Mesogenic 3,6-bis(4-hydroxyphenyl)-1,2,4,5-tetrazine alkanoate esters

A novel series of 3,6-bis(4-hdroxyphenyl)-1,2,4,5-tetrazine alkanoate esters were synthesized and their mesogenic properties were studied using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The impact of changing the tail-core linkage from alkyl or alkoxy to ester is profound. Compared to the alkyl or alkoxy linkages, the ester linkage reduced mesogenic properties. Short-tailed compounds are non mesogenic (4a-4e), while long-tailed compounds (4f-4r) exhibit nematic phases. Unlike the alkyl or alkoxy tail series, none of the 18 presented esters in this series exhibits a smectic phase.     

The molecular and crystal structure of endo-2-methyl-7-hydroxy-7-oxo-N-phenyl-7-phosphabicyclo-[2.2.1] hept-2-ene-5,6-dicarboximide

The structure of the title compound1 has been determined by X-ray crystallography analysis. The following crystal data were found: orthorhombic,Pca2_l,a=9.60691),b=16.356(1),c=8.686(1) . Both the phospholane and phospholene rings involved in the 7-phosphabicyclo-[2.2.1] hept-2-ene system have almost regular envelope conformations, and the cyclohexene ring has a significantly deformed boat conformation. The low value of the C–P–C angle, 84.2(2)°, reflects the steric strain around the phosphorus bridge and may be responsible for the reactivity of esters and amides derived from1 in the O-insertion reaction with m-chloro-perbenzoic acid. The dihedral angle between the plane of the benzene and succinimide rings is 82.4(2)°.     

Supramolecular Architecture of Two Modifications of Flavone-6,2′-dicarboxylic acid

Abstract  

Two crystalline forms of flavone-6,2′-dicarboxylic acid (fla): one N,N-dimethylformamide (DMF) solvate (modification 1) and one without any solvate molecules (modification 2), have been obtained and their structures were determined by X-ray diffraction technique. Modification 1 crystallized in the orthorhombic space group Pbca; and modification 2 crystallized in the monoclinic space group P2(1)/c. In 1 and 2 fla molecules are both joined to helix chain structures via O–H···O hydrogen-bonds between carboxylic group of B ring and carbonyl oxygen atom of C ring, however, in 1 helix chains are further joined by DMF molecules; and in 2 helix chains are further linked via rich hydrogen-bonds between fla molecules, which result in different packing of modifications 1 and 2.     

An X-ray Crystallographic Study of the Related Triazenes, 1,4-Di[(<Emphasis Type="Italic">E</Emphasis>)-2-(2-nitrophenyl)-1-diazenyl]piperazine and Methyl 4-{(E)-2-(4-methylpiperazino)-1-diazenyl}benzoate

Abstract The crystal structures of methyl 4-{(E)-2-(4-methylpiperazino)-1-diazenyl}benzoate (2a) and 1,4-di[(E)-2-(2-nitrophenyl)-1-diazenyl]piperazine (3a) have been determined by single crystal X-ray diffraction analysis. The bis-triazene (3a) adopts an unusual pseudo-boat conformation in the piperazine ring, with a dihedral angle of 52.20(0.06)° between the two planes defined within the piperazine ring. The crystal structures of 2a and 3a are compared with the structure of the triazene (4) and the closely related bis-triazene (5). The piperazine ring of 2a adopts a typical chair conformation, whereas the piperazine ring of 3a adopts an unusual boat conformation. Crystal data: 2a C₁₃H₁₈N₄O₂, monoclinic, space group P2₁ /n, a = 13.849(3) ?, b = 6.577(1) ?, c = 14.904(3) ?, α = 90°, β = 96.098(3)°, γ = 90° and V = 1,349.8(4) ?³, for Z = 4. 3a C₁₆H₁₆N₈O₄, triclinic, space group P-1, a = 7.6066(6) ?, b = 8.3741(7) ?, c = 14.507(1) ?, α = 78.673(1)°, β = 81.877(1)°, γ = 73.445(1)° and V = 865.0(1) ?³, for Z = 2. Index abstract The crystal structures of methyl 4-{(E)-2-(4-methylpiperazino)-1-diazenyl}benzoate (2a) and 1,4-di[(E)-2-(2-nitrophenyl)-1-diazenyl]piperazine (3a) have been determined by single crystal X-ray diffraction analysis.     

