Pentafluorophenyl Derivative Research Articles

Structures and Supramolecular Properties of Inclusion Complexes of Anthracene-Triptycene Nanocages with Fullerene Guests and Their Dynamic Motion as Molecular Gyroscopes.

Three derivatives of macrocyclic cage compounds consisting of diarylanthracene and triptycene units were synthesized. These nanocages formed host-guest complexes with C60 and other fullerene guests as confirmed by 1 H NMR and fluorescence spectroscopy. The association constant of the mesityl and 2,4,6-tributoxyphenyl derivatives with C60 was determined to be 2.2 × 104 L mol-1 , which was larger than that of the pentafluorophenyl derivative. Direct experimental evidence of the complexation was obtained by X-ray diffraction analysis: the guest C60 molecule was included in the cavity via multipoint CH⋅⋅⋅π interactions. Dynamic disorders of the included C60 molecule in variable-temperature X-ray analysis indicated uniaxial motion, such as gyroscopic motion. The unique dynamic behavior of the spherical C60 rotor anchored by the cage stator via CH⋅⋅⋅π interactions in the crystal, as well as substituent effects on the association properties, are discussed with the aid of DFT calculations.

New Pyrano-4H-benzo[g]chromene-5,10-diones with Antiparasitic and Antioxidant Activities.

New pyranonaphthoquinone derivatives were synthesized and investigated for their activity against Trypanosoma brucei, Leishmania major, and Toxoplasma gondii parasites. The pentafluorophenyl derivative was efficacious against T. brucei with single digit micromolar EC50 values and against T. gondii with even sub-micromolar values. The 3-chloro-4,5-dimethoxyphenyl derivative showed an activity against amastigotes of Leishmania major parasites comparable to that of amphotericin B. In addition, antioxidant activities were observed for the bromophenyl derivatives, and their redox behavior was studied by cyclovoltammetry. Anti-parasitic and antioxidative activities of the new naphthoquinone derivatives appear uncorrelated.

Silver Compounds in Synthetic Chemistry. Part 8. Complexes of Perfluoroorgano Silver(I) Derivatives with 4‐Dimethylaminopyridine (DMAP)

AbstractAttempted syntheses of AgRf·DMAP were performed using the established route starting from AgF and Me3SiRf (Rf = CF3, C2F5, C6F5) followed by the addition of DMAP. Unexpectedly, reactions with perfluoroalkylsilver(I) derivatives yielded products, which underwent known equilibria, while exclusively the pentafluorophenyl derivative exhibits its zwitterionic nature in solution and in the solid state. Moreover, both perfluoroalkyl derivatives investigated decomposed slowly but more or less selectively even at –20 °C in solution: AgC2F5·DMAP mainly into AgOCOCF3 (probably under the influence of moisture) and AgCF3·DMAP mainly into the unprecedented derivative 3‐trifluoromethyl‐4‐dimethylaminopyridine. The molecular structure of AgC6F5·DMAP was elucidated showing a twist arrangement of the aromatic rings quite unusual for linear coordinated species.

UV‐Photoelectron Spectroscopy of a Tetrakis(trimethylsilyl)tetrahedrane and Its Pentafluorophenyl Derivative

Strained cages: UV-photoelectron spectroscopy studies of tetrakis(trimethylsilyl)tetrahedrane and its pentafluorophenyl derivative (see figure) demonstrate the effectiveness of the neutral hyperconjugation in the latter, which was initially proposed on the basis of electronic spectra and computational data.

Fine-Tuning the Luminescence and HOMO–LUMO Energy Levels in Tetranuclear Gold(I) Fluorinated Amidinate Complexes

Tetranuclear gold(I) fluorinated amidinate complexes have been synthesized and their photophysical properties and structures described. DFT calculations were carried out to illustrate how a minor change in the ligand resulted in a loss of emission in the perfluorophenyl amidinate complex compared with nonfluorinated phenyl amidinate complexes reported previously. The fluorinated complexes reported here [Au(ArN)(2)C(H)](4) (1, Ar = 4-FC(6)H(4); 2, 3,5-F(2)C(6)H(3); 3, 2,4,6-F(3)C(6)H(2); 4, 2,3,5,6-F(4)C(6)H) emit in the blue-green region at 470, 1, 478, 2, 508, 3, and 450 nm, 4, by excitation at ca. 375 nm at room temperature with nanosecond lifetimes. The emissions observed at 77 K in the solid state show structured emission for complexes 1 and 2, with a vibrational spacing of ca. 1200 and 1500 cm(-1), corresponding to the vibrational modes of the amidinate ligand. The pentafluorophenyl derivative 5, Ar = C(6)F(5,) shows no photoluminescence in the solid state nor in the solution. This result is different from results in which the pentafluorophenyl group is attached to a phenylpyridine ligand in an Ir(III) complex and other organics. This quenching appears to be related to a nonradiative de-excitation process caused by the ππ*-πσ* crossover in the excited state of the pentafluorophenyl amidinate ligand. With increasing numbers of fluorine atoms, there is a progressive decrease in the contribution of the amidinate ligands to the corresponding HOMO orbital. There also is a slight decrease in the ligand contribution to the LUMO with increased numbers of fluorine atoms and an exchange of the character of the orbitals of the gold centers.

