DMF Solvate Research Articles

Synthesis, characterization, and antimicrobial properties of two Cu(II) complexes derived from a benzimidazole ligand

Two copper(II) complexes, [Cu(L)2](ClO4)2] and [Cu(L)(bipy)](ClO4)2, were prepared and characterized by the spectroscopic and analytic methods, where L is N-butylbenzimidazole and bipy is 2,2′-bipyridine. Single crystals of [Cu(L)(bipy)](ClO4)2 suitable for X-ray diffraction study were obtained by slow diffusion of diethyl ether into a DMF solution of the complex and the complex was found to crystallize as [Cu(L)(bipy)](ClO4)2·DMF. The asymmetric unit contains one [Cu(L)(bipy)]2+, two uncoordinated perchlorates, and one DMF solvate. Coordination geometry around Cu(II) is distorted square pyramidal with τ value of 0.31. Thermal properties of the complexes were examined by thermogravimetric analysis, indicating that the complexes are thermally stable to 310 °C. The metal complexes were screened for their in vitro antibacterial and antifungal activities Bacillus subtilis and Bacillus cereus (as Gram(+) bacteria), Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae (as Gram(–) bacteria), and Saccharomyces cerevisiae, Candida utilis, and Candida albicans (as yeasts). The complexes show antibacterial and antifungal activities against bacteria and yeasts.

Super‐Efficient Platinum Catalyst Derived from a Semiconducting, DMF Solvate: Structural, Spectroscopic, Electrochemical, and Catalytic Characterization

AbstractThe reaction of [(NH3)4Pt](NO3)2 with LiTCNQF4 (TCNQF4=2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane) in dimethylformamide gives the product [(NH3)4Pt](TCNQF4)2⋅(DMF)4 (1). Subtle changes in the solvent conditions, however, result in a different product, [(NH3)4Pt](TCNQF4)2⋅Et2O⋅(CH3OH)4/3 (2). Both 1 and 2 have been characterized by X‐ray crystallography, vibrational (FTIR, Raman) and UV/vis spectroscopy, thermogravimetric analysis and electrochemistry. Single crystals of 1 indicate the presence of 3 D networks supported by hydrogen bonding, whereas the structural analysis of 2 indicates a 2 D layered network, which consists of alternating TCNQF4− and [(NH3)4Pt]2+ layers. The conductivity of a single crystal of 1 at room temperature lies in the semiconducting range (≈2.5×10−6 S cm−1). Unexpectedly, 1 was found to exhibit an exceptionally high catalytic activity for the electron transfer reaction between ferricyanide and thiosulfate ions in aqueous media. Our analysis indicates that the DMF solvates were removed prior to the catalytic reaction, but no other changes that occur in the chemical composition were found. Thus, the active catalyst is [(NH3)4Pt](TCNQF4)2 (3) rather than the starting material 1.

Crystal Structures of S-Shaped Phenylenediurea Dibenzoic Acids and Their Cocrystals with Melamine: Unusual Zigzag Tape of H-Bonded Melamine Network

Phenylenediurea dibenzoic acid derivatives 1, 2, 3, and 5 and an amide derivative 4 were synthesized, and their molecular structures were elucidated to be an S-shape by single crystal X-ray analysis. Crystals of 1 were obtained as a DMF solvate, while those of 2 and 3 were not. Sheet and ladder structures were created in the crystal packing of 1 and 3, and 2, respectively. Unlike the para-substituted diureas 1–3 which possessed meso-conformation, the meta-substituted diurea 5 exhibited helical-conformation in its crystal structure. The way of crystal packing of 4 is analogous to that of the corresponding dicarboxylic acid derivative 2. A water cluster of a chair-shaped hexagonal array of water molecules was created in the crystal structure of 4. Diureas 1 and 2 gave cocrystals with melamine recrystallized from DMF/ethyl acetate and DMF/H2O, respectively. Unusual zigzag tapes of a H-bonding network of melamine were created in both cocrystals. The zigzag tapes were connected with S-shaped diureas by H-bondi...

