Plane Of Phenyl Ring Research Articles

Self-assembly of biaxial ordering and molecular tilt angle of chiral smectic liquid crystals in homeotropically aligned cells investigated using infrared spectroscopy

Temperature dependences of the infrared absorbance have been measured for the four chiral liquid crystal samples in the homeotropic cell configuration. It is shown that the values of the orientational order parameter obtained using this method exhibit a remarkable similarity to the x-ray diffraction results of the smectic layer spacing and lead to accurate values of the molecular tilt angle. This has important consequences for the existing interpretation of the x-ray data. The proposed method, in many cases, may be considered as a valuable alternative to the x-ray diffraction, giving additional, important information about the orientations and the ordering of the molecular fragments. It is found that if the experimentally obtained order parameter is low, then the molecular biaxiality is exceptionally large. The average phenyl ring plane is found to lie close to the molecular tilt plane.

(E)-2-Methyl-3-(2-methyl-2-nitrovinyl)-1H-indole and (E)-3-(2-methyl-2-nitrovinyl)-2-phenyl-1H-indole

In the title compounds, C12H12N2O2, (I), and C17H14N2O2, (II), respectively, the indole rings are planar and the vinyl groups lie out of the indole planes, making dihedral angles of 33.48 (5) and 41.31 (8) degrees , respectively. In (II), the dihedral angle between the phenyl and indole ring planes is 32.06 (6) degrees . In both molecules, the double bond connecting the methylnitrovinyl group and the indole nucleus adopts an E configuration. Notwithstanding the differences in space group [C2/c for (I) and P2(1)2(1)2(1) for (II)], the mode of packing of compounds (I) and (II) is determined by similar intermolecular N-H...O hydrogen-bonding interactions, forming chains that run parallel to [101] in (I) and [001] in (II).

Self-assembly of copper(II) complexes with a dibasic tridentate ligand and monodentate N-heterocycles: structural, magnetic and EPR studies

Three ternary copper(II) complexes of general formula [Cu(bhac)(hc)], with a tridentate Schiff base, acetylacetone benzoylhydrazone (H 2bhac) and monodentate N-heterocycles (hc=pyrazole, imidazole and pyridine), have been synthesized. Elemental analysis, various forms of spectroscopy (infrared, electronic absorption and EPR), cyclic voltammetry, cryomagnetic measurements and X-ray crystallography were used for the characterization of the complexes. Analytical data, infrared and electronic spectral features and molar conductivity values are consistent with the proposed molecular formulae and the +2 oxidation state of the metal ion in these complexes. In each complex, the enolate-O, the imine-N and the deprotonated amide-O donor tridentate ligand (bhac 2−) and the sp 2 N donor heterocycle form an O 2N 2 square-plane around the metal ion. The whole molecule of none of the complexes is perfectly planar because of different orientation of the phenyl ring plane of the tridentate ligand and that of the heterocycle ring plane with respect to the plane containing rest of the molecule. In the solid state, the complexes having the pyrazole and the pyridine as the heterocyclic ligand, exist as centrosymmetric dimeric species due to very weak apical coordination of the metal bound enolate-O. The complex of imidazole has no such apical coordination and exists as a monomer. In the crystal lattice, the molecules of these complexes are involved in a variety of intermolecular non-covalent interactions such as O–H⋯O, N–H⋯O, N–H⋯N, C–H⋯π and π⋯π. Self-assembly via these interactions lead to a one-dimensional arrangement of [Cu(bhac)(Hpyrz)]·C 2H 5OH, a two-dimensional layered structure of [Cu(bhac)(Himdz)] and a three-dimensional network of [Cu(bhac)(py)]. Cryomagnetic and EPR spectral measurements indicates weak antiferromagnetic spin-exchange in all the three complexes.

Benzoin thiosemicarbazone

In the title compound, C15H15N3OS, the thio­semicarbazone moiety is planar, with a maximum deviation of 0.0369 (11) A, and has an E configuration. The planar phenyl rings make dihedral angles of 26.56 (9) and 81.20 (5)° with the plane of the thio­semicarbazone moiety. In the mol­ecule, there are two intramolecular interactions of types N—H⋯O and N—H⋯N. In the crystal structure, there are two intermolecular interactions of types O—H⋯S and N—H⋯S, leading to the formation of dimers.

(R,S)-1,4-Bis(benzylsulfinyl)butane

The molecular structure of the title compound, C18H22O2S2, exhibits an R,S configuration for the S atoms. The mol­ecule sits on a centre of symmetry located at the midpoint of the central C—C bond. The C and S atoms between the two phenyl rings are essentially coplanar and make a 87.3 (3)° dihedral angle with the phenyl ring planes.

