DMF Molecules Research Articles

Zn(II)-formate Framework of mab topology: Synthesis from tea extract, electronic structure, and DNA-binding

A new synthetic method for developing novel Metal Organic Frameworks(MOFs) of Zn(II) is reported here. Its formation is confirmed by single X-ray crystallography, FT-IR and UV-visible spectroscopy measurement. The polymeric (ZnC2H6O6)n (1) complex was synthesized from a mixture of tea extract, LiCl and zinc nitrate in DMF-Dioxane-H2O solvent. In contrast to the well-known perovskite-type Zn(II)-formate frameworks of pcu topology the resulting compound has topology of different 6-c net mab. Herein we studied the relations between structural characteristics of the less usual mab-type formate and properties. The origin of the formation of formate is not established but may form via the hydrolysis of DMF molecules. The oxidation state of Zn in the complex was +2 and confirmed by BVS calculation. The optical band gap of the polymeric complex was 5.2eV indicates its electronic properties. Density Function Theory (DFT) also justified the structural and electronic parameters of the complex. The bioactivity of the complex 1 has been established by the ability to bind CT-DNA with intercalation mode and the binding constant was Kb =1.74 × 102 M−1.

Gd(III) metal-organic framework as an effective humidity sensor and its hydrogen adsorption properties

Metal-organic frameworks (MOFs) represent a class of nanoporous materials built up by metal ions and organic linkers with several interesting potential applications. The present study described the synthesis and characterization of Gd(III)-based MOF with the chemical composition [Gd(BTC)(H2O)]·DMF (BTC – trimesate, DMF = N,N′-dimethylformamide), known as MOF-76(Gd) for hydrogen adsorption/desorption capacity and humidity sensing applications. The structure and morphology of as-synthesized material were studied using powder X-ray diffraction, scanning and transmission electron microscopy. The crystal structure of MOF-76(Gd) consists of gadolinium (III) and benzene-1,3,5-tricarboxylate ions, one coordinated aqua ligand and one crystallization DMF molecule. The polymeric framework of MOF-76(Gd) contains 1D sinusoidally shaped channels with sizes of 6.7 × 6.7 Å propagating along c crystallographic axis. The thermogravimetric analysis, heating infrared spectroscopy and in-situ heating powder X-ray diffraction experiments of the prepared framework exhibited thermal stability up to 550 °C. Nitrogen adsorption/desorption measurement at −196 °C showed a BET surface area of 605 m2 g−1 and pore volume of 0.24 cm3 g−1. The maximal hydrogen storage capacity of MOF-76(Gd) was 1.66 wt % and 1.34 wt % −196 °C and −186 °C and pressure up to 1 bar, respectively. Finally, the humidity sensing measurements (water adsorption experiments) were performed, and the results indicate that MOF-76(Gd) is a suitable material for moisture sensing application with a fast response (11 s) and recovery time (2 s) in the relative humidity range of 11–98%.

A Smart Molecule Showing Spin Crossover Responsive Aggregation-Induced Emission

A Smart Molecule Showing Spin Crossover Responsive Aggregation-Induced Emission

Electrochemical synthesis of 2D copper coordination-polymers: Layer-stacking deviation induced by the solvent and its effect on the adsorptive properties

A 2D Cu-based Metal-Organic Framework (MOF), namely copper-terephthalate (Cu(1,4-BDC)), was successfully synthesized by electrochemical method for effective methylene blue (MB) sorption from aqueous solutions. The composition, morphology, and the presence of functional groups in the obtained material were verified by Fourier Transform Infrared spectroscopy (FTIR), Powder X-Ray Diffraction (PXRD), Thermal (TGA), and Elemental (EA) analysis, as well as Scanning Electron Microscopy (SEM). The effect of electrochemical parameters applied in the synthesis protocol (i.e., a potentiometric or amperometric mode) on the resulting product composition was evaluated. The electric current value was determined as a variable controlling the type of crystal structure present in the obtained MOF. A structure with open channels - CuBDC1 was favored under the current higher than 0.35 A conditions. In contrast, for the lower current values and upon the amperometric mode in the material, a CuBDC2 phase with DMF molecules occupying the grids of the layers was also present. The MB sorption studies were analyzed both with kinetic and equilibrium models. The obtained results showed the time evolution could be fitted with a pseudo-second-order model with the rate constant k2 equal to 0.047 g μmol−1 h−1. According to the Langmuir isotherm model, the maximum sorption capacity was determined as 76.63 μmol g−1. After MB sorption, the MOF material could be easily regenerated under mild conditions with good recyclability up to the four cycles (76.77%).

