DMF Solvent Molecules Research Articles

Crystal structure and Hirshfeld surface analysis of (E)-2-[2-(2-amino-1-cyano-2-oxoethylidene)hydrazin-1-yl]benzoic acid N,N-dimethylformamide monosolvate

In the title compound, C10H8N4O3·C3H7NO, the asymmetric unit contains two crystallographically independent molecules A and B, each of which has one DMF solvate molecule. Molecules A and B both feature intramolecular N—H...O hydrogen bonds, forming S(6) ring motifs and consolidating the molecular configuration. In the crystal, N—H...O and O—H...O hydrogen bonds connect molecules A and B, forming R 2 2(8) ring motifs. Weak C—H...O interactions link the molecules, forming layers parallel to the (\overline{2}12) plane. The DMF solvent molecules are also connected to the main molecules (A and B) by N—H...O hydrogen bonds. π–π stacking interactions [centroid-to-centroid distance = 3.8702 (17) Å] between the layers also increase the stability of the molecular structure in the third dimension. According to the Hirshfeld surface study, O...H/H...O interactions are the most significant contributors to the crystal packing (27.5% for molecule A and 25.1% for molecule B).

Crystal Design, Antitumor Activity and Molecular Docking of Novel Palladium(II) and Gold(III) Complexes with a Thiosemicarbazone Ligand.

The current research describes the synthesis and characterization of 2-acetylpyridine N(4)-cyclohexyl-thiosemicarbazone ligand (HL) and their two metal complexes, [Au(L)Cl][AuCl2] (1) and [Pd(L)Cl]·DMF (2). The molecular structures of the compounds were determined by physicochemical and spectroscopic methods. Single crystal X-ray diffraction was employed in the structural elucidation of the new complexes. The complexes showed a square planar geometry to the metal center Au(III) and Pd(II), coordinated with a thiosemicarbazone molecule by the NNS-donor system and a chloride ion. Complex (1) also shows the [AuCl2]- counter-ion in the asymmetric unit, and complex (2) has one DMF solvent molecule. These molecules play a key role in the formation of supramolecular structures due to different interactions. Noncovalent interactions were investigated through the 3D Hirshfeld surface by the dnorm function and the 2D fingerprint plots. The biological activity of the compounds was evaluated in vitro against the human glioma U251 cells. The cytotoxicity results revealed great antitumor activity in complex (1) compared with complex (2) and the free ligand. Molecular docking simulations were used to predict interactions and properties with selected proteins and DNA of the synthesized compounds.

Thiocyanato and Schiff base coordinated mono/di-nuclear Ni(II) complexes: Syntheses, crystal structures and protein binding

Two Ni(II) complexes, [Ni2(L1)2(SCN)2(dmf)2] (1) and [Ni(L2)(SCN)] (2) [where HL1 = 2-ethoxy-6-[(2-phenylamino-ethylimino)-methyl]-phenol, HL2 = 2-[(2-pyrrolidin-1-yl-ethylimino)-methyl]-phenol, dmf = N,N-dimethylformamide], have been synthesized and characterized by single crystal X-ray diffraction, IR and mass spectroscopic studies. In the centrosymmetric complex 1, two Ni(L1) fragments are connected via µ2-oxo bridges and the metals complete the octahedral coordination with one thiocyanate and one dmf solvent molecule. In complex 2, the Ni(II) ion is coordinated by the tridentate Schiff base and a thiocyanate in a square planar environment. Both the complexes form 1D supra-molecular network through CH…π interactions and complex 2 also via H-bonding. The interaction of complexes with serum albumins was investigated using UV–Vis absorption and fluorescence spectroscopic techniques.

