Plane Of Phenyl Ring Research Articles

Linear free energy relationships of the 1H and 13C NMR chemical shifts in 3-cyano-4-(substituted phenyl)-6-phenyl-2(1 H)pyridones

Linear free energy relationships (LFER) were applied to the 1H and 13C NMR chemical shifts in 3-cyano-4-(substituted phenyl)-6-phenyl-2(1 H)pyridones. The correlation analysis for the substituent-induced chemical shifts (SCS) with inductive ( σ I), and various resonance ( σ R) parameters were carried out using SSP (single substituent parameter), DSP (dual substituent parameter), and DSP-NLR (dual substituent parameter non-linear resonance) methods, as well as by multiple regression analysis. The presented calculation accounts satisfactorily for the polar and resonance substituent effects operating at pyridone carbon atoms. Negative ρ values were found for several correlations (reverse substituent effect). The conformations of investigated compounds have been studied by the use of semi-empirical MO-PM6 method and B3LYP density functional (DFT) hybrid methods. The twist of the plane of 4-substituted phenyl ring ( θ 1) is determined by electronic substituent effects, while the angles θ 2 are almost constant.

(Z)-3-Ferrocenyl-2-phenylacrylonitrile

In the structure of the title compound, [Fe(C5H5)(C14H10N)], the unsubstituted cyclo­penta­diene (Cp) ring is disordered over two positions, with site-occupancy factors 0.76 (2) and 0.24 (2). The dihedral angles between the substituted Cp ring and the major and the minor components of the disordered ring are 0.9 (5) and 6(2)°, repectively. The plane of the acrylonitrile unit makes dihedral angles of 6.1 (18) and 6.5 (4)° with the substituted Cp ring and the phenyl ring planes, respectively.

2-Phenyl-2H-1,2,3-triazole-4-carboxylic acid

In the title compound, C9H7N3O2, the dihedral angle between the triazole and phenyl ring planes is 4.72 (6)°. In the crystal structure, classical inversion dimers arise from O—H...O hydrogen bonds between carboxylic acid groups.

(S)-3-[(R)-2,4-Dimethylpent-4-enoyl]-4-isopropyl-5,5-diphenyl-1,3-oxazolidin-2-one

The title compound, C25H29NO3, was prepared in the course of the generation of depsipeptide libraries resembling the Jasplakinolide family of natural products. The dihedral angle between the phenyl ring planes is 74.1 (3)° The oxazolidinone ring adopts a slightly distorted 4 E conformation with an axial projection of the isopropyl substituent, which is easily rationalized by pseudo-allylic strain exerted by the exocyclic imide carbonyl. The two carbonyl groups adopt a noncolinear S-shaped conformation.

3-Phenyl-1H-pyrazole-5-carboxylic acid

In the title compound, C10H8N2O2, the dihedral angle between the phenyl and pyrazole ring planes is 21.27 (6)°. Inter­molecular O—H⋯O and N—H⋯N hydrogen bonds link the mol­ecules into chains along c. These are further connected by inter­molecular C—H⋯O hydrogen bonds, resulting in a two-dimensional framework.

Temperature-induced sign reversal of biaxiality observed by conoscopy in some ferroelectricSm−C*liquid crystals

We have studied various ferroelectric liquid crystals to find the average molecular direction of the shortest axis in the perfectly unwound state by using tilted conoscopic measurements. We find that there exist two types of temperature dependencies of the biaxiality. Some materials exhibit increasing biaxiality while others show decreasing biaxiality with increasing temperature. The former shows a temperature-induced sign reversal of biaxiality. Three different physical mechanisms are identified as responsible for the emergence of biaxiality: (i) anisotropic fluctuations of the long molecular axis, (ii) a biased rotation around the long axis, and (iii) the local field effect. By means of a simple theoretical investigation, we conclude that these two types of trends are due mainly to the opposite signs of the biaxial order parameter C , which represents the second mechanism: the biased rotation around the long axis. This means that the central phenyl planes of molecules belonging to materials having biaxiality that increases with temperature are oriented on the average parallel to the tilt plane (the shortest index of refraction axis normal to the tilt plane), and, on the contrary, in those of the others molecules are oriented perpendicular to the tilt plane (the shortest index of refraction axis lying in the tilt plane). Thus, the direction of the phenyl ring plane of the liquid crystal molecules determines the different temperature dependencies of the biaxiality. It is also shown that the phenomenon of sign reversal of the biaxiality is due to the competitive contributions of the first and second physical mechanisms.

