1D Coordination Research Articles

Heterometallic Benzenehexathiolato Coordination Nanosheets: Periodic Structure Improves Crystallinity and Electrical Conductivity.

Coordination nanosheets are an emerging class of 2D, bottom-up materials having fully π-conjugated, planar, graphite-like structures with high electrical conductivities. Since their discovery, great effort has been devoted to expand the variety of coordination nanosheets; however, in most cases, their low crystallinity in thick films hampers practical device applications. In this study, mixtures of nickel and copper ions are employed to fabricate benzenehexathiolato (BHT)-based coordination nanosheet films, and serendipitously, it is found that this heterometallicity preferentially forms a structural phase with improved film crystallinity. Spectroscopic and scattering measurements provide evidence for a bilayer structure with in-plane periodic arrangement of copper and nickel ions with the NiCu2 BHT formula. Compared with homometallic films, heterometallic films exhibit more crystalline microstructures with larger and more oriented grains, achieving higher electrical conductivities reaching metallic behaviors. Low dependency of Seebeck coefficient on the mixing ratio of nickel and copper ions supports that the large variation in the conductivity data is not caused by change in the intrinsic properties of the films. The findings open new pathways to improve crystallinity and to tune functional properties of 2D coordination nanosheets.

Strong Red Up‐Conversion Emission in Thin Film Devices Based on Rare‐Earth Oxides Obtained from Templating 2D Coordination Networks

AbstractCoordination networks (CNs) with tailorable multi‐metallic composition were designed and then used as sacrificial materials to obtain promising materials with Up‐conversion (UC) properties. The metal‐organic precursors led to solid solutions of Rare‐Earth Oxides (REO)Y2O3:Yb3+/Er3+or Y2O3:Yb3+/Er3+/Gd3through a calcination process. In order to obtain luminescent UC platforms, spin‐coating technique was implemented to deposit these materials onto glass supports. The synthesized solids and the resulting films were characterized by Scanning Electron Microscopy – Energy Dispersive Spectroscopy (SEM‐EDS), infrared spectroscopy, powder (PXRD), and grazing incidence (GIXRD) X‐ray diffraction techniques. Moreover, the photophysical properties of bulk and deposited Y2O3:Ln3+doped oxides were evaluated after being irradiated with NIR wavelength (980 nm) laser to excite the Yb3+sensitizer ion. Besides, decay emission profiles from each sample were also obtained and lifetime (τobs) values were calculated. These results open up the implementation of REO thin films obtained through CN calcination for promising applications such as solar cells and sensor devices.

Metallo‐Ligand Based 3d/4f Coordination Polymers: Synthesis, Structure and Magnetic Properties

AbstractEmployment of N,N′‐bis(2‐hydroxy‐4‐carboxyphenyl)oxalamide (H6L) in Cu2+ chemistry afforded the mononuclear complex (Et4N)4[CuL] ⋅ 13H2O (A) which comprises a square planar [CuL]4− complex with several O donor atoms in its periphery. The 1 : 1 reaction between complex A and Ln(NO3)3 ⋅ xH2O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb, x=6 or 9) in 1 : 4 mixture of ethanol/water in the presence of excess of KCl yielded two families of isomorphous 3d/4f coordination polymers, namely (Et4N)0.5[K0.5(H2O)Ln(H2O)4(CuL)] ⋅ 3H2O [Ln=La(1), Ce(2), Pr(3), Nd(4), Sm(5), Eu(6) and Gd(7)] and [K(H2O)Ln(H2O)4(CuL)] ⋅ ⋅6H2O [Ln=Tb(8), Dy(9), Ho(10), Er(11) and Yb(12)]. The crystal structures of 2–4 revealed the presence of 3D coordination polymers while the crystal structure of 9 the presence of a 2D coordination polymer. In both 3d/4f families, complex A retains its original structure and serves as a “metallo‐ligand”. The magnetic properties of 2–4, 7–9, 11 and 12 are discussed.

