DMF Ligands Research Articles

Ligand-Induced Motion and Self-Assembly Pathways between Nanocubes.

Nanoparticle motion and self-assembly have been regarded as a promising pathway for forming ordered nanostructures. However, the detailed dynamics processes induced by ligand involvement remained poorly understood. Here, we used in situ liquid-cell electron microscopy technology to image the formation of face-to-face Pt cube ordered structures: pairs, linear chains, and squares. The van der Waals interaction between the two neighboring cubes was quantified in real time. Interestingly, the two different formation processes of the square phase were achieved via a rotational and translational method. It is found that the space between two neighboring cubes was the same as the ex-TEM results. The density functional theory calculation demonstrated that it was attributed to the DMF ligand interactions of the cubes that promoted their face-to-face attachment.

Crystal Structure of a Lantern-type Diruthenium(II,III) Complex with Axial Thiocyanato and DMF Ligands, [Ru<sub>2</sub>(O<sub>2</sub>CCMe<sub>3</sub>)<sub>4</sub>(NCS)(DMF)

Crystal Structure of a Lantern-type Diruthenium(II,III) Complex with Axial Thiocyanato and DMF Ligands, [Ru<sub>2</sub>(O<sub>2</sub>CCMe<sub>3</sub>)<sub>4</sub>(NCS)(DMF)

A fluorescent Zn(II)-based complex for the selective detection of PA and treatment effect on uveitis by reducing the inflammatory response and inflammatory cytokine release

By using a pyrimidine-functionalized ligand 4,6-di(1H-imidazol-1-yl)pyrimidine (L), a new Zn(II)-based coordination polymer with the chemical formula of {[Zn0.5(L)(H2O)]·(NO3)} (1) was prepared via the reaction of Zn(NO3)2·6H2O with the L ligand in water and DMF mixed solvent under solvothermal conditions. The results of fluorescence titration experiments revealed that complex 1 exhibited real-time, fluorescence quenching behavior with high sensitivity and selectivity for picric acid, and the detection limit was in the nanomole level. Furthermore, the treatment effect of the compound on uveitis was evaluated. RT-PCR was conducted to measure the relative expression levels of tlr-4 and nf-κb in the HXO-RB44 cells. ELISA assay was carried out to detect the IL-1β and IL-18 contents after compound treatment.

Formation thermodynamic parameters of nano copper (II) acetate monohydrate with 4,6-diacetylresorcinol in mixed solvents

The formation thermodynamic parameters, formation constants (Kf), Gibbs free energies of formation (ΔGf), enthalpies of formation (ΔHf) and entropies of formation (ΔSf) of nano copper (II) acetate monohydrate with 4,6-diacetylresorcinol as a ligand in pure DMF and in mixed DMF - water solvents are measured in different concentrations of dimethylformamide - water mixed solvents (70% DMF, 80% DMF, 90% DMF and 100% DMF) at different temperatures, 293.15, 303.15, 313.15 and 323.15K. The data indicate that three types of complexes with metal to ligand ratios 1:2, 1:1 and 2:1 stoichiometric complexes are formed. A comparison between the thermodynamic parameters of formation for the three complexes is studied.

Two Copper(II) coordination polymers constructed from 3,3-dimethylglutarate and citrate ligands

Two new Cu(II) coordination polymers, formulated as [Cu(μ4-dmg)(DMF)]n (1) and [Cu4(μ4-cit)2(H2O)8]n (2) (H2dmg = 3,3-dimethylglutaric acid and H4cit = citric acid) were successfully synthesized by using H2dmg and H4cit ligands under solvothermal conditions and characterized by single crystal X-ray diffraction, elemental analyses, IR spectroscopy and powder X-ray diffraction (PXRD). Single crystal X-ray analyses indicate that compound 1 features a two-dimensional (2D) structure with a uninodal 4-connected sql/Shubnikov tetragonal plane net, whereas 2 displays a three-dimensional frameworks (3D) with a pcu topology. Cu1 ion in 1 is connected by four bridging carboxylates to produce a paddlewheel-shaped {Cu2(CO2)4} SBU, and each Cu(II) ion is also coordinated to a DMF ligand at the axial site of the paddlewheel SBU. In 2, citrate anion acts as a heptadentate ligand and three independent Cu(II) ions are bridged by two carboxyl and one hydroxy groups to form the trinuclear {Cu3} core. Moreover, thermal and optical band gap properties of the compounds were determined in detailed.

