Benzene Substituents Research Articles

Distribution of benzo-substituted crown-ethers between chloroform and water: effects of macrocycle ring size and lithium chloride

Small size benzo-substituted crown ethers are attractive complexing agents for lithium isotope separation by solvent extraction. Low transfer of the crown ethers from solvent to water is a key point for applicability of the extractants. In the present study, 9- and 12-membered crown ethers were synthesized, and their distribution between chloroform and water was studied. Polyether ring size, benzene substituents and addition of LiCl to water were found to effect on distribution constants. Low losses of the macrocycles were observed at single-stage contact with aqueous phase. However, these losses should be taken into account in the design of multistage processes for the preparation of highly enriched lithium isotopes.

9-(4-Formylphenyl)-3,3,6,6-tetramethyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione

In the title compound, C24H26O4, the central 4H-pyran ring adopts a flattened boat conformation, with the mean and maximum deviations of the ring being 0.0582 (6) and 0.1012 (3) Å, respectively. The two cyclohexenone rings on opposite sides of the pyran ring each adopt an envelope conformation; the C atom bearing a dimethyl substituent is the flap atom in each case. The mean planes of the pyran ring and the substituent benzene ring subtend a dihedral angle of 86.45 (2)°. In the crystal, molecules are linked into inversion dimers via pairs of C—H...O hydrogen bonds.

Effects of Pressure on Model Compounds of Meteorite Organic Matter

Extraterrestrial organic matter has been widely studied; however, its response to pressure has not. Primitive organic matter bearing meteorites, such as CI and CM carbonaceous chondrites, have experienced variable pressures, up to 10 GPa. To appreciate the effects of these pressures on the organic content of these bodies, the model compounds isophthalic acid, vanillin, and vanillic acid were subjected to pressures of up to 11.5 GPa and subsequently decompressed. High-resolution synchrotron source Fourier transform infrared spectroscopy was used to determine the effects of different benzene substituents at high pressure on both the vibrational assignments of the benzene core of the molecules and the ability of the aromatic compounds to form intermolecular hydrogen bonds. The presence of additional peaks at high pressure was found to coincide with molecules that contain carboxyl groups; these features are interpreted as C–H···O intermolecular hydrogen bonds. The formation of these hydrogen bonds has implications for the origination of macromolecular organic matter (MOM), owing to the importance of such attractive forces during episodes of cross-linking, such as esterification. Pressure-induced hydrogen-bond formation is a process by which aromatic MOM precursors could have cross-linked to generate the organic polymers found within extraterrestrial bodies today.

Encapsulation of Arenes within a Porous Molybdenum Oxide {Mo132 } Nanocapsule.

The use of confined space to modulate chemical reactivity and to sequester organic compounds spans significant disciplines in chemistry and biology. Here, the inclusion and assembly of arenes into a water-soluble porous metal oxide nanocapsule [{(MoVI )MoV5 O21 (H2 O)6 }12 {MoV2 O4 (CH3 COO)}30 ]42- (Mo132 ) is reported. The uptake of benzene, halobenzenes, alkylbenzenes, phenols, and other derivatives was studied by NMR, where it was possible to follow the encapsulation process from the outside of the capsule through its pores and then into the interior. The importance of size or shape of the arenes, and various intermolecular bond interactions contributed by the benzene substituent on the encapsulation process was studied, showing the importance of π-π stacking and CH-π interactions. Furthermore, by using NOESY, ROESY, and HOESY NMR techniques it was possible to understand the interaction of the encapsulated arenes and the acetate linkers or ligands that line the interior of the Mo132 capsule.

Fine electronic state tuning of cobaltadithiolene complexes by substituent groups on the benzene ring

A series of 3,6- and 4,5-dihalogen-substituted 1,2-benzenedithiol (H2bdt) ligands, (3,6-X12-4,5-X22-1,2-H2bdt) (X2=H, X1=F (1a), Cl (1b), Br (1c); X1=H, X2=Cl (4)), and their cobalt complexes, [Cp∗Co(3,6-X12-4,5-X22-1,2-bdt)] (X2=H, X1=F (2a), Cl (2b), Br (2c); X1=H, X2=Cl (5)), were synthesized by a modified selective thiolation reaction. The 1,2-diphenyl-substituted cobaltadithiolene complex (2d) was also synthesized. The molecular structures of all cobaltadithiolene complexes were determined by single crystal X-ray diffraction analysis. Compounds 2a, 5 and 12 showed unique packing structures with intermolecular interactions that confirmed them as the first examples of half-sandwich-type metalladithiolene complexes with a Cp∗ ligand. The effects of the benzene substituent type and position on the metalladithiolene ring were investigated using UV–vis spectroscopy measurements and cyclic voltammetry. The results indicate that substitution of halogen atoms at the 3 and 6 position of the benzene ring had a larger effect on the dithiolene ring than substitution at the 4 and 5 positions.

