Structural studies of some derivatives of cis,cis-cyclohexane-1,3,5-tricarboxylic acid

cis,cis-Cyclohexane-1,3,5-tricarboxylic acid (1) its trimethyl ester (2) and their 1,3,5-trimethylated and 1,3,5-tribenzylated derivatives were prepared, and their structures studied by two-dimensional NMR spectroscopy in conjunction with X-ray crystallography. The results show that these molecules adopt a chair conformation in solution, with all the carboxyl groups in1 and all the methoxycarbonyl groups in2 occupying the equatorial positions, but with the corresponding functionalities in the alkylated derivatives occupying the axial positions. For2, its 1,3,5-tribenzylated derivative4, andcis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid (5), the same conformational preferences are seen to persist in the crystalline state as in solution.On leave from The National Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, China.On leave from Central Laboratory, Nankai University, Tianjin, China.     

Crystal structure of 2-nitrimino-5-nitro-hexahydro-1,3,5-triazine

The crystal and molecular structure of 2-nitrimino-5-nitro-hexahydro-1,3,5-triazine (NNHT) was determined. The relationship between the structural features of NNHT and its properties that pertain to its suitability as a potential oxidizer candidate for gun propellants is discussed. The NNHT structural features are also compared with analogous structural features of nitroguanidine (NQ) (Bracuti, A. J. J. Chem. Crystallogr. 1999, 29, 671) the more highly energetic triazine derivative, 1,3,5-trinitro-hexahydro-1,3,5-triazine (RDX) (Choi, C. S. and Prince, E. Acta.Crystallogr. B 1972, 28, 2857).     

1,3,5-三(羧基甲氧基)苯镍配位聚合物的合成、晶体结构及性质研究

采用溶剂热法,1,3,5-三(羧基甲氧基)苯为定向配体和乙酸镍反应构筑了一个新型的金属配位聚合物[Ni(TB)₂(H₂O)₂]_n·2H₂O,其中H₃TB=1,3,5-三(羧基甲氧基)苯,通过元素分析、IR及X射线单晶衍射对配合物结构进行表征,并研究其荧光性质、热稳定性及Hirshfeld表面作用力。单晶结构分析表明,该配合物属于三斜晶系,空间群$P \overline{1}$,配合物中心离子Ni(Ⅱ)分别与来自两个水分子上的氧原子及四个不同1,3,5-三(羧基甲氧基)苯配体的羧酸氧原子配位,形成六配位的NiO₆八面体构型,并通过与1,3,5-三(羧基甲氧基)苯配体的氧原子配位不断延伸形成具有孔洞结构的一维链状构型。配合物具有良好的荧光性能和热稳定性。Hirshfeld表面作用分析表明配合物分子中O…H/H…O作用占主导且占比为39.0%,而H…H的作用力占比为25.9%,O…O的作用力占比为13.6%。     

Glass-forming Photoconductive Organic Compounds II1: Glass-forming Properties of 1,3,5-Triaryl-2-pyrazolines

Glass-forming properties of 2-pyrazoline derivatives were examined and discussed in terms of the molecular structure. The results show that the molecular shape of 1,3,5-triaryl-2-pyrazolines is responsible for the glass-forming properties of these compounds. Glass transition points of several 1,3,5-triaryl-2-pyrazoline derivatives were measured.     

Molecular structures of 17αβ-acetoxy-3-methoxy-6-oxa-D-homo-8-isoestra-1,3,5(10)-triene and its 4-methyl derivative

The molecular structures of 17αβ-acetoxy-3-methoxy-6-oxa-D-homo-8-isoestra-1,3,5(10)-triene (I) and 17αβ-acetoxy-3-methoxy-4-methyl-6-oxa-D-homo-8-isoestra-1,3,5(10)-triene (II) have been established by X-ray diffraction analysis. The presence of the methyl group at the C(4) atom in compound II leads to slight changes in the conformation of the carbon skeleton of this molecule and the orientation of the methoxy group with respect to the C(2)-C(3) bond.     

