Journal of Chemical Crystallography最新文献

A new polymorph of tert-butyl (2-aminophenyl)carbamate was identified using single crystal X-ray diffraction. The compound crystallised in the centrosymmetric, monoclinic space group P2₁/n with an asymmetric unit comprising two crystallographically-independent molecules (Zʹ = 2). This new structure was compared to that of the known polymorph with the differences between the two being attributed to a combination of space group symmetry, conformational variation, hydrogen bonding network dimensionality and crystal packing.

The crystal and molecular structure of 7-dimethylamino-4-hydroxycoumarin as its hydrate (1, C₁₁H₁₁NO₃ • H₂O) has been determined. Crystals are monoclinic, space group P2(1)/n with a = 7.1435(4) Å, b = 20.1763(6) Å, c = 7.8590(3) Å, β = 110.018(5)^o and V = 1064.28(8)ų for 4 formula units per cell. Both coumarin enol ester hydroxy and carboxy groups engage in hydrogen-bonding with the water of crystallization. Several 3-substituted derivatives were prepared from this material including 7-dimethylamino-3-benzyl-4-hydroxycoumarin (2) and 7-dimethylaminowarfarin (4). Compound 2 (C₁₈H₁₆NO₃) crystallizes in the triclinic system, space group P-1, with a = 7.0180(7) Å, b = 7.8143(7) Å, c = 14.3158(10) Å, α = 90.586(6)^o, β = 94.738(5)^o, γ = 104.639(7)^o, and V = 756.57(9) ų for 2 molecules in the cell. For compound 2, the crystal structure shows infinite hydrogen-bonded translational β-chains linking well aligned hydroxy and ester carboxy groups with a repeat distance of 7.018 Å. The dipolar nature of the substituted 4-hydroxycoumarin strengthens the β-chains compared to unsubstituted systems in which the repeat is longer and weaker at 7.17 Å. Computations (DFT) support the bond length changes due to a dipolar influence of the 7-dimethylamino group (compared to the unsubstituted compounds), and a more negative carboxy oxygen hydrogen-bond acceptor. For compound 4 (C₂₁H₂₁NO₄), a stereoselective synthesis allowed preparation of the (S)-isomer which crystallized in the orthorhombic system, space group P2(1)2(1)2(1), with a = 6.7857(3) Å, b = 14.7140(5) Å, c = 17.4652(7) Å and V = 1743.81(12) ų for 4 molecules in the cell. Compound 4 forms the trans cyclic hemiketal from methanol in the crystal. In CDCl₃ solution (298 K), 4 exists as an equilibrium mixture of three tautomers: 12.8% open form, 45.5% cis hemiketal and 41.7% trans hemiketal (coumarin forms).

Graphical Abstract

Elisei Cosovan, Victor Cosovan, Daniel A. Osborne, David H. Magers, Edward J. Valente-3-Benzyl-4-hydroxy-7-dimethylaminocoumarin forms enhanced translational β-chain hydrogen-bonded arrays in the crystal

Synthesis, characterization and structural relevance of four new copper carboxylate complexes (1–4) has been presented here. The complexes have been synthesized by direct treatment of the substituted phenyl acetate and pyridine ligands in aqueous medium. The complexes were stable indefinitely with excellent yields and were characterized using spectroscopic and single crystal XRD techniques. FTIR spectroscopy revealed the bridging bidentate coordination mode for the carboxylate moiety in accordance to the actual structure revealed by XRD. Moreover, UV-Visible spectroscopic and cyclic voltammetric studies helped in their characterization and yielded signals which were typical of the copper(II) complexes. Successfully solved single crystal XRD data showed binuclear paddlewheel structures for all the complexes with both copper ions linked through four OCO bridges of ortho-methoxy phenyl acetate (1–3) and ortho-methyl-meta-nitrophenyl acetate (4). The geometry around each copper was distorted square pyramidal where the apical positions are occupied by meta-bromopyridine (1), meta-methylpyridine (2) and DMSO (3 and 4) molecules. The complexes exhibited excellent DNA-binding activity majorly via intercalation as revealed by four experimental techniques. This preliminary study showed that the synthesized complexes add to the existing treasury on the paddlewheel complexes.