Li2(tF‐BDC)(DMF)2]: A New Alkali Metal Salt of Tetra­fluoroterephthalic Acid (H2tF‐BDC)

AbstractThe DMF solvate of lithium tetrafluoroterephthalate [Li2(tF‐BDC)(DMF)2] (H2tF‐BDC = tetrafluoroterephthalic acid) was synthesized and structurally characterized from X‐ray single crystal data (Pbcn, Z = 8). Li+ (CN = 4) is coordinated tetrahedrally by four oxygen atoms of three different tF‐BDC2– linkers and one DMF molecule. The LiO4 tetrahedra are connected by common vertices to chains, which are bridged by tF‐BDC2– linkers to form a 2D polymeric unit. The DMF molecules are oriented perpendicular to these polymeric sheets, which are stacked along [100] in an AB fashion and held together by weak van der Waals interactions. Single crystals of [Li2(tF‐BDC)(DMF)2] were synthesized by precipitation from an ethanol/DMF solvent mixture, but single‐phase samples were only obtained by a mechanochemical approach starting from lithium acetate and H2tF‐BDC by adding DMF. The thermal stability of [Li2(tF‐BDC)(DMF)2] was investigated by DTA/TG measurements. The (endothermic) decomposition starts at 170 °C and is followed by a second exothermic decomposition at approx. 300 °C. The weight losses are in good agreement with a release of DMF and CO2. LiF is identified in the residue after heating at 500 °C.

The N–H···X Hydrogen Bonds in the Crystal Structures of (Thio)Isochromene Derivatives

The 6-amino-8-(2,3-dichlorophenyl)-8,8a-dihydro-1H-isothiochromene-5,7,7(3H)- tricarbonitrile DMF solvate (1) and 6-amino-8-(2,4-dichlorophenyl)-8,8a-dihydro-1H-isochromene-5,7,7(3H)-tricarbonitrile DMF solvate (2) were synthesized and characterized by IR, 1H NMR and HRMS. The molecular structures were further confirmed by X-ray diffraction analysis. The former 1, C21H19Cl2N5OS, is monoclinic, space group P2(1)/c, a = 9.8139(3), b = 7.4629(2), c = 29.2903(9) A, β = 96.299(1), Z = 4, V = 2132.27(11) A3. The latter 2, C21H19Cl2N5O2, is monoclinic, space group P2(1)/c, a = 17.0495(4), b = 8.9021(2), c = 16.1718(4) A, β = 116.668(2), Z = 4, V = 2193.39(9) A3. It is very interesting that they are all form a inter-molecular hydrogen bond of N–H···O, linking a molecule of DMF. Another hydrogen atom on the same amino group forms a hydrogen bond of N–H···S, forming polymers in 1. However, it links adjacent molecules forming dimmers via hydrogen bond of N–H···N in 2.

Conformational Polymorphism in a Non-steroidal Anti-inflammatory Drug, Mefenamic Acid

For several years, the non-steroidal anti-inflammatory drug mefenamic acid, MA, has been known to exist as dimorphs (I and II). We report a new metastable polymorph (III) of MA obtained during attempted co-crystallization experiments and establish its stability relationship with existing forms. At elevated temperatures I and III convert to II, as evident from DSC experiments. On the basis of the lattice energy calculations in conjunction with thermal analysis, the stability order is proposed to be I > II > III at ambient conditions, whereas at elevated temperature the order is II > I > III. In either condition III is a metastable form and hence transforms to I at ambient conditions and to II at higher temperatures. Also we report the structural studies of a DMF solvate and a cytosine complex.

Structural Flexibility and Sorption Properties of 2D Porous Coordination Polymers Constructed from Trinuclear Heterometallic Pivalates and 4,4′‐Bipyridine

