Molecular Cocrystals of Carboxylic Acids. XXI. The Role of Secondary Group Interactions in Adduct Formation Between 2-Aminopyrimidine and Substituted Benzoic Acids: the Crystal Structures of the Adducts With o-Phthalic Acid, o-Nitrobenzoic Acid, o-Aminobenzoic Acid and m-Aminobenzoic Acid

1995 ◽  
Vol 48 (6) ◽  
pp. 1151 ◽  
Author(s):  
G Smith ◽  
JM Gentner ◽  
DE Lynch ◽  
KA Byriel ◽  
CHL Kennard
Keyword(s):  
Phthalic Acid ◽  
Adduct Formation ◽  
Benzoic Acids ◽  
Aminobenzoic Acid ◽  
X Ray Diffraction ◽  
Group Interactions ◽  
X Ray ◽  
Nitrobenzoic Acid ◽  
Substituted Benzoic Acids

The crystalline adducts of 2-aminopyrimidine (2-ap) with a series of mainly ortho-substituted benzoic acids, o-phthalic acid ( opht ) [(2-ap)( opht )] (1), 2-nitrobenzoic acid (2-nba) [(2-ap)(2-bna)2] (2), 2-aminobenzoic acid (2-aba) [(2-aba) [(2-ap)(2-aba)2] (3) and 3-aminobenzoic acid (3-aba) [(2-ap)(3-aba)] (4) have been prepared and their hydrogen-bonding motifs characterized by using single-crystal X-ray diffraction. The role of substituent groups in secondary associations with cocrystal formation is considered for the 2-aminopyrimidine system.

Molecular Cocrystals of Carboxylic Acids. XXVI Adducts of the Amino-Substituted Benzoic Acids with Nitroaromatic Lewis Bases: the Influence of Associative Polyfunctional Substituents on Self-Assembly of Molecules in Cocrystallization Processes

1997 ◽  
Vol 50 (10) ◽  
pp. 977 ◽  
Author(s):  
Daniel E. Lynch ◽  
Graham Smith ◽  
Karl A. Byriel ◽  
Colin H. L. Kennard
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectroscopy ◽  
Self Assembly ◽  
Benzoic Acids ◽  
Aminobenzoic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lewis Bases ◽  
Aminobenzoic Acids ◽  
Substituted Benzoic Acids

A series of molecular adducts of the isomeric aminobenzoic acids with the nitro-substituted Lewis bases 2-chloro-5-nitropyridine, 5-nitroquinoline and 5-nitroisoquinoline has been prepared and characterized by using infrared spectroscopy and X-ray powder diffraction, and in four cases by single-crystal X-ray diffraction methods. These four compounds are the adducts of 3-aminobenzoic acid with 5-nitroquinoline [(C7H7NO2)(C9H6N2O2)], 4-aminobenzoic acid with 5-nitroquinoline [(C7H7NO2)2(C9H6N2O2)], 2-aminobenzoic acid with 5-nitroisoquinoline [(C7H7NO2)(C9H6N2O2)] and 4-aminobenzoic acid with 5-nitroisoquinoline [(C7H7N2O2)(C9H6N2O2)]. Other compounds described are the (1 : 1) adducts of 4-aminobenzoic acid with 2-chloro-5-nitropyridine, and 2-aminobenzoic acid with 5-nitroquinoline. All adducts involve hydrogen-bonding network associations while in none of the examples is any proton transfer involved.

Molecular Cocrystals of Carboxylic Acids. XIII. Spectral Characterization of the Adducts of Triphenylphosphine Oxide With Substituted Benzoic Acids and the Crystal Structures of the 1 : 1 Adducts With 2,4,6-Trinitrobenzoic Acid and 3,5-Dinitrobenzoic Acid

1993 ◽  
Vol 46 (10) ◽  
pp. 1535 ◽  
Author(s):  
DE Lynch ◽  
G Smith ◽  
NJ Calos ◽  
CHL Kennard ◽  
AK Whittaker ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Triphenylphosphine Oxide ◽  
Benzoic Acids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Acid Proton ◽  
Phosphoryl Oxygen ◽  
Substituted Benzoic Acids ◽  
Convenient Technique