Crystal Structure of Diethyl[(4chlorophenyl)(dibenzylamino)methyl]propanedioate

Abstract  

The titled new functionalized N,O,O-ligand of type diethyl[(4-chlorophenyl)(dibenzylamino)methyl]propanedioate (4) is prepared in good yield through condensation of dibenzylamine, with 2-arylidene-malonic acid diethyl esters 3. The structure of 4 was determined by spectral (IR, ¹H NMR), elemental analyses and X-ray diffraction data. The molecular conformation shows two possible pockets ready to coordinate two metal atoms.     

Annulated bicyclo[2.2.2]octenones: 9-hydroxy-9-chloromethyl-endo-tricyclo[5.2.2.02,6]undeca-4,10-diene-3-spiro(1′-cyclopropane)-8-one and 12-hydroxy-12-chloromethyl-endo-tricyclo [8.2.2.02,9]tetradeca-13-en-11-one

A single crystal X-ray diffraction study of two annulated bicyclo[2.2.2]octenones has been carried out to establish their precise stereostructures. The compounds, with their crystal data, are:1, 9-hydroxy-9-chloromethyl-endo-tricyclo[5.2.2.0^2,6]undeca-4,10-diene-3-spiro(1-cyclopropane)-8-one, C₁₄H₁₅O₂Cl, space group P2₁/c,a=10.540(2),b=9.668(1),c=11.841(4)Å, =95.67(2)°,Z=4, and2, 12-hydroxy-12-chloromethyl-endo-tricyclo[8.2.2.0^2,9]tetradeca-13-en-11-one, C₁₅H₂₁O₂Cl, space group C2/c,a=20.747(8),b=6.498(1),c=20.525(3)Å, =93.04(3)°,Z=8. The molecule of1 has endo stereochemistry at the ring junction and the spirocyclopropane ring is proximal to the hydroxyl group. In2, the eight membered ring deviates from a chair conformation and one ring atom is disordered. Crystals of1 and2 contain centrosymmetric dimers formed by C=O...O–H hydrogen bonds.     

Co-crystal structures of 2,4-diamino-6-phenyl-1,3,5-triazine – 4-chlorobenzoic acid/4-methoxybenzoic acid: Synthesis,structural and Hirshfeld surface analysis

The co-crystal structure of 2,4-diamino-6-phenyl-1,3,5-triazine with 4-chlorobenzoic acid/4-methoxybenzoic acid molecules are explain the link between the dimension and shape of their hydrogen-bonded assembly. The co-crystal structure of 2,4-diamino-6-phenyl-1,3,5-triazine with 4-chlorobenzoic acid/4-methoxybenzoic acid forming a cyclic R₂²(8) ring motif via N–H?O and O–H?N hydrogen bonding interactions, to form a supramolecular heterosynthon. In both the co-crystal structures, self-association of 2,4-diamino-6-phenyl-1,3,5-triazine moieties are connected via N-H^….N base pairs with cyclic R₂²(8) motif form a supramolecular homosynthon. In co-crystal II, the centrosymmetrically paired methoxy group of 4-methoxy benzoic acid form a supramolecular homosynthon via weak intermolecular C-H^….O hydrogen bonds, generating R₂²(6) ring motif. Both the co-crystal structures are stabilized by weak aromatic π-π and C—Cl???π stacking interactions. Hirshfeld surface and fingerprint plots were used to study the intermolecular interactions both of the crystal structures.     

