1D, 2D, and 2D Parallel Interpenetrated Dicarboxylato Bridged Co(II) Metal Organic Frameworks: Synthesis, Crystal Structure, Fluorescence Sensing and Band Gap Calculation

A Multifunctional 3D Supermolecular Co Coordination Polymer With Potential for CO2 Adsorption, Antibacterial Activity, and Selective Sensing of Fe3+/Cr3+ Ions and TNP

A 3D supermolecular structure [Co₃(L)₂ (2,2′-bipy)₂](DMF)₃(H₂O)₃ 1) (H₃L = 4,4′,4″-nitrilotribenzoic acid) has been constructed based on H₃L, and 2,2′-bipy ligands under solvothermal conditions. Compound 1 can be described as a (3, 6)-connected kgd topology with a Schläfli symbol (4³)₂(4⁶.6⁶.8³) formed by [Co₃(CO₂)₆] secondary building units. The adsorption properties of the activated sample 1a has been studied; the result shows that 1a has a high adsorption ability: the CO₂ uptakes were 74 cm³·g⁻¹ at 273 K, 50 cm³·g⁻¹ at 298 K, the isosteric heat of adsorption (Q_st) is 25.5 kJ mol⁻¹ at zero loading, and the N₂ adsorption at 77 K, 1 bar is 307 cm³ g⁻¹. Magnetic measurements showed the existence of an antiferromagnetic exchange interaction in compound 1, besides compound 1 exhibits effective luminescent performance for Fe³⁺/Cr³⁺ and TNP.

Field-induced slow magnetic relaxation in mixed valence di- and tri-nuclear CoII-CoIII complexes

Two novel mixed valence Co^II-Co^III complexes, namely [Co^IICo^III(L1)(ab)(mb)₂(H₂O)]·dmf (1) and [CoCo^II(L2)₄(H₂O)₄]·2H₂O (2) [H₂L1 = (E)-2-((1-hydroxybutan-2-ylimino)methyl)-6-methoxyphenol, ab = 2-amino-butan-1-ol anion, mb = p-methyl benzoate, H₂L2 = 3-((2-hydroxy-3-methoxy-benzylidene)-amino)-propionic acid, and dmf = N,N-dimethyl-formamide], were synthesized and characterized by single crystal X-ray diffraction and magnetic studies at low temperature. The structure determination reveals that both complexes belong to the monoclinic system with P21/c (1) and I2/a (2) space groups. Complex 1 is a dinuclear Co^IIICo^II compound with distorted octahedral cobalt centers showing different coordination environments. In 2, a bent trinuclear CoCo^II complex, the coordination environments around the two terminal Co^III sites are alike, whereas they are different in the central Co^II ion. Alternating current/direct current (ac/dc) magnetic studies revealed that both complexes show field-induced slow magnetic relaxation. The dc magnetic susceptibility and magnetization data were analyzed with the following Hamiltonianwhere D and E are the axial and rhombic zero-field splitting (zfs) parameters, respectively, and a good agreement between experimental and simulated results was found using the parameters g_⊥ = 2.585, g_∥ = 2.437, D = +98.1 cm^-1, E/D = 0.008 and F = 8.2× 10^-5 for 1 and g_⊥ = 2.580, g_∥ = 2.580, D = +55.4 cm^-1, and E/D = 0.000 for 2.

Sensing organic analytes by metal–organic frameworks: a new way of considering the topic

In this review, our goal is comparison of advantageous and disadvantageous of MOFs about signal-transduction in different instrumental methods for detection of different categories of organic analytes.