The 1:1 adducts of triphenylphosphine oxide with the 2-, 3- and 4-nitro-, 3,5-dinitro-, and 2,4,6-trinitro-substituted benzoic acids have been prepared, and characterized by infrared and 31P n.m.r. spectroscopy. The crystal structures of two of these adducts, (triphenylphosphine oxide-3,5-dinitrobenzoic acid) and ( triphenylphosphine oxide-2,4,6-trinitrobenzoic acid), have been determined by X-ray diffraction. In all examples, the presence of single directed hydrogen bonds between the phosphoryl oxygen and the carboxylic acid proton is confirmed. For the X-ray structures, the O…O distances are 2.54(4) and 2.55(1)Ǻ respectively. Solid-state 31P n.m.r. spectroscopy has also proved a convenient technique for the detection of the presence of a single conformational adduct type in cocrystals.

Designing Linear Hydrogen-Bonded Arrays by Using Substituted Charge-Transfer Complexes. The Crystal Structure of the 1 : 1 Adduct of Indole-2-carboxylic Acid with 3,5-Dinitrobenzoic Acid

1998 ◽  
Vol 51 (11) ◽  
pp. 1019 ◽  
Author(s):  
Daniel E. Lynch ◽  
Graham Smith ◽  
Karl A. Byriel ◽  
Colin H. L. Kennard
Keyword(s):  
Crystal Structure ◽  
Carboxylic Acid ◽  
Second Harmonic ◽  
Charge Transfer Complexes ◽  
Benzoic Acids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Linear Optical Properties ◽  
Substituted Benzoic Acids ◽  
Indole 3 Acetic Acid

Five adducts consisting of carboxylic acid-substituted indoles with nitro-substituted benzoic acids have been synthesized and tested for second-order non-linear optical properties. These were indole-2-carboxylic acid with 2,4-dinitrobenzoic acid (1), 3,5-dinitrobenzoic acid (2), and 2,4,6-trinitrobenzoic acid (3), and indole-3-acetic acid with 3,5-dinitrobenzoic acid (4), and 2,4,6-trinitrobenzoic acid (5). Compound (2) produced clear, yellow crystals (space group P -1 with a 6·8400(7), b 15·150(2), c 16·097(2) Å, α 84·911(9), β 87·088(10), γ 77·865(9)°, Z 4) which allowed the structure to be determined by X-ray diffraction. Of the five adducts, compounds (3) and (5) gave second harmonic intensities of 0·15 and 0·16 times respectively that of a urea standard.

Optimization of molecular geometry of para-substituted benzoic acids and their anions by means of gradient CNDO/2 method

1982 ◽  
Vol 47 (12) ◽  
pp. 3393-3404 ◽  
Author(s):  
Stanislav Böhm ◽  
Josef Kuthan
Keyword(s):  
Diffraction Data ◽  
Molecular Geometry ◽  
Benzoic Acids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Substituted Benzoic Acids

21 conformers of benzoic acids I and corresponding anions II have been optimized by the title semiempirical MO approach. The calculated geometry characteristics are confronted systematically with X-ray diffraction data, and quality of the calculated parameters is critically evaluated.

Optimization of molecular geometry of meta-substituted benzoic acids and their anions by gradient CNDO/2 method

1983 ◽  
Vol 48 (4) ◽  
pp. 1019-1029 ◽  
Author(s):  
Stanislav Böhm ◽  
Josef Kuthan
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Geometry ◽  
Published Data ◽  
Benzoic Acids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Substituted Benzoic Acids

32 conformers of meta-substituted benzoic acids I and the corresponding anions II have been optimized with respect to all geometrical degrees of freedom by the title semiempirical MO approach. The calculated geometry characteristics are compared with some published data obtained by means of X-ray diffraction.