Stable Nickel-Based Metal–Organic Framework Containing Thiophene/Diimidazole Units for Effective Near-Infrared Photothermal Conversion

Herein, a new Ni-based metal–organic framework (MOF, 1) bearing highly structural stability is synthesized by the reaction of utilizing a rigid and functionalized linker, 2,6-bis(pyridin-4-yl)-1,7-dihydrobenzo[1,2-d:4,5-d′]diimidazole (BBI4PY), in combination with Ni(NO3)2·6H2O and dibenzo[b,d]thiophene-3,7-dicarboxylic acid 5,5-dioxide (L1) under solvothermal conditions. The crystal structure of complex 1 is determined by single-crystal X-ray diffraction and is demonstrated to be a two-dimensional layered structure. In addition, PXRD, IR, TGA and UV/Vis-NIR spectra are also tested carefully to explore the solid structure of this complex. Remarkably, although no significant accumulation effect could be observed between the two-dimensional layers, a stacking interaction between DMF solvent molecules and ligand L1 could be found, which might promote non-radiative transitions and trigger obvious near-infrared photothermal conversion. Under 660 nm laser (0.6 W cm−2) illumination, the temperature of complex 1 increased rapidly from room temperature to 45.2 °C, with good thermal stability and cycle durability. Its photothermal conversion efficiency could reach 10.75%. This work provides an efficient way for assessing the promise of materials in the field of photothermal therapy.

A binuclear copper(II) complex based on hydrazone ligand: Characterization, molecular docking, and theoretical and antimicrobial investigation

AbstractA new binuclear copper(II) complex [Cu2L2(μ‐SO4)(dmf)] with the 2‐acetylpyridinebenzoylhydrazone (HL) ligand was synthesized and characterized by elemental analysis, Fourier transform infrared (FT‐IR), ultraviolet–visible (UV–Vis), single‐crystal X‐ray diffraction, density functional theory (DFT), and molecular docking studies. The crystal structure revealed each copper(II) atom coordinated to the NNO chelating system of the anionic hydrazone ligand and a sulfate bridged. The copper ions are connected by a sulfate bridge, which keeps a distance of 3.292(3) Å between the two copper(II) centers. Additionally, only one of the copper(II) atoms is coordinated to the oxygen atom of the N,N‐dimethylformamide (dmf) solvent molecule, resulting in two different geometry to each metal center. Cu···O interactions are observed for the secondary coordination sphere of Cu1 and Cu2 atoms with distances of 2.545(2) and 2.821(3) Å, respectively. Theoretical studies with DFT were performed to optimize the geometry of the complex and investigate its spectroscopic properties supporting the experimental results. Two different approaches were used in computational calculations, the plane wave using Perdew–Burke–Ernzerhof (PBE) functional and the localized basis set using the following functionals: B3LYP, B3PW91, CAM‐B3LYP, LC‐wPBE, M06‐2X, ωB97‐XD, PBE1PBE, and HSEH1PBE. The in vitro antibacterial potential of the new complex was evaluated against pathogenic bacteria and fungi and compared with the free ligand. The molecular docking was used to predict the inhibitory activity of the ligand and complex against one Gram‐positive bacteria (Enterococcus faecalis), one Gram‐negative bacteria (Enterobacter aerogenes), and one fungi (Candida albicans) species.

Electrodeposited PtNi nanoparticles towards oxygen reduction reaction: A study on nucleation and growth mechanism

In this work, highly monodispersed Pt-Ni alloy nanoparticles were directly deposited on carbon substrate through a facile electrodeposition strategy in the solvent system of N,N-dimethylformamide (DMF). A series of carbon supported Pt-Ni alloy electrocatalysts were synthesized under different applied electrode potentials. Among all as-obtained samples, the Pt-Ni/C electrocatalyst deposited at –1.73 V exhibits the optimal specific activity up to 1.850 mA cm−2 at 0.9 V vs. RHE, which is 6.85 times higher than that of the commercial Pt/C. Comprehensive physiochemical characterizations and computational evaluations via density functional theory were conducted to unveil the nucleation and growth mechanism of PtNi alloy formation. Compared to the aqueous solution, DMF solvent molecule must not be neglected in avoiding particle agglomeration and synthesis of monodispersed nanoparticles. During the alloy co-deposition process, Ni sites produced through the reduction of Ni(II) precursor not only facilitates Pt-Ni alloy crystal nucleation but also in favor of further Pt reduction on the Ni-inserted Pt surface. As for the deposition potential, it adjusts the final particle size. This work provides a hopeful extended Pt-based catalyst layer production strategy for proton exchange membrane fuel cells and a new idea for the nucleation and growth mechanism exploration for electrodeposited Pt alloy.