Synthesis, structure, and properties of catechol functionalized tripodal chelate and its radical complex of strontium

A new tripodal chelate ligand (NaH3L·1.5H2O) was synthesized via Mannich reaction from iminodiacetic acid and t-butyl-catechol in MeOH/H2O in the presence of polyformaldehyde and NaOH. Colorless NaH3L·1.5H2O react with Sr(OH)2 affords a deep-blue 2D-coordination polymer [Sr3L̇2·8H2O]·10.5H2O in aqueous solution. Crystal structure shows [Sr3L̇2·8H2O]·10.5H2O is a free radical 2D coordination polymer with g = 2.004 and guest accessible cavity 35.6% after removal water molecules in solid state. N2 adsorption indicates [Sr3L̇2·8H2O]·10.5H2O has specific surface area 5.4561 m2 g−1, average pore diameter is 18.48 nm, maximum N2 adsorption capacity is 18.05 cm3·g−1. [Sr3L̇2·8H2O]·10.5H2O is relatively stable in DMSO, with absorbance maximum at 259(7095), 305(6940) and 623 nm (4495 M−1 ·cm−1), but will decompose in the presence of HCl, citric acid and ascorbic acid. Stronger acid decomposes faster. Large excess H2O2 can also decompose [Sr3L̇2·8H2O]·10.5H2O. The decomposition reaction is first-order to concentration of H+/H2O2 and [Sr3L̇2·8H2O]·10.5H2O. The second-order rate constants at room temperature DMSO solution are 6.86 × 10−4 and 15.5 s−1·M−1 for H2O2 and H+ respectively.

Unique Ligand Exchange Dynamics of Metal–Organic Polyhedra for Vitrimer-like Gas Separation Membranes

Unique Ligand Exchange Dynamics of Metal–Organic Polyhedra for Vitrimer-like Gas Separation Membranes

Synthesis, molecular and supramolecular structure aspects and biological evaluations of a novel [Ag2(phthalazine)(NO3)2]n 3D coordination polymer

The novel [Ag2(phth)(NO3)2]n 3D coordination polymer of phthalazine (phth) ligand was synthesized by reaction of silver nitrate and the hydrazonophthalazine (E)-2-(1-(2-(Phthalazin-1-yl)hydrazono)ethyl)phenol. The molecular and supramolecular structural aspects of the complex were investigated using single crystal X-ray diffraction combined with Hirshfeld calculations. There are two crystallographically independent Ag1 and Ag2 sites having completely different coordination environments. Ag1 is tetra-coordinated with mixed organic and inorganic AgN2O2 coordination sphere from two phth ligands and one bidentate nitrate ion. The two phth ligands are bridging two Ag1 sites leading to significantly short Ag1-Ag1 distance of 3.152(7) Å indicating the presence of argentophillic interactions. The Ag2 site is hexa-coordinated with four nitrate groups hence, having only inorganic AgO6 coordination environment. The nitrate groups acting as connectors between the Ag-sites leading to the 3D coordination polymer. A novel T12 coordination mode for one of the NO3¯ group was detected. Based on Hirshfeld calculations, the O…H (37.8%), C…O (4.7%) and C…C (3.5%) as well as Ag-O (13.2%) interactions have great importance in the supramolecular structure of the studied complex. The [Ag2(phth)(NO3)2]n complex showed broad-spectrum activity against both bacteria and fungus. It showed significant cell growth inhibition against lung carcinoma A-549 cell line (IC50 of 4.32 ± 0.86 µg/mL) compared to Doxorubicin (0.95 ± 0.17 µg/mL).