Molecular Cocrystals of Carboxylic Acids. XXV The Utility of Urea in Structure Making with Carboxylic Acids and the Crystal Structures of a Set of Six Adducts with Aromatic Acids

1997 ◽  
Vol 50 (7) ◽  
pp. 727 ◽  
Author(s):  
Graham Smith ◽  
Katherine E. Baldry ◽  
Karl A. Byriel ◽  
Colin H. L. Kennard
Keyword(s):  
Hydrogen Bonding ◽  
Infrared Spectroscopy ◽  
Dicarboxylic Acid ◽  
Carboxylic Acids ◽  
Phthalic Acid ◽  
Aromatic Acids ◽  
Aminobenzoic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polymeric Structures

Molecular adducts of urea with six aromatic carboxylic acids have been prepared and characterized by using X-ray diffraction methods and infrared spectroscopy. These compounds are with 5-nitrosalicylic acid [(C7H5NO5)2(CH4N2O)] (1), 3,5-dinitrosalicylic acid [(C7H4N2O7)(CH4N2O)] (2), 4-aminobenzoic acid [(C7H7NO2)2(CH4N2O)] (3), o-phthalic acid [(C8H6O4)(CH4N2O)] (4), pyrazine-2,3-dicarboxylic acid [(C4H4N2O4)(CH4N2O)] (5) and pyridine-2,6-dicarboxylic acid [(C7H5NO4)(CH4N2O)2] (6). In the majority of the adducts, all six potential interactive sites on the urea molecules are utilized in hydrogen bonding, giving polymeric structures.

Role of the Structure and Electronic Properties of Fe2O3-MoO3 Catalyst on the Dehydration of Isopropyl Alcohol

1993 ◽  
Vol 58 (7) ◽  
pp. 1591-1599 ◽  
Author(s):  
Abd El-Aziz A. Said
Keyword(s):  
Active Sites ◽  
Isopropyl Alcohol ◽  
Oxide Catalyst ◽  
Flow System ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalyst Composition ◽  
Surface Active

Molybdenum oxide catalyst doped or mixed with (1 - 50) mole % Fe3+ ions were prepared. The structure of the original samples and the samples calcined at 400 °C were characterized using DTA, X-ray diffraction and IR spectra. Measurements of the electrical conductivity of calcined samples with and without isopropyl alcohol revealed that the conductance increases on increasing the content of Fe3+ ions up to 50 mole %. The activation energies of charge carriers were determined in presence and absence of the alcohol. The catalytic dehydration of isopropyl alcohol was carried out at 250 °C using a flow system. The results obtained showed that the doped or mixed catalysts are active and selective towards propene formation. However, the catalyst containing 40 mole % Fe3+ ions exhibited the highest activity and selectivity. Correlations were attempted to the catalyst composition with their electronic and catalytic properties. Probable mechanism for the dehydration process is proposed in terms of surface active sites.

scholarly journals Modeling of magneto-conductivity of bismuth selenide: a topological insulator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yogesh Kumar ◽  
Rabia Sultana ◽  
Prince Sharma ◽  
V. P. S. Awana
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Field Range ◽  
X Ray ◽  
Bulk Carriers ◽  
Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

scholarly journals Crystallization and X-ray diffraction data analysis of human deoxyhaemoglobin A0 fully stripped of any anions

1999 ◽  
Vol 55 (11) ◽  
pp. 1914-1916 ◽  
Author(s):  
F. A. V. Seixas ◽  
W. F. de Azevedo ◽  
M. F. Colombo
Keyword(s):  
Diffraction Data ◽  
Oxygen Affinity ◽  
X Ray Diffraction ◽  
Structural Explanation ◽  
Human Haemoglobin ◽  
X Ray ◽  
High Resolution Structure ◽  
Allosteric Properties

In this work, initial crystallographic studies of human haemoglobin (Hb) crystallized in isoionic and oxygen-free PEG solution are presented. Under these conditions, functional measurements of the O2-linked binding of water molecules and release of protons have evidenced that Hb assumes an unforeseen new allosteric conformation. The determination of the high-resolution structure of the crystal of human deoxy-Hb fully stripped of anions may provide a structural explanation for the role of anions in the allosteric properties of Hb and, particularly, for the influence of chloride on the Bohr effect, the mechanism by which Hb oxygen affinity is regulated by pH. X-ray diffraction data were collected to 1.87 Å resolution using a synchrotron-radiation source. Crystals belong to the space group P21212 and preliminary analysis revealed the presence of one tetramer in the asymmetric unit. The structure is currently being refined using maximum-likelihood protocols.

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