Evaluation of nucleation rate by in‐situ focused beam reflectance measurement in an unseeded batch cooling crystallization

Nucleation kinetics in the cooling crystallization of hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX) from γ‐butyrolactone was studied by converting total counts/s measured by in situ focused beam reflectance measurement (FBRM) into number of crystals. The classical nucleation rate model, which is derived exclusively from the thermodynamic state for the nucleation and molecular collision frequency, was found to be inadequate to describe the experimentally measured nucleation rates. However, the nucleation rates predicted by the modified classical nucleation rate model, inclusive of an additional temperature term, were found to be in good agreement with those measured in the present work. Furthermore, the metastable zone widths are also found to be more accurately predicted by the modified classical nucleation rate model than the classical approach, which assumes that the mass‐based nucleation rate is an exponential function of supersaturation and is equal to the supersaturation rate.     

Crystal Structure of a Metallohybrid Acid of 1,3,5-Benzenetricarboxylic Acid of Copper(II)

Abstract The crystal structure of a metallohybrid carboxylic acid obtained from the reaction of 1,3,5-benzenetricarboxylic acid (TCAH3) with copper(II)acetate monohydrate in the presence of pyridine (py) having composition Cu(py)₂(TCAH2)₂(H₂O)₂ [1] is reported. It crystallizes in triclinic space group P-1 and with a = 7.0110(3)?, b = 8.9523(5)?, c = 11.5370(5) ?, α = 79.776(3) °, β = 82.881(3)°, γ = 83.628(3)°, and V = 704.18(6)?³. The hydrogen bond in 1 is compared with the hydrogen bond pattern in the structure of 1,3-dicarbomethoxy 4,6-benzenedicarboxylic acid, which crystallizes in mononclinic space group P21/c and has unit cell parameters of a = 6.9549(16)?, b = 8.7676(15)?, c = 20.111(4)?; β = 92.585(17) ° and V = 1225.1(4) ?³. Index Abstract Crystal structure of a metallohybrid carboxylic acid obtained from the reaction of 1,3,5-benzenetricarboxylic acid with copper(II)acetate monohydrate in the presence of pyridine is determined and compared with hydrogen bond pattern present in the structure of 1,3-dicarbomethoxy 4,6-benzenedicarboxylic acid. Crystal structure of a metallohybrid acid of 1,3,5-benzenetricarboxylic acid of copper(II). Kusum Bania, Nilotpal Barooah, Rupam Sarma, Jubaraj B. Baruah     

Molecular structures of some 8-isoanalogues of steroid estrogens

The molecular structures of three steroids, namely, 17β-acetoxy-3-methoxy-8-isoestra-1,3,5(10)-triene (I), 17β-acetoxy-3-methoxy-7α-methyl-8-isoestra-1,3,5(10)-triene (II), and 17β-acetoxy-3-methoxy-1-methyl-8-isoestra-1,3,5(10)-triene (III), are determined by X-ray diffraction analysis. It is shown that the substituents in the A and B rings of the compounds of the 8-iso series have a slight effect on the conformation of the steroid skeleton as a whole, which manifests itself only in insignificant distortions of the B and D rings. The methyl group in the 1-position (compound III) affects the geometric parameters of the steroid nucleus less than the same substituent in the 7-position (compound II). A sharp decrease in the uterotropic activity of compounds II and III (compared to compound I) revealed in biological studies can be attributed to unfavorable steric interactions of the substituents in the A and B rings with the estradiol receptor.     

