Fluoro-benzene Rings Research Articles

2-[4-(2-Chloro-benz-yl)-3-methyl-6-oxo-1,6-di-hydro-pyridazin-1-yl]-N-(4-fluoro-phen-yl)acetamide.

The conformation of the title mol-ecule, C20H17ClFN3O2, is partly determined by an intra-molecular C-H⋯O hydrogen bond, which leads to a dihedral angle of 14.7 (4)° between the fluoro-benzene ring and the acetamide group. The 2-chloro-benzyl group is rotationally disordered over two orientations in a 0.656 (2): 0.344 (2) ratio. In the crystal, a layered structure is formed by N-H⋯O, C-H⋯O and C-H⋯F hydrogen bonds plus slipped π-π stacking inter-actions.

Electric-Field-Induced Chirality in Columnar Liquid Crystals.

We describe a novel class of tetraphenylbenzene-based discotic molecules with exceptional self-assembling properties. Absorption and fluorescence studies confirmed the formation of J-type aggregates in solution. The discotic mesogens also show an enhancement of the emission upon aggregation. Interestingly, these discotic molecules displayed enantiotropic hexagonal columnar liquid crystal (LC) phases that can be switched into a helical columnar organization by application of an electric field. The helical columns arise from the electric-field-induced tilt of the polar fluorobenzene ring that directs all of the peripheral phenyl groups into a propeller-like conformation with respect to the central benzene core. A cooperative assembly process of these propeller-shaped molecules resolves into a helical columnar organization, in which the preferred helical sense is obtained from the stereogenic center proximate to the polar carbon-fluorine bond. The ease of inducing chirality in columnar LCs by an electric field presents opportunities to create next-generation chiral materials for a variety of applications.

Ferroelectric and Spin Crossover Behavior in a Cobalt(II) Compound Induced by Polar-Ligand-Substituent Motion.

Ferroelectric spin crossover (SCO) behavior is demonstrated to occur in the cobalt(II) complex, [Co(FPh-terpy)2 ](BPh4 )2 ⋅3ac (1⋅3 ac; FPh-terpy=4'-((3-fluorophenyl)ethynyl)-2,2':6',2''-terpyridine) and is dependent on the degree of 180° flip-flop motion of the ligand's polar fluorophenyl ring. Single crystal X-ray structures at several temperatures confirmed the flip-flop motion of fluorobenzene ring and also gave evidence for the SCO behavior with the latter behavior also confirmed by magnetic susceptibility measurements. The molecular motion of the fluorobenzene ring was also revealed using solid-state 19 F NMR spectroscopy. Thus the SCO behavior is accompanied by the flip-flop motion of the fluorobenzene ring, leading to destabilization of the low spin cobalt(II) state; with the magnitude of rotation able to be controlled by an electric field. This first example of spin-state conversion being dependent on the molecular motion of a ligand-appended fluorobenzene ring in a SCO cobalt(II) compound provides new insight for the design of a new category of molecule-based magnetoelectric materials.

Ferroelectric and Spin Crossover Behavior in a Cobalt(II) Compound Induced by Polar‐Ligand‐Substituent Motion

AbstractFerroelectric spin crossover (SCO) behavior is demonstrated to occur in the cobalt(II) complex, [Co(FPh‐terpy)2](BPh4)2⋅3ac (1⋅3 ac; FPh‐terpy=4′‐((3‐fluorophenyl)ethynyl)‐2,2′:6′,2′′‐terpyridine) and is dependent on the degree of 180° flip–flop motion of the ligand's polar fluorophenyl ring. Single crystal X‐ray structures at several temperatures confirmed the flip–flop motion of fluorobenzene ring and also gave evidence for the SCO behavior with the latter behavior also confirmed by magnetic susceptibility measurements. The molecular motion of the fluorobenzene ring was also revealed using solid‐state 19F NMR spectroscopy. Thus the SCO behavior is accompanied by the flip–flop motion of the fluorobenzene ring, leading to destabilization of the low spin cobalt(II) state; with the magnitude of rotation able to be controlled by an electric field. This first example of spin‐state conversion being dependent on the molecular motion of a ligand‐appended fluorobenzene ring in a SCO cobalt(II) compound provides new insight for the design of a new category of molecule‐based magnetoelectric materials.

Designed Synthesis and Crystallization of Isomorphic Molecular Gyroscopes with Cell-like Bilayer Self-Assemblies

Two molecular rotors featuring pyridine and fluorobenzene rings as polar rotators and 9-octylfluorenyl stators were synthesized. Their crystal structures were established through SXRD techniques, crystallizing in the monoclinic chiral P21 space group. The supramolecular assemblies of both isomorphs showed an orientation of static dipoles through the crystal lattice and the formation of intriguing 2D layers that resemble cell membranes, a typical example of an amphidynamic system. Small activation energies and the modulation of the first-order hyperpolarizabilities of these compounds as a function of rotational dynamics were revealed through DFT computations at the CAM-B3LYP/M06-2X/cc-pVDZ level of theory and correlated with a potential use of these materials as photonic switches.