Electron-poor N-substituted imide-fused corannulenes

N-Substituted imide-fused corannulenes can be generated from the corresponding tetramethylfluoranthenes. Syntheses, crystal structure and electronic properties are reported. The solid state structure of the pentafluorophenyl derivative shows nearly perfect π-stacking in a convex-concave fashion and is expected to possess useful electronic properties.

Synthesis and structural, electronic, optical and FET properties of thiophene–pyrrole mixed hexamers end-capped with phenyl and pentafluorophenyl groups

α-Linked thiophene–pyrrole mixed hexamers 3a–5a end-capped with two phenyl, two pentafluorophenyl and both phenyl and pentafluorophenyl units were newly synthesized, and their structural, electronic, optical and FET properties were investigated. Structural analyses by means of X-ray crystallography and theoretical calculations showed that the π-system of the oligomer chains is twisted due to the steric repulsion between the hexyl group of the pyrrole unit and the adjacent thiophene moiety. From comparison of the absorption maxima and redox potentials, end-capping with phenyl and pentafluorophenyl units did not affect the HOMO–LUMO gap for the thiophene–pyrrole hexamer, and the multiple fluorine substituents slightly decreased both HOMO and LUMO levels by the inductive effects of the electronegative fluorine atoms. Although the diphenyl derivative 3a with a herringbone-type packing structure did not serve as an active layer for FET devices, a unique crystal-to-crystal phase transition with a color change from yellow to red was observed upon heating. In contrast to the herringbone-type packing structure of 3a, the unsymmetrical phenyl–pentafluorophenyl derivative 5a showed a partially π-stacked structure, most likely due to dipole–dipole interactions. The π-stacked structure of 5a caused a good hole mobility of 4.1 × 10−2 cm2 V−1s−1 in a single crystal FET device.

Synthesis, Characterization, Luminescence, and Electrochemistry of the Tetranuclear Gold(I) Amidinate Clusters, Precursors to CO Oxidation Catalysts: Au4[(ArNC(H)NAr)]4, Au4[(PhNC(Ph)NPh)]4 and Au4[PhNC(CH3)NPh)4

AbstractA summary of the chemistry of the tetranuclear Au(I) amidinate complexes is presented. Tetranuclear Au(I) amidinate clusters are produced by the reaction of the sodium salt of a amidine ligand with the gold precursor Au(THT)Cl in a (1:1) stoichiometry. The structures of the tetranuclear Au4[ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, C6H3‐3,5‐Cl, C6H4‐4‐Me, C6H4‐3‐CF3, C6F5, C10H7 and the tetranuclear Au4[(PhNC(Ph)NPh]4 and Au4[PhNC(CH3)NPh]4 have been characterized by X‐ray crystallography. The average Au···Au distance between adjacent Au(I) atoms is ˜3.0 Å, typical of compounds having an aurophilic interaction. The four gold atoms are located at the corner of a rhomboid with the amidinate ligands bridged above and below the near plane of the four Au(I) atoms. The angles at Au···Au···Au in the cyclic units are between 70° and 116°. The tetranuclear gold(I) amidinate clusters each show different luminescence behavior. The tetranuclear clusters Au4[(ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, Ar = C6H4‐3‐CF3, Ar = C6H4‐4‐Me and Ar = C6H4‐3,5‐Cl are the first tetranuclear gold(I) cluster species from group 11 elements that show fluorescence at room temperature. The tetranuclear naphthyl derivative Ar = C10H7 is luminescent only at 77 K. The pentafluorophenyl derivative Ar = C6F5 does not show any photoluminescence in the solid state nor in the solution. The lifetimes of the naphthyl and trifluoromethylphenyl complexes are in the millisecond range indicating phosphorescent processes. Electrochemical and chemical oxidation studies of the tetranuclear Au(I) amidinate clusters are presented. The tetranuclear complexes Au4[ArNC(H)NAr]4, Ar = C6H4‐4‐OMe, Ar = C6H4‐4‐Me, and Ar = C6H3‐3,5‐Cl, show three reversible waves at 0.75, 0.95, 1.09 V vs. Ag/AgCl at a scan rate of 500 mV/s in 0.1 M Bu4NPF6/CH2Cl2 at a Pt working electrode in CH2Cl2. Three reversible waves at 0.87, 1.19, 1.42 V vs. Ag/AgCl at a scan rate of 100 mV/s are also observed for the tetranuclear complex Au4[PhNC(Ph)NPh]4 in CH2Cl2. The pentafluorophenyl amidinate derivative, Au4[ArNC(H)NAr]4, Ar = C6F5 shows no oxidation wave below 1.8 V. Recently it has been shown that Au4[ArNC(H)NAr]4 is a very effective catalyst precursor for room temperature CO oxidation.

