Crystal Structures and Spectroscopic Properties of Metal–Organic Frameworks Based on Rigid Ligands with Flexible Functional Groups

Two rigid linear ligands with alkoxy functional groups (L1 = 4,4′-(2,5-dimethoxy-1,4-phenylene) dipyridine; L2 = 4,4′-(2,5-diethoxy-1,4-phenylene) dipyridine) incorporating carboxyl-containing auxiliary ligands (isophthalic acid = H₂IPA; terephthalic acid = H₂TPA; biphenyl-4,4′-dicarboxylate = H₂BPDC) have been adopted to build a series of complexes with M­(II) (M = Zn, Co, Cd) under solvothermal conditions. The formula of these complexes are {[Zn­(L1)­(IPA)]}_<i>n</i> (<b>1</b>), {[Zn­(L1)­(TPA)]·DMF}_<i>n</i> (<b>2</b>), {[Co­(L1)­(TPA)­(H₂O)₂]·2DMF}_<i>n</i> (<b>3</b>), {[Cd­(L1)­(TPA)­(H₂O)₂]·2DMF}_<i>n</i> (<b>4</b>), and {[Co­(L2)­(BPDC)]·0.5H₂O}_<i>n</i> (<b>5</b>). Five complexes have been characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction and thermogravimetry measurements. Topological analyses reveal that complex <b>2</b> is a 6-connected <b>pcu</b> net with point symbol {4¹²·6³}, while complex <b>5</b> is a 6-connected <b>rob</b> net with point symbol {4⁸·6⁸·8}, the other complexes <b>1</b>, <b>3</b>, and <b>4</b> can be simplified as 4-connected <b>sql</b> nets with point symbol {4⁴.6²}. Complexes <b>1</b>, <b>3</b>, and <b>4</b> are 2D layer motifs, <b>2</b> and <b>5</b> are both 2-fold interpenetrating 3D frameworks. The optical absorption spectra of <b>3</b> and <b>5</b> indicate the nature of semiconductivity. The strong fluorescence emissions and long emission lifetimes of <b>1</b>, <b>2</b>, and <b>4</b> display that they are promising phosphorescent materials

Syntheses, Structures, and Properties of Four Metal–Organic Frameworks Based on a N‑Centered Multidentate Pyridine-Carboxylate Bifunctional Ligand

Four new metal–organic frameworks have been synthesized under hydrothermal conditions by the self-assembly of a N-centered multidentate bifunctional ligand (H₂L: 4,4′-((4-(pyridin-4-yl)­phenyl)­azanediyl)­dibenzoic acid) with different N-containing heterocyclic coligands (BIMB = 4,4′-bis­((imidazol-1-yl)­methyl)­biphenyl, BPY = 4,4′-bipyridine, BIP = 1,4-bis­(imidazol-1-yl)­phenyl) and transition metal salts (Co­(NO₃)₂·6H₂O, Zn­(NO₃)₂·6H₂O). They are [Co­(L)­(BIMB)_0.5­(H₂O)]·2DMF (<b>1</b>), [Co­(L)­(BPY)_0.5­(H₂O)₂]­·3DMF­·2H₂O (<b>2</b>), [Zn₂(L)₂]­·4DMF­·3H₂O (<b>3</b>), and [Zn₂(L)₂(BIP)]­·2DMF­·2H₂O (<b>4</b>). Compound <b>1</b> is an infrequent 3,4-connected self-penetration three-dimensional (3D) architecture. Compound <b>2</b> has been classified as a trinodal (3,4,4)-connected 3D <b>sqc69</b> framework. Compound <b>3</b> displays a 2-fold interpenetrating 3D net based on the [Zn₂(CO₂)₄] units which are connected by L^2– ligands. For compound <b>4</b>, the larger potential voids lead to a 4-fold interpenetration, which can be classified as type <b>IIIa</b>. In addition, their thermal stability, the adsorption isotherms, and optical properties have been studied in detail

Crystal Structures and Spectroscopic Properties of Metal–Organic Frameworks Based on Rigid Ligands with Flexible Functional Groups

