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The reactivity of an electron-rich Ni-difluorocarbene complex, Ni=[CF.sub.2][(dppe)[P(OMe).sub.3]] (1), with a variety of fluorinated alkenes was investigated (dppe = 1,2-bis(diphenylphosphino)ethane). Reactions of 1 with perfluoro(methyl vinyl ether) and chlorotrifluoroethylene (CTFE) give regiospecific formation of metallacyclobutanes, in which the carbene C attacks the most electron-rich carbon of the fluoroalkene. Further reaction of the CTFE-derived metallacycle in the presence of tetrahydrofuran affords a single isomer of NiCl(r-[CF.sub.2]CF=CFH) (dppe), 8, proposed to be formed by Ni-mediated [C.sub.a]-Cl activation followed by hydride abstraction and loss of HF. Although 1 also undergoes a cyclization reaction with trifluoroethylene (TrFE), instability of the presumed nickelacyclobutane affords the C3 fluoroalkene, [F.sub.2]C=CH([CF.sub.3]), and subsequent formation of isomeric metallacyclopentanes from two additional TrFEs. Alternatively, reaction of 1 with hexafluoropropene forms an unexpected Ni--[CF.sub.3] r-perfluoroallyl complex. Key words: nickel difluorocarbene, fluoroalkene, cycloaddition, C--F bond activation. La reactivite d'un complexe de difluorocarbene-nickel riche en electrons, le Ni-[CF.sub.2](dppe)[P(OMe)] (1), avec une variete d'alcenes fluores a ete etudiee [dppe = 1,2-bis(diphenylphosphino)ethane]. Les reactions du complexe 1 avec le perfluoro(methylvinylether) et le chlorotrifluoroethylene (CTFE) donnent lieu a la formation regiospecifique de metallacyclobutanes, dans lesquels le C du carbene attaque le carbone le plus riche en electrons du fluoroalcene. La poursuite de la reaction du metallacycle derive du CTFE en presence de tetrahydrofurane produit un seul isomere de NiCl([sCF.sub.2]CF=CFH) (dppe), le complexe 8, dont la formation pourrait etre attribuable a l'activation de la liaison [C.sub.a]Cl catalysee par le Ni, suivie de l'abstraction de l'hydrure et de la perte d'une molecule de HF. Bien que le complexe 1 subisse egalement une reaction de cyclisation avec le trifluoroethylene (TrFE), l'instabilite du suppose nickelacyclobutane permettrait la formation du fluoroalcene en C3, le [F.sub.2]C=CH([CF.sub.3]), puis la formation subsequente de metallacyclopentanes isomeriques provenant de deux autres molecules de TrFE. Sinon, la reaction du complexe 1 avec l'hexafluoropropene forme un complexe inattendu de [CF.sub.3]sperfluoroallylNi. [Traduit par la Redaction] Mots-cles : difluorocarbene-nickel, fluoroalcene, cycloaddition, activation de liaisons C--F., Introduction Reactions involving metal alkylidenes and carbenes are some of the most valuable and desired catalytic transformations. (1-4) Although the reactivity of metal carbenes has been thoroughly studied and established, [...]

The correlations between stimulated Brillouin scattering (SBS) characteristics of perfluoro-compound (PFC) and perfluoropolyether (PFPE) and their chemical structure are analyzed in detail and a series of new PFC and PFPE are reported. In the Nd:YAG laser system, the absorption coefficient, optical breakdown threshold (OBT), SBS threshold, and Brillouin frequency shift of new media such as FC-87, FC-43, HT-55, and DET are measured. Parameters such as gain coefficient, Brillouin linewidth, and phonon lifetime are calculated. The results demonstrate their good SBS properties: the absorption coefficients are below [10.sup.-3][cm.sup.-1] and OBTs are above 100 GW/[cm.sup.2]. These media also exhibit a series of unique physicochemical properties, i.e., high heat-resistance, high oxidation stability, good chemical inertness, and insulation properties. The discovery of new media not only diversifies SBS medium, but also improves the performance of the SBS system, thereby laying a good foundation for the application of a SBS phase conjugation mirror in a high-power laser system. OCIS codes: 190.0190, 290.5830, 190.2640.