Coordination framework of cadmium(II), harvested from dithiolate-imidazole binary ligand systems: Crystal structure, Hirshfeld surface analysis, antibacterial, and DNA cleavage potential

The novel one-dimensional coordination polymer with binuclear building node {[Cd2(i-mnt)2(Im)2]DMF2}n (1) harvested from 1,1-dicyanoethylene-2,2-dithiolate (i-mnt2−) and imidazole (Im) has been systemically designed, synthesized and structurally characterized by elemental analysis, FT-IR and 1H NMR spectroscopy. Single crystal X-ray diffraction analysis revealed that in 1, each Cd(II) is in penta-coordinated environment having slightly distorted square pyramidal geometry (τ5 = 0.24) and have two bridging thiolate ends of i-mnt−2- along with one DMF solvent molecule. The flexible i-mnt2− ligand acts as a tridentate connector by ligating with Cd(II) centers in parallel dimeric units forming a 1D polymeric chain. Hirshfeld surface analyses and two dimensional (2D) finger print plots were employed to decode all types of non-covalent contacts in the crystal frameworks, allowing a systematic evaluation of the crystal structure. From HS analysis, it was observed that N⋯H/H⋯N type interactions (22.1%) have the major contribution compared to overall non-covalent interacrtions. The share of H⋯O/O⋯H interactions of the total surface is only 3.7%, their role is important in the direction and organization of crystal packaging. The in-vitro antimicrobial study of 1 against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (E. coli and P. aeruginosa) human pathogenic bacterial strains show promising antimicrobial activities. Furthermore, DNA cleavage study (E. coli DNA) of 1 using gel electrophoresis method revealed promising DNA cleaver property similar to H2O2 due to the efficient coordination of Cd(II) ion.

Crystal structures of two heterotrimetallic dysprosium-manganese-sodium 12-metallacrown-4 complexes with the bridging ligands 3-hy-droxy-benzoate and 4-hy-droxy-benzoate.

The syntheses and crystal structures for the compounds tetra-μ-aqua--tetra-kis-{2-[aza-nid-yl-ene(oxido)meth-yl]phenolato}tetra-kis-(μ2-3-hy-droxy-benzoato)dys-pro-s-ium(III)-tetra-manganese(III)sodium(I) N,N-di-methyl-acetamide deca-solvate, [DyMn4Na(C7H5O3)4(C7H4NO2)4(H2O)4]·10C4H9NO or [DyIIINa(4-OHben)4{12-MCMn(III)N(shi)-4}(H2O)4]·10DMA, 1, and tetra-μ-aqua--tetra-kis-{2-[aza-nid-yl-ene(oxido)meth-yl]phenolato}tetra-kis-(μ2-3-hy-droxy-benzoato)dys-pros-ium(III)tetra-manganese(III)sodium(I) N,N-di-methylformamide tetra-solvate, [DyMn4Na(C7H5O3)4(C7H4NO2)4(H2O)4]·4C3H7NO or [DyIIINa(3-OHben)4{12-MCMn(III)N(shi)-4}(H2O)4]·4DMF, 2, and where MC is metallacrown, shi3- is salicyl-hydroximate, 3-OHben is 3-hy-droxy-benzoate, DMA is N,N-di-methyl-acetamide, 4-OHben is 4-hy-droxy-benzoate, and DMF is N,N-di-methyl-formamide, are reported. For both 1 and 2, the macrocyclic metallacrown consists of an [MnIII-N-O] ring repeat unit, and the domed metallacrown captures two ions in the central cavity: a DyIII ion on the convex side of the metallacrown and an Na+ ion the concave side. The MnIII ions are six-coordinate with an elongated tetra-gonally distorted octa-hedral geometry. Both the DyIII and Na+ ions are eight-coordinate. The DyIII ions possess a square-anti-prismatic geometry, while the Na+ ions have a distorted biaugmented trigonal-prismatic geometry. Four 3-hy-droxy-benzoate or 4-hy-droxy-benzoate ligands bridge each MnIII ion to the central DyIII ion. For 1, whole-mol-ecule disorder is observed for the main mol-ecule, excluding only the DyIII and Na+ ions, and the occupancy ratio refined to 0.8018 (14):0.1982 (14). Three DMA mol-ecules were refined as disordered with two in general positions by an approximate 180° rotation and the third disordered twice by general disorder as well as by an exact 180° rotation about a twofold axis that bis-ects it. The occupancy ratios refined to 0.496 (8):0.504 (8), 0.608 (9):0.392 (9), and 2×0.275 (7):2×0.225 (7), respectively. For 2, segments of the metallacrown are disordered including the DyIII ion, one of the Mn ions, two of the Mn-bound 4-hy-droxy-benzoate ligands, the Mn-bridging salicyl-hydroximate ligand, and portions of the remaining three shi3- ligands. The occupancy ratio for the metallacrown disorder refined to 0.849 (9):0.151 (9). Two DMF solvent mol-ecules are also disordered, each over two orientations. The disorder ratios refined to 0.64 (3):0.36 (3) and to 0.51 (2):0.49 (2), respectively. For 2, the crystal under investigation was refined as a non-merohedric twin by a 90° rotation around the real a axis [twin ratio 0.9182 (8):0.0818 (8)].