Specificity in Chemical Perturbation of Crystal Structures

The specificity in chemical perturbation of crystal structure is examined by investigating the efffect of the position of particular substituent group on the crystal structure. 1,2,3,5-tetra-halobenzenes are chosen for this study. A comparative study of Raman phonon spectra of 1,2,3,5-tetrachlorobenzene; 1,2,3-trichloro-5-bromobenzene; and 1,3,5-trichloro-2-bromo-benzene crystals reveals that former two have the same crystal structure, while the latter has a different crystal structure. It is inferred that a bromine group substitution in 2-position of 1,2,3,5-tetrachlorbenzene creates a lattice instability which gives rise to a different crystal structure for 1,3,5-trichloro-2-bromobenzene. The nature of this instability is discussed. Mixed crystals of 1,2,3,5-tetrachlorobenzene and 1,2,3-trichloro-5-bromobenzene are studied to establish phonon correlation and deloalization.     

Differing Patterns in the Self-Assembly of Radially Anchored Imidazoles, 1,3,5-Tris(1<Emphasis Type="Italic">H</Emphasis>-imidazol-2-yl)benzene and 1,3-Bis(1<Emphasis Type="Italic">H</Emphasis>-imidazol-2-yl)benzene

Abstract The novel 3-fold symmetric 1,3,5-tris(1H-imidazol-2-yl)benzene, having a propensity for a 3-fold salt formation by hydrogen bonding at the periphery, was prepared from oxidation of the hexahydro imidazole precursor. The transformation proved difficult and, of the many reagents tried, only barium manganate and o-iodoxy benzoic acid were successful. The oxidation to the aromatic 1,3,5-tris imidazolyl benzene produces dramatic changes, particularly when the X-ray structures of their tris-TFA (trifluoroacetic acid) salts are compared. While the hexahydro precursor exhibited a herringbone type arrangement in the crystal, the oxidation resulted in almost co-planar molecules that formed parallel stacks separated by 3.57 ? between the atoms in separate planes. 1,3-Bis(1H-imidazole-2-yl)benzene is an attractive core unit for assembly using a variety of auxiliaries. Several attempts to complex the bis-imidazole with organic acids failed. These efforts lead to the serendipitous discovery of a novel tetrameric assembly, mediated by water molecules, which was confirmed by crystallization of the bis imidazole from water. Index Abstract Differing Patterns in the Self-Assembly of Radially Anchored Imidazoles, 1,3,5-Tris(1 H -imidazol-2-yl)benzene and 1,3-Bis(1 H -imidazol-2-yl)benzene A. Infinite stacks of the TFA salt from 1,3,5-tris(1H-imidazol-2-yl)benzene with a separation of 3.57 ? between atoms in separate planes (The TFA moiety has been omitted for clarity). B. Tetrameric assembly of 1,3-bis(1H-imidazol-2-yl)benzene, mediated by water molecules. Differing Patterns in the Self-Assembly of Radially Anchored Imidazoles, 1,3,5-Tris(1 H -imidazol-2-yl)benzene and 1,3-Bis(1 H -imidazol-2-yl)benzene Y.B.R.D. Rajesh, ⁽²⁾ Subramania Ranganathan, ⁽²⁾* Richard D. Gilardi ^(1,3) and Isabella L. Karle, ⁽¹⁾* (1) Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, D.C. 20375-5341 (2) Discovery Laboratory, Organic III, Indian Institute of Chemical Technology, Hyderabad 500 007, India (3) Retired Richard D. Gilardi—Retired.     

Co-crystal structures of 2,4-diamino-6-phenyl-1,3,5-triazine – 4-chlorobenzoic acid/4-methoxybenzoic acid: Synthesis,structural and Hirshfeld surface analysis

The co-crystal structure of 2,4-diamino-6-phenyl-1,3,5-triazine with 4-chlorobenzoic acid/4-methoxybenzoic acid molecules are explain the link between the dimension and shape of their hydrogen-bonded assembly. The co-crystal structure of 2,4-diamino-6-phenyl-1,3,5-triazine with 4-chlorobenzoic acid/4-methoxybenzoic acid forming a cyclic R₂²(8) ring motif via N–H?O and O–H?N hydrogen bonding interactions, to form a supramolecular heterosynthon. In both the co-crystal structures, self-association of 2,4-diamino-6-phenyl-1,3,5-triazine moieties are connected via N-H^….N base pairs with cyclic R₂²(8) motif form a supramolecular homosynthon. In co-crystal II, the centrosymmetrically paired methoxy group of 4-methoxy benzoic acid form a supramolecular homosynthon via weak intermolecular C-H^….O hydrogen bonds, generating R₂²(6) ring motif. Both the co-crystal structures are stabilized by weak aromatic π-π and C—Cl???π stacking interactions. Hirshfeld surface and fingerprint plots were used to study the intermolecular interactions both of the crystal structures.     

