Conductive In Situ Reduced Graphene Oxide-Silk Fibroin Bionanocomposites.

This research paper describes the fabrication of bionanocomposites (BNCs) based on silk fibroin (SF) and reduced graphene oxide (rGO). The recorded UV-visible (UV-vis) spectra of the sample confirm the reduction of GO to rGO in SF by showing a plasmon resonance band within the wavelength range of 261-268 nm. The X-ray diffraction (XRD) peak at 11.6° corresponding to the GO intensity decreases with increasing reaction time, resulting in rGO in the SF host matrix. The morphological behavior of the SF-rGO BNCs is scrutinized using scanning electron microscopy (SEM), and the images clearly indicate the existence of rGO within the matrix. The increasing amount of GO in the SF shows broken graphene sheets, which can increase the surface roughness and establish a strong physical contact between the SF and rGO nanosheets. The high-resolution transmission electron microscope (HR-TEM) image of the bionanocomposite showed that the formed rGO encompassments of fewer layers are stacked, each with fewer wrinkles and folding. The Raman spectroscopy confirmed the formation of rGO by showing the increased intensity ratio of D to G band (I D/I G) in the bionanocomposite samples. The rGO effect on the electrical conductivity is measured, and the results show that DC conductivity increases from 1.28 × 10-9 to 82.4 × 10-9 S/cm with an increase in the GO content in the SF biopolymer. The investigations demonstrate loss of the insulation property and improved conducting behavior of the SF biopolymer.

A study on adsorption behavior of newly synthesized banana pseudo-stem derived superabsorbent hydrogels for cationic and anionic dye removal from effluents.

In this work, an environmentally benign superabsorbent hydrogel based on banana pseudo-stem has been synthesized by free radical graft co-polymerization of sodium acrylate (NaAc) and acrylamide (AM) on to modified banana pseudo-stem cellulose backbone using ammonium persulfate (APS) and N,N-methylene-bis-acrylamide (MBA) as initiator and crosslinker respectively.The optimum condition for initiator, monomers and crosslinker concentrations was found to be 0.0032molL-1, 0.013molL-1 and 0.00048molL-1 respectively. Structural confirmation of the hydrogel prepared is performed by FT-IR spectroscopy whereas the morphology and thermal properties assessments were performed by SEM and TGA analysis respectively. Swelling behavior in solutions with different pH (2, 4, 7, 9 and 12) and contact time (5-750min) indicated 323.54gg-1 in pH 7 solutions for 570min. The optimized hydrogel was used as adsorbent for methylene blue (MB) and methyl orange (MO) with a maximum adsorption of 333.3 and 124 mgg-1 respectively. Kinetics and Isotherm adsorption studies revealed pseudo second-order and Freundlich isotherm as befitting models.

Spectroscopic, single crystal X-ray, Hirshfeld, in vitro and in silico biological evaluation of a new series of potent thiazole nucleus integrated with pyrazoline scaffolds.

In the present study, the spectroscopic characterization of a new series of substituted thiazole linked pyrazoline scaffolds 4a-l was performed. The formation of 4a-l from the intermediate 3-(4-chlorophenyl)-5-[4-(propan-2-yl)phenyl]-4,5-dihydro-1H-pyrazole-1-carbothioamide 2 and substituted 2-bromo-1-phenylethanone 3a-l was evidenced through the changes in FTIR, 1H NMR, 13C NMR, LCMS data. The X-ray diffraction studies revealed that compound 2 and 4g crystallized in monoclinic crystal system with P21/n space group. Compound 4j crystallized in triclinic system, P1̄ space group with Z=4. The percentage of intermolecular contacts and distribution of electrostatic potential of molecular crystal structures was resolved by Hirshfeld surface analysis with 2D finger plots and electrostatic potential map. The newly synthesized derivatives were screened for their in vitro antioxidant and antimicrobial activity. The single crystal studies revealed that, for compounds 2, 4g and 4j the isopropyl phenyl ring is positioned at near right angle with the other rings. Due to the lack of planarity of bulkier group substituted to phenyl ring (ring B), all the synthesized molecules showed weak to moderate radical scavenging capacity owing to the destabilization of the radical formed during oxidation. Also, on performing molecular docking studies to explore the interactions of ligand with the target pyrimidine nucleoside hydrolase YbeK with bound ribose complex (PNH, PDB ID-3GHW), disclosed that active compounds emerged for in vitro studies also bound to PNH more efficiently. The compounds with polar group substitution interacted through hydrogen bonding while other molecules with non-covalent interactions.