Synthesis of two novel [18F]fluorobenzene-containing radiotracers via spirocyclic iodonium ylides and positron emission tomography imaging of translocator protein (18 kDa) in ischemic brain.

Two novel radiotracers, namely, N-(4-[18F]fluorobenzyl)-N-methyl-2-(7-methyl-8-oxo-2-phenyl-7,8-dihydro-9H-purin-9-yl)acetamide ([18F]5) and 2-(5-(4-[18F]fluorophenyl)-2-oxobenzo[d]oxazol-3(2H)-yl)-N-methyl-N-phenylacetamide ([18F]6), were developed for positron emission tomography (PET) imaging of translocator protein (18 kDa) (TSPO) in ischemic brain in this study. The two radiotracers with a [18F]fluorobenzene ring were derived from the corresponding [18F]fluoroethyl tracers [18F]7 and [18F]8 which underwent [18F]defluoroethylation in vivo easily. [18F]5 or [18F]6 was synthesized by the radiofluorination of the spirocyclic iodonium ylide precursor 10 or 17 with [18F]F- in 23 ± 10% (n = 7) or 56 ± 9% (n = 7) radiochemical yields (decay-corrected, based on [18F]F-). [18F]5 and [18F]6 showed high in vitro binding affinities (Ki = 0.70 nM and 5.9 nM) for TSPO and moderate lipophilicities (log D = 2.9 and 3.4). Low uptake of radioactivity for both radiotracers was observed in mouse bones. Metabolite analysis showed that the in vivo stability of [18F]5 and [18F]6 was improved in comparison to the parent radiotracers [18F]7 and [18F]8. In particular, no radiolabelled metabolite of [18F]5 was found in the mouse brains at 60 min after the radiotracer injection. PET studies with [18F]5 on ischemic rat brains revealed a higher binding potential (BPND = 3.42) and maximum uptake ratio (4.49) between the ipsilateral and contralateral sides. Thus, [18F]5 was shown to be a useful PET radiotracer for visualizing TSPO in neuroinflammation models.

Enhanced Relative Stability of Metallabenzenes versus Metallocenes upon Ring Perfluorination: Nickel, Palladium, and Platinum Systems

Perfluorination of one η5‐C5H5 ring in the MC10H10 system (M = Ni, Pd, Pt) to give an MC10H5F5 system greatly destabilizes structures containing a perfluorinated pentahapto η5‐C5F5 ring. As a result, the metallapentafluorobenzene structures (η5‐C5H5)(MC5F5) are the lowest‐energy structures for all three metals, with energy differences of 1.4, 6.2, and 16.2 kcal/mol for nickel, palladium, and platinum, respectively. In addition, palladium and platinum isomeric metallatetrafluorocyclopentadiene structures, with a complexed fluorobenzene ring; that is, (C6H5F)(MC4F4) (M = Pd, Pt), are lower‐energy structures than the lowest‐energy metallocene structures. Furthermore, for palladium and platinum, the lowest‐energy metallocene structures are slipped metallocenes with a trihapto, rather than a pentahapto, pentafluorocyclopentadienyl ring. These theoretical results suggest the pentafluorocyclopentadienyl anion as a reagent for synthesizing metallapentafluorobenzene derivatives by reactions with (η5‐C5R5)M(CO)X, (η5‐C5R5)2M2(µ‐CO)2, or (η5‐C5R5)2Ni (R = H, Me; M = Ni, Pt).

(2Z)-2-(5-Fluoro-1-methyl-2-oxoindolin-3-ylidene)-N-(3-fluorophenyl)hydrazine-1-carbothioamide

In the title compound, C16H12F2N4OS, the whole molecule is essentially planar (r.m.s deviation = 0.003 Å), with only the H atoms of the methyl group lying out of the molecular plane. A planar indole fused-ring system (r.m.s deviation = 0.004 Å) is linked through a hydrazine–carbothioamide bridge to a fluorobenzene ring, with the indole ring system and inclined to the fluorobenzene ring by 4.26 (14)°. The planarity of the molecule is strengthened by three intramolecular N—H...N, N—H...O and C—H...S hydrogen bonds that generateS(5),S(6) andS(6) ring motifs, respectively. In the crystal, π–π stacking interactions combine with C—H...·F hydrogen bonds to link the molecules into layers parallel to the (10-1) plane.

