Manganese Coordination Polymers Research Articles

A three-dimensional manganese(II) coordination polymer: synthesis, structure and catecholase activity

A manganese-based coordination polymer, [Mn2L2(µ-MeOH)2]n (H2L = 2-hydroxy-1-naphthaldehyde isonicotinoylhydrazone) was obtained by self-assembly of 2-hydroxy-1-naphthaldehyde isonicotinoylhydrazone and manganese(II) acetate. The coordination polymer was characterized by IR, EPR and UV–Vis spectroscopy. The single-crystal X-ray diffraction study reveals that the dibasic tridentate ligand (L2−) is bound via ONO donor sites to manganese(II). Two such [ML] fragments are connected by µ2-bridged methanol (MeOH) to form a di-manganese species. The sixth site of each of the manganese is occupied by the pyridyl N atom of the isonicotinoyl group. This arrangement gives a polynuclear complex of the formula [Mn2L2(µ-MeOH)2]n. The coordination geometry of manganese is distorted octahedral. The X-band electron paramagnetic resonance (EPR) measurement of the complex at 77 K shows a six-line spectrum and a signal at the half field, with g = 4.88. The half-field signal indicates the dimeric nature of the complex in the solution state. The cyclic voltammetric measurement of the complex shows a reversible MnIII/MnII redox couple. The complex catalyzes the conversion of 3,5-di-tert-butyl catechol to the corresponding o-quinone with a catalytic turnover rate of (kcat) 27.22 h−1.

1-D manganese(ii)-terpyridine coordination polymers as precatalysts for hydrofunctionalisation of carbonyl compounds.

Reductive catalysis with earth-abundant metals is currently of increasing importance and shows potential in replacing precious metal catalysis. In this work, we revealed catalytic hydroboration and hydrosilylation of ketones and aldehydes achieved by a structurally defined manganese(ii) coordination polymer (CP) as a precatalyst under mild conditions. The manganese-catalysed methodology can be applied to a range of functionalized aldehydes and ketones with turnover numbers (TON) of up to 990. Preliminary results on the regioselective catalytic hydrofunctionalization of styrenes by the Mn-CP catalyst are also presented.

Crystal structure, thermal behavior and luminescence of a new Manganese(Ⅱ) coordination polymer constructed with 1, 10-phenanthroline-5, 6-dione and 2, 5-dihydroxyl-1, 4-terephthalic acid

A new Mn(II) coordination polymer, [Mn0.5(PHDI)0.5(DHTA)0.5]n was synthesized under hydrothermal conditions (PHDI = 1,10-phenanthroline-5,6-dione, DHTA = 2,5-dihydroxyl-1,4-terephthalic acid). Crystallographic data for 1: Monoclinic, space group C2/c, with a = 16.6224(12) Å, b = 11.2536(8) Å, c = 9.3621(7) Å, α = 90°, β = 97.7800(10)°, γ = 90°, V = 1735.2(2)Å3, Z = 8, C10H5Mn0.50NO4, Mr = 230.62, Dc = 1.766 g/cm3, F(000) = 932, μ = 0.820 mm−1, R1 = 0.0356, wR2 = 0.0753. The metal center Mn(II) is six-coordinated, in which two nitrogen atoms come from a chelating didentate ligand of the PHDI, and four oxygen atoms come from four different carboxylic acid ligands of the DHTA, forming a deformed octahedral geometry. The two metal Mn are connected by four single dentate coordination oxygen atoms of two carboxylic acid of the DHTA, and continue to extend in different directions to form an infinite three-dimensional network structure. Additionally, the O(3)–H(3)···O(1), O(3)–H(3)···O(2)i hydrogen bonds further stabilize the structure of 1. The IR, TGA behaviors, Luminescence and PXRD of 1 have been studied in detail.