Crystal structures of two C,N-disubstituted acetamides: 2-(4-chloro-phen-yl)-N-(2-iodo-phen-yl)acetamide and 2-(4-chloro-phen-yl)-N-(pyrazin-2-yl)acetamide.

In the crystal of 2-(4-chloro-phen-yl)-N-(2-iodo-phen-yl)acetamide, C14H11ClINO, mol-ecules are linked by a combination of N-H⋯O and C-H⋯O hydrogen bonds to form a C(4)C(4)[R21(7)] chain of rings and chains of this type are linked by a combination of C-Cl⋯π(arene) and C-I⋯π(arene) inter-actions to form deeply puckered twofold inter-woven sheets. In the crystal of 2-(4-chloro-phen-yl)-N-(pyrazin-2-yl)acetamide, C12H10ClN3O, mol-ecules are linked into complex sheets by N-H⋯N, C-H⋯N and C-H⋯O hydrogen bonds, and by C-H⋯π(arene) inter-actions.

Different molecular conformations co-exist in each of three 2-aryl-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamides: hydrogen bonding in zero, one and two dimensions.

4-Antipyrine [4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one] and its derivatives exhibit a range of biological activities, including analgesic, antibacterial and anti-inflammatory, and new examples are always of potential interest and value. 2-(4-Chlorophenyl)-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide, C19H18ClN3O2, (I), crystallizes with Z' = 2 in the space group P\overline{1}, whereas its positional isomer 2-(2-chlorophenyl)-N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)acetamide, (II), crystallizes with Z' = 1 in the space group C2/c; the molecules of (II) are disordered over two sets of atomic sites having occupancies of 0.6020 (18) and 0.3980 (18). The two independent molecules of (I) adopt different molecular conformations, as do the two disorder components in (II), where the 2-chlorophenyl substituents adopt different orientations. The molecules of (I) are linked by a combination of N-H...O and C-H...O hydrogen bonds to form centrosymmetric four-molecule aggregates, while those of (II) are linked by the same types of hydrogen bonds forming sheets. The related compound N-(1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-2-(3-methoxyphenyl)acetamide, C20H21N3O3, (III), is isomorphous with (I) but not strictly isostructural; again the two independent molecules adopt different molecular conformations, and the molecules are linked by N-H...O and C-H...O hydrogen bonds to form ribbons. Comparisons are made with some related structures, indicating that a hydrogen-bonded R2(2)(10) ring is the common structural motif.

Crystal structure of 2-benzoyl-amino-N'-(4-hy-droxy-benzyl-idene)-3-(thio-phen-2-yl)prop-2-eno-hydrazide.

In the title compound, C21H17N3O3S, the non-H atoms, apart from those in the benzoyl group, are almost coplanar (r.m.s. deviation = 0.049 Å) and the benzoyl group is almost orthogonal to the plane of the rest of the mol-ecule [dihedral angle = 80.34 (6)°]. In the crystal, a combination of N-H⋯O and asymmetric bifurcated O-H⋯(N,O) hydrogen bonds link the mol-ecules into a three-dimensional network. Weak C-H⋯O inter-actions are also observed.

Crystal structure of (RS)-(4-chloro-phen-yl)(pyridin-2-yl)methanol.

In the title racemic compound, C12H10ClNO, the dihedral angle between the benzene and pyridine rings is 74.34 (6)°. In the crystal, the mol-ecules are linked by O-H⋯N hydrogen bonds, forming zigzag C(5) [001] chains in which alternating R- and S-configuration mol-ecules are related by c-glide symmetry. In addition, inversion-related pairs of mol-ecules are linked into dimers by pairs of weak C-Cl⋯π(pyrid-yl) inter-actions, which link the hydrogen-bonded chains into (100) sheets. Structural comparisons are drawn with a number of related compounds.

Dihydrooxazolones and dihydroimidazolones derived from acylglycines: syntheses, molecular structures and supramolecular assembly.