Crystal Structure of N-Methyl-3-t-isopropyl-r-2,c-6-diphenylpiperidin-4-one

N-Methyl-3-t-isopropyl-r-2,c-6-diphenylpiperidin-4-one (NMIDPPO), crystallizes in monoclinic space group P21/c with a = 16.666(6), b = 12.349(5), c = 18.778(7)A; β = 111.74(1)°, V = 3590(2)A3, Z = 8, Dcal = 1.138 Mg/m3. The structure was solved by direct methods and refined by full-matrix least-squares procedures to a final R-value of 0.0556 for 5078 observed reflections. There are two crystallographically independent molecules in the asymmetric unit. The piperidine rings in both molecules adopt the chair conformation with the planar phenyl rings substituted equatorially at the 2,6 positions. The C-H…O type of intermolecular hydrogen bonds and C-H…π weak interactions stabilize the molecules in the unit cell in addition to the van der Waals forces.

Infrared study of orientational order parameters of a ferroelectric liquid crystal

A method of determining the set of four order parameters S , D , P , and C for a ferroelectric liquid crystal, using complementary results for different sample geometries, is presented. IR measurements have been performed for homeotropic, planar heterogeneous and, planar homogenous sample geometries. Orientational order parameters were determined in two frames of reference to obtain complete information on molecular arrangement. Results for the D , P , and C parameters indicate the importance of both the intrinsic and extrinsic biaxialities. The molecular rotation around the long molecular axis is not free, and the carbonyl dipole and plane of the central phenyl ring are oriented close to the tilt plane. It has been found that transition dipole moments show significant correlations, antiparallel for longitudinal dipoles and parallel for transversal ones.

New synthetic route to polyphosphine ligands bearing 1,2,4,5-tetrakis(phosphino)benzene framework: structural characterizations of 1,4-(PPh 2) 2-2,5-(PR 2) 2-C 6F 2 (R = Ph, iPr, Et)

Reactions of 1,4-dibromo-2,5-difluorobenzene with two equivalents of lithium diisopropylamide at low temperature ( T < −90 °C) followed by a quench with a slight excess of ClPPh 2 afford 1,4-dibromo-2,5-bis(diphenylphosphino)-3,6-difluorobenzene ( 1) in good yields. Reacting 1 with two equivalents of BuLi followed by a quench with a slight excess of ClPR 2 yield novel 1,2,4,5-tetrakis(phosphino)-3,6-difluorobenzenes 1,4-(PPh 2) 2-2,5-(PR 2) 2-C 6F 2 (R = Ph ( 2a); R = i Pr ( 2b); R = Et ( 2c)) in moderate yields. Compounds 1 and 2a– c were characterized by multinuclear NMR spectroscopy and elemental analyses. In addition, molecular structures of 2a– c have been determined by single crystal X-ray crystallography. Phosphorus atoms of PPh 2/PR 2 substituents in 2a– c are displaced from the plane of the central phenyl ring due to steric interactions with neighboring groups.

Crystal structure of 2,6‐diphenyl azabicyclo [3.3.1] nonan‐9‐one thiosemicarbazone

AbstractThe title compound (C21H24N4S, CCDC 206345) crystallizes in triclinic space group P&amp;#38;1macr; with cell parameters a =12.557(2) Å, b = 12.743(2) Å, c = 13.703(2) Å, α =90.005(3)°, β = 113.663(3)°, γ = 106.756(3)°, V = 1906.2(5) Å3, Z = 4, Dcal = 1.270 Mg/m3 at T =293 K. The structure was solved by direct methods and refined by full‐matrix least‐squares procedures to a final R1= 0.0573and wR2 = 0.1364 using 8192 observed reflections. The piperidine and cyclohexane rings adopt chair conformation. The planar phenyl rings are the equatorial substituents of the piperidine ring. The molecules in the unit cell are stabilized by N‐H…N, N‐H…S &amp; C‐H…π intra and intermolecular hydrogen bond networks in addition to van der Waals forces. (© 2004 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Molecular Structure and Internal Rotation Potential of Dimethylphenylphosphine, According to Gas-Phase Electron Diffraction Data and Quantum-Chemical Calculations

Geometric parameters of dimethylphenylphosphine molecule were determined by gas-phase electron diffraction using a dynamic model in which the rotation of the PMe2 group is treated as large-amplitude motion. Refinement of the structural parameters and parameters of the potential function was performed taking into account the geometry relaxation on the basis of HF/6-311++G** calculations. The internal rotation potential has a single minimum at ϕ 0° (ϕ is the angle between the bisector of the MePMe angle and the phenyl ring plane) and may be described by the function of the form V(ϕ) = 0.5V2(1 - cos2ϕ), where V2 = 0.38±0.36 kcal mol-1. The data obtained are compared with those for related molecules. Steric effects affect the geometry of the phenylphosphine molecule more significantly than does p-π interaction.