Two rigid linear ligands with alkoxy functional groups (L1 = 4,4′-(2,5-dimethoxy-1,4-phenylene) dipyridine; L2 = 4,4′-(2,5-diethoxy-1,4-phenylene) dipyridine) incorporating carboxyl-containing auxiliary ligands (isophthalic acid = H₂IPA; terephthalic acid = H₂TPA; biphenyl-4,4′-dicarboxylate = H₂BPDC) have been adopted to build a series of complexes with M­(II) (M = Zn, Co, Cd) under solvothermal conditions. The formula of these complexes are {[Zn­(L1)­(IPA)]}_<i>n</i> (<b>1</b>), {[Zn­(L1)­(TPA)]·DMF}_<i>n</i> (<b>2</b>), {[Co­(L1)­(TPA)­(H₂O)₂]·2DMF}_<i>n</i> (<b>3</b>), {[Cd­(L1)­(TPA)­(H₂O)₂]·2DMF}_<i>n</i> (<b>4</b>), and {[Co­(L2)­(BPDC)]·0.5H₂O}_<i>n</i> (<b>5</b>). Five complexes have been characterized by elemental analysis, infrared spectroscopy, powder X-ray diffraction and thermogravimetry measurements. Topological analyses reveal that complex <b>2</b> is a 6-connected <b>pcu</b> net with point symbol {4¹²·6³}, while complex <b>5</b> is a 6-connected <b>rob</b> net with point symbol {4⁸·6⁸·8}, the other complexes <b>1</b>, <b>3</b>, and <b>4</b> can be simplified as 4-connected <b>sql</b> nets with point symbol {4⁴.6²}. Complexes <b>1</b>, <b>3</b>, and <b>4</b> are 2D layer motifs, <b>2</b> and <b>5</b> are both 2-fold interpenetrating 3D frameworks. The optical absorption spectra of <b>3</b> and <b>5</b> indicate the nature of semiconductivity. The strong fluorescence emissions and long emission lifetimes of <b>1</b>, <b>2</b>, and <b>4</b> display that they are promising phosphorescent materials

Syntheses, Structures, Photochemical and Magnetic Properties of Novel Divalent Cd/Mn Coordination Polymers Based on a Semirigid Tripodal Carboxylate Ligand

The reactions of a semirigid tripodal carboxylic ligand, 3,5-bi­(4-carboxy-phenoxy)-benzoic acid (H₃BCPBA) with Cd­(NO₃)₂/Mn­(NO₃)₂ afford five novel complexes, {[Cd₃(BCPBA)₂·(DMA)₂­·(H₂O)₅]·7H₂O·2DMA}_<i>n</i> (<b>1</b>), {[Cd₃(BCPBA)₂(L¹)­(H₂O)₆]·(L¹)}_<i>n</i> (L¹ = 4-[(E)-4-pyridinylazo]­pyridine) (<b>2</b>), {[Cd₃(BCPBA)₂(L²)­·(H₂O)₃(DMF)₂]·2DMF}_<i>n</i> (L² = 1,3-bis­(4-pyridyl)­propane) (<b>3</b>), {[Mn₃(BCPBA)₂(H₂O)₄]·11H₂O}_<i>n</i> (<b>4</b>), {[Mn₃(BCPBA)₂(DMF)₂(H₂O)₂]­·2DMF·9H₂O}_<i>n</i> (<b>5</b>) in the presence or absence of an auxiliary ligand. Compound <b>1</b> is a three-dimensional (3D) structure with 3,4-connected net structure. Compound <b>2</b> possesses 3D networks with two 3D → 3D interpenetration frameworks. Compound <b>3</b> is a 3D sheet structure with a decorated tfz-d topology. Compound <b>4</b> is a 3D structure which consists of a two-dimensional (2D) Mn honeycomb net with six infinite Mn rings and BCPBA^3– ligands. Compound <b>5</b> is also a 3D structure, while its 2D Mn honeycomb net with eight infinite Mn rings is different from that of compound <b>4</b>. The photochemical property of <b>1</b>–<b>3</b> is performed in the solid state at room temperature. Magnetic susceptibility measurements indicate that compounds <b>4</b> and <b>5</b> exhibit antiferromagnetic coupling between adjacent Mn­(II) ions