Syntheses and structures are described for some alkylidene-substituted dihydrooxazolones and dihydroimidazoles derived from simple acylglycines. A second, triclinic, polymorph of 4-benzylidene-2-(4-methylphenyl)-1,3-oxazol-5(4H)-one, C17H13NO2, (I), has been identified and the structure of 2-methyl-4-[(thiophen-2-yl)methylidene]-1,3-oxazol-5(4H)-one, C9H7NO2S, (II), has been rerefined taking into account the orientational disorder of the thienyl group in each of the two independent molecules. The reactions of phenylhydrazine with 2-phenyl-4-[(thiophen-2-yl)methylidene]-1,3-oxazol-5(4H)-one or 2-(4-methylphenyl)-4-[(thiophen-2-yl)methylidene]-1,3-oxazol-5(4H)-one yield, respectively, 3-anilino-2-phenyl-5-[(thiophen-2-yl)methylidene]-3,5-dihydro-4H-imidazol-4-one, C10H15N3OS, (III), and 3-anilino-2-(4-methylphenyl)-5-[(thiophen-2-yl)methylidene]-3,5-dihydro-4H-imidazol-4-one, C21H17N3OS, (IV), which both exhibit orientational disorder in their thienyl groups. The reactions of 2-phenyl-4-[(thiophen-2-yl)methylidene]-1,3-oxazol-5(4H)-one with hydrazine hydrate or with water yield, respectively, N-[3-hydrazinyl-3-oxo-1-(thiophen-2-yl)prop-1-en-2-yl]benzamide and 2-(benzoylamino)-3-(thiophen-2-yl)prop-2-enoic acid, which in turn react, respectively, with thiophene-2-carbaldehyde to form 2-phenyl-5-[(thiophen-2-yl)methylidene]-3-{[(E)-(thiophen-2-yl)methylidene]amino}-3,5-dihydro-4H-imidazol-4-one, C19H13N3OS2, (V), which exhibits orientational disorder in only one of its thienyl groups, and with methanol to give methyl (2Z)-2-(benzoylamino)-3-(thiophen-2-yl)prop-2-enoate, C15H13NO3S, (VI). There are no direction-specific intermolecular interactions in the crystal structure of the triclinic polymorph of (I), but the molecules of (II) are linked by two independent C-H···O hydrogen bonds to form C2(2)(14) chains. Compounds (III) and (IV) both form centrosymmetric R2(2)(10) dimers built from N-H···O hydrogen bonds, while compound (V) forms a centrosymmetric R2(2)(10) dimer built from C-H···O hydrogen bonds. In the structure of compound (VI), a combination of N-H···O and C-H···π(arene) hydrogen bonds links the molecules into sheets. Comparisons are made with some similar compounds.

A chalcone showing positional disorder, two related diarylcyclohexenones showing enantiomeric disorder and a related hydroxyterphenyl, all derived from simple carbonyl precursors.

Four compounds are reported, all of which lie along a versatile reaction pathway which leads from simple carbonyl compounds to terphenyls. (2E)-1-(2,4-Dichlorophenyl)-3- [4-(prop-1-en-2-yl)phenyl]prop-2-en-1-one, C18H14Cl2O, (I), prepared from 4-(prop-1-en-2-yl)benzaldehyde and 2,4-dichloroacetophenone, exhibits disorder over two sets of atomic sites having occupancies of 0.664 (6) and 0.336 (6). The related chalcone (2E)-3-(4-chlorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one reacts with acetone to produce (5RS)-3-(4-chlorophenyl)-5-[4-(propan-2-yl)phenyl]cyclohex-2-en-1-one, C21H21ClO, (II), which exhibits enantiomeric disorder with occupancies at the reference site of 0.662 (4) and 0.338 (4) for the (5R) and (5S) forms; the same chalcone reacts with methyl 3-oxobutanoate to give methyl (1RS,6SR)-4-(4-chlorophenyl)-6-[4-(propan-2-yl)phenyl]-2-oxocyclohex-3-ene-1-carboxylate, C23H23ClO3, (III), where the reference site contains both (1R,6S) and (1S,6R) forms with occupancies of 0.923 (3) and 0.077 (3), respectively. Oxidation, using 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, of ethyl (1RS,6SR)-6-(4-bromophenyl)-4-(4-fluorophenyl)-2-oxocyclohex-3-ene-1-carboxylate, prepared in a similar manner to (II) and (III), produces ethyl 4''-bromo-4-fluoro-5'-hydroxy-1,1':3',1''-terphenyl-4'-carboxylate, C21H16BrFO3, (IV), which crystallizes with Z' = 2 in the space group P-1. There are no significant intermolecular interactions in the structures of compounds (I) and (II), but for the major disorder component of compound (III), the molecules are linked into sheets by a combination of C-H...O and C-H...π(arene) hydrogen bonds. The two independent molecules of compound (IV) form two different centrosymmetric dimers, one built from inversion-related pairs of C-H...O hydrogen bonds and the other from inversion-related pairs of C-H...π(arene) hydrogen bonds. Comparisons are made with related compounds.