Crystal structure and Hirshfeld surface analysis of poly[tris-(μ4-benzene-1,4-di-carboxyl-ato)tetra-kis-(di-methyl-formamide)-trinickel(II)]: a two-dimensional coordination network.

The crystal structure of the title compound, [Ni3(C8H4O4)3(C3H7NO)4], is a two-dimensional coordination network formed by trinuclear linear Ni3(tp)3(DMF)4 units (tp = terephthalate = benzene-1,4-di-carboxyl-ate and DMF = di-methyl-formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal-organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides inter-actions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF mol-ecule, which shows positional disorder. Parallel planes are connected mainly through weak C-H⋯O, H⋯H and H⋯C inter-actions between DMF mol-ecules, as shown by Hirshfeld surface analysis.

Preparation of a dimer from self-complementary of cobalt(III) complex with dissymmetric compartmental ligand and study of the interaction of the complex with DNA and BSA

Synthesis of [Co(L)(H2O)(HOCN(CH3)2)](ClO4) (where L denotes N,N′-bis(3-methoxysalicylidene)-1,2-diaminopropane) was reported. The complex was characterized by 1H NMR, elemental analysis, IR and UV–vis spectroscopy and the structural features have been solved by X-ray crystallography. The crystal structure analysis showed that the arrangement around cobalt atom is octahedral with two imine nitrogen atoms (N1 and N2) and two oxygen atoms of hydroxyl groups (O2 and O3) at equatorial positions and an aqua ligand and a DMF ligand at the axial positions. The hydrogen-bonding interactions between coordinated H2O and phenoxo/methoxy oxygens connect the complex molecules in dimers. Interaction of the complex with FS-DNA and protein (BSA) was explored by fluorescence and absorption spectroscopy, viscosity measurements, circular dichroism (CD), cyclic voltammetry (CV) and agarose gel electrophoresis. According to the Kb value about 103, the complex is moderately bound to DNA. The complex interacts with protein (BSA) by both static and dynamic quenching. According to cleavage experiment, the complex destroys annular DNA and causes double strand break. Molecular docking was done to achieve detailed binding information of the complex to DNA and BSA. Moreover, cytotoxic activity was evaluated by MTT assay. The complex has low toxicity against the MCF-7 and LNCaP cancer cells.

Conductance studies on complex formation of nano Cu(NO3)2.2.5H2O with 4,6-diacetylresorcinol in mixed solvents

The different complexation thermodynamic parameters for example, formation constants (Kf), free energies of formation (∆Gf), enthalpies of formation (∆Hf) and entropies of formation (∆Sf) for nano copper nitrate hemi pentahydrate (Cu(NO3)2.2.5H2O) with 4,6-diacetylresorcinol as a ligand in pure DMF and in mixed solvents of DMF and water are calculated at different temperatures, 293.15, 303.15, 313.15 and 323.15 K by using conductance measurements. By drawing the relation between molar conductance and ratio of metal to ligand, the figures indicate the formation of two types of complexes with M:L ratios 1:2 and 1:1 stoichiometric complexes.

The Anisotropic Responses of a Flexible Metal-Organic Framework Constructed from Asymmetric Flexible Linkers and Heptanuclear Zinc Carboxylate Secondary Building Units.

A new porous and flexible metal–organic framework (MOF) has been synthesized from the flexible asymmetric linker N-(4-carboxyphenyl)succinamate (CSA) and heptanuclear zinc oxo-clusters of formula [Zn7O2(carboxylate)10DMF2] involving two coordinated terminal DMF ligands. The structural response of this MOF to the removal or exchange of its guest molecules has been probed using a combination of experimental and computational approaches. The topology of the material, involving double linker connections in the a and b directions and single linker connections along the c axis, is shown to be key in the material’s anisotropic response. The a and b directions remain locked during guest removal, whereas the c axis linker undergoes large changes significantly reducing the material’s void space. The changes to the c axis linker involve a combination of a hinge motion on the linker’s rigid side and conformational rearrangements on its flexible end, which were probed in detail during this process despite the presence of crystallographic disorder along this axis, which prevented accurate characterization by experimental methods alone. Although inactive during guest removal, the flexible ends of the a and b axis linkers are observed to play a prominent role during DMF to DMSO solvent exchange, facilitating the exchange reaction arising in the cluster.