Three dimensional manganese(II) coordination polymers constructed from 2,2-dimethylglutarate and bis(pyridyl) type ligands

Hydrothermal reactions of Mn(CH3COO)2·4H2O and 2,2-dimethylglutaric acid (H2dmg) in the presence of pyridyl group ligands (4,4′-bipyridine (bipy) or 1,2-di(4-pyridyl)ethylene (dpeten)) are produced under the same conditional. Two new three dimensional coordination polymers, namely, [Mn2(μ4-dmg)(μ4-dmg)(μ-bipy)]n (1), and [Mn2(μ4-dmg)(μ4-dmg)(μ-dpeten)]n (2), were characterized by IR spectroscopy, elemental analysis, single crystal and powder X-ray diffractions as well as thermal analysis techniques. The X-ray single crystal data exhibits that 1 displays 3D framework without interpenetrating, whereas 2 shows a 2-fold 3D → 3D interpenetrating structure. The dmg anions coordinate to Mn(II) ions as a chelate and bis-bridging ligand to form 1D chain. The adjacent 1D chains are connected by bipy or dpeten ligands to generate 3D frameworks. Additionally, the dmg ligand exhibits two unprecedented coordination modes.

Control of dimensionality in Manganese Coordination Polymers using rigid tetrahedral-shaped [1.1.1.1]metacyclophane ligands bearing benzoate coordinating sites: From homochiral 1D to 3D diamond-like structures

Solvothermal synthesis involving tetrasubstituted carboxylic derivatives of [1.1.1.1]metacyclophane (1–2) bearing rigid phenyl spacer, that inherently adopt the 1,3-Alternate conformation, with Manganese salts (acetate and nitrate) led to new 1D and 3D coordination polymers: {13-Mn9O3(CH3COO)6(C5H5N)12} (13-Mn9) and {2-Mn2(C3H7NO)2} (2-Mn2), respectively. The X-ray diffraction analysis revealed that: (i) ligand 1, containing meta-benzoate coordinating sites, forms a 1D chiral helicoidal Coordination Polymer (13-Mn9) with trinuclear metallic clusters (MnIIMnIII2(μ3-O)) acting as linear connection nodes; (ii) ligand 2, bearing para-benzoate moieties forms, a 3D diamond-like Coordination Polymer (2-Mn2) presenting Mn(II) polymeric chains bridged by tetrahedral-shaped ligand. The obtained Mn-based compounds are the first examples of coordination polymers based on tetrasubstituted [1.1.1.1]metacyclophane ligands bearing carboxylate coordinating groups.

Manganese(II) and zinc(II) coordination polymers based on 2-(5-bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylic acid: synthesis, structure and properties

Two metal–organic frameworks based on a multifunctional ligand 2-(5-bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylic acid (H3L), [Mn(HL)(C2H5OH)]n (1) and {[Zn(HL)(H2O)2]·H2O}n (2), have been hydro/solvothermally synthesized and characterized by IR, elemental analyses, X-ray powder and single-crystal diffractions, and thermogravimetric analyses. In 1, (HL)2– ligands adopt the μ3-kN,O:kN′,O′:kN′′ coordination mode and use their imidazoledicarboxylates to bis-chelate MnII into left- and right-handed helixes which are further bridged into a mesolayer structure with (4·82) topology through the coordination of their pyridyl groups. In 2, (HL)2– ligands only use their imidazoledicarboxylates to bis-chelate ZnII into linear chains which are further linked into a 2D supramolecular framework through interchain hydrogen–bonding interactions. Interestingly, the structures of 1 and 2 are mainly dominated by the bis-N,O-chelation of the imidazoledicarboxylate in (HL)2–. As for the formation of the imidazoledicarboxylate-bridged helical chains in 1 or straight chains in 2, it largely depends on the cis- or trans-chelation of two imidazoledicarboxylates around the same metal center. Magnetostructural analysis of 1 discloses that the bis-N,O-chelating imidazoledicarboxylate of (HL)2– transmits antiferromagnetic interactions along the imidazoledicarboxylate-bridged helical chain with the spin-coupling constant of –0.71 cm–1. Additionally, 2 emits greatly enhanced blue fluorescence mainly originating from the intraligand charge transition.

