Conformations of Bridged Diphenyls. I. Crystal Structure of 2-(3′-Methyl-4′-nitrophenoxy)-1,3-diisopropylbenzene

1972 ◽  
Vol 50 (18) ◽  
pp. 2963-2971 ◽  
Author(s):  
E. A. H. Griffith ◽  
W. D. Chandler ◽  
B. E. Robertson
Keyword(s):  
Bond Angle ◽  
The Other ◽  
X Ray Diffraction ◽  
Hexagonal Symmetry ◽  
X Ray ◽  
Ether Oxygen Atom ◽  
Phenyl Rings ◽  
Ether Oxygen ◽  
Independent Molecules ◽  
Oxygen Bond

The structure of 2-(3′-methyl-4′-nitrophenoxy)-1,3-diisopropylbenzene, C19H23NO3, has been determined by X-ray diffraction. The crystals are triclinic, a = 12.422(24), b = 13.180(25), c = 11.241(30) Å, α = 89.99(20), β = 95.81(15), γ = 105.46(12)°, [Formula: see text] with Z = 4. The intensities of 8153 independent reflections were measured on a four circle diffractometer, of which 3701 were used in the refinement of the structure to give a final least-squares weighted residue of 0.053.The ether oxygen bond angle in each of the two independent molecules is 120°. The two phenyl rings are nearly orthogonal in each case, while the ring containing the electron withdrawing nitro group is conjugated with the ether oxygen atom. The rings show significant deviations from hexagonal symmetry and the nitro-substituted ring is bent away from the other ring.

scholarly journals Conformations of Bridged Diphenyls. II. Crystal Structure of 2-(2′,4′-Dinitrophenoxy)-1,3,5-tri-t-butylbenzene

1972 ◽  
Vol 50 (18) ◽  
pp. 2972-2978 ◽  
Author(s):  
E. A. H. Griffith ◽  
W. D. Chandler ◽  
B. E. Robertson
Keyword(s):  
Crystal Structure ◽  
Oxygen Atom ◽  
Least Squares ◽  
Bond Angle ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ether Oxygen Atom ◽  
Phenyl Rings ◽  
Ether Oxygen

The structure of 2-(2′,4′-dinitrophenoxy)-1,3,5-tri-t-butylbenzene, C24H32N2O5, has been determined by X-ray diffraction. The crystals are triclinic, a = 12.160(30), b = 10.564(17), c = 10.684(16) Å, α = 119.23(10), β = 96.06(15), γ = 96.55(15)°, [Formula: see text] with Z = 2. The intensities of 5359 independent reflections were measured on a four circle diffractometer of which 2471 were used in the refinement to give a final least-squares weighted residue of 0.063. The presence of two electron withdrawing groups on one of the phenyl rings increases the conjugation between the ring and the ether oxygen atom to a greater degree than was found in the previous work. The tri-t-butyl-substituted ring is nearly orthogonal to the other ring. The bond angle at the ether oxygen atom is less than the value found earlier but ring distortions are similar.

Conformations of Bridged Diphenyls. III. Crystal Structure of 2-(2′-Carbomethoxy-4′-nitrophenoxy)-1,3,5-trichlorobenzene

1972 ◽  
Vol 50 (18) ◽  
pp. 2979-2988 ◽  
Author(s):  
E. A. H. Griffith ◽  
W. D. Chandler ◽  
B. E. Robertson
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Unit Cell ◽  
Steric Effects ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diphenyl Ethers ◽  
Ether Oxygen ◽  
Independent Molecules ◽  
Similar Conformation

The structure of 2-(2′-carbomethoxy-4′-nitrophenoxy)-1,3,5-trichlorobenzene, C14H8NO5Cl3, has been determined by X-ray diffraction. The crystals are triclinic, a = 8.862(10), b = 15.164(10), c = 13.028(14) Å, α = 90.35(8), β = 116.28(8), γ = 97.54(8)°, [Formula: see text] with Z = 4. The intensities of 6417 independent reflections were measured on a four circle diffractometer of which 4526 were used in the refinement to give a final least-squares residue of 0.047. The two independent molecules in the unit cell show a similar conformation to that found in earlier studies of diphenyl ethers, and the conformation appears to be determined partly by steric effects, since conjugation between the nitro-substituted ring and the ether oxygen atoms is less pronounced than found previously.