Tuning White Light Emission in Dinuclear Phenoxo Bridged DyIII Complexes.

A new series of dinuclear dysprosium(III) complexes, [Dy2(LCH3)2(NO3)2(MeOH)2] (I), [Dy2(LCH3)2(NO3)2(DMF)2]·2DMF (II), [Dy2(LCl)2(NO3)2(DMF)2]·2DMF (III), and [Dy2(LCH3O)2(NO3)2(DMF)2] (IV), with 2,2'-[[(2-pyridinylmethyl)imino]di(methylene)]bis(4-R-phenol), where R = CH3, Cl, and CH3O, were investigated as potential white light emitters. All octacoordinated dysprosium(III) are phenoxo-bridged species and have a similar coordination environment. Nevertheless, I has a MeOH ligand molecule, while for II-IV a DMF ligand replaces that of MeOH. The nature of the coordinated solvent molecule plays an important role in the behavior of the thermal dependence of the Y/B (yellow/blue) emission ratio of the DyIII complexes (Y: 4F9/2 → 6H13/2, yellow and B: 4F9/2 → 6H15/2, blue transitions),, since for I the variation of this ratio is significant, while for the other DyIII complexes with DMF as ligand the ratio remains constant within experimental error. At room temperature the CIE (Commission International d'Eclairage) color coordinates for the DyIII complexes, I (0.286, 0.317), III (0.302, 0.324), and IV (0.322, 0.348) are close to the NTSC (National Television System(s) Committee) standard value for white color. Varying the temperature from 16 to 300 K the CIE coordinates for I change from the blueish to white region of the chromaticity diagram, while those of II present an inverse thermal dependence as compared to I. The CCT (Correlated Color Temperature) values at room temperature for I (8384 K), II (17235 K), and IV (5948 K) permit us to consider these complexes as candidates for white cold light emitters, the high value of II being uncommon. For I and II the CCT values vary strongly with temperature, showing a decrease with increasing temperature for I, and an increase with increasing temperature for II, thus making evident the influence on the photophysical properties of the nature of the coordinated solvent molecule in these complexes.

Selective Sensing of Peroxynitrite by Hf-Based UiO-66-B(OH)2 Metal–Organic Framework: Applicability to Cell Imaging

The first boronic acid functionalized Hf-based UiO-66 (UiO = University of Oslo) metal-organic framework (MOF) having the ability to detect both extracellular and intracellular peroxynitrite is presented. The Hf-UiO-66-B(OH)2 material (1) was synthesized under solvothermal conditions from a mixture of HfCl4 and 2-borono-1,4-benzenedicarboxylic acid [H2BDC-B(OH)2] ligand in DMF in the presence of formic acid (modulator) at 130 °C for 48 h. The desolvated material (1') was utilized as a fluorescent turn-on probe for the rapid sensing of extracellular peroxynitrite (ONOO-) under conditions mimicking those of biological medium (10 mM HEPES buffer, pH 7.4). Selective sensing of ONOO- over other ROS/RNS was also achieved by 1'. The oxidative cleavage of attached boronic acid groups forming corresponding hydroxy-functionalized ligands can be accounted for the fluorescent increment phenomenon in the presence of ONOO-. The probe showed extraordinary sensitivity (detection limit = 9.0 nM) toward ONOO- in 10 mM HEPES buffer at pH 7.4. Probe-loaded cells did not exhibit cytotoxicity and morphological deformities. It is remarkable that the probe inside the cells responded toward the peroxynitrite solution to give an intense blue fluorescent signal. The fluorescence microscopy study with J774A.1 macrophage cells unambiguously demonstrated that probe 1' is suitable to image peroxynitrite in living cells.