Syntheses, Structures, Photochemical and Magnetic Properties of Novel Divalent Cd/Mn Coordination Polymers Based on a Semirigid Tripodal Carboxylate Ligand

The reactions of a semirigid tripodal carboxylic ligand, 3,5-bi­(4-carboxy-phenoxy)-benzoic acid (H₃BCPBA) with Cd­(NO₃)₂/Mn­(NO₃)₂ afford five novel complexes, {[Cd₃(BCPBA)₂·(DMA)₂­·(H₂O)₅]·7H₂O·2DMA}_<i>n</i> (<b>1</b>), {[Cd₃(BCPBA)₂(L¹)­(H₂O)₆]·(L¹)}_<i>n</i> (L¹ = 4-[(E)-4-pyridinylazo]­pyridine) (<b>2</b>), {[Cd₃(BCPBA)₂(L²)­·(H₂O)₃(DMF)₂]·2DMF}_<i>n</i> (L² = 1,3-bis­(4-pyridyl)­propane) (<b>3</b>), {[Mn₃(BCPBA)₂(H₂O)₄]·11H₂O}_<i>n</i> (<b>4</b>), {[Mn₃(BCPBA)₂(DMF)₂(H₂O)₂]­·2DMF·9H₂O}_<i>n</i> (<b>5</b>) in the presence or absence of an auxiliary ligand. Compound <b>1</b> is a three-dimensional (3D) structure with 3,4-connected net structure. Compound <b>2</b> possesses 3D networks with two 3D → 3D interpenetration frameworks. Compound <b>3</b> is a 3D sheet structure with a decorated tfz-d topology. Compound <b>4</b> is a 3D structure which consists of a two-dimensional (2D) Mn honeycomb net with six infinite Mn rings and BCPBA^3– ligands. Compound <b>5</b> is also a 3D structure, while its 2D Mn honeycomb net with eight infinite Mn rings is different from that of compound <b>4</b>. The photochemical property of <b>1</b>–<b>3</b> is performed in the solid state at room temperature. Magnetic susceptibility measurements indicate that compounds <b>4</b> and <b>5</b> exhibit antiferromagnetic coupling between adjacent Mn­(II) ions

Two Lanthanide Metal–Organic Frameworks as Remarkably Selective and Sensitive Bifunctional Luminescence Sensor for Metal Ions and Small Organic Molecules

Two lanthanide metal–organic frameworks (Ln-MOFs) with similar structures have been synthesized through objective synthesis. The two compounds are both 2-fold interpenetrating 3D frameworks. Topological analyses reveal that complexes <b>1</b> and <b>2</b> are 6-connected <i>pcu</i> net. In addition, both structures were embedded in uncoordinated nitrogen atoms. As the uncoordinated pyridine groups can be used as functional groups, we tested their sensing ability toward metal ions and small organic molecules. To our delight, fluorescence measurements show the two complexes can selectively and sensitively detect for Fe³⁺ ion and nitromethane, which suggests that the two Ln-MOFs are promising bifunctional luminescence sensor materials with sensing metal ions and small organic molecules

Three 2D/2D → 2D or 3D Coordination Polymers: Parallel Stacked, Interpenetration, and Polycatenated

Three fascinating coordination polymers, {[Zn₂(TPPBDA)­(HCO₂^–)₄]·2H₂O}_<i>n</i> (<b>1</b>), {[Zn­(TPPBDA)_1/2(4,4′-sdb)]·2H₂O }_<i>n</i> (<b>2</b>), and {[Zn­(TPPBDA)_1/2(oba)·2DMF·2H₂O]}_<i>n</i> (<b>3</b>), have been successfully synthesized and characterized by the self-assembly of the TPPDBA ligand as well as Zn²⁺ metal salts, or in the presence of carboxylate ligands (TPPDBA = <i>N</i>,<i>N</i>,<i>N</i>′,<i>N</i>′-tetrakis­(4-(4-pyridine)-phenyl) biphenyl-4,4′-diamine), 4,4′-H₂sdb = 4,4′-sulfonyldibenzoate, 4,4′-H₂oba = 4,4′-oxybis­(benzoate), DMF = <i>N</i>,<i>N</i>-dimethylformamide). In complex <b>1</b>, the 2D ABAB parallel stacked network in which left- and right-handed helical chains coexist and array alternately (2D_chiral/2D_chiral → 2D_achiral) makes <b>1</b> give rise to a new interesting 2D interwoven network. Complex <b>2</b> exhibits a 2D + 2D → 2D parallel interpenetrated network. For compound <b>3</b>, the polycatenation among the 2D layer further extends the 2D net into a 3D framework

