Rapid Creation of Three-Dimensional, Tactile Models from Crystallographic Data

A method for the conversion of crystallographic information framework (CIF) files to stereo lithographic data files suitable for printing on three-dimensional printers is presented. Crystallographic information framework or CIF files are capable of being manipulated in virtual space by a variety of computer programs, but their visual representations are limited to the two-dimensional surface of the computer screen. Tactile molecular models that demonstrate critical ideas, such as symmetry elements, play a critical role in enabling new students to fully visualize crystallographic concepts. In the past five years, major developments in three-dimensional printing has lowered the cost and complexity of these systems to a level where three-dimensional molecular models may be easily created provided that the data exists in a suitable format. Herein a method is described for the conversion of CIF file data using existing free software that allows for the rapid creation of inexpensive molecular models. This approach has numerous potential applications in basic research, education, visualization, and crystallography.

Finite Element Simulation and X-Ray Microdiffraction Study of Strain Partitioning in a Layered Nanocomposite

The depth-dependent strain partitioning across the interfaces in the growth direction of the NiAl/Cr(Mo) nanocomposite between the Cr and NiAl lamellae was directly measured experimentally and simulated using a finite element method (FEM). Depth-resolved X-ray microdiffraction demonstrated that in the as-grown state both Cr and NiAl lamellae grow along the 111 direction with the formation of as-grown distinct residual ~0.16% compressive strains for Cr lamellae and ~0.05% tensile strains for NiAl lamellae. Three-dimensional simulations were carried out using an implicit FEM. First simulation was designed to study residual strains in the composite due to cooling resulting in formation of crystals. Strains in the growth direction were computed and compared to those obtained from the microdiffraction experiments. Second simulation was conducted to understand the combined strains resulting from cooling and mechanical indentation of the composite. Numerical results in the growth direction of crystal were compared to experimental results confirming the experimentally observed trends.

Synthesis, Crystal Structure, and Characterization of Ternary Copper(II) Complex Derived from N-(salicylidene)-L-valine

Ternary Schiff base copper(II) complex [CuL(tmpda)] (where H2L is N-(salicylidene)-L-valine; tmpda is N,N,N′,N′-tetramethyl-1,3-propanediamine) has been characterized by UV-Vis., FTIR, and single crystal XRD. The crystal structure displays a distorted square pyramidal geometry in which Schiff base is bonded to the Cu(II) ion via phenolate oxygen, imine nitrogen, and an oxygen atom of the carboxylate group through the basal plane and the chelating diamine, N,N,N′,N′-tetramethyl-1,3-propanediamine, displays an axial and equatorial mode of binding via NN-donor atoms.

Structure and Properties of 9,14,15,16,17,18,19,20-Octahydro-9,14[1′,4′]-benzenobenzo[b]triphenylene

The compound 9,14,15,16,17,18,19,20-octahydro-9,14[1′,4′]-benzenobenzo[b]triphenylene, C28H24, was prepared by hydrogenation of the 4πs+4πs photocycloadduct of dibenz[a,c]anthracene and 1,3-cyclohexadiene with Pt/C in ethyl acetate. The X-ray diffraction analysis shows that the compound crystallizes in the monoclinic space group P21/c with the geometric parameters of a = 11.0090(17) Å, b = 13.733(2) Å, c = 13.091(2) Å, and β = 109.583(13)°. In addition to several close intramolecular contacts involving hydrogens derived from the dibenzanthracene moiety, long interannular C–C single bonds of about 1.593 Å are present. These bonds are shorter by about 0.18 Å than the corresponding bonds in the unsaturated precursor, which can be attributed to reduced strain in the more saturated polycyclic ring system. Anisotropic shielding of the four endo-methylene hydrogens in the 1H NMR spectrum is larger for the two hydrogens lying above the phenanthrene unit, which resonate at 1.03 ppm, than those above the benzenoid ring, which resonate at 1.24 ppm. Theoretical calculations reproduce the geometry with good agreement.

The X-Ray Structure of the Ligand-Free Antibiotic Ristocetin-A Reveals the Role of the Monomer/Dimer Equilibrium in Its Binding Mode

Ristocetin-A belongs to the group of the glycoheptapeptide antibiotics. The sulfate salt of ristocetin-A was crystallized in the P21 monoclinic space group with a homodimer in the asymmetric unit. The two subunits are linked back-to-back like the other members of the family via four peptide bonds forming a twisted β-sheet and exposing the binding pockets to the exterior. The two tetrasaccharide parts of this ligand-free antibiotic are in the anti/anti orientations contrary to what was found in the mono- and diliganded ristocetin-A/-(D-Ala-D-Ala) complexes in which the two tetrasaccharides of the dimer are syn/anti. The ligand-free dimer shows however some conformational differences between the two subunits, particularly in the terminal arabinose leading to one extended and one bent conformation of the tetrasaccharide moiety. Comparison between this structure and the two available mono- and diliganded structures confirms that the anti/anti to syn/anti flipping of the tetrasaccharide is a key step in the binding to the D-Ala-D-Ala-containing target sequence and cannot proceed without displacement of the monomer/dimer equilibrium.