The Electron Effect of Aromatic Group: Control Conformation of 2-Aromatic Cyclododecanone Derivatives

2020 ◽  
Vol 24 (10) ◽  
pp. 1139-1147
Author(s):  
Yang Mingyan ◽  
Wang Daoquan ◽  
Wang Mingan
Keyword(s):  
1H Nmr ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
The Other ◽  
Repulsive Interaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Effect ◽  
Group Control

2-Phenylcyclododecanone and 2-cyclohexylcyclododecanone derivatives were synthesized and characterized by 1H NMR, 13C NMR, HR-ESI-MS and X-ray diffraction. Their preferred conformations were analyzed by the coupling constants in the 1H NMR spectra and X-ray diffraction, which showed the skeleton ring of these derivatives containing [3333]-2-one conformation, and the phenyl groups were located at the side-exo position of [3333]-2-one conformation due to the strong π-π repulsive interaction between the π- electron of benzene ring and π-electron of carbonyl group. The cyclohexyl groups were located at the corner-syn or the side-exo position of [3333]-2-one conformation depending on the hindrance of the other substituted groups. The π-π electron effect played a crucial role in efficiently controlling the preferred conformation of 2-aromatic cyclododecanone and the other 2-aromatic macrocyclic derivatives with the similar preferred square and rectangular conformations.

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

PHASE TRANSITION IN LAYERED PEROVSKITE LIKE MANGANATE Ca3Mn2O7 UNDER HIGH PRESSURE

2001 ◽  
Vol 15 (18) ◽  
pp. 2491-2497 ◽  
Author(s):  
J. L. ZHU ◽  
L. C. CHEN ◽  
R. C. YU ◽  
F. Y. LI ◽  
J. LIU ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
The Other ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Diamond Anvil

In situ high pressure energy dispersive X-ray diffraction measurements on layered perovskite-like manganate Ca 3 Mn 2 O 7 under pressures up to 35 GPa have been performed by using diamond anvil cell with synchrotron radiation. The results show that the structure of layered perovskite-like manganate Ca 3 Mn 2 O 7 is unstable under pressure due to the easy compression of NaCl-type blocks. The structure of Ca 3 Mn 2 O 7 underwent two phase transitions under pressures in the range of 0~35 GPa. One was at about 1.3 GPa with the crystal structure changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic back to another tetragonal.

Studies Directed Towards the Total Synthesis of Anticapsin and Related Compounds. IV. Competitive Reaction of Amino and Carboxy Substituents in the Halohydrination of 2-Aminobicyclo[2.2.2]oct-5-ene-2-carboxylic Acid Derivatives

1994 ◽  
Vol 47 (12) ◽  
pp. 2221 ◽  
Author(s):  
MJ Crossley ◽  
SR Davies ◽  
TW Hambley
Keyword(s):  
Total Synthesis ◽  
The Other ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
Competitive Reaction ◽  
Trimethylsilyl Group ◽  
X Ray ◽  
Tricyclic Compounds ◽  
Tricyclic Compound ◽  
Related Compounds

Bromohydrination of benzyl (1RS,2SR,4SR)-2-benzyloxycarbonylamino-1-trimethylsilyloxy-bicyclo[2.2.2]oct-5-ene-2-carboxylate (6a) and the (1RS,2RS,4SR)- diastereomer (6b) with N- bromoacetamide in aqueous dioxan has been investigated. These reactions are highly regio-and stereo-selective and give the corresponding bromohydrins (9a) and (9b), but in moderate to low yield. These bromohydrins have the necessary stereochemistry for conversion into anticapsin. The other products from the reaction are tricyclic compounds formed by capture of the anti- bromonium cation intermediates or resultant bromohydrins by interaction with the proximal protected carboxy and amino groups within the molecules. Thus the carbolactone (11) is formed from the endo -adduct (6a), and the carbonimidic acid derivative (12) and the cyclic urethane (13) are formed from the exo-adduct (6b). Cleavage of the trimethylsilyl group from the tricyclic compound (12) gives benzyl (1RS,2RS,3RS,7RS,8RS)-5-benzyloxy-2-bromo-8-hydroxy-4-oxa-6-azatricyclo[5.3.1.03,8]undec-5-ene-7-carboxylate(14), the structure of which was determined by X-ray diffraction methods and refined to a residual of 0.035 for 1549 independent observed reflections. The crystals of (14) are monoclinic, P21/c, a 12.954(3), b 6.197(3), c 26.784(7) Ǻ, β 95.33(2)°, Z 4. Reactions attempting to generate iodohydrins from the alkenes (6) were also highly regioselective and gave detrimethylsilylated iodo analogues of (11) and (13).