Theoretical Modeling of TPPS&lt;sub&gt;4&lt;/sub&gt; J-Aggregates

The mechanism and conditions of meso-tetra (4-sulfonatophenyl) porphine (TPPS4) molecular aggregate formation and their geometrical structure are investigated by methods of molecular mechanics and quantum chemistry. J- type aggregates are formed of zwitterionic forms of TPPS4via interaction of their positively charged porphyrin rings and negatively charged SO3- groups. According to ab initio and PM3 calculations it was found that TPPS4zwitterion has asymmetrical structure (parts of porphyrin ring are asymmetrically bent out of plane), although the porphyrin ring of TPPS4molecule in neutral aqueous solution (at pH 7) is flat and the planes of phenyl rings are nearly perpendicular to the porphyrin plane. We propose that asymmetrical porphyrin rings are able to form bent threads. The thread is bent approx. 5° for each monomer, so approximately 60 monomers should form the loop (diameter ~20 nm).

Crystal Structure of N-Benzlidene-N'-(2-carboxyphenyl)hydrazine

Molecules of the title compound (alternative name, benzaldehyde-2-carboxyphenylhydrazone), C14H12N2O2 adopt an E configuration about the azomethine C=N double bond. The molecule is almost planar and the dihedral angle between the planes of phenyl and carboxy phenyl rings are only 4.9(1)°. The crystal structure is stabilized by the two intermolecular O2-H…O1 hydrogen bonds between O atoms and the π-π interactions between the phenyl rings.

Bis(2,5-dimethoxy-4-methylphenyl)methane and bis(2,5-dimethoxy-3,4,6-trimethylphenyl)methane.

Bis(2,5-dimethoxy-4-methylphenyl)methane, C(19)H(24)O(4), (IIa), was obtained and characterized as a minor product from the reaction of toluhydroquinone dimethyl ether (1,4-dimethoxy-2-methylbenzene) with N-(hydroxymethyl)trifluoroacetamide. Similarly, bis(2,5-dimethoxy-3,4,6-trimethylphenyl)methane, C(23)H(32)O(4), (IIb), was prepared from the corresponding reaction of trimethylhydroquinone dimethyl ether (2,5-dimethoxy-1,3,4-trimethylbenzene). The molecules of (IIa) and (IIb) each lie on a twofold axis passing through the methylene group. The dihedral angle between the planar phenyl rings is 73.4 (1) degrees in (IIa) and 77.9 (1) degrees in (IIb). The external bond angles around the bridging methylene group are 116.6 (2) and 117.3 (2) degrees for (IIa) and (IIb), respectively. In (IIa), the methoxy substituents lie in the plane of the ring and are conjugated with the aromatic system, whereas in (IIb), they are almost perpendicular to the phenyl ring and are positioned on opposite sides.

Hydrogen Bond between Water and the Phenyl Ring in the Structure of a Dipeptide H–Phe–Leu–NH2 at 90 K and the Structure-based Energy Estimations

Abstract A water molecule forms a hydrogen bond with the aromatic π-electron system within the crystal structure of H–Phe–Leu–NH2 hydrochloride monosolvate. This water molecule located above the phenyl ring plane, 3.119 Å from the centroid of the ring. Ab initio energy calculations revealed the stabilization energy of the phenyl ring–water hydrogen bond to be 3.26 kcal/mol.

T-3-Isopropyl-1-methyl-r-2,c-6-diphenylpiperidin-4-one thiosemicarbazone.

The piperidine ring in the title compound, C(22)H(28)N(4)S, exhibits a chair conformation. The thiosemicarbazone moiety adopts an extended conformation, and the planar phenyl rings are oriented equatorially with respect to the piperidine ring. Two intermolecular hydrogen bonds involving the S atom form molecular pairs, and the crystal structure is stabilized by weak C-H.pi interactions in addition to van der Waals forces.

5-Ethyl-6-oxo-4-thioxo-1,3,2-oxazaphospholidino[3,2-a][1,3,2]benzodiazaphosphorine

The title fused tricyclic phospho­roheterocycle, C11H13N2O2PS, was unexpectedly synthesized by the reaction of a multifunctional compound, 2-[N-(2′-hydroxy)­ethyl]­amino-N′-ethyl­benz­amide, with tris­(diethyl­amino)­phosphine in the presence of iodine as catalyst. The crystallographic data analysis reveals that the title compound is triclinic with space group P\overline 1 and there are three rings in the mol­ecule. The phenyl ring, the two N atoms and the carbonyl C atom are coplanar; the P atom and the carbonyl C atom deviate by −0.692 (2) and 0.1116 (13) Å, respectively, from the phenyl ring plane. The five-membered ring exists in an boat conformation.

