Effect of the implantation of fluorine on the mobility of channel electron for partially depleted SOI nMOSFET

The mobility of channel electron, for partially depleted Sol nMOSFET in this paper, decreases with the increase of implanted fluorine dose in buried oxide layer. But, the experimental results also show that it is larger for the transistor corresponding to the lowest implantation dose than no implanted fluorine in buried layer. It is explained in tern-is of a "lubricant" model. Mien fluorine atoms are implanted in the top silicon layer, the mobility is the largest. In addition, a positive shift of threshold voltage has also been observed for the transistors fabricated on the Sol wafers processed by the implantation of fluorine. The causes of all the above results are discussed.

Ultracold fluorine production via Doppler cooled BeF

Large parts of the periodic table cannot be cooled by current laser-based methods. We investigate whether zero energy fragmentation of laser cooled fluorides is a potential source of ultracold fluorine atoms. We report new ab initio calculations on the lowest electronic states of the BeF diatomic molecule including spin-orbit coupling, the calculated minima for the valence electronic states being within 1 pm of the spectroscopic values. A four colour cooling scheme based on the A2? ? X2S+ transition is shown to be feasible for this molecule. Multi-Reference Configuration Interaction (MRCI) potentials of the lowest energy Rydberg states are reported for the first time and found to be in good agreement with experimental data. A series of multi-pulse excitation schemes from a single rovibrational level of the cooled molecule are proposed to produce cold fluorine atoms.

Synthesis and characterisation of novel nitrogen and fluorine containing spirobifluorene derivatives for electronic applications and crystal engineering

Among organic materials, spirobifluorene derivatives represent a very attractive class of materials for electronic devices. These compounds have high melting points, glass transitions temperatures and morphological stability, which makes these materials suitable for organic electronic applications. In addition, some of spirobifluorenes can form porous supramolecular associations with significant volumes available for the inclusion of guests. These molecular associations based on the spirobifluorenes are noteworthy because they are purely molecular analogues of zeolites and other microporous solids, with potential applications in separation, catalysis, sensing and other areas.

N-H center dot center dot center dot F hydrogen bonds in fluorinated benzanilides: NMR and DFT study

Using F-19 and H-1-NMR (with N-14 decoupling) spectroscopic techniques together with density functional theoretical (DFT) calculations, we have investigated weak molecular interactions in isomeric fluorinated benzanilides. Simultaneous presence of through space nuclear spin-spin couplings ((1h)J(N-H center dot center dot center dot F)) of diverse strengths and feeble structural fluctuations are detected as a function of site specific substitution of fluorine atoms within the basic identical molecular framework. The transfer of hydrogen bonding interaction energies through space is established by perturbing their strengths and monitoring the effect on NMR parameters. Multiple quantum (MQ) excitation, up to the highest possible MQ orders of coupled protons, is utilized as a tool for accurate H-1 assignments. Results of NMR studies and DFT calculations are compared with the relevant structural parameters taken from single crystal X-ray diffraction studies.

Substitution-Modulated Anticancer Activity of Half-Sandwich Ruthenium(II) Complexes with Heterocyclic Ancillary Ligands

Ten new organometallic half-sandwich ruthenium complexes with heterocyclic ligands have been synthesized (H1-H10). The substituents on the ancillary heterocyclic ligands were varied to understand the effect of substitution on anticancer activity. The crystallographic characterization of five complexes confirms that they adopt three-legged piano-stool structures and are stabilized by intramolecular hydrogen bonding. Complexes H2 and H3 also exhibit halogen bonding in the solid state. In aqueous media, the complexes form dinuclear ruthenium species. Complex H1 with a noncytotoxic heterocycle, 6-fluoro-2-mercaptobenzothiazole, and complex H11 with the unsubstituted 2-mercaptobenzothiazole are the most active against A2780 and KB cell lines. The substitution of the H atoms on the ancillary ligand with Cl or Br atoms leads to a decrease in the anticancer activity. With the exception of fluorine-substituted H5, the complexes with mercaptobenzoxazole (H6-H9) are inactive against all of the tested cell lines. Ruthenium complexes with mercaptonaphthimidazole (H10) and mercaptobenzimidazole (H13) do not show any anticancer activity. The active complexes show a biphasic melting curve when incubated with calf thymus (CT) DNA. These complexes only inhibit thioredoxin reductase (TrxR) enzyme activity to a small extent. The substitution of hydrogen atoms with fluorine atoms in the aromatic heterocyclic ligands on organometallic half-sandwich ruthenium complexes has the most beneficial effect on their anticancer activity.