Crystal structure of 5-(4-meth-oxy-phen-yl)-3-(4-methyl-phen-yl)-4,5-di-hydro-1H-pyrazole-1-carbaldehyde.

In the title compound, C18H18N2O2, the pyrazole ring has a twisted conformation on the CH-CH2 bond. The tolyl ring and the 4-meth-oxy-phenyl ring are inclined to the mean plane of the pyrazole ring by 4.40 (9) and 86.22 (9)°, respectively, while the two aromatic rings are inclined to one another by 88.75 (9)°. In the crystal, mol-ecules are linked via bifurcated C-H⋯(O,O) hydrogen bonds and C-H⋯π inter-actions, forming sheets lying parallel to the ab plane.

(2E)-3-(6-methoxynaphthalen-2-yl)-1-(pyridin-3-yl)prop-2-en-1-one and its cyclocondensation product with guanidine, (4RS)-2-amino-4-(6-methoxynaphthalen-2-yl)-6-(pyridin-3-yl)-3,4-dihydropyrimidine monohydrate: two types of hydrogen-bonded sheet.

The structures of a chalcone and of its cyclocondensation product with guanidine are reported. In (2E)-3-(6-methoxynaphthalen-2-yl)-1-(pyridin-3-yl)prop-2-en-1-one, C19H15NO2, (I), the planes of the pyridine and naphthalene units make dihedral angles with that of the central spacer unit of 23.61 (13) and 23.57 (15)°, respectively, and a dihedral angle of 47.24 (9)° with each other. The molecules of (I) are linked into sheets by a combination of C-H···O and C-H···π(arene) hydrogen bonds. In the cyclocondensation product (4RS)-2-amino-4-(6-methoxynaphthalen-2-yl)-6-(pyridin-3-yl)-3,4-dihydropyrimidine monohydrate, C20H18N4O·H2O, (II), the dihydropyrimidine ring adopts a conformation best described as a shallow boat. The molecular components are linked by two N-H···O hydrogen bonds, two O-H···N hydrogen bonds and one N-H···N hydrogen bond to form complex sheets, with the methoxynaphthalene interdigitated between inversion-related pairs of sheets.

Three closely-related cyclohexanols (C35H27X2N3O3; X = F, Cl or Br): similar molecular structures but different crystal structures.

Three highly-substituted cyclohexanol derivatives have been prepared from 2-acetylpyridine and 4-halogenobenzaldehydes under mild conditions. (1RS,2SR,3SR,4RS,5RS)-3,5-Bis(4-fluorophenyl)-2,4-bis(pyridine-2-carbonyl)-1-(pyridin-2-yl)cyclohexanol, C35H27F2N3O3, (I), (1RS,2SR,3SR,4RS,5RS)-3,5-bis(4-chlorophenyl)-2,4-bis(pyridine-2-carbonyl)-1-(pyridin-2-yl)cyclohexanol acetone 0.951-solvate, C35H27Cl2N3O3·0.951C3H6O, (II), and (1RS,2SR,3SR,4RS,5RS)-3,5-bis(4-bromophenyl)-2,4-bis(pyridine-2-carbonyl)-1-(pyridin-2-yl)cyclohexanol, C35H27Br2N3O3, (III), all crystallize in different space groups, viz. Pbca, Fdd2 and P1, respectively. In compound (II), the acetone molecule is disordered over two sets of atomic sites having occupancies of 0.690 (13) and 0.261 (13). Each of the cyclohexanol molecules contains an intramolecular O-H···N hydrogen bond and their overall molecular conformations are fairly similar. The molecules of (I) are linked by two independent C-H···O hydrogen bonds to form a C(5)C(10)[R2(2)(15)] chain of rings, and those of (III) are linked by a combination of C-H···O and C-H···N hydrogen bonds, forming a chain of alternating R2(2)(16) and R2(2)(18) rings. The cyclohexanol molecules in (II) are linked by a single C-H···N hydrogen bond to form simple C(4) chains and these chains are linked by a π-π stacking interaction to form sheets, to which the disordered acetone molecules are weakly linked via a number of C-H···O contacts.