The Index Abstract

Air stable newly synthesized and purified crystalline complexes with their preliminary structural relevance.

The presented study describe the crystal structure of 2-(Ethoxymethylene)malononitrile (1), C₆H₆N₂O, in the monoclinic space group P2₁/m with Z = 2, a = 6.798(3), b = 6.172(3), c = 8.844(5) Å. The unit cell of a single crystal of 1 contains two antiparallel oriented molecules. Ethyl fragment demonstrates a disorder with equal occupancy values of 0.5 and a total site-occupation factor (s.o.f.) of 1.0. The molecules of 1 are linked into infinite chains of co-oriented molecules parallel to the a axis via N-H···N ≡ C close contacts with the distance of 2.494(3) Å. There are also weak hydrogen bonds > O···H- between the oxygen atom and the ethyl moiety. The estimation of the energy of non-covalent interactions was conducted by DFT method with different functionals. The best reproducibility of the geometric parameters of those interactions was obtained by using M06-2X functional. The estimated energy value was found to be − 1.20 kcal/mol.

Graphical Abstract

The interplay between conformation and hydrogen bond pattern was studied in 211 (C(O)NH)(N)₂P(O)-based phosphoric triamides retrieved from the Cambridge Structural Database (CSD) and one new molecular structure, (CHCl₂C(O)NH)(CH₃CH₂CH₂NH)₂P(O). The O═C–N–P and C–N–P═O torsion angles were extracted for the conformational study of the C(O)NP(O) segment, and the conformations of ±sp±ap, ±sp±sc and ±ap±sp were found (sp = synperiplanar, ap = antiperiplanar, sc = synclinal). The conformations of hydrogen bond donor group(s) with respect to the acceptor group(s) were also considered. The investigated structures belong to three classes of (RC(O)NH)(R¹R²N)₂P(O) (R¹ and R² ≠ H), (RC(O)NH)(R¹NH)₂P(O) (R¹ ≠ H) and heterocyclic (RC(O)NH)P(O)[NR¹]₂R² phosphoric triamides (R¹ = H or ≠ H, R² = a hydrocarbon fragment), and the hydrogen bond patterns include dimer, tetramer, chain, tape, ladder, two-dimensional assembly and three-dimensional architecture. In the new structure, the conformation of the C(O)NP(O) fragment is –sp+ap, and molecules are assembled in a tape arrangement (parallel to the [110] axis) through N_CP–H···O═P and N_P–H···O═C hydrogen bonds (N_CP is the nitrogen atom of the C(O)NHP(O) fragment and N_P is the other N atom bonded to phosphorus).

Graphical Abstract

The interplay between conformation and hydrogen bond pattern was studied in 211 (C(O)NH)(N)₂P(O)-based phosphoric triamides retrieved from the Cambridge Structural Database (CSD) and one new structure, (CHCl₂C(O)NH)(CH₃CH₂CH₂NH)₂P(O).

A homochiral metal-organic framework, [Ni(D-L)(py)₂(H₂O)₂]_n (1) [D-H₂L = 4,4′-[[(1R,3S)-1,2,2-trimethylcyclopentane-1,3-dicarbonyl]bis-(azanediyl)]dibenzoic acid], has been successfully synthesized based on D-camphorate-derived enantiopure ligand. 1 was characterized by single-crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), Fourier transform infrared spectral analysis (FTIR), thermogravimetric analysis (TGA) and the circular dichroism (CD) spectrum. The experimental results show that 1 features a homochiral triple helix and is formed a 3D supramolecular framework by supramolecular interactions. In addition, the circular dichroism (CD) spectrum verifies the chirality introduction from the ligand to crystal. The successful preparation of the homochiral Ni-MOF provides more possibilities of employing the chiral ligand to produce various chiral MOFs.