Applications of nuclear magnetic resonance spectroscopy to the study of medium-sized rings. I. Conformational properties of cycloheptane. II. Conformational properties of cycloöctane

Conformational equilibrium in medium-sized rings has been investigated by the temperature variation of the fluorine-19 n.m.r. spectra of 1, 1-difluorocycloalkanes and various substituted derivatives of them. Inversion has been found to be fast on the n.m.r. time scale at -180˚ for 1, 1-difluorocycloheptane, but slow for 1, 1-difluoro-4, 4-dimethylcycloheptane at -150˚. At low temperature, the latter compound affords a single AB pattern with a chemical-shift difference of 841 cps. which has been interpreted in terms of the twist-chair conformation with the methyl groups on the axis position and the fluorine atoms in the 4-position. At room temperature, the n.m.r. spectrum of 1, 1-difluoro-4-t-butylcycloheptane affords an AB pattern with a chemical-shift difference of 185 cps. The presence of distinct trans and gauche couplings from the adjacent hydrogens has been interpreted to suggest the existence of a single predominant form, the twist chair with the fluorine atoms on the axis position.

Investigation of 1, 1-difluorocycloöctane and 1, 1, 4, 4-tetrafluorocycloöctane has led to the detection of two kinetic processes both having activation energies of 8-10 kcal./mole but quite different A values. In light of these results eleven different conformations of cycloöctane along with a detailed description of the ways in which they may be interconverted are discussed. An interpretation involving the twist-boat conformation rapidly equilibrating through the saddle and the parallel-boat forms at room temperature is compatible with the results.

Increasing the flexoelastic ratio of liquid crystals using highly fluorinated ester-linked bimesogens.

We present experimental results on the bulk flexoelectric coefficients e and effective elastic coefficients K of non-symmetric bimesogenic liquid crystals when the number of terminal and lateral fluoro substituents is increased. These coefficients are of importance because the flexoelastic ratio e/K governs the magnitude of flexoelectro-optic switching in chiral nematic liquid crystals. The study is carried out for two different types of linkage in the flexible spacer chain that connects the separate mesogenic units: these are either an ether or an ester unit. It is found that increasing the number of fluorine atoms on the mesogenic units typically leads to a small increase in e and a decrease in K, resulting in an enhancement of e/K. The most dramatic increase in e/K, however, is observed when the linking group is changed from ether to ester units, which can largely be attributed to an increase in e. Increasing the number of fluorine atoms does, however, increase the viscoelastic ratio and therefore leads to a concomitant increase in the response time. This is observed for both types of linkage, although the ester-linked compounds exhibit smaller viscoelastic ratios compared with their ether-linked counterparts. Highly fluorinated ester-linked compounds are also found to exhibit lower transition temperatures and dielectric anisotropies. As a result, these compounds are promising materials for use in electro-optic devices.

多氟稀土（Sm、Tb）有机配合物的合成及发光性质的研究

本文合成了几种多氟β-二酮配合物，并将其引入无机／有机杂化基质及中孔分子筛材料中，从而制备了发光性能良好的杂化材料。选用新型的多氟β-二酮作为有机配体，合成了几种衫、试配合物，通过IR、1H NMR等手段证实了配合物的生成，并研究了其发光性质。首次得到了以4,4,5,5,6,6,6-七氟-1-2-噻吩基）-1-已二酮（HTH）为配体的衫的配合物单晶（Sm（HT）3Phen），解析了其结构，结果表明其配位多面体为三角十二面体。将多氟三元配合物Tb（Tfacac）3phen通过溶胶一凝胶过程掺杂到γ-缩水甘油丙基醚三甲氧基硅烷（GPTMS）改性的有机／无机杂化基质中，制备了有机／无机杂化发光块状材料一及其薄膜材料；研究了稀土配合物在未改性基质和改性基质中的发光性质，以及不同基质对发光性能的影响，结果发现该杂化材料最大激发峰位相对于纯配合物发生了蓝移，且激发谱带变窄；考察了两种基质中配合物掺杂浓度对杂化材料的发光强度的影响，结果表明。稀土配合物在改性基质中比在未改性基质中掺杂浓度提高了。比较了粉末材料与相应薄膜的发光性能，发现薄膜材料巴的发光强度和荧光寿命有所降低，表明材料的不同状态对其发光性能有一定的影响。制备了中孔分子筛MCM-41及GPTMS、TMSPMC改性的有机／无机杂化中孔材料。回时成功地将稀土配合物Sm（HTH）3Phen、Tb（Tfacac）3Phen组装到MCM-41及两种改性的MCM-41中，合成了担载新型稀土有机配合物的无机-有机杂化中孔发光材料。通过对稀土配合物及其在分子筛中的荧光光谱分析，发现激发光谱发生了蓝移；而且不同的改性剂对不同的稀土配合物的影响不同。并制得了发光色纯度较高的稀土-TMSPMC-MCM-41复合发光体。