Homeotropic alignment through charge-transfer-induced columnar mesophase formation in an unsymmetrically substituted triphenylene derivative

2010 ◽  
Vol 82 (11) ◽  
pp. 1993-2003 ◽  
Author(s):  
Juanjuan Li ◽  
Zhiqun He ◽  
Huan Zhao ◽  
Hemant Gopee ◽  
Xiangfei Kong ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Charge Transfer Complex ◽  
X Ray Diffraction ◽  
Hexagonal Symmetry ◽  
X Ray ◽  
Mesophase Formation ◽  
Homeotropic Orientation ◽  
Donor Acceptor ◽  
Homeotropic Alignment ◽  
Spectroscopy Optical

An unsymmetrically substituted triphenylene, with two adjacent chloroethoxyethyl lateral flexible chains, was synthesized and characterized. Although this compound showed no mesomorphic behavior, it formed a donor–acceptor charge-transfer complex with 2,4,7-trinitrofluorenone (TNF). The resulting 1:1 complex has been investigated using UV–vis and IR spectroscopy, optical microscopy, thermal analysis, and X-ray diffraction. A columnar mesophase with hexagonal symmetry was found. More interestingly, this charge-transfer complex can be easily aligned on a glass surface in a homeotropic orientation, which is stable at room temperature (RT) and over a wide temperature range.

Molecular tapes in the structure of isoguaninium chloride

2017 ◽  
Vol 74 (1) ◽  
pp. 108-112 ◽  
Author(s):  
Urszula Anna Budniak ◽  
Paulina Maria Dominiak
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Charge Density ◽  
Interaction Energy ◽  
Electrostatic Interaction ◽  
Electrostatic Interactions ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Structure

Isoguanine, an analogue of guanine, is of intrinsic interest as a noncanonical nucleobase. The crystal structure of isoguaninium chloride (systematic name: 6-amino-2-oxo-1H,7H-purin-3-ium chloride), C5H6N5O+·Cl−, has been determined by single-crystal X-ray diffraction. Structure analysis was supported by electrostatic interaction energy (E es) calculations based on charge density reconstructed with the UBDB databank. In the structure, two kinds of molecular tapes are observed, one parallel to (010) and the other parallel to (50\overline{4}). The tapes are formed by dimers of isoguaninium cations interacting with chloride anions. E es analysis indicates that cations in one kind of tape are oriented so as to minimize repulsive electrostatic interactions.

Comparative Spectroscopic Studies on Luminescence Performance of Er3+ Doped Tellurite Glass Embedded with Different Nanoparticles (Ag Co and Fe) at 0.55 μm Emission

2021 ◽  
Vol 317 ◽  
pp. 81-86
Author(s):  
Syariffah Nurathirah Syed Yaacob ◽  
Md. Rahim Sahar ◽  
Faizani Mohd Noor ◽  
Nur Liyana Amiar Rodin ◽  
Siti Khadijah Mohd Zain ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Ground State ◽  
Tellurite Glass ◽  
Spectroscopic Studies ◽  
The Other ◽  
X Ray Diffraction ◽  
Melt Quenching ◽  
X Ray ◽  
Doped Glass ◽  
Luminescence Performance

The spectroscopic performance of Er3+ doped glass at 0.55 mm emission contain different nanoparticles NPs have been comparatively evaluated. Glass containing 1.0 mol % of Er3+ doped with different NPs (Ag, Co and Fe ) have been prepared using melt quenching technique. X-ray diffraction analysis reveals the all the prepared samples are amorphous. The UV-Vis absorption spectra of all glasses show several prominent peaks at 525 nm, 660 nm, 801nm, 982 nm and 959 nm due to transition from ground state 4I15/2 to different excited of 2H11/2, 4F9/2, 4I9/2, 4I11/2, and 4I13/2. The emission of Er3+ at 0.55 mm for glass contain Ag NP shows significant enhancement about 3 folds up to 0.6 mol%. On the other hand, the emission of Er3+ at 0.55 mm for glass containing Fe NPs and Co NPs intensely quench probably due to the energy-transfer from Er3+ ion to NPs and magnetic contributions.

Are mesoionic compounds aromatic?

1998 ◽  
Vol 76 (6) ◽  
pp. 869-872 ◽  
Author(s):  
Alfredo Mayall Simas ◽  
Joseph Miller ◽  
Petrônio Filgueiras de Athayade Filho
Keyword(s):  
Experimental Evidence ◽  
Key Words ◽  
Dipole Moments ◽  
The Other ◽  
Side Chain ◽  
Theoretical Studies ◽  
X Ray Diffraction ◽  
Ring Plane ◽  
X Ray ◽  
Single Bonds

We have evaluated the experimental evidence relevant to the structure and character of mesoionic compounds, accumulated for more than 100 years and including X-ray diffraction studies. We have also evaluated relevant theoretical studies. All these, including our own extensive work, lead us to conclude that mesoionic compounds are not aromatic. According to our recent definition “mesoionic compounds are planar five-membered heterocyclic betaines with at least one side chain whose α-atom is also in the ring plane and with dipole moments of the order of 5 D. Electrons are delocalized over two regions separated by what are essentially single bonds. One region, which includes the a-atom of the side chain is associated with the HOMO and negative π-charge whereas the other is associated with the LUMO and positive π-charge.” Key words: mesoionic compounds, betaines, aromaticity.

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