Progressive Structure Designing and Property Tuning of Manganese(II) Coordination Polymers with the Tetra(4-pyridyl)-tetrathiafulvalene Ligand

Three new Mn(II) coordination polymers (CPs) derived from the redox-active tetra(4-pyridyl)-tetrathiafulvalene ligand (TTF(py)4), namely, {[MnCl2(TTF(py)4)]·4CH2Cl2·CH3OH}n (1), {[Mn(N3)(TTF(py)4)]·(ClO4)·2CHCl3·CH3OH)}n (2), and {[Mn(dca)2(TTF(py)4)0.5]·CH3OH}n (3) (dca = dicyanamide), were synthesized and characterized. Their topology and dimensionality are dependent on the counteranion used: Cl– forms a two-dimensional network, N3– induces a (4,6)-connected binodal sqc11-type three-dimensional (3D) framework, while dca results in a 2-fold interpenetrated (4,6)-connected binodal sqc173-type topological 3D framework. All compounds exhibit redox activity and display antiferromagnetic interactions. A single-crystal-to-single-crystal transformation from 2 to 2′ induced by solvent exchange was observed and structurally characterized.

Synthesis, structure and magnetic properties of manganese(II) and cobalt(II) coordination polymers with bis(4-pyridyl)benzylamine

Coordination polymers [Mn2(bpba)3(NO3)4]n·nCH3CN·nCH3CH2OCH2CH3 (1) and [Co2(bpba)3(NO3)4]n·nCH3CN·nCH3CH2OCH2CH3 (2) were synthesized by the reaction of Mn(NO3)2·4H2O or Co(NO3)2·6H2O with bis(4-pyridyl)benzylamine (bpba) in CH3CN/CH3OH. The polymers were characterized by elemental analysis, spectroscopy, magnetic measurement, and single crystal X-ray diffraction. The manganese(II) ion of 1 was coordinated by three N atoms of three different bpba ligands and four O atoms of NO3− anions and displays a T-shaped geometry via bpba ligands. The extended structure of 1 shows a wave-like distorted brick wall configuration. The structure of 2 is isomorphous to that of 1. Polymers 1 and 2 showed weak antiferromagnetic interactions between the metal ions, respectively.

Manganese oxides with hierarchical structures derived from coordination polymers and their enhanced catalytic activity at low temperature for selective catalytic reduction of NOx.

Hierarchical manganese oxides with enhanced catalytic performance have been successfully synthesized via simple thermal annealing of manganese coordination polymer precursors, which is a facile, cost-effective, and environmentally benign preparation method. The resultant manganese oxide particles formed hierarchical structures with a starfish-like morphology and exhibited enhanced low-temperature SCR performance below 200 °C without dopants or supporting materials. In addition, the morphology, chemical states, crystal structure and acidity of manganese oxide catalysts prepared at different calcination temperatures were investigated. It is elucidated that enhanced SCR catalytic performance was strongly dependent on the hierarchical morphology of the catalysts.

A SHG-active manganese coordination polymer with noncentrosymmetric structure based on achiral carboxyphosphinate ligand

The hydrothermal reaction of MnSO4 with the achiral 2-carboxyethyl(phenyl)phosphinate ligand (H2L) afforded a 2 D coordination polymer manganese phosphinate, [Mn(HL)2]n (1) (H2L = 2-carboxyethyl(phenyl) phosphinic acid). It contains two types of dimeric ring motifs, which can generate a layer structure through edge-sharing. The interlayer stacking by C-H…π interactions between the C-H groups of the phenyl rings of HL- and the phenyl rings of the adjacent layers results in its crystallization in a noncentrosymmetric crystal structure with (43)2(46·66·83) topology. Compound 1 shows a second harmonic generation response that is 0.8 times that of urea. The luminescence spectrum indicates an emission maximum at 457 nm, attributed to an intra-ligand emission state.

