporous nature of <b>JXNU-4</b> was established by the N₂ adsorption data, which gives Langmuir and Brumauer–Emmett–Teller surface areas of 1800 and 1250 m² g^–1, respectively. Noticeably, <b>JXNU-4</b> shows potential as a separation agent for the selective removal of propane and ethane from natural gas with high selectivities of 144 for C₃H₈/CH₄ (5:95) and 14.6 for C₂H₆/CH₄ (5:95), respectively. Most importantly, <b>JXNU-4</b> shows an aqueous-phase adsorption of a positively charged ion of methylene blue selectively over a negatively charged ion of resorufin, which is pertinent to the anionic nature of the framework, and provides a size-exclusive sieving of methylene blue over other positively charged ions of Janus Green B and ethyl violet, which is relevant to its pore structure, enabling the efficient aqueous-phase separation of organic dyes

Two cadmium compounds with adenine and carboxylate ligands: syntheses, structures and photoluminescence

<p>Two cadmium(II) coordination compounds, [Cd₃(CH₃CO₂)₄(ad)₂(CH₃CN)₂]_n (<b>1</b>) and [Cd₃(5-SIP)₂(H-ad)₂(H₂O)₆]_n (<b>2</b>) (H-ad = adenine and 5-SIP = 5-sulfoisophthalate), were synthesized and characterized. Compound <b>1</b> features a two-dimensional (2-D) layered structure based on linear trinuclear [Cd₃(CH₃CO₂)₄] units bridged by monoanionic adenine ligands. In <b>2</b>, the 5-SIP³⁻ ligands link Cd(II) ions to form a one-dimensional (1-D) ladder, which is further linked by neutral adenine ligands to give a 2-D layered structure. In both structures, the carboxylate ligands link Cd(II) ions to form low-dimensional structures, which are further connected by adenine ligands to give high-dimensional structures. Compounds <b>1</b> and <b>2</b> exhibit emissions centered at 382 and 416 nm, respectively, which can be attributed to the ligand centered <i>π</i>–<i>π</i>* transition.</p

Two 2-dimensional cadmium(II) coordination polymers with 3-amino-5-methylthio-1,2,4-triazolate ligand

<p>Reactions of cadmium(II) salts with 3-amino-5-methylthio-1H-1,2,4-triazole (Hamstz) afforded two cadmium(II) coordination polymers, [Cd₂(amstz)₂Cl₂]_n (<b>1</b>) and [Cd₂(amstz)₂(NO₃)₂]_n (<b>2</b>). Compounds <b>1</b> and <b>2</b> feature 2-D layered structures based on the dinuclear [Cd₂(amstz)₂] subunits. The cadmium coordination polyhedra are tetrahedral and tetragonal pyramidal in <b>1</b> and <b>2</b>, respectively, due to the presence of different coordinated anions, Cl⁻ and NO₃⁻. Compounds <b>1</b> and <b>2</b> exhibit photoluminescence emission with maxima at 620 and 621 nm upon excitation at 470 and 472 nm, respectively, which can be attributed to the ligand-to-metal charge transfer emssion.</p

Two 2-dimensional cadmium(II) coordination polymers with 3-amino-5-methylthio-1,2,4-triazolate ligand

<p>Reactions of cadmium(II) salts with 3-amino-5-methylthio-1H-1,2,4-triazole (Hamstz) afforded two cadmium(II) coordination polymers, [Cd₂(amstz)₂Cl₂]_n (<b>1</b>) and [Cd₂(amstz)₂(NO₃)₂]_n (<b>2</b>). Compounds <b>1</b> and <b>2</b> feature 2-D layered structures based on the dinuclear [Cd₂(amstz)₂] subunits. The cadmium coordination polyhedra are tetrahedral and tetragonal pyramidal in <b>1</b> and <b>2</b>, respectively, due to the presence of different coordinated anions, Cl⁻ and NO₃⁻. Compounds <b>1</b> and <b>2</b> exhibit photoluminescence emission with maxima at 620 and 621 nm upon excitation at 470 and 472 nm, respectively, which can be attributed to the ligand-to-metal charge transfer emssion.</p

Enhancement of Propadiene/Propylene Separation Performance of Metal–Organic Frameworks by an Amine-Functionalized Strategy

Here, a hexanuclear Co6(μ3-OH)6 cluster-based metal–organic framework (MOF), [Co6(μ3-OH)6(BTB)2(bpy)3]n (JXNU-15) (bpy = 4,4′-bipyridine), with the 1,3,5-tri(4-carboxyphenyl)benzene (BTB3–) ligand was synthesized for the challenging propadiene/propylene separation. The combination of a large pore volume and a suitable pore environment boosts the significantly high propadiene (C3H4) uptake (311 cm3 g–1 at 298 K and 100 kPa) for JXNU-15. An amine-functionalized MOF of JXNU-15(NH2) was further obtained with the 1,3,5-tri(4-carboxyphenyl)benzene analogue of 3,3″-diamino-5′-(3-amino-4-carboxyphenyl)-[1,1′:3′,1″-terphenyl]-4,4″-dicarboxylic ligand. The comparative studies of propadiene/propylene(C3H4/C3H6) separation performance between isostructural JXNU-15 and JXNU-15(NH2) are provided. JXNU-15(NH2) exhibits an impressive C3H4 capacity at low pressures with 69.1 cm3 g–1 at 10 kPa, which is twice that of JXNU-15 under the same conditions. Moreover, the separation selectivity of JXNU-15(NH2) is 1.3-fold higher as compared to JXNU-15. JXNU-15(NH2) with enhanced C3H4/C3H6 separation performance was elegantly illustrated by gas separation experiments and theoretical simulations. This work presents an amine-functionalized strategy for the enhancement of the C3H4/C3H6 separation performance of MOF

Field-Induced Slow Magnetic Relaxation and Gas Adsorption Properties of a Bifunctional Cobalt(II) Compound

A new compound, {[Co­(bmzbc)₂]·2DMF}_<i>n</i> (<b>JXNU-1</b>, <b>JXNU</b> denotes Jiangxi Normal University), based on the 4-(benzimidazole-1-yl)­benzoate (bmzbc^–) ligand has been synthesized and structurally characterized. The Co­(II) ions are bridged by the rod-like bmzbc^– ligands to give a two-dimensional (2D) sheet wherein the Co­(II) ions are spatially separated from each other by the long bmzbc^– rods. The 2D sheets are further stacked into a 3D framework with 1D channels occluding the guest DMF molecules. Detailed magnetic studies show that the individual octahedral Co­(II) ions in <b>JXNU-1</b> exhibit field-induced slow magnetic relaxation, which is characteristic behavior of single-ion magnets (SIMs). The rarely observed positive value of zero-field splitting (ZFS) parameter <i>D</i> for the Co­(II) ion in <b>JXNU-1</b> demonstrates that <b>JXNU-1</b> is a unique example of Co­(II)-based SIMs with easy-plane anisotropy, which is also confirmed by the calculations. The microporous nature of <b>JXNU-1</b> was established by measuring CO₂ sorption isotherms. The abrupt changes observed in the C₃H₈ and C₂H₆ adsorption isotherms indicate that a structural transformation occurred in the gas-loading process. The long connection between the magnetic metal centers in <b>JXNU-1</b> meets the requirements for construction of porosity and SIM in a well-defined network, harmoniously providing a good candidate of functional molecular materials exhibiting SIM and porosity