Influence of emulsion types on nucleation kinetics and growth habit in the cooling crystallization

Experiments on unseeded batch cooling crystallization were made to investigate the influence of emulsion [solution in non‐solvent (S/NS) emulsion and non‐solvent in solution (NS/S) emulsion] on crystal size and growth habit of various materials such as hexahydro‐1,3,5‐trinitro‐1,3,5‐triazine, ammonium sulfate, potassium dihydrogen phosphate (KDP), and γ‐glycine. Size of crystals obtained from the S/NS emulsions was found to be significantly larger than that obtained from the NS/S emulsions. Those results were explained by broad induction time distribution of nucleation in the isolated solution droplets and subsequent seeding effect by free movement of early‐induced crystals by vigorous agitation. As a result, the population density of crystals was shown to be smaller in the S/NS emulsions than that in the NS/S emulsions. In the S/NS emulsions, desupersaturation rate should be slow and high supersaturation is subsequently generated during crystal growth stage. Therefore, it may be concluded that crystal morphology of the materials with supersaturation dependent growth habit, such as ammonium sulfate, KDP and γ‐glycine, can be controlled by selection of emulsion type.     

Synthesis and structure of (±)-4-O-methanesulfonyl-myo-inositol 1,3,5-orthoformate

Racemic 4-O-methanesulfonyl-myo-inositol 1,3,5-orthoformate was prepared by methanolysis of racemic 2,4-di-O-benzoyl-4-O-methanesulfonyl-myo-inositol 1,3,5-orthoformate, in the presence of triethylamine. The diol crystallizes in space group P2₁2₁2₁ with cell dimensions a = 6.094(1), b = 6.502(2), c = 25.947(3) Å, V = 1028.1(4) Å, Z = 4. The molecular crystals show both intra- and intermolecular O—H···O short contacts. The methine and the methyl hydrogens are involved in several C—H···O interactions.     

The structure of [Co(H-tptz)Cl3]·H2O (tptz=2,4,6-tri(2-pyridyl)-1,3,5-triazine) prepared by crystallization from the ionic liquid, N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide

The structure of tris-chloro[2,6-bis(2′-pyridyl)-4-(2′-pyridinium)-1,3,5-triazine]cobalt(II) monohydrate, [Co(C₁₈H₁₃N₆)Cl₃]·H₂O (C2/c (No. 15), a=7.783(11), b=22.42(3), c=11.001(15) ?, β=90.05(2)°), crystallized from the open air reaction of CoCl₂ and 2,4,6-tri(2-pyridyl)-1,3,5-triazine in the ionic liquid, N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide is reported. The structure consists of six coordinate cobalt in an octahedral geometry bonded to the tridentate tptz ligand and three chlorines. The non-coordinating pyridyl group in the tptz ligand is protonated (with the protonated nitrogen crystallographically disordered over two possible sites), providing overall charge neutrality for the complex.     

Prediction of crystal morphology of 1,3,5-triamino-2,4,6-trinitrobenzene in dimethyl sulfoxide via modified attachment energy modeling and its experimental validation

A new computational method was established to investigate the solvent effects on the crystal morphology of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). The modified attachment energy (MAE) method was applied on TATB in dimethyl sulfoxide (DMSO). This MAE E_satt method accounting for the attachment energy effect of the solvent was proposed to replace the vacuum attachment energy using the solvent-crystal interaction energies. In our simulation study, TATB crystals in DMSO grew into a hexagonal-flake structure and are in good agreement with the experimental data.     