N-[(3-Bromo-1-phenylsulfonyl-1H-indol-2-yl)methyl]-4-fluoroaniline

In the title compound, C21H16BrFN2O2S, the indole ring system makes dihedral angles of 87.23 (10) and 77.58 (9)° with the fluorobenzene and phenyl rings, respectively. The molecular structure is stabilized by a C—H...O and a C—H...Br intramolecular hydrogen bond, which generateS(6) andS(8) ring motifs, respectively. In the crystal, molecules are linked by C—H...π interactions, forming ribbons propagating along thea-axis direction. Within the ribbons, there are offset π–π interactions present involving inversion-related molecules [intercentroid distance = 3.650 (1) Å].

9-Fluoro-2,4,4a,6-tetrahydrospiro[benzo[c]chromene-3,2′-[1,3]dioxolane

In the title compound, C15H15FO3, the dihedral angle between the mean plane through all the non-H atoms of the dioxolane ring with those of the rest of the atoms of the chromene ring system, including the substituent F atom, is 81.1 (1)°. The pyran ring has an envelope conformation with the O atom as the flap. The cyclohexene ring has a half-chair conformation, while the dioxolane ring has a twisted conformation on an –O—CH2– bond. In the crystal, molecules are linked via C—H...O hydrogen bonds, forming chains along [100]. The chains are linked by C—H...π interactions, involving the fluorobenzene ring, forming layers parallel to the ac plane.

Crystal structure of canagliflozin hemihydrate.

There are two canagliflozin mol-ecules (A and B) and one water mol-ecule in the asymmetric unit of the title compound, C24H25FO5S·0.5H2O [systematic name: (2S,3R,4R,5S,6R)-2-(3-{[5-(4-fluoro-phen-yl)thio-phen-2-yl]meth-yl}-4-methylphen-yl)-6-(hy-droxy-meth-yl)-3,4,5,6-tetra-hydro-2H-pyran-3,4,5-triol hemihydrate]. The dihedral angles between the methyl-benzene and thio-phene rings are 115.7 (4) and 111.7 (4)°, while the dihedral angles between the fluoro-benzene and thio-phene rings are 24.2 (6) and 20.5 (9)° in mol-ecules A and B, respectively. The hydro-pyran ring exhibits a chair conformation in both canagliflozin mol-ecules. In the crystal, the canagliflozin mol-ecules and lattice water mol-ecules are connected via O-H⋯O hydrogen bonds into a three-dimensional supra-molecular architecture.

Crystal structure of 4-[(E)-(4-fluoro-benzyl-idene)amino]-3-methyl-1H-1,2,4-triazole-5(4H)-thione.

The title compound, C10H9FN4S, crystallizes with two mol­ecules (A and B) in the asymmetric unit. The dihedral angle between the planes of the trizole and fluoro­benzene rings is 7.3 (3)° in mol­ecule A and 41.1 (3)° in mol­ecule B. Mol­ecule A features an intra­molecular C—H⋯S hydrogen bond, which closes an S(6) ring. In the crystal, A+B dimers linked by pairs of N—H⋯S hydrogen bonds occur, generating R 2 2(8) loops. Weak π–π stacking contacts [centroid–centroid separation = 3.739 (6) Å] are also observed.

Crystal structure of 2-fluoro-N-(1,3-thia-zol-2-yl)benzamide.

In the title compound, C10H7FN2OS, the mean plane of the central amide fragment (r.m.s. deviation = 0.048 Å) makes dihedral angles of 35.28 (8) and 10.14 (12)° with those of the fluoro­benzene and thia­zole rings, respectively. The thia­zole S and amide O atoms lie to the same side of the mol­ecule. In the crystal, pairs of N—H⋯N hydrogen bonds connect the mol­ecules into inversion dimers with R 2 2(8) motifs, and weak C—H⋯O inter­actions connect the mol­ecules into C(6) [001] chains. Together, the N—H⋯N and C—H⋯O hydrogen bonds generate (100) sheets.

Crystal structure of 2-amino-N-(2-fluoro-phen-yl)-4,5,6,7-tetra-hydro-1-benzo-thio-phene-3-carboxamide.

In the title compound, C15H15FN2OS, the dihedral angle between the planes of the benzo­thio­phene ring system and the fluoro­benzene ring is 3.74 (14)°. The six-membered ring of the benzo­thio­phene moiety adopts a half-chair conformation. The mol­ecular conformation is consolidated by intra­molecular N—H⋯F and N—H⋯O hydrogen bonds. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds, generating C(6) [001] chains.

Crystal structure of dimethyl 3,3'-[(4-fluoro-phen-yl)methyl-ene]bis-(1H-indole-2-carboxyl-ate).