X-ray crystal structure of the 1:1 dimethylpicric acid–acenaphthene complex

The dimethylpicric acid–acenaphthene complex is orthorhombic, space group P2₁2₁2₁; at 24° a = 7.3685(1), b = 15.4159(1), c = 16.1296(3) Å, D _x = 1.491(2) g cm^–3, V = 1832.19(4) ų, Z = 4. The phenolic OH group in the dimethylpicric acid is intramolecularly hydrogen bonded to one of the ortho nitro groups with an OO distance of 2.500(2) Å. This nitro group is twisted out of the plane of the benzene ring by 8.2°; the twist angles of the other nitro groups are 52.6 and 83.5°. The acenaphthene molecule deviates slightly from planarity as a consequence of the torsion angle at CH ₂-CH ₂ being 1.8 rather then 0°. The molecules pack in stacks of alternating picric acid and acenaphthene molecules. Each stack is surrounded by a close-packed arrangement of six other stacks. The acenaphthene molecules are 2.7° away from being parallel to the benzene ring in the picric acid. The distances from the benzene ring to the acenaphthene carbon atoms range from 3.26 to 3.49 Å on one side of the ring and from 3.30 to 3.54 Å on the other.     

The stereochemistry of organosulfur compounds. XX. The x-ray crystal and molecular structures of two tetrathiaspiroalkanes

The X-ray crystal structures of 1,4,6,9-tetrathiaspiro[4.4]nonane (4) and 1,5,7,11-tetrathiaspiro[5.5]undecane (3) have been determined. Crystals of4 are tetragonal, space groupI4₁ cd, with eight molecules in a unit cell of dimensionsa=9.521 (2) andc=19.052(5) Å. Crystals of3 are orthorhombic,Pbca, with eight moleucles in a cell havinga=8.955(3),b=12.356(4), andc=18.425(4) Å. Compound4 was solved from the Patterson map and3 by use ofMultan, and they refined to finalR values of 6.4 and 2.5%, respectively. Compound4 consists of two 1,3-dithiolane rings connected via C(2), both of which appear to be somewhat disordered at room temperature. The uncorrected C-C distance is 1.476 Å and the average S-C distance is 1.786 Å. Compound3 consists of two 1,3-dithiane rings connected at C(2), both in chair conformations. In both compounds there appear to be electronic repulsions between S lone pairs and axial hydrogens of the opposite ring system. Analysis of endocyclic torsion angles in3 indicates that the ring conformations themselves are not significantly altered by the positional shift caused by the repulsion.     

Oxazoles XXI. Three Ester Ammonium Salts Resulting from the Rupture of an Oxazoline Ring

Abstract  

The synthesis and characterisation of three ammonium salts that are formed via a ring opening of a 2-oxazoline (i.e., a 4,5-dihydro-1,3-oxazole) are described. Compound 1, derived from 2-phenyl-2-oxazoline (Phox), was isolated as a major reaction product during an unrelated synthesis using Phox which was being carried out in the presence of NO₃ ⁻ ions. The isolated compound is identified as the nitrate salt of the terminal ammonium ester [H₃NCH₂CH₂OC(=O)Ph]⁺ (1). The X-ray crystal structure (C₉H₁₂N₂O₅) of 1 is revealed to be orthorhombic (space group Pna2₁) with a = 21.1304(8), b = 7.5975(2) and c = 6.8629(3)?. The analogous material 2a, obtained from the related oxazole 4,4-dimethyl-2-phenyl-2-oxazoline (MePhox) under identical conditions to that of 1, contains the [H₃NCMe₂CH₂OC(=O)Ph]⁺ cation. The X-ray crystal structure (C₁₁H₁₆N₂O₅) of 2a is monoclinic with a = 6.1270(3), b = 6.3603(3), c = 16.1632(8)? and β = 90.662(3)o and of space group P2₁. Chiral derivative 2b, was isolated from a wet CH₂Cl₂/THF solution upon treatment of MePhox with (S)-mandelic acid. This material was shown to also contain the [H₃NCMe₂CH₂OC(=O)Ph]⁺ cation, a lattice water molecule and an (S)-mandalate anion. The X-ray crystal structure of 2b (C₁₉H₂₃NO₅·H₂O) is orthorhombic (space group P2₁2₁2₁) with a = 6.4733(3), b = 11.4661(5) and c = 24.5791(11)?. One proposed mechanism by which all three materials are formed was first presented in seminal work by Deslongchamps. The compounds reported herein are representatives of a class of rarely isolated intermediates in heterocyclic ring opening reactions and they are also the first examples of (ω-ammoniumethyl)(aryl) esters to be structurally characterised.     