Mixed Tb/Dy coordination ladders based on tetra(carboxymethyl)thiacalix[4]arene: a new avenue towards luminescent molecular nanomagnets.

The macrocyclic ligand calix[4]arene (L1) and its sulphur-containing analogue thia[4]calixarene (L2) are promising precursors for functional molecular materials as they offer rational functionalization with various organic groups. Here, we present the first example of lanthanide-based coordination polymers built from the macrocyclic thiacalix[4]arene backbone bearing four carboxylic moieties, namely, ligand H4L3. The combination of H4L3 with the Tb3+ and Dy3+ cations led to the formation of 1D ladder-type coordination polymers with the formula [LnIIIHL3DMF3]·(DMF) (where DMF = dimethylformamide and Ln = Tb or Dy, denoted as HL3–Tb and HL3–Dy), which resulted from the coordination of the lanthanide cations with the partially deprotonated ligand HL33− that behaved as a T-shape connector. The coordination sphere around the metal was completed by the coordinated DMF solvent molecules. By combining both Tb3+ and Dy3+ cations, isostructural heterobimetallic solid solutions HL3–Tb1−xDyx were also prepared. HL3–Tb and HL3–Dy showed visible light photoluminescence originating from the f–f electronic transitions of pale green emissive Tb3+ and pale yellow emissive Dy3+ with efficient sensitization by the functionalized thia[4]calixarene ligand HL3. In the HL3–Tb1−xDyx solid solutions, the Tb/Dy ratio governed both the emission colour as well as the emission quantum yield, which reached even 28% at room temperature for HL3–Tb. Moreover, HL3–Dy exhibited a slow magnetic relaxation effect related to the magnetic anisotropy of the dodecahedral Dy3+ complexes, which were well isolated in the crystal lattice by expanded organic spacers.

Crystal structure of bis(μ-{2-[(5-bromo-2-oxido-benzyl-idene)amino]-eth-yl}sulfanido-κ3 N,O,S){2,2'-[(3,4-di-thia-hexane-1,6-di-yl)bis-(nitrilo-methanylyl-idene)]bis-(4-bromo-phenolato)-κ4 O,N,N',O'}dicobalt(III) di-methyl-formamide monosolvate.

The title binuclear CoIII complex, [Co2(C9H8BrNOS)2(C18H16Br2N2O2S2)]·C3H7NO, with a Schiff base ligand formed in situ from cyste-amine (2-amino-ethane-thiol) and 5-bromo-salicyl-aldehyde crystallizes in the space group P21. It was found that during the synthesis the ligand undergoes spontaneous oxidation, forming the new ligand H2 L' having an S-S bond. Thus, the asymmetric unit consists of one Co2(L)2(L') mol-ecule and one DMF solvent mol-ecule. Each CoIII ion has a slightly distorted octa-hedral S2N2O2 coordination geometry. In the crystal, the components are linked into a three-dimensional network by several S⋯ Br, C⋯ Br, C-H⋯Br, short S⋯C (essentially shorter than the sum of the van der Waals radii for the atoms involved) contacts as well by weak C-H⋯O hydrogen bonds. The crystal studied was refined as an inversion twin.