Graphical Abstract

A homochiral Ni(II)-MOF 1 was prepared by using D-camphorate-derived enantiopure ligand under solvothermal condition, in which the chirality of 1 was confirmed by the circular dichroism (CD) spectrum

Bis-[2-(3,4-dihydroxyphenyl)-4,5-diphenyl-1H-imidazol-3-ium] Oxalate ethanol solvate crystal has been isolated from slow solvent evaporation method and the structure was characterized by FT-IR, NMR and Single crystal XRD. The compound crystallizes in the triclinic space group P (overline{1 }) with a = 7.7925(16), b = 10.716(3), c = 13.952(3), α = 106.545(5), β = 97.514(5), γ = 110.152(5), V = 1014.0(4) Å3 and Z = 1. The single crystal X-ray data of the compound confirms two proton transfers from an oxalic acid to the pyrimidine-type-nitrogen of two separate imidazole rings. The structure and symmetry of the Imidazolium Oxalate is dictated by N–H⋯O and O–H⋯O hydrogen bonding interactions and are confirmed by hydrogen bonding analysis and hirshfeld surface analysis. The partial double bond character in the imidazolium ring confirms delocalization across the molecular framework. The partial double bond character of the C–O bonds also confirms delocalization in the oxalate anion. The crystal is 3-dimensional structure, with crystal growth in all the crystallographic axis. Computational analysis [DFT, B3LYP/6-311G(d,p)] reveals close correlation of the constrained optimized structure with the experimental data.

Graphical Abstract

Imidazolium oxalate crystal form by the protonation of Imidazole compound and complex formation with oxalate ion.

Three crystalline organic salts (melamine)₂: (itaconic acid): 3H₂O [(Hmem)₂²⁺·(itca²⁻)·(H₂O)₃, itca²⁻ = itaconate] (1), (melamine)₂:(2-bromo-but-2-enedioic acid):DMF:2H₂O [(Hmem⁺)₂·(bbda²⁻)·DMF·(H₂O)₂, bbda²⁻ = 2-bromo-but-2-enedioate] (2) and (melamine):(α-ketoglutaric acid) [(Hmem⁺)·(Hketglua⁻), Hketglua⁻ = hydrogen α-ketoglutarate] (3) were featured by X-ray diffraction analysis, IR, mp, and elemental analysis. Significant non-covalent interactions were calculated by means of the Hirshfeld surface analysis. All salts involve extensive N–H···OH-bonds as well as other non-covalent associations. The melamine polymers/dimers were set up at 1–2/3 by the pair of complmentary N–H···NH-bonds. The role of these non-covalent interactions in the crystal packing is ascertained. These weak interactions combined, all salts exhibited 3D framework motifs.

Graphical Abstract

The crystal structures of the salts from melamine, itaconic acid, 2-bromo-but-2-enedioic acid and α-ketoglutaric acid are predominantly stabilized by the classical hydrogen bonds as well as CH2···O, CH3···O, Br···Br, C···C, O···C, and π···π interactions.

Measurement of the unit cell of (R)-BINOL over a 200° temperature range (300–100 K) reveals an anisotropic contraction where the c-axis contracts ca. 2.3% compared to a ca. 0.45% contraction of the a and b axes, a ca. six-fold difference in linear thermal expansion coefficient. This contraction corresponds to a decrease in the helical pitch of the 3₁ screw axis in the [001] direction. The anisotropic nature of the contraction is rationalised by a thorough analysis of intermolecular contacts within the crystal and their impact on the conformation of the molecule and crystal packing.

Graphical Abstract

The crystal structure of (R)-BINOL exhibits a pronounced anisotropic thermal expansion.

A chelating N-heterocyclic carbene palladium complex (3) containing N-(3-bromopropyl)-N’-thioether di-functionalized imidazol-2-ylidene was synthesized by the direct metalation of N-(3-bromopropyl)-N’-thioether di-functionalized imidazolium bromide (2) with Pd(OAc)₂ in the presence of NaOAc and NaBr at room temperature using CH₂Cl₂ as solvent. The structure was characterized by NMR, HR-MS and X-ray crystallography. The results showed that complex 3 consists of two independent molecules with configuration of S_C, R_S in molecule a, and S_C, S_S in molecule b, respectively. The crystal is triclinic, P1 space group, with a = 8.4815(3), b = 8.6338(3), c = 19.2371(7) Å, V = 1245.66(8) ų, and Z = 2 (at 293(2)K).

Graphical Abstract

A chelating N-heterocyclic carbene palladium complex (3) consists of two independent molecules with configurations of S_C, R_S and S_C, S_S respectively has been synthesized through the direct metalation of the precursor imidazolium bromide (2).