Synthesis,Characterization and Mesomorphic Properties of New Rod-like Thiophene Based Liquid Crystals

Two new mesogenic homologous series of Schiff base esters, 2-[4-(4′-n-Alkoxy benzoyloxy) benzylidenamino] 3-cyno thiophine (Series-A) and Schiff base cinnamates, 2-[4-(4′-n-alkoxy cinnamoyloxy) benzylidenamino] 3-cyano thiophene (Series-B), comprising a thiophene moiety were synthesized. Structural elucidation was carried out using elemental analysis and spectroscopic techniques such as FT-IR, ¹H-NMR and ¹³C-NMR, and mass spectrometry. The mesomorphic properties and thermal stabilities of the title compounds were studied by using differential scanning calorimetry and optical polarizing microscopy. All the derivatives are mesomorphic in nature showing the nematic phase, and the higher members of Series-A show a smectic C phase whereas Series-B exhibits only the nematic mesophase. The mesomorphic properties of the present series are compared with other structurally related compounds.     

Liquid Crystal Compounds Incorporating the Trans-1,4-Substituted Cyclohexane Ring System

A number of esters and other compounds containing a trans-1,4-substituted cyclohexane ring system-have been prepared, and the liquid crystal thermal stabilities of these new mesogens are discussed in relation to those of their analogues containing the 1,4-phenylene ring. The observed effects are discussed in terms of a possible thermal energy absorption by the cyclohexane ring in causing minor conformational changes.

Other physical properties of these new mesogens are also discussed with particular reference to their potential in applications. In relation to electro-optical display devices, such properties as birefringence, dielectric anistropy, viscosity etc., are important parameters, and the new materials have been assessed in this context as possible additives to the 4-n-alkyl- and 4-n-alkyloxy-4′-cyanobiphenyls for producing a favorable combination of physical parameters.

Also reported is a liquid crystal mixture which has a 100°C nematic range and which contains only materials which are aliphatic. This mixture is assessed for its potential application as an anistropic solvent in analytical techniques such as ultra-violet spectroscopy and nuclear magnetic resonance spectroscopy.     

Crystal and Molecular Structures of Two Triazole Derivatives: 4-Cyclopropyl-4,5-dihydro-1H-1,2,3-triazole and Methyl 1-benzyl-1H-1,2,3-triazole-4-carboxylate

Abstract  

The molecule in 4-cyclopropyl-4,5-dihydro-1H-1,2,3-triazole (I) is disposed about a mirror plane with the triazole ring lying in the plane and being orthogonal to the cyclopropyl ring. Considerable delocalization of π-electron density within the triazole ring is indicated by the pattern of bond distances in (I). The molecule of methyl 1-benzyl-1H-1,2,3-triazole-4-carboxylate (II) adopts a curved shape with the dihedral angle formed between the triazole and benzene rings being 63.23(8)°. By contrast to (I), localization of π-electron density within the triazole ring in (II) is indicated. Both (I), via N–H···N hydrogen bonding, and (II), via C–H···O and C–H···N interactions, associate in the solid state to form supramolecular chains. In (I), the chain is a zigzag with a flat topology, whereas in (II) the linear chain has a curved topology. Compound (I) crystallizes in the orthorhombic space group Pnma with a = 5.6470(2) ?, b = 7.3359(4) ?, c = 13.4404(7) ?, and Z = 4. Compound (II) crystallizes in the monoclinic space group P2₁/c with a = 12.1314(5) ?, b = 5.5951(2) ?, c = 16.4339(7) ?, β = 111.269(2)°, and Z = 4.     