Density functional calculations for the structure and magnetic parameters of the perfluorinated ethyl and n-propyl radicals are described. It is seen that fluorine substitution leads not only to nonplanarity at the radical center but to delocalization of spin density onto the [F.sup.alpha] atoms and to spin polarization effects that lead to anomalies.

The comparison results of the standard molar enthalpies of formation of fluoromethylaniline in gaseous state with the Cox scheme and the G3MP2/B3LYP calculations are presented.

The interactions between the aromatic portion of the fluorinated n-(4-sulfamylbenzoyl)benzylamine (SBB) inhibitors and two residues of Human Carbonic Anhydrase II (HCAII)- Phe-131 and Pro-202 are studied. The structure of proteins is determined by the interactions between aromatic rings.

A systematic density functional theory (DFT) calculations is performed on the stabilities and electronic properties of two different structures [Csub.58][X.sub.18] and [C.sub.58][X.sub.1], where X = H, F, and Cl. It is seen that the large energy gaps between the highest occupied molecular orbitals and the lowest unoccupied molecular orbital and the aromatic character possess high stabilities.

The investigation of the circular differential transmission in thick films of poly{9.9-bis[(3S)-3,7-dimethyloctyl}-2,7-fluorene} is presented. A specifically designed chiroptical setup is used to show that the circular selective reflection of light, in which the circular polarization of the light is retained after reflection, makes a negligible contribution to the differential transmission.

An analytical potential energy surface (PES-2006) was developed and quasi-classical trajectory (QCT) calculations were used to analyze the F + C[D.sub.4] gas-phase abstraction reaction. The state-specific scattering distributions at different collision energies were found to reproduce the experimental behavior with a clear propensity toward forward scattering.

Reaction free energetics and dynamics of unimolecular electron-transfer processes in ionic liquid 1-ethyl-3-methylimidazolium hexafluorophosphate are investigated using a model diatomic solute. It is found that the overall characteristics of electron transfer free energetics are similar between two solvents.

Vertical excitation energies of the C[F.sub.3]Cl molecule are determined from a response function approach with a coupled cluster (CC) reference function in order to examine the absolute photoabsorption oscillator strengths in the molecular-adapted quantum defect orbital formalism (MQDO). The results for the molecular Rydberg transitions have provided better f-values of the isolated Cl atom than the MQDO results.

A series of fluorinated analogues of the dye thiazole orange that exhibit improved fluorescence quantum yields and photostabilities is described. As per the findings, the computational studies on the dyes revealed that twisting about the monomethine bridge beyond an interplanar angle of 60 degree leads to a dark state that decays nonradiatively to the ground state accounting for the observed fluorogenic behavior.

Two novel series of polyfluorinated amino acids (PFAs) were conceptualized and synthesized as per a very short and scalable synthetic sequence. Results reveal that a short peptide that represents the amino acid sequence of a protein that is recognized by another protein could be tagged with one of the novel PFAs.

The synthesis of new cyclam derivatives with diametrically disubstituted pyrene fluorophores is described and their fluoroionophoric properties towards transition metal ions [Cu.sup.2} - and [Hg.sup.2} are studied. It is demonstrated that the diametrically disubstituted pyrene derivatives of cyclam exhibited a selective fluorescence quenching attitude towards [Cu.sup.2}- and [Hg.sup.2} ions in switching-off type responses in aqueous methanol or acetonitrile solution.

The systematic investigation of in-plane hydrogen-bonded complexes of ammonia with partially substituted fluorobenzenes has shown that fluorobenzene, difluorobenzene and trifluorobenzene have favored the formation of cyclic complexes with a C-H...N-H...F-C binding motif. The tendency with which fluorobenzenes adapt to the C-H...N-H...F-C binding motif has decreased with the progressive fluorination of the benzene ring and has disappeared completely when benzene ring is substituted with five or more fluorine atoms.

Ab initio quantum chemistry calculations of the decarbonylation kinetics of [C.sub.n][F.sub.2n+1]CO radicals are reported. The results have shown that [C.sub.n][F.sub.2n+1]CO radicals have a strong tendency to decompose in order to give [C.sub.n][F.sub.2n+1] and CO under atmospheric conditions.

