Three New Isostructural Coordination Polymers with Cd(II) Clusters as the SBU: Synthesis, Structural Characterization, and Luminescence Properties

Three new isostructural coordination polymers, {Cd_1.33L(Cl)_0.67(H₂O)_0.67}_<i>n</i> (<b>1</b>), {Cd_1.33L(Br)_0.67(H₂O)_0.67}_<i>n</i> (<b>2</b>), and {Cd_1.33L(I)_0.67(H₂O)_0.67}_<i>n</i> (<b>3</b>), have been synthesized using a semiflexible <i>in situ</i> generated tetrazole ligand. All the complexes crystallize in cubic space group <i>P</i>4₁32. In complex <b>1</b>, three Cd²⁺ ions along with two N atoms each from three tetrazole units form a trinuclear unit where each metal ion is additionally bridged by carboxylate O and μ₃-Cl units. This Cd(II) cluster along with the ligand form a trigonal arrangement that extends to form a two-dimensional sheet that further undergoes extensive interpenetration to generate an overall three-dimensional coordination polymer. All complexes exhibit thermal stability up to ∼330 °C losing coordinated water molecules at ∼140 °C. Upon excitation at 340 nm, the complexes exhibit solid-state luminescence with an emission peak at ∼415 nm that shows slight red shift with broadening of the band with changing the halide anion from chloride to bromide to iodide

Three New Isostructural Coordination Polymers with Cd(II) Clusters as the SBU: Synthesis, Structural Characterization, and Luminescence Properties

Three new isostructural coordination polymers, {Cd_1.33L(Cl)_0.67(H₂O)_0.67}_<i>n</i> (<b>1</b>), {Cd_1.33L(Br)_0.67(H₂O)_0.67}_<i>n</i> (<b>2</b>), and {Cd_1.33L(I)_0.67(H₂O)_0.67}_<i>n</i> (<b>3</b>), have been synthesized using a semiflexible <i>in situ</i> generated tetrazole ligand. All the complexes crystallize in cubic space group <i>P</i>4₁32. In complex <b>1</b>, three Cd²⁺ ions along with two N atoms each from three tetrazole units form a trinuclear unit where each metal ion is additionally bridged by carboxylate O and μ₃-Cl units. This Cd(II) cluster along with the ligand form a trigonal arrangement that extends to form a two-dimensional sheet that further undergoes extensive interpenetration to generate an overall three-dimensional coordination polymer. All complexes exhibit thermal stability up to ∼330 °C losing coordinated water molecules at ∼140 °C. Upon excitation at 340 nm, the complexes exhibit solid-state luminescence with an emission peak at ∼415 nm that shows slight red shift with broadening of the band with changing the halide anion from chloride to bromide to iodide

Two-Dimensional Coordination Polymer with a Non-interpenetrated (4,4) Net Showing Anion Exchange and Structural Transformation in Single-Crystal-to-Single-Crystal Fashion

A new non-interpenetrated two-dimensional (2D) rectangular-grid coordination polymer, {[Co(L)2(H2O)2]·(BF4)2·4DMF}n (1), has been synthesized using a new rod-like ligand, 3,5-bis(4-imidazol-1-ylphenyl)-[1,2,4]triazol-4-ylamine (L). Weakly H-bonded BF4− anions present within the voids can be exchanged by ClO4− and NO3− anions to generate {[Co(L)2(H2O)2]·(ClO4)2·2DMF·2H2O}n (2) and {[Co(L)2(H2O)2]·(NO3)2·2DMF·2H2O}n (3) in single-crystal-to-single-crystal (SC-SC) manner. In the case of exchange by Cl− ion, the crystallinity is not maintained, and so it is proven by IR spectroscopy, PXRD, and elemental analysis. In addition, 3 shows an interesting structural transformation (2D → 1D) with bond rupture/formation leading to the formation of a new coordination polymer, {[Co(L)2(H2O)2]·(NO3)2·2DMF·H2O}n, (5), again in SC-SC fashion

Two-Dimensional Coordination Polymer with a Non-interpenetrated (4,4) Net Showing Anion Exchange and Structural Transformation in Single-Crystal-to-Single-Crystal Fashion

A new non-interpenetrated two-dimensional (2D) rectangular-grid coordination polymer, {[Co(L)2(H2O)2]·(BF4)2·4DMF}n (1), has been synthesized using a new rod-like ligand, 3,5-bis(4-imidazol-1-ylphenyl)-[1,2,4]triazol-4-ylamine (L). Weakly H-bonded BF4− anions present within the voids can be exchanged by ClO4− and NO3− anions to generate {[Co(L)2(H2O)2]·(ClO4)2·2DMF·2H2O}n (2) and {[Co(L)2(H2O)2]·(NO3)2·2DMF·2H2O}n (3) in single-crystal-to-single-crystal (SC-SC) manner. In the case of exchange by Cl− ion, the crystallinity is not maintained, and so it is proven by IR spectroscopy, PXRD, and elemental analysis. In addition, 3 shows an interesting structural transformation (2D → 1D) with bond rupture/formation leading to the formation of a new coordination polymer, {[Co(L)2(H2O)2]·(NO3)2·2DMF·H2O}n, (5), again in SC-SC fashion