An unexpected single crystal structure of nickel(II) complex: Spectral, DFT, NLO, magnetic and molecular docking studies

This work explores the study of a synthesized nickel complex as a possible inhibitor against the main protease (Mpro) of the recent emerging coronavirus disease (COVID-19). Overall, the template reaction of 3-acetyl-2-hydroxy-6-methyl-4H-pyran-4-one with nickel(II) chloride hexahydrate in N,N-dimethylformamide (DMF) medium leads to the formation of neutral nickel complex. This resulting complex is formulated as [Ni(DHA)2(DMF)2] on the basis of FT-IR, UV-Vis., single-crystal X-ray diffraction analysis, magnetic susceptibility and CV measurements as well as DFT quantum chemical calculations. Its single crystal suggests was found to be surrounded by the both pairs of molecules of DHA and DMF through six oxygen atoms with octahedral coordination sphere. The obtained magnetic susceptibilities are positive and agree with its paramagnetic state. In addition to the experimental investigations, optimized geometry, spectroscopic and electronic properties were also performed using DFT calculation with B3LYP/6-31G(d,p) level of theory. The nonlinear optical (NLO) properties of this complex are again examined. Some suitable quantum descriptors (EHOMO, ELUMO, Energy gap, Global hardness), Milliken atomic charge, Electrophilic potion and Molecular Electrostatic Potential) have been elegantly described. Molecular docking results demonstrated that the docked nickel complex displayed remarkable binding energy with Mpro. Besides, important molecular properties and ADME pharmacokinetic profiles of possible Mpro inhibitors were assessed by in silico prediction.

Synthesis, structure and luminescent properties of Zn(II) metal–organic frameworks constructed by flexible and rigid ligands

The synthesis of new coordination polymers based on flexible ligands is a challenging task. The use of two types of ligands is a possible approach to obtain crystalline compounds. The combination of flexibility and rigidity can lead to unusual topologies and properties. We are managed to obtain two new metal–organic frameworks (MOFs) based on flexible 1,3-bis(2-methylimidazolyl)propane and rigid isophtalic (1,3-benzenedicarboxylic) acid: [Zn2(iph)2(bmip)2] (1) and [Zn4(iph)4(bmip)3]·2DMF·3.5H2O (2). Structure of both compounds were determined by single-crystal X-ray analysis. Compound 1 is 3-fold interpenetrating 3D framework with dmp topology. Compound 2 is 2-fold interconnecting 3D framework with rare topology, described as (4,6)-c net. Compound 2 contains guest DMF and water molecules. Interestingly, compound 2 easily loses guest molecules in air and undergoes to another crystalline compound 2a. The photoluminescence at room temperature of the compounds 1 and 2a were investigated in the solid state. Quantum yields (QY) of luminescence for 1 and 2a are 30.5% and 39.8%, respectively. The short decay times are allowed to attribute the emission to fluorescence characteristic for intraligand transitions.

Joining a host-guest platform and a light-emission motif: Pyrazinamide-calixarene hybrids

Calixarenes are macrocyclic polyphenols widely used as hosts in supramolecular chemistry approaches. Recently, aminopyrazine has emerged as a high-efficiency blue light emitting moiety. Inspired by this knowledge, here we prepared two pyrazinamide-calixarene hybrids, in order to join in a single molecular platform both host-guest and light-emission properties. Both compounds were decorated with pyrazinamide at the upper rim, on two phenyl rings alternated into the four-units of the calixarene macrocycle. Their difference was the t‑butyl substitution on the other two alternate phenyl rings. The t‑butyl substituted derivative crystallized in two crystal forms, a non-solvated and a DMF mono-solvate phase, both with just one crystallographically independent hybrid molecule, while the compound without t‑butyl moieties crystallized with three hybrid conformers and four DMF molecules. The molecular substitution pattern has also impacted on the crown conformation, being related to more inclined pyrazinamide-phenyl average planes in the absence of the t‑butyl substituents. The coplanarity pattern between pyrazinamide and its bonded phenyl ring and the conformational profile of this substituent changed among the three conformers of derivative without the t‑butyl group and between those assembling the two crystals forms of the other compound, which was also found in our DFT calculations. Under an excitation wavelength of 388 nm, a broad band emission between 400 nm and 550 nm was found for the three crystal forms, with maxima at ca. 500 nm, with low quantum yields of up to 0.4%. TD-DFT absorption spectra were overlaid to the experimental excitation spectra, while the low efficiency was rationalized both as an effect of the DMF guest and the tail-to-tail π…π stacking interactions between coplanar pyrazinamide-phenyl moieties of the centrosymmetric related molecules.