The role of hydrogen bonding in pseudo-macrocyclic ring formation in 2,6-dimethyl-1,3,5,7-cyclooctatetraene 1,3,5,7-tetracarboxylic acid monohydrate

2,6-Dimethyl-1,3,5,7-cyclooctatetraene-1,3,5,7-tetracarboxylic acid 3, C₁₄H₁₄O₉, was prepared by thermolysis of the corresponding semibullvalene and characterized by spectroscopic and single-crystal X-ray diffraction studies. The monohydrate of 3 crystallizes in the tetrahedral space group P-4n2, a = 11.0924(3) Å, c = 12.6799(5) Å, V = 1560.15(9) ų, Z = 4. The cyclooctatetraene ring adopts a tub-shaped conformation with a crystallograpically imposed twofold rotational symmetry, and is composed of localized C=C double bonds in the 1,3,5, and 7 positions with an average interatomic distance of 1.327 (5) Å and C–C single bonds with an average interatomic distance of 1.489(5) Å. The average C=C–C angle in the ring is 122.6(3)°. Each symmetry generated eight-membered ring contains four carboxyl groups, two of which are coplanar with the methyl groups across the C=C ring atoms. However, across the C–C bonds the carboxyl groups and the methyl groups show a torsion angle of 64.3(4)°. The presence of a water molecule in the crystal lattice generates a three-dimensional network of close hydrogen bondings between water and the carboxyl groups of multiple rings. This creates a network of orthogonal 10-membered rings between the 8-membered rings. Two given cyclooctatetraene rings are intermolecularly hydrogen bonded not only directly through their carboxyl groups but also via a bridging water molecule. This effect is rare in polycarboxylic acids and their monohydrates which bond only with water or among themselves.     

X-ray Crystallographic Structures of Two Lamotrigine Analogues: (I) 3,5-Diamino-6-(2-chlorophenyl)-1,2,4-triazine Water Solvate and (II) 3,5-Diamino-6-(3,6-dichlorophenyl)-1,2,4-triazine Methanol Solvate

Abstract The X-ray crystal structures of two lamotrigine derivatives (I) 3,5-diamino-6-(2-chlorophenyl)-1,2,4-triazine, C₉H₈ClN₅, (465BL) as a hydrate, and (II) 3,5-diamino-6-(3,6-dichlorophenyl)-1,2,4-triazine, C₉H₇Cl₂N₅, (469BR) as a methanol solvate, have been carried out at liquid nitrogen temperature and room temperature, respectively. A detailed comparison of the two structures is given. Both are centrosymmetric with (I) in the orthorhombic space group Pbca, a = 12.2507(3), b = 15.7160(6), c = 21.71496(9) ?, Z = 16, and (II) in the monoclinic space group C2/c, a = 38.553(3), b = 4.9586(2), c = 14.546(2) ?, β = 111.59(1)°, Z = 8. Final R indices [I > 2sigma(I)] for (I) are R1 = 0.0670, wR2 = 0.1515 and for (II) R1 = 0.0434, wR2 = 0.1185. Structure (I) has water of crystallization in the lattice and (II) includes a solvated CH₃OH. Structure (I) is characterized by having two crystallographically independent molecules, A and B, of 465BL, per asymmetric unit. Molecule B has a very unusual feature in that the 2-chlorophenyl ring is statistically disordered, occupying site (1) in 87.5% of the structure and site (2) in 12.5% of the structure. Sites (1) and (2) are related by an exact 180° pivot of the phenyl ring about the ring linkage bond. The presence of two independent molecules per asymmetric unit provides an ideal opportunity for the conformational flexibility of the molecule 465BL to be studied. Structure (I) also includes a further unusual feature in that the lattice contains one fully occupied water molecule and an additional solvated water which is only 33% occupied. Index Abstract Rex A. Palmer, Brian S. Potter, Michael J Leach and Babur Z. Chowdhry The crystal structures of two lamotrigine analogues: (I) 3, 5-diamino-6-(2-chlorophenyl)-1, 2, 4-triazine, water solvate and (II) 3, 5-diamino-6-(3,6-dichlorophenyl)-1, 2, 4-triazine methanol solvate are presented. Structure (I) includes two molecules per asymmetric unit labeled A and B where molecule B is unusually disordered having Cl in either position 2 (87.5% occupied) or position 6 of the phenyl ring (12.5% occupied), the two sites being related by 180deg rotation about the ring linkage bond. Molecule I(A) on the other hand shows no disorder. The relative orientations of the two rings in I(A and B) and in II is shown to be different. Lamotrigine and analogues have been investigated for some time for their effects on the central nervous system. For example both lamotrigine and 5-(2,3,5-trichlorophenyl)-2,4-diaminopyrimidine (code name BW 1003C87) are voltage-gated sodium channel blockers as well as blocking the release of the neurotransmitter glutamate. BW 1003C87 has also been shown to reduce the release of glutamate evoked by veratrine in brain tissue, providing a therapeutic approach in both cerebral ischemia and epilepsy [B. S. Meldrum, J. H. Swan, M. J. Leach, M. H. Millan, R. Gwinn, K. Kadota, S. H Graham, J. Chen, R. P. Simon , Brain Res., 1992, 593, 1.]. This is one of a series of papers on the structures of lamotrigine analogues.      