AbstractThe temperature dependence of crystal structure parameters of isostructural coordination polymers Fe2MO(Piv)6(bipy)1.5·2DMF [1·2DMF and 2·2DMF, where M = NiII or CoII, respectively, Piv = (CH3)3CCO2–, bipy = 4,4‐bipyridine and DMF is N,N‐dimethylformamide] was studied at five temperatures in the range from 120 to 296 K. The X‐ray structure of the N,N‐diethylformamide (DEF) solvate of the same coordination polymer 1, Fe2NiO(Piv)6(bipy)1.5·2DEF (1·2DEF), was studied at 173 and 260 K. Both the DMF and DEF solvates possess similar crystal structures, consisting of a series of parallel 2D polymeric layers with honeycomb voids. These series of parallel layers intersect, leading to their interpenetration and formation of zig‐zag channels. It was found that the change of temperature and/or solvent molecule in the pores causes significant structural rearrangement associated with a change of the separation between parallel layers and the angle between intersecting layers. These structural changes lead to a variation of the calculated solvent‐accessible volume from 0.21 cm3 g–1 (120 K, 2·2DMF) to 0.30 cm3 g–1 (260 K, 1·2DEF) for a probe molecule with r = 1.4 Å. These changes can model structural transformations which can occur at desolvation and adsorption of guests. Adsorption of n‐hexane, n‐octane, methanol and ethanol by Fe2MO(Piv)6(bipy)1.5 was studied. The sorption isotherms of alkanes were typical for microporous sorbents and in this case the behaviour of the coordination polymers resembled that which is typical for sorbents with a rigid structure. In a contrast, alcohol sorption capacity continuously grew at increasing pressure which may be caused by structural transformations, similar to temperature‐induced structural transformations. Among the studied sorbates, sorption capacity grew in order methanol < ethanol < n‐hexane < n‐octane which may be caused by the hydrophobic nature of the channels (due to the presence of tert‐butyl groups).

Oxidovanadium complexes with tetradentate Schiff bases: Synthesis, structural, electrochemical and catalytic studies

A series of new tridentate Schiff base ligands derived from the condensation of 4,5-dinitro-1,2-phenylenediamine and various salicylaldehyde derivatives was synthesized and characterized by common spectroscopic and analytical methods. Oxidovanadium(IV) complexes of tetradentate Schiff base ligands derived from the condensation of this diamine and salicylaldehyde derivatives were also synthesized by template method and were characterized. The crystal structures of a tridentate ligand, HL 2, and one of the complexes, VOLig 2, were determined by X-ray crystallography. HL 2 crystallizes in triclinic space group P 1 ¯ , while the VOLig 2 (which crystallizes as the DMF solvate) in monoclinic space group P2 1/ n with two [VOLig 2] DMF symmetry-independent units per asymmetric part of the unit cell. The electrochemical properties of these complexes were studied by cyclic voltammetry which shows quasi-reversible V IV/V V redox process. The new complexes are also used as catalysts for the selective oxidation of cyclooctene with tert-butylhydroperoxide (TBHP) and H 2O 2 in acetonitrile. High catalytic activities were observed and excellent selectivity was found for the epoxidation of cyclooctene.

Synthesis, Crystal Structure and Density Functional Theory Study of (2-(2-Hydroxyphenyl)benzimidazolate-based Al(III) Complex Cocrystallized by DMF Solvate and Neutral (2-(2-Hydroxyphenyl)benzimidazole

The aluminium(III) complex with 2-(2-hydroxyphenyl)benzimidazole, namely [Al2(μ-OH)2L4)]·6DMF·2HL (1·6DMF·2HL) (HL = 2-(2-hydroxyphenyl)benzimidazole), has been synthesized and characterized by X-ray crystallography. It crystallizes in monoclinic space group C2/c with cell parameters a = 23.6752(13) A, b = 20.8253(12) A, c = 18.1645(10) A, α = 90°, β = 91.929(1)°, γ = 90°, Z = 4, V = 8950.8(9) A3. The dimeric structure of 1, featuring [Al2(μ-OH)2] core has been studied with the density functional theory level (DFT) calculation and molecular orbital analyses. A new co-crystal of Al(III) complex of 2-(2-hydroxylphenyl)benzimidazole with DMF solvate and neutral 2-(2-hydroxylphenyl)benzimidazole, featuring [Al2(μ-OH)2] core has been prepared and characterized by X-ray crystallography and the density functional theory level studies (DFT).