(2E)-1-(4-Chloro-phen-yl)-3-[4-(propan-2-yl)phen-yl]prop-2-en-1-one.

In the title compound, C18H17ClO, the dihedral angle between the benzene rings is 53.5 (1)°. The mean plane of the prop-2-en-1-one group is twisted by 24.5 (8) and 33.5 (3)° from the chloro- and propanyl-substituted rings, respectively.

Hydrogen-bonded chains in 3,5-bis(4-fluorophenyl)-1-phenyl-1H-pyrazole and complex hydrogen-bonded sheets in (5RS,6SR)-6-(4-fluorobenzoyl)-5-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5,6-dihydro-4H-1,3,4-oxadiazine N,N-dimethylformamide monosolvate.

Two different heterocycles, a pyrazole and an oxadiazine, are formed by the reactions of a common precursor, (2RS,3SR)-2,3-dibromo-1,3-bis(4-fluorophenyl)propan-1-one, with different simple hydrazines. In 3,5-bis(4-fluorophenyl)-1-phenyl-1H-pyrazole, C(21)H(14)F(2)N(2), (I), formed using phenylhydrazine, there is some aromatic-type delocalization in the pyrazole ring, and the molecules are linked into simple chains by a single C-H...π(arene) hydrogen bond. The reaction with 4-hydroxybenzohydrazide gives (5RS,6SR)-6-(4-fluorobenzoyl)-5-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5,6-dihydro-4H-1,3,4-oxadiazine, which was crystallized from N,N-dimethylformamide to give the monosolvate, C(22)H(16)F(2)N(2)O(3) · C(3)H(7)NO, (II), in which the solvent molecule is disordered over two sets of atomic sites having occupancies of 0.557 (10) and 0.443 (10). The oxadiazine molecules in (II) are linked by a combination of N-H...N and C-H...O hydrogen bonds to form complex sheets, having the hydrogen bonds in the central layer and with the solvent molecules attached at the outer faces by O-H...O hydrogen bonds.

Halogenated C,N-diarylacetamides: molecular conformations and supramolecular assembly.

The structures of four halogenated N,2-diarylacetamides are reported and compared with a range of analogues. N-(4-Chloro-3-methylphenyl)-2-phenylacetamide, C(15)H(14)ClNO, (I), and N-(4-bromo-3-methylphenyl)-2-phenylacetamide, C(15)H(14)BrNO, (II), are isostructural in the space group P-1. The molecules of (I) and (II) are linked into chains of rings by a combination of N-H...O and C-H...π(arene) hydrogen bonds. The molecules of N-(4-chloro-3-methylphenyl)-2-(2,4-dichlorophenyl)acetamide, C(15)H(12)Cl(3)NO, (III), and N-(4-bromo-3-methylphenyl)-2-(2-chlorophenyl)acetamide, C(15)H(13)BrClNO, (IV), are linked into simple C(4) chains by N-H...O hydrogen bonds, but significant C-H...π(arene) interactions are absent. The N-aryl groups in compounds (III) and (IV) adopt a different orientation, by ca 180°, from that of the corresponding groups in compounds (I) and (II), but otherwise the conformations of (I)-(IV) are very similar. Comparisons are drawn between compounds (I) and (IV) and a range of analogues of the type R(1)CH(2)CONHR(2), where R(2) represents a halogenated aryl ring and R(1) represents either another halogenated aryl ring or a naphthalen-1-yl unit.

Different patterns of supramolecular assembly in constitutionally similar 6-arylimidazo[2,1-b][1,3,4]thiadiazoles.