Crystal structures of mixed ligand complexes containing saccharinate and nicotinamide: [Cu(saccharinato)2 (nicotinamide) (H2O)]⋅(H2O) and [M(nicotinamide)2 (H2O)4]⋅(saccharinate)2 (M = Ni2+, Co2+)

[M(saccharinato)₂(H₂O)₄] (M = Cu²⁺, Ni²⁺, Co²⁺) react with nicotinamide to form mixed ligand complexes, [Cu(saccharinato)₂(nicotinamide)(H₂O)](H₂O) (1) and [M(nicotinamide)₂(H₂O)₄](saccharinate)₂ (2: M = Ni²⁺; 3: M = Co²⁺), and their crystal structures have been determined by X-ray diffraction. In 1, the Cu²⁺ atom in an octahedral configuration is coordinated by two monodentate saccharinato ligands in the trans arrangement through the deprotonated ring nitrogens, by two bidentate nicotinamide ligands, one through the pyridyl ring nitrogen and the other through the amide oxygen, and by a water molecule, thus forming a nicotinamide-bridged one-dimensional extended structure. In the isomorphous complexes 2 and 3, the octahedral metal atom, which rides on a crystallographic center of symmetry, is coordinated by two monodentate nicotinamide ligands through the ring nitrogens and four water molecules to form a discrete [M(nicotinamide)₂(H₂O)₄]^{2 +} structural unit, which captures up and down two saccharinate ions, each through three hydrogen bonds: two hydrogen bonds between two water ligands and the ring N and the carbonyl O atoms and one between the amide N of the nicotinamide ligand and the carbonyl O.     

O-[(Triorganostannyl)methyl] derivatives of 1,2-O-isopropylidene-α-D-xylofuranose

The synthesis, mass, IR and NMR spectra of 3-O-benzyl-1,2-O-isopropylidene-5-O-[(triphenylstannyl)methyl]--D-xylofuranose (9) and 1,2-O-isopropylidene-3-O-(R₃SnCH₂)-5-O-triphenylmethyl--D-xylofuranose (10, R=Bu or Ph) are reported, as is the X-ray structure of10 (R=Ph). Compound10 (R=Ph), crystallizes in the orthorhombic space groupP2₁2₁2₁ (Z=4), witha=11.006(4) Å,b=17.096(6) Å,c=21.164(7) Å. The conformation of the furanose ring in solid10 (R=Ph) is a 8218 mixture of the envelope (E₄) and twist (³T₄) forms: the isopropylidene ring conformation is similarly a mixture of envelope and twist forms, with the former dominant. On dissolution, the furanose ring of10 (R=Ph) undergoes a conformation change, with the³T₂ conformation becoming the major form. The tin center in10 is four-coordinate and has a tetrahedral geometry.     