A new bis(phenol-armed) pyridazine-containing Schiff base ligand: synthesis, complexation and reduction to the amine ligand analogue

A bis(phenol-armed) acyclic Schiff base ligand H 2L has been synthesised from 3,6-diformylpyridazine and two equivalents of o-aminophenol. The H 2L ligand has been structurally characterised and is shown to be close to planar (maximum twist of pyridazine ring vs. phenyl ring planes is just 17.7°) with both intramolecular and intermolecular hydrogen-bonding interactions present. The latter hydrogen-bonding interactions in combination with offset parallel π–π stacking interactions are instrumental in the formation of columns of a stepped criss-cross type array. The ligand undergoes an irreversible oxidation in dimethylformamide at E pa=+0.91 V vs. 0.01 mol l −1 AgNO 3/Ag (s), to form an unstable new compound which exhibits closely spaced quasi-reversible processes at E 1/2≈−0.77 V. In addition, there is a process at −0.25 V which is associated with an irreversible reduction process at E pc=−1.52 V. Chemical reduction of the two imine bonds of H 2L was achieved by reaction with NaBH 4 to give the diamine analogue H 6L′ as the dihydrochloride salt: no evidence of pyridazine ring reduction was observed. Three complexes of L 2−, Co 2L(CH 3COO) 2, Ni 2L(CH 3COO) 2(H 2O) and Cu 2L(CH 3COO) 2(H 2O) 2(CH 3CN), have been prepared and partially characterised.

Quantum-Chemical Study of the Structure of Cyanophosphines and Their Oxides

The structure of cyanophosphines and their oxides was studied by ab initio (RHF/6-31G**) and semiempirical (PM3) methods. Both methods predict that MeOP(CN)2, (MeO)2PCN, and (MeO)2P(O)CN exist in noneclipsed antiperiplanar and synclinal conformations. The calculation results nicely agree with measured dipole moments and Kerr constants of these compounds. The phenyl and diphenyl derivatives PhP(CN)2, Ph2PCN, Ph(Et)PCN, and Ph2P(O)CN prefer forms in which the phenyl ring plane is eclipsing the phosphorus lone electron pair or the phosphoryl bond. The interactions of the phosphorus lone electron pair with the phenyl ring and with the cyano group are lacking in the title compounds.

Crystal and Molecular Structure of 4-Arylhexahydro-1H,3H-pyrido[1,2-c]pyrimidine-1,3-dione Derivatives

The X-ray crystal structure determination of 4-(2-methylphenyl)hexahydro-1H,3H-pyrido[ 1,2-c]pyrimidine-1,3-dione (2) and 4-(3-methylphenyl)hexahydro-1H,3H-pyrido[1,2-c]- pyrimidine-1,3-dione (3) is reported. The crystal structures show the formation of centrosymmetric dimers via intermolecular N-H···O hydrogen bonds. The saturated ring adopts a slightly distorted halfchair conformation in both 2 and 3. In either compound the planar phenyl ring is twisted with respect to the pyrimidine-1,3-dione fragment.

Organodiiron(II)-complexes containing a long conjugated hydrazonato spacer. Synthesis, characterization, electrochemical and structural studies

Organometallic hydrazines of general formula [(η 5-Cp)Fe(η 6- p-RC 6H 4NHNH 2)] +PF 6 − (Cp=C 5H 5; R=H, ( 1) +PF 6 −; Me, ( 2) +PF 6 −; MeO, ( 3) +PF 6 −; Cl, ( 4) +PF 6 −) react with equimolar quantities of ( E)-4-(2-ferrocenylvinyl)-benzaldehyde, ( E)-[(η 5-Cp)Fe(η 5-C 5H 4)CHCHC 6H 4CHO], to afford stereoselectively, the new homodimetallic hydrazones formulated as ( E)-[(η 5-Cp)Fe(η 6- p-RC 6H 4)NHNCHC 6H 4CHCH(η 5-C 5H 4)Fe(η 5-Cp)] +PF 6 − (R=H, ( 5) +PF 6 −; Me, ( 6) +PF 6 −; MeO, ( 7) +PF 6 −; Cl, ( 8) +PF 6 −). These compounds were fully characterized by elemental analysis and spectroscopic techniques ( 1H- and 13C-NMR, IR and UV–vis) and, in the case of complex ( 6) +PF 6 −, by single crystal X-ray diffraction methods. The rotations of the ferrocenyl unit by 37.2° out of the NHNCHC 6H 4CHCH spacer and coordinated phenyl ring planes, may generate an unfavorable structure to allow π-electron delocalization along the entire hydrazonato backbone between the two metals separated through bonds by more than 1.8 nm, as confirmed by the electrochemical data.