Preparation and Photoluminescent Properties of Hydrogen-bonded Discotic Liquid Crystals

Photoluminescent discotic liquid crystals (DLCs) have been prepared through intermolecular hydrogen bonding between core and peripheral units. 1,3,5-Trihydroxybenzene was employed as core molecule and peripheral stilbazole derivatives containing linearly conjugated moieties were complexed to form hydrogen-bonded DLCs. Their structures, mesophases, and optical properties were investigated. The complexation of core and peripherals made some discotic complexes form photoluminescent DLCs. The prepared luminescent DLCs exhibited columnar mesophases with strong blue or sea green photoluminescence. These findings may contribute to the development of luminescent supramolecular liquid crystals for emitting materials in light emitting devices.     

Tonalensin,a 5,10-seco-neoclerodane diterpenoid

We report the X-ray study on the structure of a newseco-neoclerodane diterpenoid, tonalensin, isolated from the aerial parts ofSalvia tonalensis. The compound crystallizes in the monoclinic space groupP2₁ witha=10.146(2),b=7.620(2),c=11.316(2) Å, =109.58(2)°. Thetrans,cis,cis-cyclodeca-1,3,5-triene ring adopts a boat-chair conformation in which the ^1,3,5-triene system is no longer coplanar. The -lactone and furan rings are essentially planar, while both five-membered rings of the dioxabicylooctane moiety arecis-fused and adopt a twist conformation.Contribution No. 1339 of Instituto de Química, UNAM.     

A twist boat: Structure and conformation oftrans-2,4,6-tris(trichloromethyl)-1,3,5-trithian

Trans-2,4,6-tris(trichloromethyl)-1,3,5-trithian, (CCl₃·CHS)₃, has been prepared free from persistent impurification bycis-trans-2,4,6-tris(trichloromethyl)-1,3,5-oxadithian and its conformation determined by single crystal x-ray crystallography. The title compound is orthorhombic,Pbca, a=10.479(10),b=27.957(14),c=11.093(3) Å,V=3250 ų,Z=8. The structure was solved by direct methods, from data collected at room temperature on an Enraf-Nonius CAD4 diffractometer, and refined by full-matrix least squares to a finalR value at 0.074 using 1186 reflections. The molecule exhibits a twist boat conformation with the –CCl₃ groups occupying pseudoequatorial positions. The torsion angles in the trithian ring are successively 29(1), –79(1), 41(1), 41(1), –84(1), 39(1)°. Average values are: S-C 1.82(2), C(ring)-C(Cl₃) 1.56(4), C-Cl 1.76(2) Å, S-C-S 112.7(2)°. The C-S-C angles are 97.4(7), 101.4(7), 97.3(7)°.     

Application of solution techniques for rapid growth of organic crystals

Single crystals of a pure hydrocarbon, 1,3,5-triphenylbenzene, with properties suitable for high-energy neutron detection were grown from toluene solutions using slow evaporation and temperature reduction methods with growth rates up to 10 mm/day. Application of the rapid growth technique developed earlier for growth of large water-soluble crystals shows that crystals of aromatic compounds can be successfully grown from solutions in large volumes required for their use as scintillator materials for radiation detection.     

Supramolecular Discotic Columnar Liquid Crystals Built through Single Hydrogen Bonding between Carboxylic Acid and Pyridine Moieties

New self-assembled discotic columnar liquid crystals were prepared via single hydrogen bonding between the core molecule of 1,3,5-cyclohexanetricarboxylic acid and the peripheral units of stilbazole derivatives. The hydrogen-bonded liquid crystals exhibited rectangular columnar and hexagonal columnar mesophases depending on the number of alkyl chains in three arms of the discotic mesogen through dipole-dipole interactions between carbonyl groups along the column axis. The intermolecular hydrogen bonding between carboxylic acid and pyridine moieties provides an effortless methodology to prepare the ordered columnar liquid crystals for electronic applications.