XPS STUDIES ON RADIATION-INDUCED STRUCTURAL-CHANGES IN THE COPOLYMER OF TETRAFLUOROETHYLENE AND ETHYLENE

In this work, the radiation-induced structural changes in the copolymer of tetrafluoroethylene and ethylene (F-40) were studied by X-ray photoelectron spectroscopy (XPS). During irradiation, some CF2 groups in the polymer were found to have been converted into carbon structures that bonded indirectly with fluorine atoms.

Effect of SO(2) on the Transport Properties of an Imidazolium Ionic Liquid and Its Lithium Solution

Transport coefficients have been measured as a function of the concentration of sulfur dioxide, SO(2), dissolved in 1-butyl-2,3-dimethylimidazolium bis(trifluoromethylsulfonyl)-imide, [BMMI][Tf(2)N], as well as in its lithium salt solution, Li[Tf(2)N]. The SO(2) reduces viscosity and density and increases conductivity and diffusion coefficients in both the neat [BMMI] [Tf(2)N] and the [BMMI][Tf(2)N]-Li[Tf(2)N] solution. The conductivity enhancement is not assigned to a simple viscosity effect; the weakening of ionic interactions upon SO(2) addition also plays a role. Microscopic details of the SO(2) effect were unraveled using Raman spectroscopy and molecular dynamics (MD) simulations. The Raman spectra suggest that the Li(+)-[Tf(2)N] interaction is barely affected by SO(2), and the SO(2)-[Tf(2)N] interaction is weaker than previously observed in an investigation of an ionic liquid containing the bromide anion. Transport coefficients calculated by MD simulations show the same trend as the experimental data with respect to SO(2) content. The MD simulations provide structural information on SO(2) molecules around [Tf(2)N], in particular the interaction of the sulfur atom of SO(2) with oxygen and fluorine atoms of the anion. The SO(2)-[BMMI] interaction is also important because the [BMMI] cations with above-average mobility have a larger number of nearest-neighbor SO(2) molecules.

Molecular dynamics simulation on devitrification: Isothermal devitrification and thermodynamics of PbF2 glasses

The vitrification and devitrification features of lead fluoride are investigated by means of molecular dynamic simulations. The influence of heating rate on the devitrification temperature as well as the dependence of the glass properties on its thermal history, i.e., the cooling rate employed, is identified. As expected, different glasses are obtained when the cooling rates differ. Diffusion coefficient analysis during heating of glass and crystal, indicates that the presence of defects on the glassy matrix favors the transition processes from the ionic to a superionic state, with high mobility of fluorine atoms, responsible for the high anionic conduction of lead fluoride. Nonisothermal and isothermal devitrification processes are simulated in glasses obtained at different cooling rates and structural organizations occurring during the heat treatments are clearly observed. When a fast cooling rate is employed during the glass formation, the devitrification of a single crystal (limited by the cell dimensions) is observed, while the glass obtained with slower cooling rate, allowing relaxations and organization of various regions on the glass bulk during the cooling process, devitrifies in more than one crystalline plane. (C) 2004 American Institute of Physics.

Graphene to fluorographene and fluorographane: A theoretical study

We report here a fully reactive molecular dynamics study on the structural and dynamical aspects of the fluorination of graphene membranes (fluorographene). Our results show that fluorination tends to produce defective areas on the graphene membranes with significant distortions of carbon-carbon bonds. Depending on the amount of incorporated fluorine atoms, large membrane holes were observed due to carbon atom losses. These results may explain the broad distribution of the structural lattice parameter values experimentally observed. We have also investigated the effects of mixing hydrogen and fluorine atoms on the graphene functionalization. Our results show that, when in small amounts, the presence of hydrogen atoms produces a significant decrease in the rate of fluorine incorporation onto the membrane. On the other hand, when fluorine is the minority element, it produces a significant catalytic effect on the rate of hydrogen incorporation. We have also observed the spontaneous formation of new hybrid structures with different stable configurations (chair-like, zigzag-like and boat-like) which we named fluorographane. © 2013 IOP Publishing Ltd.