Tris(μ2-2-meth-oxy-6-{[(2-sulfido-eth-yl)imino]meth-yl}phenolato)trinickel(II) di-methyl-formamide monosolvate: crystal structure, spectroscopic characterization and anti-bacterial activity.

The title trinuclear nickel(II) complex, [Ni3(C10H11NO2S)3]·C3H7NO, with a Schiff base ligand formed in situ from 2-amino-ethane-thiol and o-vanillin crystallizes in the ortho-rhom-bic space group Pbca. Its asymmetric unit consists of one neutral Ni3 L 3 mol-ecule and one DMF solvent mol-ecule. The solid-state organization of the complex can be described as an insertion of the solvent mol-ecules within the crystallographically independent trinuclear NiII species. Several C-H⋯π edge-to-face inter-actions and π-π stacking inter-actions link the components in the crystal. A first example of a short inter-molecular C-H⋯Ni contact is found. Anti-bacterial in vitro screening revealed that the title compound has anti-bacterial activity, the best effect being against Acinetobacter baumannii.

Crystallographic, spectroscopic and theoretical investigations on Ni(II) complexes of a tridentate NNS donor thiosemicarbazone

Five new nickel(II) complexes [Ni(L)NCS] (1b), [Ni(L)N3] (2), [Ni(L)N(CN)2] (3), [Ni(L)OAc] (4) and [Ni(HL)SO4] (5) of a thiosemicarbazone HL (where HL = 2-benzoylpyridine-N(4)-phenylthiosemicarbazone) including pseudohalides like thiocyanate, azide and dicyanamide have been synthesized and characterized by elemental analysis, magnetic susceptibility, FT-IR, electronic and NMR spectroscopic techniques. The interesting amido-iminol tautomerism enables the pro-ligand to exist in amido form as well as deprotonated iminol form thereby functioning as tridentate NNS donor, coordinating through pyridyl nitrogen atom, azomethine nitrogen atom and amido/iminolate sulfur atom in the complexes. The crystal structures were established by single crystal XRD analysis. Two different single crystals of the compound thiocyanato complex were obtained with and without DMF solvent molecule having triclinic and monoclinic lattices with P1- and P21/n space groups respectively. Also, the compound 2 is having a monoclinic lattice with P21/n space group. Nickel(II) exists in distorted square planar geometry in all the complexes. Further DFT calculations were carried out at B3LYP/TZVP level of theory to obtain an insight on the stability and the nature of frontier orbitals. Finally, electrostatic potential plots mapped on optimized geometries substantiate the noncovalent interactions found in their respective crystal structures.

Co(II), Ni(II) and Cu(II) ternary complexes with sulfadiazine and dimethylformamide: Synthesis, spectroscopic characterization, crystallographic study and antibacterial activity

Sulfadiazine Co(II), Ni(II) and Cu(II) complexes have been synthesized and characterized. The crystal structure of the cobalt(II) complex, for short [Co(SDZ)2(DMF)2], was determined by X-ray diffraction methods. It crystallizes in the monoclinic space group P21/c with Z = 2 molecules per unit cell. The complex is centre-symmetric with the metal at the centre of a rectangular bi-pyramid environment (CoN4O2 core), coordinated at the bi-pyramid base to two SDZ molecules and at the apices to two DMF solvent molecules. The crystal structure determination was combined with Hirshfeld surface analysis to obtain detailed information on the intermolecular interactions that stabilizes the crystal packing. The nature and strength of the CoN and CoO bonds were investigated by the natural bond orbital (NBO) analysis and the atoms in molecules (AIM) approach. Based on NBO and AIM analysis, the shorter CoN4 bonds are more covalent in nature than CoO bonds. The antibacterial assays of the metal complexes revealed lower activity than the free ligand, probably due to their low solubility in water. However, their low toxicity as compared with SDZ makes them potential alternatives against other microorganisms, and/or biological targets.