Four imidazo[2,1-b][1,3,4]thiadiazoles containing a simply-substituted 6-aryl group have been synthesized by reaction of 2-amino-1,3,4-thiadiazoles with bromoacetylarenes using microwave irradiation and brief reaction times. 6-(2-Chlorophenyl)imidazo[2,1-b][1,3,4]thiadiazole, C(10)H(6)ClN(3)S, (I), 6-(2-chlorophenyl)-2-methylimidazo[2,1-b][1,3,4]thiadiazole, C(11)H(8)ClN(3)S, (II), 6-(3,4-dichlorophenyl)imidazo[2,1-b][1,3,4]thiadiazole, C(10)H(5)Cl(2)N(3)S, (III), and 6-(4-fluoro-3-methoxyphenyl)-2-methylimidazo[2,1-b][1,3,4]thiadiazole, C(12)H(10)FN(3)OS, (IV), crystallize with Z' values of 2, 1, 1 and 2 respectively. The molecular skeletons are all nearly planar and the dihedral angles between the imidazole and aryl rings are 1.51 (8) and 7.28 (8)° in (I), 9.65 (7)° in (II), 10.44 (8)° in (III), and 1.05 (8) and 7.21 (8)° in (IV). The molecules in (I) are linked by three independent C-H...N hydrogen bonds to form ribbons containing alternating R2(2)(8) and R4(4)(18) rings, and these ribbons are linked into a three-dimensional array by three independent π-stacking interactions. Both (II) and (III) contain centrosymmetric dimers formed by π-stacking interactions but hydrogen bonds are absent, and the molecules of (IV) are linked into centrosymmetric R2(2)(8) dimers by C-H...N hydrogen bonds. Comparisons are made with a number of related compounds.

4-(4-Iodo-anilino)-2-methyl-ene-4-oxo-butanoic acid.

In the title compound, C11H10INO3, an addition product of itaconic acid anhydride and 4-iodo-aniline, the least-squares planes defined by the atoms of the aromatic moiety and the non-H atoms of the carb-oxy-lic acid group enclose an angle of 74.82 (11)°. In the crystal, classical O-H⋯O hydrogen bonds formed by carb-oxy-lic groups, as well as N-H⋯O hydrogen bonds formed by amide groups, are present along with C-H⋯O contacts. Together, these connect the mol-ecules into dimeric chains along the b-axis direction.

3-Chloro-4-fluoro-anilinium picrate.

In the title picrate salt of a dihalogenated aniline derivative, C(6)H(6)ClF(+)·C(6)H(2)N(3)O(7) (-), the intra-cyclic C-C-C angles in the picrate anion cover a broad range [111.95 (12)-125.38 (13)°], while those in the aromatic cation span a much narrower range [118.25 (14)-122.33 (13)°]. In the crystal, classical N-H⋯O hydrogen bonds, as well as C-H⋯O contacts, connect the ions into layers parallel to (001).

4-[Bis(4-fluoro-phen-yl)meth-yl]-1-[(2E)-3-phenyl-prop-2-en-1-yl]piperazin-1-ium 3-carb-oxy-propano-ate.

In the title salt, C(26)H(27)F(2)N(2) (+)·C(4)H(5)O(4) (-), the piperazine N atom bearing the vinylic substituent is protonated. The piperazine ring adopts a chair conformation. In ther crystal, the succinate monoanions are connected via short O-H⋯O hydrogen bonds between the carb-oxy-lic acid and carboxyl-ate groups into undulating chains extending along [001] and the flunarizinium monocations are attached to these chains via N(+)-H⋯O(-) hydrogen bonds. C-H⋯O inter-actions connect these chains into a three-dimensional network. The shortest centroid-centroid distance of 3.7256 (10) Šwas found between one of the fluorinated benzene rings and the non-fluorinated phenyl ring in the neighbouring mol-ecule related by a glide plane.

Synthesis and crystal structures of N-substituted pyrazolines.

Four pyrazole compounds, 3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde (1), 5-(4-bromophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole-1-carbaldehyde (2), 1-[5-(4-chlorophenyl)-3-(4-fluorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone (3) and 1-[3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl]propan-1-one (4), have been prepared by condensing chalcones with hydrazine hydrate in the presence of aliphatic acids, namely formic acid, acetic acid and propionic acid. The structures were characterized by X-ray single crystal structure determination. The dihedral angles formed between the pyrazole and the fluoro-substituted rings are 4.64(7)° in 1, 5.3(4)° in 2 and 4.89(6)° in 3. In 4, the corresponding angles for molecules A and molecules B are 10.53(10)° and 9.78(10)°, respectively.