Design of an Anticancer Copper(II) Prodrug Based on the Lys199 Residue of the Active Targeting Human Serum Albumin Nanoparticle Carrier.

We not only modified the types and numbers of coordinated ligands in a metal agent to enhance its anticancer activity, but we also designed a metal prodrug based on the N-donor residues of the human serum albumin (HSA) IIA subdomain to improve its delivery efficiency and selectivity in vivo. However, there may be a conflict in simultaneously achieving the two goals because Lys199 and His242 in the IIA subdomain of HSA can replace its two coordinated ligands, which will decrease its anticancer activity relative to the original metal agent. Thus, to improve the delivery efficiency of the metal agent and simultaneously avoid decreasing its anticancer activity in vivo, we decided to develop an anticancer metal prodrug by regulating its pharmacophore ligand so that it would not be displaced by the Lys199 residue of the folic acid (FA)-functionalized HSA nanoparticle (NP) carrier. To this end, we first synthesized two (E)-N'-(5-chloro-2-hydroxybenzylidene)benzohydrazide Schiff base (HL) Cu(II) compounds by designing a second ligand with a different coordinating atom with Cu2+/Cu(L)(QL)(Br) [C1, QL = quinolone] and Cu(L)(DMF)(Br) [C2, DMF = N,N-dimethylformamide]. As revealed by the structures of the two HSA complexes, the Cu compounds bind to the hydrophobic cavity in the HSA IIA subdomain. The QL ligand of C1 is replaced by Lys199, which coordinates with Cu2+, whereas the DMF ligand of C2 is kept intact and His242 is replaced with Br- of C2 and coordinates with Cu2+. The cytotoxicity of the Cu compounds was enhanced by the FA-HSA NPs in the Bel-7402 cells approximately 2-4-fold; however, they raise the cytotoxicity levels in the normal cells in vitro, and the FA-HSA NPs did not. Importantly, the in vivo data showed that FA-HSA-C2 NPs increased selectivity and the capacity to inhibit tumor growth and were less toxic than HSA-C2 NPs and C2. Moreover, C2/HSA-C2 NPs/FA-HSA-C2 NPs induced Bel-7402 cell death by potentially multiple mechanisms.

Reversible solvent-induced transformation of a one-dimensional uranyl coordination polymer using 4,4′-oxybis(benzoate)

The solvothermal synthesis of uranyl nitrate with 4,4′-oxybis(benzoic acid) produces a coordination polymer [(UO2)(C15H8O5)(DMF)]n with coordinated DMF residing in the void space. This compound consists of one-dimensional chains that extend down [010] from UO7 pentagonal bipyramidal monomers. Thermogravimetric analysis indicates that the material loses the coordinated DMF ligand at 200°C. No sensitized uranyl emission is seen within this system and the only other uranyl compound reported with the same target linker, but weak emission from the organic linker is observed and justified through molecular modeling studies. This system is able to convert between the DMF coordinated and previously reported water coordinated systems upon treatment with water or DMF, respectfully. The title compound showed marked resistance to transformation and/or degradation in a host of other organic solvents.

Three‐Dimensional Co‐ and Mn‐MOFs Containing a C2h‐Symmetric Terphenyl‐3,3′‐dicarboxylate Linker and Their Magnetic Properties

We report herein two new isostructural, three‐dimensional (3D) MOFs with the general formula [M(3,3′‐tpdc)(dmf)] [M = CoII (I), MnII (II)] resulting from the assembly of a metal ion and the C2h‐symmetric ditopic bridging ligand terphenyl‐3,3′‐dicarboxylate (3,3′‐tpdc). Both isostructural MOFs crystallize in the monoclinic space group C2/c. The metal ion is coordinated by four Ocarboxylate (η1:η1:µ2) and two µ2‐Odmf atoms in a distorted octahedral geometry. The metal centers are interconnected through bridging 3,3′‐tpdc and dmf ligands to form a 1D chain. The resulting 1D metal chains are further interconnected by 3,3′‐tpdc ligands to form 3D frameworks without porosity. The thermolabile dmf bridging ligands were easily removed by heating at 180 °C under vacuum for 5 h. The activated MOFs I and II exhibited very low gas uptake of N2, CO2, and H2 after removal of the dmf bridging ligands. The encapsulation of iodine guest molecules by the activated I and II was also investigated. The crystal structure of iodine‐encapsulated II was also elucidated. The coordination environment of the MnII atom in II changed as a result of the loss of dmf bridging ligands. The as‐prepared MOFs I and II exhibit weak antiferromagnetic interactions in their 1D metal chains; these magnetic interactions should mainly occur between the metal ions bridged by the short carboxylate‐based ligand and dmf oxygen atoms. Thermal removal of the bridging dmf molecules led to a change in the Mn···Mn distances in the 1D chains of II that also affected its magnetic properties.