In the title compound, C27H21FN2O4, the mean planes of the indole ring systems (r.m.s. deviations = 0.0263 and 0.0160 Å) are approximately perpendic-ular to one another, making a dihedral angle of 84.0 (5)°; the fluoro-benzene ring is twisted with respect to the mean planes of the two indole ring systems at 89.5 (5) and 84.6 (3)°. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules into inversion dimers, which are further linked by N-H⋯O hydrogen bonds into supra-molecular chains propagated along the b-axis direction. Weak C-H⋯π inter-actions are observed between neighbouring chains.

Crystal structure of dimethyl 3,3'-[(3-fluoro-phenyl)methyl-ene]bis-(1H-indole-2-carboxyl-ate).

In the title compound, C27H21FN2O4, the mean planes of the two indole ring systems (r.m.s. deviations = 0.0166 and 0.0086 Å) are approximately perpendic-ular to one another, making a dihedral angle of 87.8 (5)°; the fluorobenzene ring is twisted with respect to the mean planes of the two indole ring systems at 82.7 (5) and 85.5 (3)°. In the crystal, pairs of N-H⋯O hydrogen bonds link the mol-ecules into the inversion dimers, which are further linked by N-H⋯O hydrogen bonds into supra-molecular chains propagating along the b-axis direction. Weak C-H⋯π inter-actions are observed between neighbouring chains.

Crystal structure of flufenoxuron: a benzoyl-urea pesticide.

The title compound, C21H11ClF6N2O3 (systematic name: 1-{4-[2-chloro-4-(trifluoromethyl)phenoxy]-2-fluorophenyl}-3-(2,6-di­fluoro­benzo­yl)urea), is a benzoyl­urea pesticide. The dihedral angles between the central fluoro­benzene ring and the terminal di­fluoro­phenyl ring and chloro­phenyl ring system are 62.15 (5) and 88.03 (5)°, respectively. In the crystal, N—H⋯O hydrogen bonds link adjacent mol­ecules, forming R 2 2(8) inversion dimers that pack into loop chains along the a-axis direction by short F⋯F contacts [2.729 (2) Å]. In addition, the chains are linked by weak C—H⋯π and π–π inter­actions [inter-centroid distances = 3.661 (2) and 3.535 (12) Å], resulting in a three-dimensional architecture.

Crystal structure of 4-fluoro-N-[2-(4-fluoro-benzo-yl)hydra-zine-1-carbono-thio-yl]benzamide.

In the title compound, C15H11F2N3O2S, the dihedral angle between the fluoro­benzene rings is 88.43 (10)° and that between the central semithiocarbazide grouping is 47.00 (11)°. The dihedral angle between the amide group and attached fluoro­benzene ring is 50.52 (11)°; the equivalent angle between the carbonyl­thio­amide group and its attached ring is 12.98 (10)°. The major twists in the mol­ecule occur about the C—N—N—C bonds [torsion angle = −138.7 (2)°] and the Car—Car—C—N (ar = aromatic) bonds [−132.0 (2)°]. An intra­molecular N—H⋯O hydrogen bond occurs, which generates an S(6) ring. In the crystal, the mol­ecules are linked by N—H⋯O and N—H⋯S hydrogen bonds, generating (001) sheets. Weak C—H⋯O and C—H⋯F inter­actions are also observed.

4-(2-Fluoro-phen-yl)-2-meth-oxy-5,6,7,8,9,10-hexa-hydro-cyclo-octa-[b]pyridine-3-carbo-nitrile.

In the title compound, C19H19FN2O, the cyclo­octene ring adopts a twisted boat–chair conformation. The dihedral angle between the plane of the fluorophenyl substituent and that of the pyridine ring is 76.39 (8)°. The F and ortho-H atoms of the fluoro­benzene ring are disordered, with occupancy factors of 0.226 (5) and 0.774 (5). In the crystal, no significant inter­actions are observed between the mol­ecules beyond van der Waals contacts.

(5-Fluoro-4'-methyl-biphenyl-3-yl)(2,4,6-tri-methyl-phen-yl)iodo-nium tri-fluoro-methane-sulfonate.

In the title mol­ecular salt, C22H21FI+·CF3SO3 −, the dihedral angle between the rings of the biphenyl group is 65.6 (1)°. The ring of the mesitylene group is inclined to the fluoro­benzene ring at an angle of 86.1 (3)° and the C—I—C bond angle is 97.0 (2)°. In the crystal, extremely short I⋯O contacts of 2.862 (5) and 2.932 (5) Å occur, due to the strong electrostatic inter­actions between the I atom and two adjacent tri­fluoro­methane­sulfonate counter-ions. There are also C—H⋯F and C—H⋯π inter­actions present: together with the I⋯O bonds, these result in a three-dimensional network.