Zn(II) and Co(II) 3D Coordination Polymers Based on 2-Iodoterephtalic Acid and 1,2-bis(4-pyridyl)ethane: Structures and Sorption Properties.

Metal-organic frameworks [M2(2-I-bdc)2bpe] (M = Zn(II) (1), Co(II) (2), 2-I-bdc = 2-iodoterephtalic acid, and bpe = 1,2-bis(4-pyridyl)ethane) were prepared and characterized by X-ray diffractometry. Both compounds retain their 3D structure after the removal of guest DMF molecules. Selectivity of sorption of different organic substrates from the gas phase was investigated for both complexes.

A Multicenter Metal–Organic Framework for Quantitative Detection of Multicomponent Organic Mixtures

A Multicenter Metal–Organic Framework for Quantitative Detection of Multicomponent Organic Mixtures

Stereocomplex formation and hierarchical structural changes during heating of supramolecular gels obtained by polylactide racemic blends

Solvents that are capable of forming crystalline complexes with poly(ʟ-lactide) (PLLA) have been known to form thermoreversible gels. However, the gelation behavior of linear PLLA/poly(ᴅ-lactide) (PDLA) blends has not been studied. Herein, the formation of supramolecular gels using PLLA/PDLA blends in N,N-dimethylformamide (DMF) is reported. The structural changes of these gels were investigated in multiple length scales during heating. In blend gels, both homopolymers crystallize into the ε form. On heating, DMF molecules that are present in the crystal lattice of the ε form are expelled out by keeping the lamellar structure intact and the structure transformed to the α form. At 45 °C, stereocomplex (SC) crystals are also formed due to the activated thermal motion of enantiomeric chains in the presence of solvent. The α form became unstable at ∼75 °C and the enantiomeric polymer chains reorganized into the SC. In the case of low molecular weight blend gels, high chain mobility and chain diffusion ability resulted in the more stable SC. A structural model is proposed to explain the phase transition behavior of blend gels. This study not only enhances the fundamental understanding of SC formation but also provides opportunities to exploit the molecular recognition in helical polymers.

Porous Lanthanide Metal-Organic Frameworks Using Pyridine-2,4-dicarboxylic Acid as a Linker: Structure, Gas Adsorption, and Luminescence Studies.

Two types of new lanthanide coordination networks, [Ln3(pdc)4(Hpdc)(H2O)3]·8H2O [H2pdc = pyridine-2,4-dicarboxylic acid; Ln = Ce (1), Pr (2), Sm (3), Eu (4); type A) and [Tb5(pdc)4(Hpdc)]·3H2O (type B), have been synthesized using a hydrothermal synthetic method. The former type A compound has an unfamiliar architecture, even basically comprised of primitive cubic (pcu) topology, and demonstrate porous gas adsorption behavior, giving several hundreds of square meters per gram surface areas after evacuation of the water molecules, while the latter type B compound does not show any porous properties. Most interestingly, the solvothermal synthetic method using N,N-dimethylformamide (DMF) as a solvent gives compounds that crystallize in a structure analogous to that of type A for Ln = La-Ho, probably formulated as [Ln3(pdc)4(Hpdc)·(DMF)m]·nDMF. These compounds also exhibit large surface areas after evacuation of the DMF molecules and also moderate amounts of hydrogen gas uptake at 77 K. The luminescence properties were investigated for Eu and Tb analogues at elevated temperatures, at which an unusual increase in the emission intensity was observed upon the release of solvents, and discussed based on their porous structure.

Raman spectra and non-empirical calculations of dimethylformamide molecular clusters structure

The article presents the results of a study on the formation of molecular clusters of dimethylformamide. The intermolecular interactions of isolated molecular clusters have been simulated by B3LYP/(6-31G++(d,p) method. It is shown that hydrogen bonding and resonant transfer of vibrational energy play an important role in the formation of molecular clusters by dimethylformamide molecules. Methyl and aldehyde groups of a DMF molecule act as proton donors in the formation of molecular clusters, CO is a strong acceptor. It was shown that in solutions of DMF with water, an H-bond is formed between the oxygen of NCOH group and the hydrogen atom of water.