Crystal structure of hexa-kis-(di-methyl-formamide-κO)manganese(II) deca-kis-(di-methyl-formamide)-1κ(5) O,2κ(5) O-[μ-octa-deca-tungstodiphosphato(V)-κO:κO']dimanganate(II) di-methyl-formamide disolvate.

The crystal structure of the title compound, [Mn(C3H7NO)6][{Mn(C3H7NO)5}2(μ-P2W18O62)]·2C3H7NO, reveals that the Wells-Dawson-type polyanion [P2W18O62](6-), through terminal O atoms from the belts, bridges two Mn(II) octa-hedral complexes. In the complex anion [{Mn(dmf)5}2(μ-P2W18O62)](2-), located around a twofold rotation axis, the Mn(II) ions are coordinated by five O atoms from di-methyl-formamide (dmf) ligands and to a terminal O atom from the [P2W18O62](6-) polyanion. Another Mn(II) ion, located on an inversion centre, is coordinated by six O atoms from the dmf ligands and forms the [Mn(dmf)6](2+) cation. The crystal components are connected through numerous weak C-H⋯O hydrogen bonds to construct a three-dimensional network.

A thiadiazole-functionalized Zr(iv)-based metal–organic framework as a highly fluorescent probe for the selective detection of picric acid

A new, strongly luminescent Zr(IV)-based metal–organic framework (MOF) material (1) having a UiO-68 (UiO = University of Oslo) framework topology and incorporating the π-conjugated, thiadiazole-functionalized H2BTDB {H2BTDB = 4,4′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzoic acid} ligand was synthesized under solvothermal conditions (150 °C, 24 h) using ZrCl4 and the H2BTDB ligand in DMF (DMF = N,N-dimethylformamide). The phase-purity of as-synthesized 1 was ascertained by X-ray powder diffraction (XRPD) analysis, Fourier transform infrared (FT-IR) spectroscopy and elemental analysis. Based on the thermogravimetric analyses, 1 is thermally stable up to 400 °C. XRPD experiments verify that activated 1′ retains its crystallinity when exposed to water, acetic acid and 1 M HCl solutions. As revealed by the steady-state fluorescence titration experiments, the thermally activated form of the compound (1′) showed a selective sensing behaviour towards 2,4,6-trinitrophenol (TNP, commonly known as picric acid), even in the presence of other potentially competing nitroaromatic explosive compounds. The estimated detection limit of 1′ for sensing TNP in methanol suspension was found to be 1.63 × 10−6 M. The highest fluorescence quenching ability of TNP can be attributed to both energy and electron transfer processes as well as electrostatic interactions between the hydroxyl group of TNP and the Lewis basic N-donor sites of the BTDB ligand. Endowed with its excellent detection efficiency, 1′ is a promising luminescent sensor material for the long-term, practical sensing of TNP.

Three-dimensional cobalt(II) and cadmium(II) MOFs containing 1,4-naphthalenedicarboxylate: Catalytic activity of Cd-MOF