Coordination polymers of zinc(II) and manganese(II) made by complexation of calix[4]arene functionalized with carboxylates afford alveolar materials

25,27-bis(methoxycarboxylic acid)-26,28-dihydroxycalix[4]arene (calixH2), so call here calix[4]arene dimethoxycarboxylic acid, was investigated for its ability to build metal–organic frameworks. When reacted with zinc or manganese chloride in DMF and deprotonated with trimethylamine it gives Zn (1) and Mn (2) coordination compounds. These crystallize in the triclinic P-1 space group and are isostructural as shown by X-ray diffraction on single crystals. The crystal structures evidence the coordination of calix[4]arenedimethoxycarboxylic acid through the carboxylate groups. This makes a 1D coordination polymer running along the c axis direction in which [MII2(calix)2(H2O)3(DMF)2] (M = Zn or Mn) neutral units are connected. Last step refinements of the crystal structure reveal a lot of residual electron density which was ascribed to uncoordinated disordered water and DMF molecules. This was treated with the SQUEEZE routine of the program PLATON from which the solvent accessible voids per unit cell volume was calculated to be 24.5% for compound 1 (Zn) and 24.9% for compound 2 (Mn). Complementary differential thermal analyses (DTA) combined with thermogravimety analysis (TGA) and mass spectrometry (MS) are in agreement with large amount of incorporated and non-coordinated water and DMF molecules. Adsorption isotherms of N2 measured for compound 1 do not show any significant porosity. The temperature dependence of the magnetic susceptibility (χ) of compound 2 evidences antiferromagnetic interactions and was best fitted with a weak antiferromagnetic exchange coupling between the manganese(II) ions J = − 1.5 cm−1 and small antiferromagnetic inter-dinuclear interactions zJ = − 1.2 cm−1 (g = 2.02).

Luminescent Vapochromism Due to a Change of the Ligand Field in a One-Dimensional Manganese(II) Coordination Polymer.

The reactions of MnBr2 and ethane-1,2-diylbis(diphenylphosphine oxide) (dppeO2) in dichloromethane-methanol solutions gave colorless crystals with the general chemical formulas [MnBr2(dppeO2)] n (1), [MnBr2(dppeO2)(DMF)] n (1a), [Mn(dppeO2)3][MnBr4] (2), and Mn2Br4(dppeO2)2 (3) depending on the crystallization conditions. Compounds 1 and 1a display one-dimensional chain structures composed of Mn(II) ions linked by bridging dppeO2 to exhibit tetrahedral (1) or trigonal-bipyramidal (1a) coordination geometry, whereas 3 exhibits a cyclic dinuclear structure with two Mn(II) centers bridged by double dppeO2 to adopt tetrahedral geometry. Compound 2 consists of octahedrally coordinated cation [Mn(dppeO2)3]2+ and tetrahedrally arranged anion [MnBr4]2-. While 1 and 3 in crystalline and powder states are highly luminescent with green emission bands centered at ca. 510 nm, 2 shows intense orange luminescence peaking at 594 nm. Upon exposure of 1 to N, N-dimethylformamide vapor, the green emission centered at 510 nm is converted to red luminescence peaking at 630 nm, ascribed to the formation of DMF-coordinated compound 1a with a trigonal-bipyramidal ligand field, as demonstrated by X-ray crystallography. Red-emitting 1a could be reverted to the original green-emitting 1 with a tetrahedral ligand field upon heat at 160 °C, and such a reversible conversion could be perfectly repeated for several cycles. A new mechanism of luminescent vapochromism is thus proposed because of the reversible conversion of ligand fields in manganese(II) complexes.