The chemical activation techniques coupled with electronic structure calculations were used to investigate the unimolecular reactions of a series of chlorofluoropropane molecules. Fully halogenated fluorochloroethanes and propanes seem to have high threshold energies for ClF interchange, and other decomposition pathways are favored over ClF interchange.

The structure, spectra, and rearrangement mechanisms of P[H.sub.2][F.sub.3], the first member of the P[H.sub.n][F.sub.5-n] series and a prototype for molecules that undergo rotational isomerism, are analyzed. The results have identified the spectral fingerprints that could distinguish various rotational isomers that could form a powerful basis for the characterization of various rotational isomers of P[H.sub.2][F.sub.3] when used along with high resolution measurements.

Conformational equilibria in formic acid and, adduct of formic acid and hexafluoroacetone, HC[O.sub.2]C[(C[F.sub.3]).sub.2]OH were investigated. Formic acid showed separate signals for the E and Z conformations in solvents containing hydrogen and acceptor with peaks for E and Z conformations found at low temperatures for both formic acid and hexafluoroacetone.

The trimer of difluoromethane is characterized by supersonic jet Fourier transform microwave spectroscopy. The investigation of the three [super 13]C species in natural abundance has indicated that the three carbon atoms form a triangle and the three subunits are held together by nine CH...F weak hydrogen bonds.

Treatment of the hydrazone of 2H-perfluoro-2-methyl-3-pentanone with trietylamine at increased temperature has yielded a methylenecyclobutene via degradation to acetylene followed by dimerization. The finding suggests that the acidity and the conformational dynamics of the methylenecyclobutene are influenced by buttressing effects in this crowed molecule.

The properties of the low-sensitivity explosive trans-1,4,5,8-tetranitro-1,4,5,8-tetraazadecalin (TNAD)-based polymer-bonded explosives (PBXs) with four typical fluorine polymers are studied by using the molecular dynamics simulations. The results reveal that the addition of small amounts of fluorine polymers improves the mechanical properties of TNAD, whereas the detonation performances of the PBXs decrease.

The interaction of bis(pentafluorophenyl)mercury or trimeric perfluoro-o-phenylene mercury with selected arenes (naphthalene, biphenyl, and fluorene) was investigated. It was shown that cooperative effects are involved in the spin-orbit perturbation that perfluoro-o-phenylene mercury provides to arenes and bis(pentafluorophenyl)mecury readily assembles with arenes to form room-temperature phosphorescent supramolecules with short triplet lifetimes.

The preparation of two new niobium and zinconiobium fluorophosphates, NbOF[(P[O.sub.4]).sub.2][([C.sub.2][H.sub.10][N.sub.2]).sub.2] and [Zn.sub.3](NbOF)(P[O.sub.4]).sub.4][([C.sub.2][H.sub.10][N.sub.2]).sub.2] (2) was carried out under hydrothermal conditions using ethylenediamine as a template. The topolocal relationships between the 4-connected network of (2) and several reported (3,4)-connected networks were discussed.

A new layered fluoroaluminophosphate [([C.sub.4][H.sub.11]NOH).sub.3.5][[Al.sub.4][(P[O.sub.4]).sub.5]F].0.5[H.sub.3]O denoted as AlPO-CJ20 with an Al/P ratio of 4:5 was solvothermally synthesized by using 2-amino-2-methyl-1-propanol as the template in the presence of [F.sup.-] ions. The alternation of Al-centered tetrahedra (Al[O.sub.4] and Al[O.sub.3]F) and P[O.sub.3](=O) tetrahedra gives rise to a new type of 4.6 16-net sheet.

The structures, electron ionization and excitation energies and electron density distribution of symmetrical five-membered heterocycle derivatives of carbazole and fluorene are analyzed. The results have shown that the properties of consecutive oligomers have indicated their fast convergence to values characterizing polymers.