μ-Oxalato-bis[(2,2′-bipyridyl)copper(II)] bis(perchlorate) dimethylformamide disolvate monohydrate

The title compound, [Cu2(C2O4)(C10H8N2)4](ClO4)2·2C3H7NO·H2O, contains doubly charged centrosymmetric dinuclear oxalato-bridged copper(II) complex cations, perchlorate anions, and DMF and water solvate mol­ecules. In the complex cation, the oxalate ligand is coordinated in a bis-bidentate bridging mode to the Cu atoms. Each Cu atom has a distorted tetra­gonal-bipyramidal environment, being coordinated by two N atoms of the two chelating bipy ligands and two O atoms of the doubly deprotonated oxalate anion. Pairs of perchlorate anions and water mol­ecules are linked into recta­ngles by O—H⋯O bonds in which the perchlorate O atoms act as acceptors and the water mol­ecules as donors. Methyl groups of the DMF solvent molecule are disordered over two sites with occupancies of 0.453 (7):0.547 (7), and the water molecule is half-occupied.

Synthesis, Crystal Structure and Theoretical Study of Al(III) Complex with (2-(2-hydroxyphenyl) benzimidazolate Cocrystallized by DMF Solvate

Article Synthesis, Crystal Structure and Theoretical Study of Al(III) Complex with (2-(2-hydroxyphenyl) benzimidazolate Cocrystallized by DMF Solvate was published on April 1, 2010 in the journal Main Group Metal Chemistry (volume 33, issue 1-2).

Speciation in solution, solid state spectroscopy and vapochromism of [Pt(trpy)(NCS)]SbF6where trpy = 2,2′:6′,2′′-terpyridine

Treatment of [Pt(trpy)Cl]SbF(6) with AgSCN in a metathesis reaction affords after work-up yellow crystals of [Pt(trpy)(NCS)]SbF(6).CH(3)CN where trpy is 2,2':6',2''-terpyridine. A single crystal structure determination of the solvate shows that the SCN(-) ion is N-bound to the Pt atom, and that the planar cations stack as Pt(2) dimers with a PtPt separation of 3.293(1) A. The crystals rapidly de-solvate under ambient conditions to give a polycrystalline maroon material characterised as [Pt(trpy)(NCS)]SbF(6) (). A (15)N NMR spectroscopic study of a solution of isotopically labeled [Pt(trpy)((15)N(13)CS)]SbF(6) in CD(3)CN shows that both linkage isomers of the SCN(-) ion co-exist in solution with the N-bound isomer dominant, and the S-bound isomer present at a much lower concentration. Compound exhibits temperature dependent (3)MMLCT emission in the solid state; at 280 K the emission maximises at 692 nm, but red-shifts systematically on cooling to reach 762 nm at 80 K. Compound shows vapochromic behaviour that is selective and reversible for vapours of acetonitrile, DMF and pyridine. The colour change is from maroon for to yellow for all three solvates. The emission spectra recorded for the solvates maximise at wavelengths that are all significantly blue-shifted compared to lambda(em)(max) recorded for : the blue-shifts measured at 77 K are 90, 115 and 155 nm for the acetonitrile, DMF and pyridine solvates respectively. The origin of the vapochromic properties of compound is likely to do with the breaking and making of metallophilic PtPt interactions in the solid state.

Supramolecular networks of a H-shaped aromatic phenolhost

X-Ray crystal structures of 1,4-di[bis(hydroxyphenyl)methyl]benzene and its solvates and cocrystals were analyzed for the occurrence of network architectures. From the simplest 1D ladder in EtOAc, DMSO and i-PrOH solvates of 1 (R1 = R2 = R4 = H, R3 = OH), doubly-interpenetrated 1D ladders in its guest-free form and 1D/2D-interpenetrated ladder networks in a cocrystal with phenazine were identified. The dioxane and DMSO solvates of 2 (R1 = R3 = OMe, R2 = OH, R4 = H), and the DMSO and toluene solvates of 4 (R1 = H, R2 = R4 = Me, R3 = OH) also adopt 1D ladder networks. Monomethyl phenol 3 (R1 = R2 = H, R3 = OH, R4 = Me) makes 2D grids of ladders that include nitromethane solvent in the channels. The hexagonal (6,3) net in the cocrystal of 1 with pyrazine-N,N′-dioxide is triply-interpenetrated in a 2D architecture. The DMF solvate of 3 is similar to 1·(PyzNO)2, except that the (6,3) nets are doubly-interpenetrated via Hopf links. An orthorhombic nitromethane solvate of 1 is 2D → 3D polycatenated with a degree of catenation (DOC) = 2/2, whereas the monoclinic polymorph of 1·(CH3NO2)2, as well as the chloroform inclusion structure of 4, adopt the rare (5,34) pentagonal net. Platonic (6,3) and Catalan (5,34) nets in the broader category of a uniform network topology were realized from H-shaped molecules 1–4 in different solvent inclusion and cocrystal structures. Finally, a cocrystal of 1 with quinoxaline forms a polyrotaxane 1D → 1D chain of Euclidean entanglement. Polythreaded rotaxane, pentagonal Catalan and 1D/2D interpenetrated nets are, as such, rare in organic molecular crystals. The role of the solvent/co-former in affording diverse supramolecular networks and entanglement modes are rationalized in the crystal structures.