(Z)-2-Phenyl-3-(2,2′:5′,2′′-terthiophen-3′-yl)acrylonitrile

In the crystal structure of the title compound, C21H13NS3, one of the terminal thio­phene rings is disordered in approximately a 3:1 ratio of components, and the disorder is of the flip type. The terthio­phene units are far from coplanarity, in contrast to terthio­phene itself. The conformation might be described, for the unit of greater occupancy, as quasi-cis [the S—C—C—S torsion angle is 41.1 (5)°] quasi-trans [the S—C—C—S torsion angle is −140.1 (4)°], and for the less-occupied part as quasi-cis–quasi-cis [35.7 (6)°]. The dihedral angle between the terminal ring planes is as high as 71.7 (2)°. The central C—C=C—C group is almost planar [maximum deviation of 0.027 (3) A] and it is approximately equally twisted with respect to both the central thio­phene and the phenyl ring planes [26.5 (4) and 23.5 (7)°, respectively]. The crystal packing is determined by van der Waals inter­actions, and some weak C—H⋯N and C—H⋯π relatively short directional contacts.

N,N′,N′′-Triphenylguanidinium bromide

In the title compound, C19H18N3+·Br−, the dihedral angles between the phenyl ring planes and the plane defined by the central guanidinium fragment are in the range 43.1 (1)–64.0 (1)°. Inter­molecular N—H⋯Br hydrogen bonds link the anions and cations into chains.

X‐ray diffraction and optical birefringence studies on four nematogenic difluorobenzene derivatives

The results of optical microscopy, DSC, X‐ray diffraction and optical birefringence studies on four nematogenic difluorobenzene derivatives are presented. The thermal stability of the compounds increases substantially as greater flexibility is introduced into the core structure. Average intermolecular distances, obtained from X‐ray data, are found to increase when a comparatively rigid planar phenyl ring is substituted by a flexible non‐planar cyclohexyl ring in the core structure. From the values of apparent molecular lengths in the nematic phase, a short range antiferroelectric type of association is found to exist between neighbouring molecules. Density values suggest that the molecular packing is less efficient with increasing flexibility either in chain‐ or in core‐structure. All the refractive indices exhibit normal dispersive behaviour, and a positive optical anisotropy is observed in all the compounds which decreases quickly with temperature. Temperature dependences of orientational order parameters, determined from both X‐ray and optical birefringence studies, are presented. Variations of different physical properties with order parameters are discussed.

2-Diethylamino-3-phenylquinazolin-4(3H)-one

In the title compound, C18H19N3O, the quinazoline system is approximately planar. The plane of the substituent phenyl ring forms a dihedral angle of 63.9 (2)° with respect to the mean plane of the quinazolinone ring system.

Crystal Structures of Nonoxidative Zinc-dependent 2,6-Dihydroxybenzoate (γ-Resorcylate) Decarboxylase from Rhizobium sp. Strain MTP-10005

Reversible 2,6-dihydroxybenzoate decarboxylase from Rhizobium sp. strain MTP-10005 belongs to a nonoxidative decarboxylase family. We have determined the structures of the following three forms of the enzyme: the native form, the complex with the true substrate (2,6-dihydroxybenzoate), and the complex with 2,3-dihydroxybenzaldehyde at 1.7-, 1.9-, and 1.7-A resolution, respectively. The enzyme exists as a tetramer, and the subunit consists of one (alphabeta)8 triose-phosphate isomerase-barrel domain with three functional linkers and one C-terminal tail. The native enzyme possesses one Zn2+ ion liganded by Glu8, His10, His164, Asp287, and a water molecule at the active site center, although the enzyme has been reported to require no cofactor for its catalysis. The substrate carboxylate takes the place of the water molecule and is coordinated to the Zn2+ ion. The 2-hydroxy group of the substrate is hydrogen-bonded to Asp287, which forms a triad together with His218 and Glu221 and is assumed to be the catalytic base. On the basis of the geometrical consideration, substrate specificity is uncovered, and the catalytic mechanism is proposed for the novel Zn2+-dependent decarboxylation.

