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

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

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

Metal–Organic Frameworks Possessing Suitable Pores for Xe/Kr Separation

Adsorption separation of the Xe/Kr mixture remains a tough issue since Xe and Kr have an inert nature and similar sizes. Here we present a chlorinated metal–organic framework (MOF) [JXNU-19(Cl)] and its nonchlorinated analogue (JXNU-19) for Xe/Kr separation. The two isostructural MOFs constructed from the heptanuclear cobalt-hydroxyl clusters bridged by organic ligands are three-dimensional structures. Detailed contrast of the Xe/Kr adsorption separation properties of the MOF shows that significantly enhanced Xe uptakes and Xe/Kr adsorption selectivity (17.1) are observed for JXNU-19 as compared to JXNU-19(Cl). The main binding sites for Xe in the MOF revealed by computational simulations are far away from the chlorine sites, suggesting that the introduction of the chlorine groups results in the unfavorable Xe adsorption for JXNU-19(Cl). The optimal pores, high surface area, and multiple strong Xe–framework interactions facilitate the effective Xe/Kr separation for JXNU-19