Construction of Metal–Organic Frameworks Based on Two Neutral Tetradentate Ligands

The solvothermal reaction of two new neutral tetradentate ligands with different bivalent metal salts gave seven metal–organic frameworks (MOFs): [Co₂(L1) (<i>trans</i>-chdc)₂]·5H₂O (<b>1</b>), [Zn₂(L1)­(<i>trans</i>-chdc)­(NO₂)₂]·DMF (<b>2</b>), [Cd₂(L1)­(<i>trans</i>-chdc)₂]·4H₂O (<b>3</b>), [Zn₂(L1)­(1,4-bdc)₂]·(H₂O)₃ (<b>4</b>), [Cd₂(L1)­(1,4-bdc)₂]·DMF·(solvent)_<i>x</i> (<b>5</b>), [Co­(L2) (<i>trans</i>-chdc)­(H₂O)]·1.5H₂O (<b>6</b>), [Co­(L2) (1,4-bdc) (H₂O)] · 2H₂O (<b>7</b>), (L1 = 1,1′-oxybis­[3,5-diimidazole]-benzene, L2 = 1,1′-oxybis­[3,5-dipyridine]-benzene, <i>trans</i>-chdc = <i>trans</i>-1,4-cyclohexanedicarboxylic acid, 1,4-bdc = 1,4-benzenedicarboxylate). These MOFs were prepared to examine the effects of the core metal ion or organic ligand on the topology and interpenetration form. The results show that the imidazole ligand can rotate easily to coordinate to metal ions, while pyridine ligand exhibits the weaker coordinative abilities, which may influence the self-assembly. Compounds <b>1</b>, <b>3</b>, and <b>5</b> are three-dimensional (3D) frameworks with 2-fold interpenetrated forms, whereas complex <b>4</b> shows a 3-fold interpenetrated structure. Interestingly, compound <b>2</b> exhibits a 4-fold interpenetration. Compound <b>6</b> features a two-dimensional polymeric layer structure which exhibits a rare 2-fold interpenetrating 3D <b>hms</b> array if H-bonds are taken into account. For compound <b>7</b>, the dinuclear cobalt secondary building unit (SBU) assembles with mixed ligands L2 and 1,4-bdc to construct a 3D α-<b>Po</b> structure

Two New Luminescent Cd(II)-Metal–Organic Frameworks as Bifunctional Chemosensors for Detection of Cations Fe³⁺, Anions CrO₄^2–, and Cr₂O₇^2– in Aqueous Solution

Two new luminescent Cd­(II)-metal–organic frameworks (MOFs), {[Cd­(L)­(BPDC)]­·2H₂O}_<i>n</i> (<b>1</b>) and {[Cd­(L)­(SDBA)­(H₂O)]­·0.5H₂O}_<i>n</i> (<b>2</b>) [L = 4,4′-(2,5-bis­(methylthio)-1,4-phenylene)­dipyridine, H₂BPDC = 4,4′-biphenyldicarboxylic acid, H₂SDBA = 4,4′-sulfonyldibenzoic acid], have been solvothermally synthesized using Cd²⁺ ion and <b>L</b> ligand in the presence of auxiliary ligands and characterized by infrared spectroscopy, elemental analysis, powder X-ray diffraction, and thermogravimetry measurement. Topological analyses reveal that MOF <b>1</b> is a 6-connected 3-fold interpenetrating <b>pcu</b> network, and MOF <b>2</b> is a new 4-connected 2-fold interpenetrating network. Fluorescence titration, cyclic and anti-interference experiments demonstrate that MOFs <b>1</b> and <b>2</b> both are excellent probes for Fe³⁺, CrO₄^2–, and Cr₂O₇^2–. The mechanisms of quenching are also deeply studied