Crystal Structure and Conformation of a Piperidine-Containing Thiosemicarbazone Derivative

Piperidine thiosemicarbazones have the ability to inhibit the enzyme ribonucleoside diphosphate reductase (RDR), which is essential in DNA synthesis. The present compound, t-3-methyl-r-2,c-6-diphenylpiperidin-4-one thiosemicarbazone (MDPTAN), was prepared using the Mannich reaction and crystallized with acetonitrile as solvent. The crystal data are C38H44N8S2 · 2(C2H3N); M · W = 759.06, monoclinic, space group P21/c, a = 16.324(4) A˚, b = 15.179(4) A˚, c = 17.650(5) A˚, β = 104.98(5)°, V = 4225(2) A˚3, Z = 4, Dcal = 1.193 Mgm−3, μ = 0.168 mm−1, and λ (MoKα) = 0.71073 A˚. The structure was solved by direct methods and refined to final R-values of R = 0.089 and wR = 0.1962, respectively. The piperidine rings adopt chair conformations. The planar phenyl rings are oriented equatorially at 2,6-positions of the piperidine ring. The N-H···N and C-H···N types of intra- and intermolecular hydrogen bondings play a major role in stabilizing the molecules in the unit cell. The molecular packing can be viewed as chain of dimers held together by two N-H···S types of intermolecular hydrogen bond networks. C-H···π weak interactions also support the packing of the molecules in addition to van der Waals forces.

Effect of the tyramine fragment of opioid receptor ligands on their agonist and antagonist properties

A comparative analysis of correlations between the ED50 and AD50 values describing the agonist and antagonist properties of opioid receptor ligands, on the one hand, and molecular descriptors related to the electronic and geometric properties of the tyramine moiety of these ligands, on the other hand, has been carried out. The affinity of ligands to the complementary site of opioid receptors depends on the electronic properties of the tyramine moiety, such as the basicity of the TF nitrogen atom, the electron-acceptor properties of the “cation head,” the electron-donor properties of the aryl moiety, and the ability of substituent atoms in the aryl moiety to act as proton donors and form hydrogen bonds with the OR. The intrinsic activity of ligands depends on the coplanarity of atoms of the substituent in the aryl moiety to the phenyl ring plane. Substantial protrusion of substituent atoms out of the plane of the phenyl ring apparently prevents penetration of a ligand deep into “binding pocket” of the receptor, which leads to disappearance of the antagonist properties of this ligand.

Synthesis and crystal structures of extremely crowded oligophenylenes as model precursors to ‘cubic graphite’

By using drastic conditions for a Diels–Alder cycloaddition reaction, it was possible to synthesize an oligophenylene with an extremely dense packing of the benzene rings. Crystallographic data could be obtained and a projection of the structure on the plane of the central phenyl ring reveals that the molecule retained its theoretical threefold symmetry with only minor deviations. Due to its dense packing of interlocked benzene rings, this oligophenylene could be furthermore used as a suitable precursor for constructing a subunit of ‘cubic graphite’.