A new coordination compound based on 3, 3′-bis(1H-tetrazol-5-yl)-4, 4′-azofurazan (H2BTZAF): Preparation, crystal structure, and thermal properties

A new nitrogen-rich energetic complex Cd(DMF)2BTZAF (1) (DMF= N,N-Dimethylformamide, H2BTZAF= 3, 3′-bis(1H-tetrazol-5-yl)-4, 4′-azofurazan) was first synthesized by the reaction of Cd(NO3)2·4H2O with 4-amino-3-(5-tetrazolate)-furazan. The compound 1 was characterized by elemental analysis and FT-IR spectrum analysis, respectively. The crystal structure of complex 1 was determined by single-crystal X-ray diffraction. It revealed that 1 crystallizes in the monoclinic space group P21/c. A Cd2+ ion is coordinated by four N atoms and two O atoms to form a distorted octahedral structure. Among them, four nitrogen atoms are from the four BTZAF2− ions and the other two oxygen atoms are from two DMF molecules. Moreover, the thermal decomposition behavior of compound 1 was studied with DSC and TG-DTG methods. The non-isothermal kinetic parameters of compound 1 was calculated by Kissinger's method and Ozawa-Doyle's method. In addition, the thermal safety performance and the impact sensitivity of complex 1 were measured and calculated, and the results showed that the synthetic compound has good insensitivity and stability.

Solubility modeling and solvation behavior of 3,3′-diamino diphenylsulfone in binary aqueous mixtures of isopropanol, methanol, ethanol and N,N-dimethylformamide

Experimentation of equilibrium solubility of 3,3′-diamino diphenylsulfone (DDS) in binary solvents of isopropanol/N,N-dimethylformamide (DMF)/methanol/ethanol + water was executed by means of the shake-flask technique under pressure of 101.2 kPa ranging from 283.15 to 328.15 K. At the experimental conditions of same temperature and same compositions of solvent species, the maximum solubility magnitude of DDS in mole fraction was found in the DMF + water solution system; and the minimum one, in the isopropanol + water solution system. Solubility correlation was made by employing four parametric expressions, e.g. modified Wilson, Jouyban–Acree, mixture response surface (MRS) and modified Jouyban–Acree–van’t Hoff, getting the root-mean-square and relative average deviations of no greater than 323.9 × 10−5 and 7.30 %, respectively. The extended Hildebrand solubility approach was practiced here to investigate the inter- and intra-molecule interactions of studied systems. In the regions of poor organic solvent composition, association behavior appears between DDS and solvent species in solutions. What's more, quantitative evaluation of the local compositions of DMF (methanol, isopropanol or ethanol) and water in the vicinity of DDS were carried out by employing the technique of Inverse Kirkwood–Buff integrals. In rich proportions of organic solvents for the studied solution systems, DDS was preferentially solvated by DMF (methanol, isopropanol or ethanol). DDS could mostly serve as a Lewis acid in front to the molecules of DMF (methanol, isopropanol or ethanol).

Anisotropic Electrical Conductivity of a Single-Crystalline Oxo-Bridged Cr4IIIMo2VI Heterometallic Complex.

A new oxo-bridged chromium-molybdenum heterometallic complex, O-CrMoHC ([Cr4(MoO4)2O2(OAc)4(DMF)4]·2DMF), was synthesized by using a simple solvothermal reaction. In this complex, the octahedrally coordinated Cr(III) and tetrahedrally coordinated Mo(VI) metal centers are bridged by oxo ligands. O-CrMoHC has in-plane π-conjugation systems, which are interconnected by noncoordinating DMF molecules. The crystals show anisotropic conductivity with respect to the crystal planes, and theoretical calculations were used to study their origins. The O-CrMoHC single crystals exhibited that a relatively high electrical conductivity with an average value of 5.37 × 10-7 S/cm was observed along the [01-1] direction, but the current level was very low along the [100] direction. This is the first report of anisotropic conductivity observed in the single crystal of a monomeric heterometallic complex.

Paramagnetic Molecular Semiconductors Combining Anisotropic Magnetic Ions with TCNQ Radical Anions.

We report the synthesis, magnetic properties, and transport properties of paramagnetic metal complexes, [Co(DMF)4(TCNQ)2](TCNQ)2 (1), [La(DMF)8(TCNQ)](TCNQ)5 (2), and [Nd(DMF)7(TCNQ)](TCNQ)5 (3) (DMF = N,N-dimethylformamide, TCNQ = 7,7,8,8-tetracyanoquinodimethane). All three compounds contain fractionally charged TCNQδ- anions (0 < δ < 1) and mononuclear complex cations in which the coordination environment of a metal center includes several DMF molecules and one or two terminally coordinated TCNQδ- anions. The coordinated TCNQδ- anions participate in π-π stacking interactions with noncoordinated TCNQδ- anions, forming columnar substructures that provide efficient charge-transporting pathways. As a result, temperature-dependent conductivity measurements demonstrate that all three compounds exhibit semiconducting behavior.