Zn-diarylethene organic framework for anticounterfeiting: Crystal structure, photochromism and fluorescence switch

A new photochromic metal-organic framework [Zn(BCM)2(bpfb)] where H2BCM ​= ​1,2-bis(5-carboxylic acid-2-methylthien-3-yl)hexafluorocyclopentene, bpfb ​= ​N,N-bis-(4-pyridylformamide)-1,4-benzenediamine, was synthesized and characterized by Single Crystal X-ray Diffraction, Powder X-ray Diffraction, Elemental Analysis, Fourier Transform Infrared Spectroscopy (FT-IR) and Thermogravimetric Analysis (TGA). [Zn(BCM)2(bpfb)] crystallizes in a monoclinic P21/n space group. The Single crystal X-ray structure determination revealed a three dimensional (3D) coordination framework of dinuclear zinc clusters [Zn2(COO)4N2] interconnected both BCM2− and bpfb. And [Zn(BCM)2(bpfb)] exhibited reversible photochromism behavior derived from diarylethene BCM2− ligand. Besides, [Zn(BCM)2(bpfb)] can be further used to photo-switch the luminescence emission, which can achieve precisely reading out and concealing information in reversible transformation.

2D and 3D Zn(II) coordination polymers based on 4′-(Thiophen-2-yl)-4,2′:6′,4′'-terpyridine: Structures and features of sorption behavior

Reactions of Zn(II) nitrate, 4′-(Thiophen-2-yl)-4,2′:6′,4′'-terpyridine (ThioTerPy) and terephtalic (bdc) or 2-iodoterephtalic (2-I-bdc) acids result in 2D coordination polymer [Zn2bdc(ThioTerPy)2(OH)2] (1) or 3D metal-organic framework [Zn(2-I-bdc)(ThioTerPy)] (2), respectively. Both compounds were characterized by X-ray diffractometry. For 2, I2 absorption, as well as selectivity of sorption of different organic substrates from mixtures was studied.

Structural Diversity of Silver Fluorinated β-Diketonates: Effect of the Terminal Substituent and Solvent.

In order to demonstrate the role of the fluorination and some solvents in the structural organization of the Ag(I) coordination polymers with β-diketonate ligands (R1C(O)CαHC(O)R2)− we synthesized a series of the compounds containing tfac- (R1 = CH3, R2 = CF3) and pfpac- (R1 = CH3, R2 = C2F5) anions. Solvent-free [Ag(L)]∞ (L = tfac 1, pfpac 2) compounds and the corresponding acetonitrile and toluene adducts have been characterized by elemental analysis and/or NMR, IR and single-crystal XRD. This series includes five new coordination polymers. Compound 1 is a 3D coordination framework based on Ag–Ochelate/bridge, Ag–Cα bonds, and argentophilic interactions. An increase in the fluorinated group leads to a chain coordination polymer 2 of an unusual structural organization. These chains can be represented as a “DNA-type”, where two intertwined helices based on Ag–Ochelate and Ag–Cα bonds are connected through Ag–Obridge ones. Two structural types of chain coordination polymers, [Ag(tfac)(CH3CN)] and [Ag2(L)2(solvent)], have been revealed for the adducts. The latter structural type differs significantly from the previously studied toluene and acetonitrile adducts of fluorinated Ag(I) β-diketonates of the same stoichiometry. Thermal analysis in helium showed that both 1 and 2 decompose to metallic silver with the compound of pfpac-ligand being slightly more stable.

A hexanuclear discrete assembly and a two dimensional coordination polymer constructed from heterotrinuclear [(CuL)2Zn]2+ nodes and dicyanamide spacer (H2L = salen type Schiff base ligands)