Crystal structure and conformation study of N‐methyl‐t‐3‐methyl‐r‐2, c‐6‐diphenylpiperidin‐4‐one thiosemicarbazone

AbstractThiosemicarbazones are having the ability to bind with metal and inhibit the enzyme ribonucleoside diphosphate reductase (RDR), an enzyme which is involved in the synthesis of DNA precursors in the mammalian cells. The title compound N‐methyl‐t‐3‐methyl‐r‐2, c‐6‐diphenylpiperidin‐4‐one thiosemicarbazone (NMMDPT), CCDC 218052, was prepared using Mannich reaction and characterized by X‐ray diffraction methods. The crystal data are: C20H24N4S; M.W = 352.49, triclinic, space group P$ \bar 1 $, a = 8.467(2) Å, b = 10.228(2) Å, c = 12.249(2) Å; α = 92.595(3)°, β = 104.173(3)°, γ =113.628(3)°; V = 930.0(3) Å3, Z = 2, Dcal = 1.259 Mgm–3, µ = 0.184 mm–1, λ (MoKα)= 0.71073 Å, final R1 and wR2 are 0.0470 and 0.1052, respectively. The piperidine rings adopt chair conformation. The planar phenyl rings are oriented equatorially at 2,6‐positions of the piperidine ring. The molecular packing can be viewed as dimers held together by two N–H…S types of intermolecular hydrogen bonds. Weak C–H…π interactions also support the stability of the molecules in the crystal in addition to van der Waals forces. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

3-Bromomethyl-1-phenylsulfonyl-1H-indole-2-carbonitrile

In the title molecule,$C_{16}H_{11}BrN_{2}O_{2}S$, the phenyl ring and mean plane of the indole ring system make a dihedral angle of $82.9 (1){^o}$. Intermolecular C—H...O hydrogen bonds link the molecules into linear chains extended along the a axis. The crystal packing is further stabilized by van der Waals forces.

Изучение влияния тираминового фрагмента молекул лигандов опиатных рецепторов на их агонистические и антагонистические свойства

A comparative analysis of correlations between the ED 50 and AD 50 values describing the agonist and antagonist properties of opioid receptor ligands, on the one hand, and molecular descriptors related to the electronic and geometric properties of the tyramine moiety of these ligands, on the other hand, has been carried out. The affinity of ligands to the complementary site of opioid receptors depends on the electronic properties of tyramine moiety, such as the basicity of nitrogen atom, the electron-acceptor properties of cationic head, the electron-donor properties of aryl moiety, and the ability of substituent atoms in the aryl moiety to form hydrogen bonds as proton donors. The internal activity of ligand depends on the complanarity of atoms of substituents in the aryl moiety to the phenyl ring plane. Substantial protrusion of substituent atoms out of the plane of phenyl ring apparently prevents penetration of the ligand deep into binding pocket of the receptor, which causes disappearance of the antagonist properties of ligands.

Benzoin 4-ethylthiosemicarbazone

In the title compound, 2-hydroxy-1,2-diphenylethanone 4-ethylthiosemicarbazone, C17H19N3OS, the thiosemicarbazone moiety is planar and has an E configuration. The planar phenyl rings make dihedral angles of 82.34 (8) and 8.07 (17) degrees with the plane of the thiosemicarbazone moiety. The crystal structure contains two intramolecular (N-H...O and N-H...N) and one intermolecular interaction (O-H...S), as well as two C-H...pi(benzene) interactions. Molecules are stacked in columns running along the a axis. Molecules in each column are connected to each other by means of linear O-H...S hydrogen bonds and C-H...pi interactions. In addition, there are also C-H...pi(benzene) interactions between the columns.

Molecular Structure of Triphenylamine in the Gas Phase

The molecular structure of triphenylamine was studied by gas-phase electron diffraction in combination with ab initio calculations. It is found that in the gas phase at 160°C the molecule possesses C3 symmetry. The principal geometric parameters are as follows (ra structure): N-C 1.421(4), C-Cmean 1.399(1), C-H 1.123(2) A, bond angles NCC 123.6(10)° and 117.2(7)°, and CNC 119.9(2)°. Torsion angles around C-N bonds are −39° and −45°. Phenyl groups are rotated by 48° from the position in which the C3 axis lies in the phenyl ring plane.

(E)-N′-(3-Ethoxy-4-methoxybenzylidene)benzohydrazide

In the title compound, C17H18N2O3, the isovanillin group makes a dihedral angle of 9.63 (11)° with the plane of the terminal phenyl ring. Inter­molecular N—H⋯O hydrogen bonds help to consolidate the crystal packing.