Synthesis and crystal structures of 2-amino-3-cyano-4-(2-chlorophenyl)-1,4-dihydro-2H-pyrano[3, 2-h]quinoline and 2-amino-3-cyano-4-(2-chlorophenyl)-8-(2-chlorobenzylidene)-1,4,5,6,7,8-hexahydrobenzo[b]pyran

The title compounds 2-amino-3-cyano-4-(2-chlorophenyl)-1,4-dihydro-2H-pyrano[3, 2-h]quinoline 1 (C₁₉H₁₂ClN₃O, M _r = 333.77) and 2-amino-3-cyano-4-(2-chlorophenyl)-8-(2-chlorobenzylidene)-1,4,5,6,7,8-hexahydrobenzo[b]pyran 2 were synthesized and crystallized. The crystals of compound 1 are triclinic, space group P-1, a = 7.488(2), b = 9.127(3), c = 12.252(3) Å, = 73.58(2), = 78.38(2)°, = 75.39(2), Z = 2, V = 769.5(4) ų; The compound 2 crystallizes in space group P2₁/n, with cell parameters a = 13.582(2), b = 8.974(1), c = 16.960(2) Å, = 103.34(1)° and D _calc = 1.352 g/cm^–3 for Z = 4. X-ray analysis reveals that atoms C(1)—C(5) and O form a pyran ring in compound 1, which adopts half-chair conformation. In compound 2 the atoms C(12)—C(16) and O form a pyran ring which adopts boat conformation, another six-membered ring (C(8)—C(13)) adopts a half-chair conformation. In addition, there are intermolecular hydrogen bonds in the crystal structures 1 and 2.     

Crystal structures and hydrogen bond analysis of three arenesulfonate salts ofl-alanine,glycine, andl-serine

Single crystal X-ray structures are presented for three amino acid arenesulfonate salts:l-alanine 2,4-dinitrobenzenesulfonate hydrate (1), 21 glycine 1,5-naphthalene-disulfonate dihydrate (2), andl-serine 4-hydroxybenzenesulfonate (3). Hydrogen bond patterns of each salt are analyzed systematically by using hydrogen bond graph set notation. First-, second-, and selected third-level graph set motifs of the three salts are presented and discussed. Hydrogen-bonded diad, chain, ring, ribbon, and two-dimensional sheet patterns are identified in these structures. Even though the three salts contain apparently similar types of hydrogen-bonding interactions, their graph sets are quite different.Deceased June 10, 1992.     

Crystallographic and luminescence studies of ammonium and water adducts of anthraquinone fluorophores

Fluorescence and X-ray crystallographic results for ammonium adducts of an anthraquinone-containing polyether macrocycle, 1,8-oxybis(ethyleneoxyethyleneoxy)-anthracene-9,10-dione (1), and an open-chain fluorinated analogue are presented. The crystal structure of a pseudo-polymorph of a hydrate of compound 1 is also presented. [1 ₂·NH₄]PF₆·MeOH (2), triclinic, P-1, a=10.5948(13), b=14.903(2), c=15.918(2), α=71.260(3), β=82.063(2), γ=69.258(2), Z=2, 5250 reflections [I≥2σ(I)], R₁=0.0487, wR₂=0.1190, 173(2) K; 1 ₄ ·H₂O, Triclinic, P-1, a=12.0084(8) b=13.8050(9) c=23.8027(16), α=106.068(1), β=98.281(1), γ=90.047(1), Z=8, 8402 reflections [I≥2σ(I)], R₁=0.0488, wR₂=0.1086, 100(2) K. Different anti and gauche ring conformations are observed for macrocycles with and without guests complexed within the polyether ring.