Two new Cu(II)–Zn(II) complexes as a discrete hexanuclear cluster [{(CuL1)2Zn}2(μ1,5-N(CN)2)2](ClO4)2(1) and a two dimensional (2D) coordination polymer [(CuL2)2Zn(μ1,5-N(CN)2)2]n (2) have been isolated by mixing two similar tetradentate Schiff bases H2L1 (N,N′-bis(ɑ-ethylsalicylidene)-1,3-propanediamine) and H2L2 (N,N′-bis(salicylidene)-1,3-pentanediamine) separately with Cu(ClO4)2·6H2O, Zn(ClO4)2·6H2O and NaN(CN)2 ​at same reaction condition. The heterometallic complexes have been structurally characterized by single crystal X-ray analyses showing that both are formed by angular trinuclear nodes and μ1,5-dicyanamide spacers. The trinuclear nodes ([(CuL1)2Zn]2+ in 1 and [(CuL2)2Zn]2+ in 2 are produced in situ from their corresponding reactants. The two Schiff base ligands coordinating the Cu(II) ions through the N2O2 donor set are additionally bonded to a Zn(II) ion with the four phenoxido oxygen atoms that act as bridging atoms. The zinc ion completes its coordination geometry with two terminal nitrogen atoms of two different dicyanamide spacers. The orientation of spacers from zinc ion are convergent in 1 whereas divergent in 2. Thus, two [(CuL1)2Zn]2+ nodes are interconnected by double μ1,5-dicyanamide bridges via Zn(II) centres to form discrete hexanuclear assembly of complex 1. On the other hand, [(CuL2)2Zn]2+ nodes in 2 are joined by μl,5-dicyanamide that bridge Zn(II) to Cu(II) centres of symmetry related units in order to construct a 2D coordination polymer. Consequently, the final coordination environment around Zn(II) is octahedral in both complexes whereas that around Cu(II) are square planar and square pyramidal in 1 and 2 respectively.

Improvement of the fluorescent sensing biomarker 3-nitrotyrosine for a new luminescent coordination polymer by size regulation

A new 3D luminescent coordination polymer (LCP) 1 was synthesized for detecting biomarker 3-nitrotyrosine. By adjusting the reaction conditions, Nano-LCP 1 was synthesized, which has a more lower detection limit compared with LCP 1.

Vapor-triggered reversible crystal transformation of a nickel-based magnetic molecular switch.

Vapor-triggered crystal-to-crystal transformation between a discrete trinuclear complex [Ni3(sih)2(py)8] and a two-dimensional (2D) coordination polymer [Ni3(sih)2(py)2]n·2DMF·2H2O was demonstrated. It provides an example of a solid-state coordination-induced spin state switch behavior attributed to the structural phase transition triggered by solvent signal. The reversible nature can be detected by both optical (spectral) and magnetic responses in cycles.

Stereoisomeric coordination polymers based on facial and meridional six-coordinate dysprosium(III ).

Due to the small differences in the chemical properties of facial (fac) and meridional (mer) stereoisomers, selective synthesis of one of the isomers is challenging, especially for lanthanide complexes. By using a flexible bidentate phosphine oxide ligand, we managed to isolate three stereoisomeric 2D and 3D coordination polymers, in which six-coordinate Dy(III) ions possess fac- or mer-Cl3O3 coordination environments. Structural studies indicate that the stereochemistry differences result from their various supramolecular interactions (e.g., hydrogen bonding and π⋯π stacking). Magnetic property measurements reveal the different static and dynamic magnetic behaviours of the three stereoisomers. Ab initio CASSCF calculations were then performed which indicated that their distinct magnetic behaviours arise from their fac/mer configurations. Compared to fac-Dy(III), mer-Dy(III) possesses more axial ground-state KDs and higher first excited KDs.

Single crystal-to-single crystal transformation - from two distinct to three distinct spin crossover centers in 2D coordination polymer [Fe(bbtr)3](CF3SO3)2.