A 2D Zinc Coordination Polymer Built from the Mono‐deprotonated 4,4′‐Azobis(3,5‐dimethyl‐1H‐pyrazole) Ligand

4,4′‐Azobis(3,5‐dimethyl‐1H‐pyrazole) (H2azbpz) in its mono‐deprotonated form as a pyrazole‐pyrazolate ligand was assembled together with zinc(II) into the two‐dimensional coordination polymer [Zn(Hazbpz)NO3]·1.25DMF with sql‐a topology, constituted by the dinuclear {Zn2(μ‐pz)2(Hpz)2}2+ secondary building unit. The μ3‐ bridging mode of the ligand is in analogy to bridging modes observed for 4‐(4‐pyridyl)pyrazolates ligands. After the removal of the DMF solvent molecules, ethanol can be adsorbed up to a maximum uptake of 276 mg·g–1 at p/p0 = 0.9 in an S‐shaped adsorption isotherm, corresponding to two ethanol molecules per [Zn(Hazbpz)NO3] formula unit. The desorption isotherm reveals that only one EtOH is desorbed until p/p0 = 0.4 and the other one remains hydrogen‐bonded in the framework until very low pressures.

An unsymmetrical tritopic pyrazole carboxylate ligand based porous Cd(II) MOF sensor for acetone molecule

A Cd(II) based novel 3D porous MOF, {[Cd4(L)4(NO3)3(H2O)3]∙8DMF∙H2O∙NO3}n (1) (where, L = 4-(3,5-di(pyridin-4-yl)-1H-pyrazol-1-yl)benzoic acid) is reported. Compound 1 features open N sites and 6,3 connected net with ant/anatase topology having nano sized cavities in the 2D sheet structure which are masked by the adjacent layers stacked in a slipped manner in 3D packing. The open voids in 1 are occupied by DMF and water solvent molecules that constitute 46% of the total volume of crystal. Compound 1 exhibits selective H2O vapor adsorption over methanol and ethanol solvents. Its solid state luminescent property demonstrates that it can selectively detect acetone molecules on the basis of fluorescence quenching mechanism among several other solvent molecules.

M4Au12Ag32(p-MBA)30 (M = Na, Cs) bimetallic monolayer-protected clusters: synthesis and structure.

Crystals of M4Au12Ag32(p-MBA)30 bimetallic monolayer-protected clusters (MPCs), where p-MBA is p-mercapto-benzoic acid and M+ is a counter-cation (M= Na, Cs) have been grown and their structure determined. The mol-ecular structure of triacontakis[(4-carboxylatophenyl)sulfanido]dodecagolddotriacontasilver, Au12Ag32(C7H5O2S)30 or C210H150Ag32Au12O60S30, exhib-its point group symmetry at 100 K. The overall diameter of the MPC is approximately 28 Å, while the diameter of the Au12Ag20 metallic core is 9 Å. The structure displays ligand bundling and inter-molecular hydrogen bonding, which gives rise to a framework structure with 52% solvent-filled void space. The positions of the M+ cations and the DMF solvent mol-ecules within the void space of the crystal could not be determined. Three out of the five crystallographically independent ligands in the asymmetric unit cell are disordered over two sets of sites. Comparisons are made to the all-silver M4Ag44(p-MBA)30 MPCs and to expectations based on density functional theory.

Crystal structure of tetra-kis-[μ-2-(meth-oxy-carbon-yl)benzoato-κ2O1:O1']bis-[(N,N-di-methyl-formamide-κO)copper(II)](Cu-Cu) di-methyl-formamide disolvate.

The title compound, [Cu2(C9H7O4)4(C3H7NO)2]·2C3H7NO, crystallizes in the monoclinic P21/c space group, with the binuclear copper unit occupying a special position on an inversion center, i.e. the asymmetric unit of the crystal consists of one CuII ion, two 2-(meth-oxy-carbon-yl)benzoate ligands, and two DMF mol-ecules (one coordinated and one solvate). The binuclear complex displays a paddle-wheel-shaped structure with the two copper atoms being in a Jahn-Teller-distorted octa-hedral coordination environment. Each 2-(meth-oxy-carbon-yl)benzoate substituent acts as a bridging ligand and links two Cu atoms with a Cu-Cu distance of 2.633 (1) Å. The carboxyl-ate groups of the 2-(meth-oxy-carbon-yl)benzoate ligands adopt bidentate syn-syn bridging modes, with dihedral angles between the carboxyl-ate planes and the aromatic rings of 18.427 (4) and 43.029 (6)°. In the crystal, adjacent DMF mol-ecules coordinated to copper atoms are arranged in a mutual 'head-to-tail' manner by offset face-to-face π-π stacking inter-actions, resulting in chains along the c-axis direction. The planes of the coordinated DMF mol-ecules are parallel to each other, the distance between them being 3.33 (1) Å. A three-dimensional structure is assembled from the chains by weak C-H⋯O and C-H⋯π inter-molecular inter-actions involving the DMF solvent mol-ecules. One of the methyl ester groups is disordered over two sites with an occupancy ratio of 0.751 (12):0.249 (12).