Crystal structure of 2,6-bis-(2-hy-droxy-5-methyl-phen-yl)-4-phenyl-pyridinium bromide di-chloro-methane hemisolvate hemihydrate.

The asymmetric unit in the structure of the title compound, C25H22NO2 +·Br −·0.5CH2Cl2·0.5H2O, comprises two pseudosymmetry-related cations, two bromide anions, a di­chloro­methane molecule and a water mol­ecule of solvation. The two independent cations are conformationally similar with the comparative dihedral angles between the central pyridine ring and the three benzene substituent rings being 3.0 (2), 36.4 (1) and 24.2 (1)°, and 3.7 (2), 36.5 (1) and 24.8 (1)°, respectively. In the crystal, the cations, anions and water mol­ecules are linked through O—H⋯O and O—H⋯Br hydrogen bonds, forming an insular unit. Within the cations there are also intra­molecular N—H⋯O hydrogen bonds. Adjacent centrosymmetrically related aggregates are linked by π–π stacking inter­actions between the pyridine ring and a benzene ring in both cations [ring-centroid separations = 3.525 (3) and 3.668 (3) Å], forming chains extending across the ac diagonal. Voids between these chains are filled by dichloromethane molecules.

Extended Threefold‐Symmetric Second‐Harmonic‐Generation Chromophores Based on 1,3,5‐Trisubstituted Benzene Complexes

The elongation of the π system of a donor–π–acceptor (D–π–A) chromophore has often proven to be beneficial for its nonlinear optical (NLO) activity. Against this background, different alkynyl protecting groups such as organosilyl and dicobalt hexacarbonyl functions were investigated with respect to their ability to enable the coordination of an electron-withdrawing CpRu+ fragment (Cp = cyclopentadienyl) to a threefold ethynyl-substituted benzene ring, acting as a potential 2D NLOphore, without undesired side reactions. In addition, the influence of the perpendicularly coordinated CpRu+ unit on the NLO properties was examined. The obtained organometallic triisopropylsilyl-substituted benzene ruthenium complex and the multinuclear dicobalt hexacarbonyl protected ferrocene complex were fully characterized. Owing to the problems during the purification of the trimethylsilyl-protected benzene ruthenium complex and the subsequent deprotection to the free alkyne complex, it was not possible to fully characterize those complexes. The introduction of the CpRu+ fragment was sensitive to the steric demands of the benzene substituents but beneficial for the generation of NLO activity. The first hyperpolarizabilities of the triisopropyl and dicobalt hexacarbonyl complexes were investigated by hyper-Rayleigh scattering. The molecular structures were characterized by X-ray crystallography and infrared (IR) spectroscopy. The structures and IR spectra were compared with Kohn–Sham density functional theory calculations.

Crystal structure of 11-[4-(hex-yloxy)phen-yl]-1,2,4-triazolo[4,3-a][1,10]phenanthroline.

The title compound, C25H24N4O, was prepared from 2-chloro­phenanthroline and hexyl­oxyphenyl­tetra­zole. The main difference between the two independent mol­ecules (A and B) in the asymmetric unit is the orientation of the all-anti-configured hex­yloxy chain: in A the C—O—C—C torsion angle is 175.9 (2)° whereas it is −88.3 (3)° in B. The benzene substitution in the bay of the triazolophenanthroline results in a helical distorsion of the heterocyclic core, the dihedral angles between the mean planes formed by quinoline and benzotriazole ring systems are 13.73 (9) for mol­ecule A and 14.87 (8)° for B. The dihedral angles between the triazole ring and the attached benzene ring are 45.87 (15) in A and 53.93 (14)° in B. The angular annulation of four rings and the benzene substituent results in a helical distortion of the aromatic framework. The crystal is formed from layers composed of centrosymmetric pairs of A 2, B 2 mol­ecules with inter­digitating alkyl chains.