Synthesis, crystal structure, and electrochemical properties of the complex [Ni(imidazole)6](DBSH)2 · 2DMF

The title complex [Ni(Im)6](DBSH)2 · 2DMF(H2DBSH = 3,5-dibromosalicylaldehyde, Im = imidazole, DMF = N,N-dimethylformamide) has been prepared and characterized by X-ray diffraction analysis. It crystallizes in the monoclinic system, space group P21/c with a = 14.7271(13), b = 9.0221(8), c = 18.1143(16) A, β = 100.408(2)°, V = 2367.2(4) A3, Z = 2, M r = 1171.22, F(000) = 1172, ρ c = 1.643 g/cm3 and μ(MoK α) = 3.844 mm−1. The structure was refined to R = 0.0425 and wR = 0.1052 for 3646 observed reflections. The X-ray crystal structure analysis revealed that the center nickel(II) cation is bonded to six nitrogen atoms from six imidazole to form a six-coordinated elongated octahedron. The complex includes a DBSH2− anion and two DMF solvates. The intramolecular and intermolecular hydrogen bonds in the crystal structure play remarkably important role in the thermostability of the title complex. The electrochemical properties were studied in DMF with an electrochemical analyzer.

Influence of Sample Preparation, Temperature, Light, and Pressure on the Two-Step Spin Crossover Mononuclear Compound [Fe(bapbpy)(NCS)2

The three phases of the mononuclear two-step spin crossover compound [Fe(bapbpy)(NCS)2] (1) are characterized by powder X-ray diffraction, Mossbauer spectroscopy, Raman spectroscopy, calorimetry, and magnetic susceptibility measurements. Mossbauer and Raman spectroscopies confirm the results obtained from previous single crystal X-ray diffraction studies, as they show that the intermediate phase is characterized by a 1:2 high-spin/low-spin ratio and that it is not a mixture of the high-spin state (HS) and low-spin state (LS) phases. Sample preparation and sample history studies show that the spin crossover (SCO) properties of this compound are quite robust, as the two steps and hysteresis cycles are present both in the powder and in recrystallized samples and conserved when the sample is cooled and heated several times. Compound 2, a DMF solvate having the formula [Fe(bapbpy)(NCS)2]·2DMF, shows SCO properties but no cooperative effects. The origin of the strong cooperativity found in compound 1 is discuss...

Synthesis and Crystal Structure of a Polymorph of the DMF Solvate of the Dicoppertetracarboxylate Paddlewheel Complex Cu2(p-aminobenzoate)4(DMF)2

Reaction between p-aminobenzoic acid (HpABA) and Cu(NO3)2 · 2.5H2O in basic MeOH/DMF affords green crystals of the dicopper paddlewheel complex, Cu2(pABA)4(DMF)2 · 2DMF, 1, identified by single crystal X-ray crystallography: triclinic P-1, with a = 10.3728(2) A, b = 10.617(2) A, c = 11.128(2) A, α = 81.705(3)°, β = 79.984(2)°, γ = 65.965(2)° and Z = 2. The crystal structure of 1 reveals that it is the second polymorph of Cu2(pABA)4(DMF)2 · 2DMF and experiments on the stability of 1 indicate that it can be converted to Form I through desolvation followed by exposure to DMF. Crystal structure of a polymorphic discrete dicoppertetracarboxylate is investigated for the conversion between the two forms influenced by hydrogen bonds.