Band gap, sorption properties and fluorescence sensing behaviour of a novel 1D→2D cathenane-like cobalt(II)–organic framework

A novel hydrolytic stable CoII–organic framework, namely poly[[bis(2-amino-4-sulfonatobenzoato-κO 1)tetraaquatris{μ-1,4-bis[(imidazol-1-yl)methyl]benzene-κ2 N 3:N 3′}dicobalt(II)] tetrahydrate], {[Co(C7H5NO5S)(C14H14N4)1.5(H2O)2]·2H2O} n , (1), based on multifunctional 2-amino-5-sulfobenzoic acid (H2asba) and the auxiliary flexible ligand 1,4-bis[(imidazol-1-yl)methyl]benzene (bix), was prepared using the solution evaporation method. The purity of (1) was confirmed by elemental analysis and powder X-ray diffraction (PXRD) analysis. Complex (1) shows a novel 1D→2D interpenetrating network, which is further extended into a 3D supramolecular framework with channels occupied by the lattice water molecules. The 2-amino-4-sulfonatobenzoate (asba2−) ligand adopts a monodentate coordination mode. The bix ligands exhibit gauche–gauche (GG) and trans–trans (TT) conformations. A detailed analysis of the solid-state diffuse-reflectance UV–Vis spectrum reveals that an indirect band gap exists in the complex. The band structure, the total density of states (TDOS) and the partial density of states (PDOS) were calculated using the CASTEP program. The calculated band gap (E g) matches well with the experimental one. The complex exhibits a reversible dehydration–rehydration behaviour. Interestingly, gas sorption experiments demonstrate that the new fully anhydrous compound obtained by activating complex (1) at 400 K shows selective adsorption of CO2 over N2. Complex (1) retains excellent framework stability in a variety of solvents and manifests distinct solvent-dependent fluorescence properties. Moreover, the complex shows multiresponsive fluorescence sensing for some nitroaromatics in aqueous medium.

Synthesis and characterization of two one-dimensional CdII coordination polymers (CPs) with 5-amino-2,4,6-tribromoisophthalic acid and flexible N-donor bipyridyl ligands

The bromo-substituted aromatic dicarboxylic acid 5-amino-2,4,6-tribromoisophthalic acid (H₂ATBIP) was used to assemble with Cd^II ions in the presence of the N-donor flexible bipyridyl ligands 3,3'-(diazene-1,2-diyl)dipyridine (mzpy) and 1,3-bis(pyridin-3-ylmethyl)urea (3bpmu), leading to the formation of two chain coordination polymers by adopting solution methods, namely, catena-poly[[[triaqua(5-amino-2,4,6-tribromoisophthalato-κO)cadmium(II)]-μ-3,3'-(diazene-1,2-diyl)dipyridine-κ²N¹:N^1'] dihydrate], {[Cd(C₈H₂Br₃NO₄)(C₁₀H₈N₄)(H₂O)₃]·2H₂O}_n or {[Cd(ATBIP)(mzpy)(H₂O)₃]·2H₂O}_n, (1), and catena-poly[[[tetraaquacadmium(II)]-μ-1,3-bis(pyridin-3-ylmethyl)urea-κ²N¹:N^1'-[diaquabis(5-amino-2,4,6-tribromoisophthalato-κO)cadmium(II)]-μ-1,3-bis(pyridin-3-ylmethyl)urea-κ²N¹:N^1'] octahydrate], {[Cd(C₈H₂Br₃NO₄)(C₁₂H₁₂N₄O)(H₂O)₃]·4H₂O}_n or {[Cd(ATBIP)(3bpmu)(H₂O)₃]·4H₂O}_n, (2). Both complexes were characterized by FT-IR spectroscopic analysis, thermogravimetric analysis (TGA), solid-state diffuse reflectance UV-Vis spectroscopic analysis, and single-crystal and powder X-ray diffraction analysis (PXRD). The mzpy and 3bpmu ligands bridge the Cd^II metal centres in (1) and (2) into one-dimensional chains, and the ATBIP^2- ligands show a monodentate coordination to the Cd^II centres in both coordination polymers. A discrete water tetramer exists in (1). Within the chains of (1) and (2), there are halogen bonds between adjacent ATBIP^2- and mzpy or 3bpmu ligands, as well as hydrogen bonds between the ATBIP^2- ligands and the coordinated water molecules. With the aid of weak interactions, the structures of (1) and (2) are further extended into three-dimensional supramolecular networks. An analysis of the solid-state diffuse reflectance UV-Vis spectra of (1) and (2) indicates that a wide indirect band gap exists in both complexes. Complexes (1) and (2) exhibit irreversible and reversible dehydration-rehydration behaviours, respectively, and the solid-state fluorescence properties of both complexes have been studied.