Synthesis, X-Ray Structure, and Characterization of Catena-bis(benzoate)bis{N,N-bis(2-hydroxyethyl)glycinate}cadmium(II)

The reaction of N, N-bis(2-hydroxyethyl)glycine (bicine; bicH3) with Cd(O2CPh)2 · 2H2O in MeOH yielded the polymeric compound [Cd2(O2CPh)2(bicH2)2]n(1). The complex crystallizes in the tetragonal space group P41212. The lattice constants are a = b = 12.737(5) and c = 18.288(7) Å. The compound contains chains of repeating {Cd2(O2CPh)2(bicH2)2} units. One CdII atom is coordinated by two carboxylate oxygen, four hydroxyl oxygen, and two nitrogen atoms from two symmetry-related 2.21111 (Harris notation) bicH2− ligands. The other CdII atom is coordinated by six carboxylate oxygen atoms, four from two bicH2− ligands and two from the monodentate benzoate groups. Each bicinate(-1) ligand chelates the 8-coordinate, square antiprismatic CdII atom through one carboxylate oxygen, the nitrogen, and both hydroxyl oxygen atoms and bridges the second, six-coordinate trigonal prismatic CdII center through its carboxylate oxygen atoms. Compound 1 is the first structurally characterized cadmium(II) complex containing any anionic form of bicine as ligand. IR data of 1 are discussed in terms of the coordination modes of the ligands and the known structure

Use of the 2-Pyridinealdoxime/N,N′-Donor Ligand Combination in Cobalt(III) Chemistry: Synthesis and Characterization of Two Cationic Mononuclear Cobalt(III) Complexes

The use of 2-pyridinealdoxime (paoH)/N,N′-donor ligand (L-L) “blend” in cobalt chemistry has afforded two cationic mononuclear cobalt(III) complexes of the general type [Co(pao)2(L-L)]+, where L-L = 1,10-phenanthroline (phen) and 2,2′-bipyridine (bpy). The CoCl2/paoH/L-L (1 : 2 : 1) reaction system in MeOH gives complexes [CoIII(pao)2(phen)]Cl·2H2O (1·2H2O) and [CoIII(pao)2(bpy)]Cl·1.5MeOH (2·1.5MeOH). The structures of the complexes were determined by single-crystal X-ray crystallography. The CoIII ions are six-coordinate, surrounded by three bidentate chelating ligands, that is, two pao− and one phen or bpy. The deprotonated oxygen atom of the pao− ligand remains uncoordinated and participates in hydrogen bonding with the solvate molecules. IR data of the complexes are discussed in terms of the nature of bonding and the known structures

Supramolecular assemblies involving metal organic ring interactions: Heterometallic Cu(II)-Ln(III) two dimensional coordination polymers

Three isostructural two-dimensional coordination polymers of the general formula [Ln2(CuL)3(H2O)9]$5.5H2O, where Ln is La (1), Nd (2), and Gd (3), have been synthesized and isolated from aqueous solutions and their single-crystal structures determined by X-ray diffraction. The supramolecular interaction between the non-aromatic metallorings plays an important role in stabilizing the structure of these compounds. The thermal stability, reversible solvent uptake, electronic properties and magnetic studies of these compounds are also reported

Peculiar structural findings in coordination chemistry of malonamide–N,N′-diacetic acid

Unprecedented structural features are found in the coordination chemistry of malonamide–N,N′-diacetic acid. A type of supramolecular interaction involving non-aromatic rings—metallorings—designated as Metal Organic Ring interaction (MORi) is crystallographically well established

Forcing Twisted 1,7-Dibromoperylene Diimides to Flatten in the Solid State: What a Difference an Atom Makes