Co(II) Coordination Polymers with Co-Ligand Dependent Dinuclear to Tetranuclear Core: Spin-Canting, Weak Ferromagnetic, and Antiferromagnetic Behavior

Four new Co­(II) containing coordination polymers have been synthesized using an ether bridged tricarboxylic acid ligand, <i>o<b>-</b></i>cpiaH_<b>3</b> (5-(2-carboxy-phenoxy)-isophthalic acid). This ligand readily reacts with CoCl₂·6H₂O in the presence of different nitrogen donor ligands such as 1,10-phenanthroline (phen), 4,4′-bipyridyl (bpy), 4,4′-azopyridine (apy), and 1,4-bis­(4-pyridinylmethyl)­piperazine (bpmp) under hydrothermal conditions to afford three 3D and one 2D coordination polymers, {Co₃(<i>o<b>-</b></i>cpia)_<b>2</b>(phen)­(H₂O)·5H₂O}_<i>n</i><b> </b>(<b>1</b>), {Co_1.5(<i>o<b>-</b></i>cpia)­(bpy)}_<i>n</i> (<b>2</b>),<b> </b>{Co_<b>2</b>(<i>o-</i>cpia)­(OH)­(apy)_0.5}_<i>n</i> (<b>3</b>), and {Co­(<i>o</i><i><b>-</b></i>cpiaH)­(bpmp)_0<b>.</b>5<b>}</b>_<i>n</i> (<b>4</b>). Single crystal X-ray studies show that these coordination polymers contain homometallic clusters varying from dimeric to tetrameric depending upon the co-ligand used. In complexes <b>1</b> and <b>2</b>, Co­(II) ions form an angular and linear trimeric unit that extends along all directions to generate an overall 3D structure. In contrast, <b>3</b> forms a 3D coordination polymer containing a tetranuclear Co­(II) unit. When the distance between the two donor N atoms of the co-ligand is further increased as in <b>4</b>, a (4,4) net connected 2D coordination polymer results where the Co­(II) ions form a dimeric paddle wheel unit. In addition to single-crystal X-ray crystallography, the complexes are also characterized by IR spectroscopy, thermogravimetry, and elemental analysis. Variable temperature magnetic susceptibility measurements on the complexes were carried out over the temperature range 1.72–300 K. Complex <b>1</b> exhibits ferromagnetic interactions due to uncompensated magnetic moments of the system leading to spin-canted antiferromagnetic behavior, while <b>2</b> and <b>3</b> show predominantly antiferromagnetic interactions. Complex <b>4</b> exhibits weak ferromagnetic behavior below 9 K

Reversible Single-Crystal to Single-Crystal Exchange of Guests in a Seven-Fold Interpenetrated Diamondoid Coordination Polymer

A three-dimensional polymer, {[Zn(pyeb)2](DMF)(H2O)}n (1) (DMF = N,N′-dimethylformamide), has been synthesized using solvothermal reaction of Zn(NO3)2·6H2O with a linear ligand bis{4-[2-(4-pyridyl)ethenyl] benzoic acid (pyebH). It has a 7-fold interpenetrating three-dimensional (3D) diamondoid structure (dia) having 66 uninodal net with triangular channels that are filled with DMF and water as guest molecules. When a crystal of 1 is kept in acetone at RT for 12 h, all guest molecules are replaced by acetone molecules to afford the daughter product, {[Zn(pyeb)2](acetone)}n (2) in a single-crystal to single-crystal (SC-SC) transformation. When this crystal 2 is kept in acetonitrile for 12 h, a new product, {[Zn(pyeb)2](MeCN)}n (3) is formed again without losing crystallinity. Interestingly, when either 2 or 3 is kept in dry DMF for 12 h, a new compound, {[Zn(pyeb)2](DMF)}n (4) is formed. Compound 1 can be regenerated by keeping 2, 3, or 4 in aqueous DMF for 12 h at RT. All these transformations are achieved in SC-SC fashion. The compounds are characterized by X-ray crystallography, thermogravimetery, and infrared spectroscopy

Reversible Single-Crystal to Single-Crystal Exchange of Guests in a Seven-Fold Interpenetrated Diamondoid Coordination Polymer

A three-dimensional polymer, {[Zn(pyeb)2](DMF)(H2O)}n (1) (DMF = N,N′-dimethylformamide), has been synthesized using solvothermal reaction of Zn(NO3)2·6H2O with a linear ligand bis{4-[2-(4-pyridyl)ethenyl] benzoic acid (pyebH). It has a 7-fold interpenetrating three-dimensional (3D) diamondoid structure (dia) having 66 uninodal net with triangular channels that are filled with DMF and water as guest molecules. When a crystal of 1 is kept in acetone at RT for 12 h, all guest molecules are replaced by acetone molecules to afford the daughter product, {[Zn(pyeb)2](acetone)}n (2) in a single-crystal to single-crystal (SC-SC) transformation. When this crystal 2 is kept in acetonitrile for 12 h, a new product, {[Zn(pyeb)2](MeCN)}n (3) is formed again without losing crystallinity. Interestingly, when either 2 or 3 is kept in dry DMF for 12 h, a new compound, {[Zn(pyeb)2](DMF)}n (4) is formed. Compound 1 can be regenerated by keeping 2, 3, or 4 in aqueous DMF for 12 h at RT. All these transformations are achieved in SC-SC fashion. The compounds are characterized by X-ray crystallography, thermogravimetery, and infrared spectroscopy