Three-dimensional (3D) cobalt(II) and cadmium(II) metal–organic frameworks (MOFs) bearing rigid 1,4-naphthalenedicarboxylate (1,4-NDC) linkers were prepared and their solid-state structures were characterized by X-ray crystallography. Both Co-MOF and Cd-MOF exhibited isostructural frameworks. 1,4-NDC ligands bridge the metal ions in chelating/bridging and simple bridging modes to form a 1D chains, and these 1D chains are interconnected by 1,4-NDC to form 3D frameworks with the formula of [M2(1,4-NDC)2(DMF)2] (M=CoII or CdII). The as-prepared Cd-MOF was found to be catalytically active for the cyanosilylation reaction of aromatic aldehydes with nitro substituent in varying positions in the presence of trimethylsilyl cyanide to afford cyanohydrin trimethylsilyl ethers in a shape and size selective manner. The catalytic reaction is thought to have mainly occurred inside the Cd-MOF micropores which were generated through the partial dissociation of DMF ligands near the surfaces of Cd-MOF, where openly accessible coordination sites are available once the labile DMF ligands dissociate from CdII ions. The as-prepared Co-MOF did not exhibit catalytic activities for the same reaction.

Syntheses and structures of complexes {Mo2S2O2}2+ with labile Cl− and DMF ligands

Complex (Me4N)2[Mo2S2O2Cl4] ((Me4N)2[II]) is synthesized by passing gaseous HCl through a solution of (Me4N)2[Mo2O2S8] ((Me4N)2[I]). The recrystallization of (Me4N)2[II] from N,N-dimethylformamide (DMF) gives compound (Me4N)[Mo2S2O2Cl3(DMF)3] ((Me4N)[III]). The oxidation of (Et4N)2[I] with iodine in DMF affords the earlier described complex [Mo2S2O2(DMF)6]I2 ([IV]I2). However, this complex was not structurally characterized. The structures of the synthesized compounds are determined by X-ray diffraction analyses (CIF files CCDC nos. 1059924–1059926). Thus, several complexes in which the binuclear fragment {Mo2S2O2}2+ has a labile coordination environment were synthesized and characterized.

Influence of metal ions on the formation of new metal complexes constructed from tetrachlorophthalic acid

Abstract Reaction of 3,4,5,6-tetrachloro-1,2-benzenedicarboxylyic acid (1,2-H2BDC-Cl4) with transitional metal salts at room temperature in mixed DMF/H2O solvent affords three complexes formulated as [Cu(1,2-HBDC-Cl4)2(DMF)2] (1), {[Cd(1,2-HBDC-Cl4)2(H2O)4]·2DMF} (2), and {[Ni(1,2-BDC-Cl4)(H2O)5]·DMF·H2O} (3) (DMF = N,N-dimethylformamide). All these complexes have been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, and single-crystal X-ray crystallography. In 1, the CuII ion is four-coordinated with a square-planar geometry formed by two 1,2-HBDC-Cl4 anions and two DMF ligands; in 2, the CdII ion takes an octahedral geometry coordinated by two 1,2-HBDC-Cl4 anions and four aqua ligands; while in 3, the NiII ion is octahedrally coordinated by one 1,2-BDC-Cl4 dianion and five aqua ligands. Intermolecular O–H···O hydrogen bonds and Cl···Cl (or C–H···Cl) interactions provide a significant contribution to stabilizing the three mononuclear structures in the solid state. The results suggest that structural differences among them are attributed to the influence of transition metal ions. The fluorescence of the complexes and of 1,2-H2BDC-Cl4 has been investigated. No significant metal effect has been observed.

Crystal structure of poly[bis-(μ-2-amino-4,5-di-cyano-imidazolato-κ(2) N (1):N (3))-trans-bis-(N,N'-di-methyl-formamide-κO)cadmium

In the title structure, [Cd(C5H2N5)2(C3H7NO)2] n or [Cd(adci)2(DMF)2] n , the Cd(2+) ion is located on a twofold rotation axis and is six-coordinated in a CdN4O2 manner by four imidazole N atoms of four symmetry-related 2-amino-4,5-di-cyano-imidazolate (adci) anions in the equatorial plane and by two O atoms of symmetry-related N,N-di-methyl-formamide (DMF) ligands in axial positions. The adci(-) anions bridge adjacent Cd(2+) ions [shortest Cd⋯Cd separation = 6.733 (3) Å] into a layered coordination polymer extending parallel to (001). The primary amino group and the non-coordinating cyano groups of adci(-) anions are involved in hydrogen-bonding inter-actions with DMF ligands to stabilize the crystal structure.