Synthesis, Crystal Structure and Antitumor Study of a Zinc Complex of the 2-Benzoylpyridine Thiosemicarbazone Ligand

A zinc complex of the 2-benzoylpyridine thiosemicarbazone (Hbpt) ligand, Zn(bpt)2 · DMF, has been synthesized and characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. The molecular structure has a Zn2+ cation bonded to two perpendicular bpt ligands in a distorted octahedral geometry through two sulfur and four nitrogen atoms. The crystal contains a disordered DMF solvate molecule. Adjacent molecules are interconnected by means of hydrogen bonding generating a 1-D chain structure. The cytotoxic activity measurement indicates that the complex exhibits higher antitumor activity against lung cancer A549 cell lines than the free ligand.

Structural variations in rare earth benzoate complexes : Part I. Lanthanum

A series of lanthanum benzoate complexes have been prepared and structurally characterised as DMF or DMSO solvates. The structures of these complexes vary considerably as a function of the steric bulk of the ligands and the degree of solvation. With one exception, all of the complexes form coordination polymers. These experimental results are compared to reported data from the Cambridge Structural Database (CSD) in order to study the role of sterically bulky substituents in the structures of lanthanum benzoate complexes. Binding modes vary from the η1 coordination of a carboxylic acid co-ligand to carboxylate ligands adopting a bridging μ-η2 : η1 geometry. The nature of the bridging environment between adjacent lanthanum ions varies significantly in the structures and often several different environments exist within the same structure. Solvent effects are also observed, particularly in cases where the solvent is able to partake in intra- or intermolecular hydrogen bonding.

Structural variations in rare earth benzoate complexes : Part II. Yttrium and terbium

A series of lanthanum benzoate complexes have been prepared and structurally characterised as DMF or DMSO solvates. The structures of these complexes vary considerably as a function of the steric bulk of the ligands and the degree of solvation. With one exception, all of the complexes form coordination polymers. These experimental results are compared to reported data from the Cambridge Structural Database (CSD) in order to study the role of sterically bulky substituents in the structures of lanthanum benzoate complexes. Binding modes vary from the η1 coordination of a carboxylic acid co-ligand to carboxylate ligands adopting a bridging μ-η2 : η1 geometry. The nature of the bridging environment between adjacent lanthanum ions varies significantly in the structures and often several different environments exist within the same structure. Solvent effects are also observed, particularly in cases where the solvent is able to partake in intra- or intermolecular hydrogen bonding.

Interplay of coordinative and supramolecular interactions in engineering unusual crystalline architectures of low-dimensional metal–pamoate complexes under co-ligand intervention

This work presents a systematic investigation on coordination chemistry of a pharmaceutical agent pamoic acid (H2PA), and also reveals the significant function of supramolecular interactions in managing the resultant crystalline networks with the incorporation of secondary co-ligands. Assemblies of pamoic acid with transition metal ions under similar conditions yield a series of eleven MnII, CuII, ZnII, and CdII complexes, in the absence/presence of the organonitrogen ligands such as 2,2′-bipyridyl (2,2′-bipy), 1,10-phenanthroline (phen), and 4,4′-bipyridyl (4,4′-bipy). These compounds, together with the DMF solvate of pamoic acid, have been characterized by IR, elemental analysis, and single-crystal X-ray diffraction techniques. Generally, these complexes display similar 1-D pamoate-bridged coordination arrays (or 2-D coordination layers by introducing bridging 4,4′-bipy). Remarkably, distinct extended network architectures are further constructed with the aid of weak secondary interactions especially aromatic stacking. Amongst them, complexes 6, 8, 9, and 12, which exhibit unusual interpenetrating networks of (6,3) layers or 3-D 5-connected frameworks regulated by stacking forces, are representative paradigms of this research. Structural evolution under the co-ligand intervention in this series of complexes, as well as the general coordination rule of pamoate, has been further discussed. Thermal stability of these crystalline materials and fluorescent properties of the polymeric ZnII and CdII complexes have also been explored.