Crystal structure of 4-chloro-N-{[1-(4-chloro-benzo-yl)piperidin-4-yl]meth-yl}benzamide monohydrate.

In the title compound, C20H20Cl2N2O2·H2O, the piperidine ring adopts a chair conformation with the two substituent benzene rings inclined to one another [dihedral angle 84.63 (9)°]. In the crystal, the components are linked by Ow—H⋯O, N—H⋯Ow (w = water) and C—H⋯O hydrogen bonds, generating a sheet structure lying parallel to (101).

Methyl 8-bromo-3-[1-(4-methoxyphenyl)-4-oxo-3-phenylazetidin-2-yl]-1-methyl-1,2,3,3a,4,9b-hexahydrochromeno[4,3-b]pyrrole-3a-carboxylate

In the title compound, C30H29BrN2O5, the β-lactam ring is essentially planar, with the O atom displaced from this plane by 0.856 (9) Å, and forming dihedral angles of 24.35 (13) and 89.42 (14)° with the planes of the benzene substituent groups on this ring. The tetra­hydro­pyran ring adopts an envelope conformation with the C atom bearing the β-lactam ring as the flap. In the crystal, weak C—H⋯O hydrogen bonds with carboxyl and tetra­hydro­pyran O-atom acceptors give rise to a chain structure extending along the b-axis direction.

2-(4-Hydroxyphenyl)-3-methoxy-4H-chromen-4-one

In the title compound, C16H12O4, the substituent benzene ring and meth­oxy group are twisted relative to the 4H-chromene skeleton by 24.1 (1) and 61.3 (1)°, respectively. In the crystal, mol­ecules are connected by classical O—H⋯O and weak C—H⋯O hydrogen bonds, forming chains parallel to [201]. The 4H-chromene ring systems of adjacent mol­ecules are either parallel or inclined at an angle of 28.9 (1)°.

(E)-3-(4-Methoxyphenyl)-3-[3-(4-methoxyphenyl)-1H-pyrazol-1-yl]prop-2-enal

In the title mol­ecule, C20H18N2O3, the pyrazole ring forms a dihedral angle of 2.2 (1)° with its meth­oxy­phenyl substituent and a dihedral angle of 67.2 (1)° with the benzene substituent on the propenal unit. In the crystal, mol­ecules are connected by weak C—H⋯O hydrogen bonds, forming R 2 2(26) and R 2 2(28) cyclic dimers that lie about crystallographic inversion centres. These dimers are further linked through C—H⋯O and C—H⋯N hydrogen bonds, forming C(8), C(9), C(10) and C(16) chain motifs. These primary motifs are further linked to form secondary C 2 2(15) chains and R 2 2(18) rings.

3-(4-Meth-oxy-benzo-yl)-6-nitro-coumarin.

In the title coumarin derivative (also known as 2H-chromen-2-one or 2H-1-benzopyran-2-one), C17H11NO6, the coumarin ring system is nearly planar, with a dihedral angle of 3.35 (9)° between the pyrone and the benzene rings. The dihedral angle between the planes formed by the coumarin ring system and the benzene substituent is 54.60 (7)°, clearly showing the non-coplanarity of the whole aromatic system. The crystal studied was a non-merohedral twin; the minor component refined to approximately 0.44.

Meso-5,10,15,20-Tetrakis(4-hydroxy-3-methoxyphenyl)porphyrin propionic acid monosolvate

In the title compound, C48H38N4O8·C3H6O2, the porphyrin mol­ecule is centrosymmetric. The propionic acid solvent mol­ecule is disordered over two sets of sites with equal occupancy factors. The porphyrin central core is almost planar, with an r.m.s. deviation of the fitted atoms of 0.045 Å. The substituent benzene rings make dihedral angles of 70.37 (4) and 66.95 (4)° with respect to the porphyrin core plane. The crystal structure is stabilized by an inter­esting network of hydrogen bonds. Porphyrin mol­ecules are connected by O—H⋯O hydrogen bonds creating ribbons running along the [101] direction. Weak C—H⋯O hydrogen bonds connect separate mol­ecular ribbons in the [110] direction, creating (-111) layers. Intra­molecular N—H⋯N hydrogen bonds also occur. The propionic acid molecules are connected by pairs of —H⋯O hydrogen bonds, creating dimers.