Perylene diimides (PDI) are workhorses in the field of organic electronics, owing to their appealing n-semiconducting properties. Optimization of their performances is widely pursued by bay-atom substitution and diverse imide functionalization. Bulk solids and thin-films of these species crystallize in a variety of stacking configurations, depending on the geometry of the stable conformation of the polyaromatic core. We here demonstrate that 1,7-dibromo-substituted perylene diimides, PDI(H2Br2), possessing a heavily twisted conformation in the gas phase, in solution and in the solids, can be easily flattened in the solid state into centrosymmetric molecules if the polyaromatic cores form pi-pi stabilized chains. This is achieved by using axial residues with low stereochemical hindrance, as guaranteed by a single CH2/NH spacer directly linked to the imide function. Structural powder diffraction and DFT calculations on four newly designed species of the PDI(H2Br2) class coherently show that, thanks to the flexibility of the N-X-Ar link (X=CH2/NH), flat cores are indeed obtained by overcoming the interconversion barrier between twisted atropoisomers, of only 26.5 kJ mol(-1). This strategy may then be useful to induce "anomalously flat" polyaromatic cores of different kinds (substituted acenes/rylenes) in the solid state, towards suitable crystal packing and orbital interactions for improved electronic performances

Using Imidazolium in the Construction of Hybrid 2D and 3D Lead Bromide Pseudoperovskites

The field of hybrid organic–inorganic perovskite materials continues to attract the interest of the scientific community due to their fascinating properties and the plethora of promising applications in photovoltaic and optoelectronic devices. To enhance the efficiency and stability of perovskite-based devices, it is essential to discover novel compounds but also to investigate their various physicochemical, structural, and thermal properties. In this work, we report the synthesis and structural characterization of two novel hybrid lead bromide perovskites, combining the imidazolium cation (IMI) with methylammonium (MA) or formamidinium (FA) cations. The isolated polycrystalline powders were studied with X-ray powder diffraction (XPRD) and were formulated as (IMI)(MA)Pb2Br6, a 3D structure consisting of dimers of face-sharing octahedra linked in corner-sharing mode, and (IMI)(FA)PbBr4, a 2D (110) oriented layer structure with zig-zag corner-sharing octahedra. The thermal stability of (IMI)(MA)Pb2Br6 and (IMI)(FA)PbBr4 was investigated with thermogravimetric (TG) and differential scanning calorimetry (DSC) experiments which showed that both compounds are chemically stable (at least) up to 250 °C. Variable-temperature X-ray diffractometric (VT-XRD) studies of (IMI)(FA)PbBr4 highlighted a structural modification occurring above 100 °C, that is a phase transformation from triclinic to orthorhombic, via an elusive monoclinic phase

Connectivity and Topology Invariance in Self-Assembled and Halogen-Bonded Anionic (6,3)-Networks

We report here that the halogen bond driven self-assembly of 1,3,5-trifluorotriiodobenzene with tetraethylammonium and -phosphonium bromides affords 1:1 co-crystals, wherein the mutual induced fit of the triiodobenzene derivative and the bromide anions (halogen bond donor and acceptors, respectively) elicits the potential of these two tectons to function as tritopic modules (6,3). Supramolecular anionic networks are present in the two co-crystals wherein the donor and the acceptor alternate at the vertexes of the hexagonal frames and cations are accommodated in the potential empty space encircled by the frames. The change of one component in a self-assembled multi-component co-crystal often results in a change in its supramolecular connectivity and topology. Our systems have the same supramolecular features of corresponding iodide analogues as the metric aspects seem to prevail over other aspects in controlling the self-assembly process

Synthesis, Crystal Structures, and DNA Binding Properties of Zinc(II) Complexes with 3-Pyridine Aldoxime

The employment of 3-pyridine aldoxime, (3-py)CHNOH, in ZnII chemistry has afforded two novel compounds: [Zn(acac)2{(3-py)CHNOH}]⋅H2O (1⋅H2O) [where acac- is the pentane-2,4-dionato(-1) ion] and [Zn2(O2CMe)4{(3-py)CHNOH}2] (2). Complex 1⋅H2O crystallizes in the monoclinic space group P21/n. The ZnII ion is five-coordinated, surrounded by four oxygen atoms of two acac- moieties and by the pyridyl nitrogen atom of the (3-py)CHNOH ligand. Molecules of 1 interact with the water lattice molecules forming a 2D hydrogen-bonding network. Complex 2 crystallizes in the triclinic P-1 space group and displays a dinuclear paddle-wheel structure. Each ZnII exhibits a perfect square pyramidal geometry, with four carboxylate oxygen atoms at the basal plane and the pyridyl nitrogen of one monodentate (3-py)CHNOH ligand at the apex. DNA mobility shift assays were performed for the determination of the in vitro effect of both complexes on the integrity and the electrophoretic mobility of pDNA