Co(II) Coordination Polymers with Co-Ligand Dependent Dinuclear to Tetranuclear Core: Spin-Canting, Weak Ferromagnetic, and Antiferromagnetic Behavior

Four new Co­(II) containing coordination polymers have been synthesized using an ether bridged tricarboxylic acid ligand, <i>o<b>-</b></i>cpiaH_<b>3</b> (5-(2-carboxy-phenoxy)-isophthalic acid). This ligand readily reacts with CoCl₂·6H₂O in the presence of different nitrogen donor ligands such as 1,10-phenanthroline (phen), 4,4′-bipyridyl (bpy), 4,4′-azopyridine (apy), and 1,4-bis­(4-pyridinylmethyl)­piperazine (bpmp) under hydrothermal conditions to afford three 3D and one 2D coordination polymers, {Co₃(<i>o<b>-</b></i>cpia)_<b>2</b>(phen)­(H₂O)·5H₂O}_<i>n</i><b> </b>(<b>1</b>), {Co_1.5(<i>o<b>-</b></i>cpia)­(bpy)}_<i>n</i> (<b>2</b>),<b> </b>{Co_<b>2</b>(<i>o-</i>cpia)­(OH)­(apy)_0.5}_<i>n</i> (<b>3</b>), and {Co­(<i>o</i><i><b>-</b></i>cpiaH)­(bpmp)_0<b>.</b>5<b>}</b>_<i>n</i> (<b>4</b>). Single crystal X-ray studies show that these coordination polymers contain homometallic clusters varying from dimeric to tetrameric depending upon the co-ligand used. In complexes <b>1</b> and <b>2</b>, Co­(II) ions form an angular and linear trimeric unit that extends along all directions to generate an overall 3D structure. In contrast, <b>3</b> forms a 3D coordination polymer containing a tetranuclear Co­(II) unit. When the distance between the two donor N atoms of the co-ligand is further increased as in <b>4</b>, a (4,4) net connected 2D coordination polymer results where the Co­(II) ions form a dimeric paddle wheel unit. In addition to single-crystal X-ray crystallography, the complexes are also characterized by IR spectroscopy, thermogravimetry, and elemental analysis. Variable temperature magnetic susceptibility measurements on the complexes were carried out over the temperature range 1.72–300 K. Complex <b>1</b> exhibits ferromagnetic interactions due to uncompensated magnetic moments of the system leading to spin-canted antiferromagnetic behavior, while <b>2</b> and <b>3</b> show predominantly antiferromagnetic interactions. Complex <b>4</b> exhibits weak ferromagnetic behavior below 9 K

Significance of an Environmental Gas Cell to Obtain a Fully Dehydrated Form and CO₂‑Pressurized Structure of a Metal–Organic Framework Using In Situ Single-Crystal X‑ray Diffraction at 298 K

The single-crystal X-ray diffraction method was employed to characterize a rigid hydrated metal–organic framework (MOF), [Co2(MA)­(INA)·2H2O]n, that displays an affinity toward water molecules under ambient conditions after dehydration. The fully dehydrated form was obtained using an environmental gas cell technique in a stepwise manner followed by its CO2-pressurized structure at 298 K using in situ crystallography

Synthesis, Structure, and Magnetic Properties of Cobalt(II) Coordination Polymers from a New Tripodal Carboxylate Ligand: Weak Ferromagnetism and Metamagnetism

A new tripodal carboxylic ligand, 5-(4-carboxy-phenoxy)-isophthalic acid, readily (cpiaH3) reacts with Co(II) salts in the presence of pyridine-based coligands under solvothermal conditions to afford four different coordination polymers, {Co2(cpia)(OH)(bipy)0.5}n (1), {[Co2(cpia)(OH)(H2O)2]·H2O}n (2), {Co1.5(cpia)(bipyethane)}n (3), and {Co1.5(cpia)(pyridine)2}n (4). All these coordination polymers have been characterized by single crystal X-ray diffraction, IR spectroscopy, thermogravimetry and elemental analysis. The structures of 1 and 2 can be described as a repetition of a tetranuclear core with subtle differences  two tetranuclear cores are shared by an O atom in 2, while no such bridging is present in 1. The structures of 3 and 4, on the other hand, consist of a trinuclear core extending to three-dimensional networks. Variable temperature magnetic susceptibility measurements indicate that 1 exhibits ferromagnetic behavior below 13 K, while 2 shows metamagnetic behavior. These interesting magnetic features are associated with the mixed hydroxyl/carboxylate-bridged polynuclear Co(II) clusters as subunits