A three‐dimensional (3D) manganese (II) coordination polymer: Synthesis, structure and catalytic activities

A new Mn (II)‐containing coordination polymer, [Mn6(Ipa)6(ad)⋅6H2O] (1; Ipa = isophthalate ligand; ad = adenine), was synthesized by reacting hydrated manganese nitrate with isophthalic acid and adenine under solvothermal reaction conditions. Polymer 1 was characterized using single‐crystal X‐ray diffraction analysis and other techniques such as Fourier transform infrared spectroscopy, elemental analyses and powder X‐ray diffraction. The solid‐state structure of 1 confirmed the formation of a three‐dimensional framework structure based on Mn6 secondary building units. Phase purity of bulk 1 and its thermal stability were investigated. Polymer 1 was evaluated for its performance as a heterogeneous catalyst for the Henry (nitroaldol) reaction of nitromethane with several aldehydes. The recyclability of 1 and heterogeneity of the reaction were also explored. A plausible mechanism for such reaction is proposed. To the best of our knowledge, polymer 1 represents the first example of a Mn (II)‐ and adenine‐containing coordination polymer as well as the first example of a Mn (II)‐containing coordination polymer that has been employed for the Henry reaction.

Solvent-dependent variations of both structure and catalytic performance in three manganese coordination polymers.

Three new manganese 4'-(3,5-dicarboxyphenyl)-2,2':6',2'''-terpyridine (H2DATP) metal-organic framework materials have been generated through regulating the ratios of a binary solvent mixture (DMA/H2O) under solvothermal conditions. Compound 1 {[Mn2(DATP)(HDATP)(H2O)4](OH)·10H2O}n displaying a one-dimensional (1D) chainlike structure was crystallized from the DMA/H2O mixture with a molar ratio of 1 : 1, while the two-dimensional (2D) layer species, {[Mn(DATP)(H2O)]·2H2O}n (2) was produced by increasing the ratio of DMA/H2O to 5 : 1. Interestingly, the crystallization in pure DMA yields a three-dimensional (3D) interpenetrating network {[Mn(DATP)]·4H2O}n (3), featuring higher solvent stability and pH stability than compounds 1 and 2. It is proved that solvent not only influences the structural transformation process of crystals but also has a significant effect on their properties. These three compounds present different catalytic performances in the CO2 cycloaddition to epoxides with various substituent groups into corresponding cyclic carbonates, and only 3 can serve as an efficient and recyclable catalyst at mild temperature.

Binuclear Mn2+ complexes of a biphenyltetracarboxylic acid with variable N-donor ligands: syntheses, structures, and magnetic properties

A series of manganese(ii) coordination polymers show a variety of features due to the recognition and assembly processes of the N-donor ligands.

Muconato‐bridged Manganese Coordination Polymer exhibiting rare Distorted‐trigonal Prismatic Coordination Arrangement

Novel poly[Mn(H2O)(dmb)(muco)] (1) (H2muco = trans,trans‐muconic acid; dmb = 5,5′‐dimethyl‐2,2′‐bipyridine) was obtained by self‐assembly, one‐pot, solution reaction. 1 crystallizes in a monoclinic system with P21 space group and forms an infinite one‐dimensional (1D) polymer. Remarkably, the six‐coordinate MnII display a rare distorted trigonal prismatic configuration. This unusual coordination arrangement appears to be acquired due to the supramolecular interactions of the polymeric structure of 1, mainly throughout hydrogen bonding, giving rise to a 2D framework. Magnetic properties measurements reveal that 1 possesses weak antiferromagnetic interactions with θ(C–W) = –1.0 K and J = 458 cm–1.