The syntheses, structural and spectroscopic characterization, fluoride abstraction reactions, and photochemical reactivity of cationic uranyl(VI) phosphine oxide complexes are described. The results illustrate an equal degree of lability associated with uranium(IV) oxidation as is found with uranyl(VI) reduction, presumably as both proceed through the same reactive uranyl(V) intermediate.

A critical and comprehensive overview on the synthetic potential of hexafluoroacetone (HFA) as bidentate reagent for the synthesis of new monomers for peptide, depsipeptide, and glycopeptide modification, which would be helpful to enlarge the synthetic repertoire, is presented. Application of HFA as a bidentate protecting and activating reagent to compounds such as Asp, malic, citramalic and thiomalic acids and homologues as well as iminodiacetic acid permits efficient site-selective mono-, di-, and trifunctionalization, saving steps compared to conventional methodologies.

Techniques of fluorous mixture synthesis are used to make four candidate stereoisomers for the natural product lagunapyrone B. Stille coupling of the resulting pure quasienantiomers with the quasiracemic mixture has provided two quasi-diastereomeric samples that are demixed and detagged to provide all four lagunapyrone B stereoisomers, which are assigned the 6R,7S,19S,20S,21R configuration by comparison of optical rotations.

The X-ray analyses shows that the difluorcarbene complex [[Fe.sub.2][(CO).sub.8](mu-C[F.sub.2])] reacts with As[Me.sub.3] under CO substitution to give the [mu]-C[F.sub.2] containing complexes [[Fe.sub.2][(CO).sub.6][(AsMe3).sub.2](mu-C[F.sub.2)] and [[Fe.sub.2][(CO).sub.5][(AsMe3).sub.3](mu-C[F.sub.2])] which have an [[Fe.sub.2][(CO).sub.9].sup.-] like structure. The AIM analysis of the complexes indicates that there is no direct [sigma]-bonding interaction between the two iron atoms inside the dinuclear complexes which support the leading rule of the CO and C[F.sub.2] bridges in keeping the dinuclear integrity found from MO analysis in similar compounds.

The interactions of nitrous oxide with fluorinated liquids was investigated by reporting original experimental results on gas solubility and interpreting them using molecular simulation. Nitrous oxide was found to be highly soluble in the three fluorinated liquids studied, with mole fraction solubilities on the order of 0.03 under ambient conditions.

Four osmium(VII) fluorine compounds, OsO3[F.sup.9], OsO2F3, OsOF5 and OsF7 are reinspected to see whether they exist and whether they are true Os(VII) compounds. It was found that of the four osmium fluorine compounds in the oxidation state &, only one (OsOF5) are a real Os(VII) compound.

Rare-earth-doped fluorochlorozirconate (FCZ) glass-ceramic materials are developed as scintillators and their properties are investigated as a function of dopant level. The inorganic scintillators such as single crystals or polycrystalline films have limitations in resolution or size, but the transparent glass-ceramic can be scaled to any shape or size with excellent resolution.

The degradation of polyfluorenes (PFs) and fluorene oligomers with alkyl and aromatic substitutions under ultraviolet (UV)-light irradiation is studied. The experiments have concluded that the degradation of fluorene is a radical chain process propagated by alkyl side chains and the different stability between alkyl and aromatic substitution can be well described.

Experimental vibrational spectroscopy in conjunction with DFT quantum chemical calculations is applied to characterize two fluorofullerenes, C60F48 and C60F36. The study reveals that vibrational spectroscopy, supplemented with reliable theoretical modeling could provide a powerful structural tool to meet the challenges of the structure determination for fullerene derivatives when other method, such as X-ray or NMR are unable to provide unambiguous solutions to the problem.

Helix induction in melitting and beta-lactoglobulin A is enhanced by fluorinated diols with the order to efficiency 2,2,3,3-tetrafluoro-1,4-butanediol (TFBD) < 2,2,3,3,4,4-hexafluoro-1,6-pentanediol (HFPD) < 2,2,3,3,4,4,5,5,-octafluoro-1,6-hexanediol (OFHD). The negligible red-edge excitation shift in the fluorescence of melittin has shown that the fluorinated diol/water solvent shell surrounding the tryptophan chromophore is less immobilized than is molecules in a lamellar vesicle.