1,4-Di(1,2,3-triazol-1-yl)butane (bbtr) forms a two-dimensional (2D) coordination polymer (1) in a reaction with iron(II) triflate. In the crystal lattice there are two crystallographically unique iron(II) ions surrounded octahedrally by a 1,2,3-triazole ring coordinated through nitrogen atoms N3. Single crystal X-ray diffraction studies revealed that spin crossover for each crystallographically independent iron(II) ion proceeds at a different temperature (T1/2(Fe1) = 201 K; T1/2(Fe2) = 216 K), while the magnetic measurements showed that there is one step, complete thermally induced spin crossover (T1/2 = 205 K). Complex 1 undergoes, with time, single crystal-to-single crystal transformation (SCSC) to the converted system (1c) from the R3̄ to the P63 space group, accompanied by significant changes in the lattice parameter c (a shortening of approximately one-third) and consequently unit cell volume. Structural transformation is associated with rebuilding of the polymeric layer as well as the anion network, which is reflected in the results of Mössbauer studies. In the polymorphic system (1c) there are three crystallographically independent iron(II) ions. The temperature dependence results for magnetic susceptibility indicated complete, one-step spin crossover very similar to that of 1; however, single-crystal X-ray diffraction studies of 1c revealed that spin crossover for each crystallographically independent iron(II) ion occurs in a different manner, revealing three elementary stages (T1/2(Fe1) = 200 K; T1/2(Fe2) = 212 K, T1/2(Fe3) = 214 K).

Regioisomeric core-shell cuprofullerene C60@Cu24.

The controlled synthesis of high-nuclear regioisomeric core-shell exohedral metallofullerenes (ExMFs) is challenging. Herein, we demonstrated the synthesis of regioisomeric core-shell cuprofullerene C60@CuI24 and its 3-D coordination polymer using heteroleptic ligands, realizing high-nuclear regioisomeric ExMFs and a polymeric ExMF structure.

Efficient and reusable catalysis of benzylic C-H oxidation over layered [Co5(OH)6]4+ derivatives.

Aerobic oxidation of benzylic C(sp3)-H bonds in a green and heterogeneous manner is a major target in organic catalysis. Herein, we report the synthesis of 3D coordination polymers containing [Co5(OH)6]4+ layers, affording reusable and efficient oxidation of ethylbenezene and tetralin by using O2 as the oxidant. Moreover, the cleavage of CoII-carboxylate bonding renders atomically thin cobaltate nanosheets and enhanced catalytic performance. This is one of the top catalytic performances for CoII-catalyzed benzylic C(sp3)-H oxidation (∼0.02 mol% Co and 76% conversion for nanosheets), ascribed to the exposed, accessible and coordinatively unsaturated CoII species.

A new Ca(II) coordination polymer: Structural characterization and treatment activity on childhood asthma

In the present study, a 3D coordination polymer with the chemical composition of[(CH3)2NH2][Ca(tcpbH)(H2O)] (1) has been solvothermally obtained from a rigid tetracarboxylic acid ligand tetrakis-(4-carboxyphenyl)benzene (H4tcpb) and alkaline-earth ion CaII. Complex 1 has been well studied via Fourier-transform infrared spectroscopy, elemental analysis (EA), TG analysis and single-crystal X-ray diffraction analysis. Its application values on the childhood asthma were determined and the internal principle has been discussed simultaneously. Firstly, the ELISA is utilized to measure the content of inflammatory cytokines released into the Broncho alveolar lavage fluid (BALF) after compound treatment. In addition to this, the real time RT-PCR was conducted to measure the relative expression levels of NF-κB signaling pathway in the alveolar epithelial cells.

Solvatochromism and the effect of solvent on properties in a two-dimensional coordination polymer of cobalt-trimesate

A 2D coordination polymer can exchange guest species from liquid sorption, with accompanying visible colour changes.

Photocatalytic hydrogen evolution from water based on Zn–terpyridine 2D coordination nanosheets

A zinc bis-terpyridine coordination nanosheet (Zn–Typ CONASH) is designed and shows a reduced optical band gap of 1.70 eV and impressive photocatalytic hydrogen evolution activity of 11.84 mmol g−1 h−1.

Photoinduced magnetic hysteresis in a cyanide-bridged two-dimensional [Mn2W] coordination polymer

A 2D coordination polymer [Mn2W] underwent photoinduced singlet (S= 0) to triplet (S= 1) transition on the WIVions, resulting in magnetic ordering with a transition temperature of 24 K and a hysteresis loop up to 15 K.