Modular Construction, Structures, and Magnetic Properties of Two Manganese Coordination Polymers Based on 3,5‐Bis(2–carboxylphenoxy)benzoic Acid

Two manganese(II) coordination polymers, namely, [Mn1.5(BCB)(bpy)1.5(H2O)]n (1), and [Mn(HBCB)(bibp)2(H2O)] (2), were assembled from the mixed ligands of the flexible tripodal ligand of 3,5‐bis(2‐carboxylphenoxy)benzoic acid (H3BCB) and two rigid N‐donors [bpy = 4,4′‐bipyridine, and bibp = 4,4′‐bis(imidazolyl)biphenyl]. Their structures were determined by single‐crystal X‐ray diffraction analyses and further characterized by elemental analyses (EA), IR spectra, powder X‐ray diffraction (PXRD), and thermogravimetric (TG) analyses. Structural analysis reveals that complex 1 is a 3D (3,4,6)‐connected {5·62}2{56·64·7·82·92}{64·8·9} net based on two kinds of inorganic nodes of dinuclear {Mn2(COO)2} SBUs and Mn(2) ions. Complex 2 is a hydrogen bonds based 3D supramolecule with 6‐connected {412·63}‐pcu net. Besides, the variable‐temperature susceptibilities of 1 and 2 were investigated.

Tetrazole-bridged manganese coordination polymer as high-energy material

Metal organic frameworks (MOFs) containing nitrogen-rich organic linkers and light-metal ions which exhibit remarkable thermal stability and shock resistivity, can be considered as potential high energetic materials. This work presents a three-dimensional framework MOF structure with manganese and sodium ions as the connecting nodes and N,N-bis(tetrazol-5-yl)amine (bta) di-anionic ligands as the organic linker, generated in-situ through solvothermal synthesis. This solid is considerably robust, and it shows attractive energetic performance as estimated by sensitivity tests and semi-empirical calculations of its detonation properties.

Crystal structure, spectroscopic and thermal properties of copper(II) and manganese(II) coordination polymers based on triazole-benzoic acid ligands

Two transition metal coordination polymers {[Cu(tba)2(H2O)]·2H2O} n (1) and {[Mn(Htta)2(H2O)2]·2H2O} n (2) {Htba = 3-[1,2,4]triazol-1-yl-benzoic acid, H2tta = 2-[1,2,4]triazol-1-yl-terephthalic acid} have been synthesized under solvothermal conditions. Both complexes have been characterized by single-crystal X-ray diffraction, X-ray powder diffraction, elemental analysis and FTIR spectroscopy. Complex 1 has a 1-D chain structure in which Cu(II) atoms are doubly bridged by tba− ligands, which is further stabilized by hydrogen bonding and π–π stacking interactions to give a 3-D supramolecular framework. In complex 2, Mn(II) atoms are doubly bridged by Htta− ligands to form 1-D chains, which are further connected by intermolecular hydrogen bonds to form a 3-D supramolecular framework. The electronic spectra and thermal behaviors of complexes 1 and 2 are also reported.

A new 1D manganese(II) coordination polymer with end-to-end azide bridge and isonicotinoylhydrazone Schiff base ligand: Crystal structure, Hirshfeld surface, NBO and thermal analyses

A new manganese (II) coordination polymer, [MnL2 (μ-1,3-N3)2]n, with co-ligands including azide anion and Schiff base based on isonicotinoylhydrazone has been synthesized and characterized. The crystal structure determination shows that the azide ligand acts as end-to-end (EE) bridging ligand and generates a one-dimensional coordination polymer. In this compound, each manganes (II) metal center is hexa-coordinated by four azide nitrogens and two pyridinic nitrogens for the formation of octahedral geometry. The analysis of crystal packing indicates that the 1D chain of [MnL2 (μ-1,3-N3)2]n, is stabilized as a 3D supramolecular network by intra- and inter-chain intermolecular interactions of X–H···Y (X = N and C, Y = O and N). Hirshfeld surface analysis and 2D fingerprint plots have been used for a more detailed investigation of intermolecular interactions. Also, natural bond orbital (NBO) analysis was performed to get information about atomic charge distributions, hybridizations and the strength of interactions. Finally, thermal analysis of compound showed its complete decomposition during three thermal steps.