N′-[(E)-4-Benzyloxy-2-hydroxybenzylidene]benzohydrazide

The title compound, C21H18N2O3, exists in the E conformation with respect to the azomethane C=N double bond. The central benzene ring is almost coplanar with one of the substituent benzene rings [dihedral angle = 1.74 (5)°] and is approximately orthogonal to the other benzene ring of the mol­ecule [dihedral angle = 86.61 (7)°]. An intra­molecular O—H⋯N hydrogen bond occurs. The crystal packing is dominated by N—H⋯O hydrogen bonds, which lead to an infinite chain running parallel to [010].

3-Benzyl-2H-chromen-2-one

The title compound, C16H12O2, is a coumarin which was isolated from stones of the Chinese traditional medicine Clausena lansium. The pyrone ring is almost planar, with a mean deviation of 0.0135 (4) Å. The benzene ring (A) of the benzopyrone unit forms dihedral angles of 1.82 (5) and 72.86 (2)° with the pyrone ring and the substituent benzene ring, respectively. The crystal structure is stabilized by weak π–π stacking inter­actions, with a minimum centroid–centroid distance between benzene rings of 3.6761 (7) Å.

Local intermolecular interactions for selective CO2 capture by zeolitic imidazole frameworks: energy decomposition analysis

Intermolecular energy decomposition analysis (EDA) is reported for the binding of CO2 with zeolitic imidazole frameworks (ZIF) to provide a molecular level interpretation of the recent capacity and selectivity measurements of several ZIFs and to suggest a theoretical guideline to improve their performance further, using 1 nm size of organic linker fragment of the ZIFs as a target molecule. The EDA suggests that the local electronic interaction of CO2 and the substituent groups, mainly frozen density and polarization interactions with little charge transfer, is the primary binding interaction, but the electron correlation effects can be equally or more important depending on the binding geometry and functional groups. The present correlated calculations identify the preferred ZIF binding sites for various gases including CO2 to be mostly near the benzene substituent groups rather than the plane of imidazole rings. We predict that the NH2-substituted ZIF would have an enhanced capacity of CO2 as compared to the NO2-substituted ZIF that was recently synthesized and reported to be one of the materials with the best capacity results along with high gas selectivity. The present calculations may imply that the local functionality of the linking organics, rather than detailed framework structures, may be of primary importance in designing certain high capacity MOF or ZIF materials.

5-Hydroxy-3,4′,6,7-tetramethoxyflavone

The title compound, C19H18O7 [systematic name 5-hy­droxy-3,6,7-tri­meth­­oxy-2-(4-meth­oxy­phen­yl)-4H-1-benzopyran-4-one], is a flavonoid which was isolated from the traditional Chinese medicine Laggera alata. The benzene ring of the benzopyran­one unit forms dihedral angles of 1.72 (3) and 37.39 (5)° with the pyran ring and the substituent benzene ring, respectively. The mol­ecular conformation is stabilized by an intra­molecular phenol O—H⋯Oketone hydrogen bond.

4-(4-Chlorophenyl)-8-methyl-2-oxo-1,2,5,6,7,8-hexahydroquinoline-3-carbonitrile

The six-membered N-heterocyclic ring of the title compound, C17H15ClN2O, is fused with a methyl-substituted cyclo­hexene ring. The approximately planar nitro­gen-bearing ring (r.m.s. deviation 0.019 Å) is aromatic, and the N atom shows a trigonal–planar coordination; its benzene substituent is aligned at 77.1 (1) °. The cyclo­hexene ring adopts a half-chair conformation. In the crystal, inversion-related mol­ecules are linked by pairs of N—H⋯O hydrogen bonds, generating dimers.

3-(Diphenylmethylidene)indolin-2-one

The title mol­ecule, C21H15NO, has an indoline-2-one and two benzene substituent groups which are arranged in a propeller-like fashion around the central C atom. The dihedral angle between the two benzene rings is 73.32 (16)° and those between the benzene rings and the indoline-2-one group are 76.54 (14) and 67.69 (14)°. In the crystal, there is an inter­molecular N—H⋯O hydrogen-bonding inter­action, which links the mol­ecules into chains extending along c.