Synthesis and Crystal Structure of C1-Symmetric 3,3′-Bi(1,1′-dinaphthyl-camphopyrazole)

The compound 3,3′-bi(1,1′-dinaphthyl-camphopyrazole) 1, C42H42O4, was obtained in good yield and structurally characterized by 1H and 13C NMR spectroscopy, elemental analysis, and X-ray diffraction. It consists of a 3,3′-bipyrazole group with each pyrazole ring containing a fused camphor group and a naphthalene ring bonded to the adjacent nitrogen atom in the ring. Both of the trimethyl, 5-membered rings of the fused camphor group form an envelope with the apex carbon atom as the flap in each case. In the crystal, weak π–π stacking interactions are observed between nearby 6-carbon rings of the two naphthalene rings linking the molecules into extended chains. Weak π–ring intermolecular interactions are also observed between naphthalene atoms and pyrazole rings from each of the groups helping to stabilize the crystal packing. No classical hydrogen interactions are formed.

Solid State Structure of Bis[(bromo)(dicyclopentadienyl)vanadium(μ2-fluoro)][(bromo)(cyclopentadienyl)vanadium][tetrafluoroborate]

The new complex [V(C5H5)2Br]2(μ2-F)2[V(C5H5)Br]+[BF4]− has been isolated from the reaction of vanadocene monobromide with the ferrocenium cation. The complex is a mixed valence compound composed of two V(IV) and one V(III) centers. The V(III) center has one cyclopentadienyl ligand in its coordination sphere, as well as a bromide and two fluoride ligands. Each fluoride ligand is also attached to one of the V(IV) centers, which additionally is coordinated by a bromide and two cyclopentadienyl ligands. The complex crystallizes in the monoclinic space group P21/m, with a=7.66490(10) Å, b=15.2457(2) Å, c=13.3185(2) Å, and β=101.2721(8)° at 150(1) K.

Crystal Structure, Spectroscopy, SEM Analysis, and Computational Studies of N-(1,3-Dioxoisoindolin-2yl)benzamide

The compound N-(1,3-dioxoisoindolin-2yl)benzamide, C15H10N2O3, was prepared by the heating of an ethanolic solution of 2-hydroxy-1H-isoindole-1,3(2H)-dione and 4-chloroaniline. The product was characterised using a combination of IR spectroscopy, SEM, and single crystal X-ray diffraction techniques. In addition to the experimental analysis, theoretical calculations were used to investigate the crystal structure in order to compare experimental and theoretical values. The X-ray diffraction analysis shows that the compound crystallises in the monoclinic space group P21/c with the geometric parameters of a=13.5324(11) Å, b=9.8982(8) Å, c=9.7080(8) Å, and β=95.425(6)°. The crystal structure is held together by a network of N-H⋯O hydrogen bonds involving the carboxamide group.

Crystal Structures of Two Macrocyclic Bischalcones Possessing 26-Membered Rings

Single crystal X-ray diffraction of two macrocyclic bischalcones, namely, (2E,25E)-11,17,33,37-tetraoxapentacyclo[36.4.0.05,10.018,23.027,32]dotetraconta-1(42),2,5,7,9,18,20,22,25,27,29,31,38,40-tetradecaene-4,24-dione(1) and (2E,24E)-11,16,32,37-tetraoxapentacyclo[36.4.0.05,10.017,22.026,31]dotetraconta-1(42),2,5,7,9,17,19,21,24,26,28,30,38,40-tetradecaene-4,23-dione(2), each containing a 26-membered ring, has been studied. Compound 1 belongs to the monoclinic system, space group C2/c with a = 34.3615(9) Å, b = 12.7995(3) Å, c = 14.6231(3) Å, β = 96.912(2)°, V = 6,384.6(3) Å3, and Z = 8. Compound 2 is triclinic, space group P-1 with a = 10.066(2) Å, b = 10.670(3) Å, c = 16.590(3) Å, α = 85.95(2), β = 89.244(14), γ = 62.211(13), V = 1572.0(6) Å3, and Z = 2. Intermolecular C–H⋯O hydrogen bonding interactions are present in both compounds.

Synthesis and Molecular Structure of 4′,9′,4″,9″-Tetra-tert-butyl-1′,6′,1″,6″-tetramethoxy-2,5-dioxa[3.3]metabiphenylophane

A large calixarene-like metacyclophane, 4′,9′,4″,9″-tetra-tert-butyl-1′,6′,1″,6″-tetramethoxy-2,5-dioxa[3.3]metabiphenylophane, was synthesized by an intermolecular condensation reaction of its corresponding bischloromethyl-biphenyl and bishydroxymethyl-biphenyl precursors. After molecular characterization by 1H NMR spectroscopy and mass spectrometry, the compound generated single crystals by recrystallization from a dichloromethane/hexane mixture, facilitating an exact conformational determination via X-ray diffraction analysis. The crystal was found to belong to the monoclinic space group P21/n with cell parameters a = 19.908(2) Å, b = 9.7193(11) Å, c = 23.350(3) Å, β = 109.594(1)°, and Dcalc=1.150 g/cm3 at 90 K. The compound adopted quite strained 1,2-alternate-like conformations because its biphenyl parts displayed large dihedral angles and rigidity. The crystal did not incorporate any solvent molecule but its molecular cavity and crystal space were effectively filled by the substituents.