A fluorescence-based chemical sensor for fluorene was created by molecularly imprinting a sol-gel comprising the bridged silsesquioxane, bis(trimethoxysilylethyi)benzene. The template was covalently bound to the sol--gel matrix using a fluorene analogue functionalized silane. After chemical removal of template via cleavage of a carbamate linkage, an amine group was left that provided an attachment site for the environmentally sensitive fuorescent probe 7-nitrobenz-2-oxa-1,3-diazole (NBD). Fluorene binding was detected by a change in NBD fluorescence intensity induced by a difference in the local polarity around the probe when the recognition site is filled. Such an approach eliminated response to nonspecific binding to the matrix. Sensing films deposited on glass slides were shown to have response times of

An investigation is conducted of the heterogenous uptake of 8-2 fluorotelomer alcohol (FTOH) on liquid water surfaces and on 1-octanol surfaces with a droplet of train flow reactor. The larger uptake coefficient measured for 1-octanol surfaces indicates that FTOH partitioning to organic-containing cloud/fog droplets and aerosol particles may be an atmospheric loss mechanism.

The double bond of 2,3-dimethyl-2-butene (DMB) was very receptive to addition and even at -15degrees C instead of being inhibited to addition of Th+ by its four attached methyl groups. The reaction of Th+ with DMB was followed with cyclic voltammetry and was found to exhibit redox catalysis in which Th was generated.

Syntheses of fluorinated mucin core 2 tri- and tetrasaccharides modified at the C-3 or C-4 position of the pertinent galactose residue is discussed. The results revealed that the activities of only Gal 3-O-sulfotransferases and not sialyltransferases were adversely affected by a C-3 fluoro substituting at the other Gal terminal of mucin core 2.

Fluorescence excitation, multiphoton ionization and dispersed fluorescence spectra of bare and hydrogen-bonded 2-fluoropyridine with water are calculated in a supersonic free jet. The appearance of low frequency vibronic bands, which are seen for bare 2-fluoropyridine, is attributed to the existence of closely lying (n,pi(super star)) state.

A study was conducted about triplet-state formation and intersystem crossing in an A-alt-B series of fluorene copolymers using flash photolysis and pulse radiolysis-energy transfer. Fluorene-thiophene copolymers PFaT and PF3T, the triplet energies are closer to those of thiophene oligomers, indicating that there is significant conjugation between fluorene and thiophene units but also that there is a more localized triplet state than with the homopolymers.

The structure of bis(trifluoromethanesulfonyl) imide(TFSI(super minus)) in the liquid state was studied by means of Raman spectroscopy and DFL Calculations. The results concluded that a conformational equilibrium was established between the C(sub 1) and C(sub 2) conformers of TFSI(super minus) in the liquid EMI(super plus)TFSI(super -) and the C2 conformer is more favorable than the C1 one.

A significantly improved procedure that provides efficient access to a highly congested 1,8-diacridylnaphthalene fluorosensor is reported. Screening of palladium-catalyzed Negishi, Kumada, Suzuki, Hiyama, and Stille coupling methods showed that the latter affords highly congested 1,8-diarylnapthalenes in superior yields.

A convenient route for the total synthesis of a number of hydrofluorene natural products and their analogues is developed. The protocol is followed to realize the total synthesis of (plusmn)-dichroanal B, (plusmn)-dichroanone, (plusmn)-taiwaniaqunol B and (plismn)-taiwaniaquinones D and H.

An investigation is conducted of the relative importance of hydrogen bonding versus pie stacking interactions in DNA where the hydrogen-bonded complexes of the nucleobase mimic 2-pyridone (2PY) with seven different fluorinated benzenes. Ab initio studies are performed on the individual hydrogen bonds occurring between nucleobases and fluronated isomers.

A study conducted on modified DNA oligomers and polymerase reactions have demonstrated that canonical nucleobases can exhibit stable and even selective pairing with shape-complementary fluorobenzene nucleotides. Hydrogen bonds are believed to be absent because of the fluorination of the pairing edges and the local DNA stability is attributed pie-stacking and shape complementarity.