Tetranuclear Gold(I) Clusters with Nitrogen Donor Ligands: Luminescence and X-Ray Structure of Gold(I) Naphthyl Amidinate Complex

The syntheses and characterization of gold(I) naphthyl, pentafluorophenyl, and trifluoromethylphenyl amidinate complexes are reported. The tetranuclear clusters are obtained from the reaction of Au(tetrahydrothiophene)Cl with the potassium salt of the corresponding amidinate in a THF solvent. The crystal structures of the gold(I) naphthyl, 2, and pentafluorophenyl, 3, amidinates show a short Au···Au distance of ~3. 0 A typical of compounds having an aurophilic interaction. The gold atoms are arranged in a square (Au···Au···Au = 87°–92°) in the pentafluorophenyl derivative and in a parallelogram (Au···Au···Au = 68°–110°) in the naphthyl amidinate complexes. The naphthyl and trifluoromethylphenyl complexes are visibly luminescent in the solid state at liquid nitrogen temperature displaying asymmetric emission bands at 538 and 473 nm, respectively. The luminescent lifetimes of these species are in the millisecond range indicating phosphorescent processes.

Synthesis and crystal structure of an assembly of three ortho‐carborane cages linked via para‐phenylene units: effect of aryl orientation on cage CC bond lengths in C‐aryl‐ortho‐carboranes

AbstractThe synthesis and crystal and molecular structure are described of (C2B10H11)C6H4(C2B10H10)C6H4(C2B10H11) (4), an acyclic assembly of three ortho‐carborane units connected through their carbon atoms by two para‐phenylene units. For this compound, and published structures of other aryl‐ortho‐carboranes, correlations are noted between the orientations of aryl substituents and cage carbon–carbon distances (C1C2). Ab initio RHF/6‐31G* and MP2/6‐31G* studies on 1‐phenyl‐ortho‐carborane, PhC2B10H11, and other model systems have been used to explore the variations in their energies, C1C2 bond lengths, and C2C1Caryl bond angles with the orientation of their aryl groups, variations believed to reflect weak interactions between the aryl substituents' π systems and the carborane cages. The synthesis of a pentafluorophenyl derivative of 4, (C2B10H11)C6H4(C2B10H10)C6H4(C2B10H10)C6F5, is also described. Copyright © 2003 John Wiley & Sons, Ltd.

Acetylenephosphino gold(i) derivatives: structure, reactivity and luminescence properties

We have synthesised the acetylenephosphino gold(I) derivatives, AuX(PPh2CCH) (X = Cl, Br, I, C6F5). X-Ray diffraction studies show that the chloro derivative is a dimer connected by two short hydrogen bonds from the acetylenic hydrogen to chlorine, whilst the iodo derivative is also a dimer because of a gold–gold interaction of 3.0625(9) A. The crystal structure of the pentafluorophenyl derivative shows the presence of intermolecular hydrogen bonds Au⋯H (3.07 A, 143°), also from the acetylenic hydrogen, which link the molecules into chains. The possibility of preparing alkynyl derivatives has been investigated but only complex [Au(C6F5)(PPh2CC)Au(C6F5)][N(PPh3)2] 6 has been obtained in a pure state. Complex 6 luminesces at room temperature in the solid state, and all the complexes are luminescent at 77 K with excitation maxima in the range 292–335 nm and emission maxima between 445 and 533 nm.

The infra-red spectra of fluorinated aromatic compounds—II The pentafluorobenzyl and pentafluorobenzylidene halides

The vibrations which are characteristic of the pentafluorophenyl group are discussed. The frequencies of the a 1 and b 1 νCC modes appear to be fairly constant when compared with other pentafluoroaromatics. The νCF modes are much more variable and are very sensitive to the nature of the substituent group Y in the pentafluorophenyl derivative C 6F 5Y. The ν(Aryl)—CH 2X modes of the pentafluorobenzyl halides are very similar in frequency to the same modes in benzyl halides. The CX stretching modes of the benzyl and the benzylidene halides are considered in detail; those of the pentafluorobenzyl halides are compared with the corresponding benzyl halides.