Construction of unsymmetrical bis‐ureamacrocyclic host for neutral molecule and chloride‐ion binding

AbstractConstruction of synthetic macrocyclic host that can bind with neutral molecules and anions has potential applications in supramolecular chemistry. Herein, we have designed and synthesized blue light emitting an unsymmetrical neutral bis‐urea macrocyclic host. This macrocycle can bind with neutral DMF molecule (1:1) as well as Cl−ion (1:1) through noncovalent interactions. X‐Ray crystal structure,1H NMR titrations with Job's Plot, HRMS with isotropic distribution pattern, FT‐IR, and density functional theory analysis revealed the binding of bis‐urea macrocyclic host with the guest molecule.

Quantum chemical calculations on dissolution of dimethylformamide in ethaline

Deep-eutectic solvents (DESs) gained attention of researchers as green solvents. Making binary mixtures of DESs with appropriate cosolvents is a strategy to obtain more favorable mixtures. Here, structural features and hydrogen bonding (H-bonding) properties of binary mixtures containing ethaline (ETH) DES, (choline chloride (ChCl):2 ethylene glycol (EG)) with N,N-dimethylformamide (DMF) are reported. Such investigations are carried out by density functional theory (DFT) calculations. The results show that in ETH-DMF mixtures, DMF molecules can hardly overcome the strong Columbic interaction and doubly ionic H-bonds between the ions Ch+ and Cl− or the ionic H-bonds between Ch+ and EG. Upon EG addition to ChCl to obtain ETH or DMF addition to ETH, the Cl− … Ch+ connectivity decreases, implying charge delocalization from Cl− to other components rather than Ch+. This is supported by the blue shift of Ch+ hydroxyl observed in the calculated infrared spectra.

Calculation of the Free Energy of Mixing as a Tool for Assessing and Improving Potential Models: The Case of the N,N-Dimethylformamide-Water System.

The Helmholtz free energy, energy, and entropy of mixing of N,N-dimethylformamide (DMF) and water are calculated in the entire composition range by means of Monte Carlo computer simulations and thermodynamic integration using all possible combinations of five DMF and three widely used water models. Our results reveal that the mixing of DMF and water is highly non-ideal. Thus, in their dilute solutions, both molecules induce structural ordering of the major component, as evidenced by the concomitant decrease in the entropy. Among the 15 model combinations considered, only 4 reproduce the well-known full miscibility of DMF and water, 3 of which strongly exaggerate the thermodynamic driving force of the miscibility. Thus, the combination of the CS2 model of DMF and the TIP4P/2005 water model reproduces the properties of the DMF-water mixtures far better than the other combinations tested. Our results also reveal that moving a fractional negative charge from the N atom to the O atom of the DMF molecule, leading to the increase in its dipole moment, improves the miscibility of the model with water. Starting from the CS2 model and optimizing the charge to be moved, we propose a new model of DMF that reproduces very accurately both the Helmholtz free energy of mixing of aqueous DMF solutions in the entire composition range (when used in combination with the TIP4P/2005 water model) and also the internal energy of neat DMF.

Crystal Engineering of Schiff Base Zn(II) and Cd(II) Homo- and Zn(II)M(II) (M = Mn or Cd) Heterometallic Coordination Polymers and Their Ability to Accommodate Solvent Guest Molecules.

Based on solvothermal synthesis, self-assembly of the heptadentate 2,6-diacetylpyridine bis(nicotinoylhydrazone) Schiff base ligand (H2L) and Zn(II) and/or Cd(II) salts has led to the formation of three homometallic [CdL]n (1), {[CdL]∙0.5dmf∙H2O}n (2) and {[ZnL]∙0.5dmf∙1.5H2O}n (3), as well as two heterometallic {[Zn0.75Cd1.25L2]∙dmf∙0.5H2O}n (4) and {[MnZnL2]∙dmf∙3H2O}n coordination polymers. Compound 1 represents a 1D chain, whereas 2–5 are isostructural and isomorphous two-dimensional structures. The entire series was characterized by IR spectroscopy, thermogravimetric analysis, single-crystal X-ray diffraction and emission measurements. 2D coordination polymers accommodate water and dmf molecules in their cage-shaped interlayer spaces, which are released when the samples are heated. Thus, three solvated crystals were degassed at two temperatures and their photoluminescent and adsorption–desorption properties were recorded in order to validate this assumption. Solvent-free samples reveal an increase in volume pore, adsorption specific surface area and photoluminescence with regard to synthesized crystals.