Synthesis and Characterization of New Organometallic Hybrid Material LCP-1 Based on MOF (Metal–Organic Framework) and Maghnite-H+, a Protons Exchanged Montmorillonite Clay, as Catalytic Support

In this work, a new 3D crystalline metal–organic framework formulated as [Zn2(BTC)4, (BTC: 1,2,4,5-Benzenetetracarboxylate)] and called LCP-1 (LCP: Laboratoire de Chimie des Polymeres), with unsaturated coordinated Zn(II) sites as metal ion and pyromellitic acid (H4BTC: 1,2,4,5-Benzenetetracarboxylic acid) as organic ligand, has been successfully synthesized under solvothermal conditions. In-Situ polymerization of this material was also carried out using an amount of clay called Maghnite-H+, an acid-exchanged montmorillonite, as an eco-catalyst with the aim to respect the principles of green chemistry, to give a new hybrid composite material LCP-1/Mag-H+ with a better yield, a significantly reduced time and temperature reaction than those of LCP-1. LCP-1 and LCP-1/Mag-H+ have been structurally characterized and established by fourier transform infrared spectroscopy (FT-IR). The morphology of these compounds was studied by the X-ray diffraction (XRD) and revealed a highly crystalline and ordered structure for both LCP-1 and LCP-1/Mag-H+. FT-IR and XRD spectra showed also that the stability and structural integrity of LCP-1 and LCP-1/Mag-H+ was maintained even after being evacuated from the DMF solvent molecules. The thermal stability identified by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that Maghnite-H+, as inorganic support, has also improved the thermal stability of LCP-1 compound.

Lipophilic Decyl Chain-Pterin Conjugates with Sensitizer Properties.

A new series of decyl chain [-(CH2)9CH3] pterin conjugates have been investigated by photochemical and photophysical methods, and with theoretical solubility calculations. To synthesize the pterins, a nucleophilic substitution (SN2) reaction was used for the regioselective coupling of the alkyl chain to the O site over the N3 site. However, the O-alkylated pterin converts to N3-alkylated pterin under basic conditions, pointing to a kinetic product in the former and a thermodynamic product in the latter. Two additional adducts were also obtained from an N-amine condensation of DMF solvent molecule as byproducts. In comparison to the natural product pterin, the alkyl chain pterins possess reduced fluorescence quantum yields (ΦF) and increased singlet oxygen quantum yields (ΦΔ). It is shown that the DMF-condensed pterins were more photostable compared to the N3- and O-alkylated pterins bearing a free amine group. The alkyl chain pterins efficiently intercalate in large unilamellar vesicles, which is a good indicator of their potential use as photosensitizers in biomembranes. Our study serves as a starting point where the synthesis can be expanded to produce a wider series of lipophilic, photooxidatively active pterins.

First-principles calculation of electronic energy level alignment at electrochemical interfaces

Energy level alignment at solid–solvent interfaces is an important step in determining the properties of electrochemical systems. The positions of conduction and valence band edges of a semiconductor are affected by its environment. In this study, using first-principles DFT calculation, we have determined the level shifts of the semiconductors TiO2 and ZnO at the interfaces with MeCN and DMF solvent molecules. The level shifts of semiconductor are obtained using the potential difference between the clean and exposed surfaces of asymmetric slabs. In this work, neglecting the effects of present ions in the electrolyte solution, we have shown that the solvent molecules give rise to an up-shift for the levels, and the amount of this shift varies with coverage. It is also shown that the shapes of density of states do not change sensibly near the gap. Molecular dynamics simulations of the interface have shown that at room temperatures the semiconductor surface is not fully covered by the solvent molecules, and one must use intermediate values in an static calculations.