Vidros e vitrocerâmicas em sistemas oxifluoretos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sistemi adesivi con applicazioni in campo biomedicale

Polymeric adhesives have been used for many applications like suture and embolization, instead of classic surgical methods or as for dental uses. In this work both subjects have been investigated and the results separated in two parts. In the first, new dentinal adhesives with different polymerizable groups (methacrylic or vinyl-ethereal) were synthesized. A low sensitivity to hydrolysis and equal or enhanced properties, compared to existing commercial products, were considered essentials. Moreover, these monomers need to polymerize by radical photopolymerization and functional groups of different characteristics were tested. All these products were characterized by microtensile bond strength test to determine the bonding strength between the adhesive and tooth. Concerning embolization, cyanoacrylates are nowadays the most-used adhesives in surgery. Thus, they must respond to several requirements. For instance, polymerization time and adhesive strength need to be low, to avoid diffusion of the products in the body and adhesion to the catheter. In order to overcome these problems we developed new cyanoacrylates, which practically instantly polymerize upon contact with blood but do not demonstrate strong adhesion to the catheter, thank to the presence of fluorine atoms, linked to the ester chain. The synthesis of these products was carried out in several steps, such as the depolymerization of the corresponding oligomers at high temperature in acid conditions. Two types of adhesion strengths were determined. Bonding strength between human veins and a microcatheter was determined in vitro by using organic materials as the most realistic model. Another test, on two layers of skin, was conducted to verify the possible use of these new cyanoacrylates as a glue for sutures. As a conclusion, we were able to demonstrate that some of the prepared monomers posses adhesive strength and polymerization time lower than the commercial product Glubran2.

Synthese von selbstaggregierenden Glycopeptidkonjugaten mit (per)fluorierten Membranankern

Für eine effektive Erkennung tumorassoziierter Kohlenhydratantigene durch das Immun-system in der Krebs¬immuntherapie ist eine multivalente Präsentation der Haptene notwendig. In der vorliegenden Arbeit wurde ein neuer Zugang zu einer solch räumlichen Konzentration der Haptene untersucht, indem MUC1-Antigene mit perfluorierten Alkylketten funktionalisiert und in einer geeigneten Lipidmatrix entmischt wurden. Perfluoralkyl-Amphiphile zeichnen sich durch eine hohe Entmischungstendenz in Alkyllipiden aus und bewirken dadurch eine Anreicherung der Erkennungsstrukturen (Haptene) in Analogie zu den natürlichen raft-Domänen auf der Zelloberfläche.rnDazu wurden zunächst verschiedene Membranankersysteme mit unterschiedlichem Fluorierungsgrad entwickelt. Beispielsweise konnte ausgehend von einem zentralen Glycerin-fragment ein Membrananker mit zwei Perfluoralkylketten hergestellt werden. Letztere wurden mittels radikalischer Perfluoralkylierung eingeführt, wobei der Fluorgehalt der Verbindung über die Kettenlänge gesteuert wurde. Daneben konnte ein weiteres Ankersystem, basierend auf der Aminosäure Lysin, synthetisiert werden, dass einen bequemen Einbau der Perfluoralkylketten durch Peptidkupplungen von entsprechenden perfluorierten Aminen bzw. perfluorierten Carbonsäuren erlaubte. In diesem Fall wurde der Fluorgehalt durch die Einführung von Alkyl- bzw. Perfluoralkylketten verändert.rnBeide Systeme konnten für erste Untersuchungen ihres Phasenverhaltens mit polaren Kopf-gruppen ausgestattet werden, wobei neben einem hydrophilen, nicht-immunogenen Triethylenglycolspacer vor allem ein TN-Antigen tragendes Dipeptid zum Einsatz kam. In Gegenwart des Matrixlipids DODAMA konnten in Langmuir-Blodgett-Untersuchungen mit diesen Verbindungen eine Entmischung und die Ausbildung mikroseparierter Bereiche nachgewiesen werden. Auch war es möglich, durch Anbindung eines Fluoreszenzfarbstoffes zu zeigen, dass solche amphiphilen Membrananker auf perfluorierten Oberflächen effektiv und dauerhaft immobilisiert werden können. Damit eröffnet diese Verbindungsklasse interessante Anwendungsmöglichkeiten in der Entwicklung von diagnostischen Microarray-Formaten.rnUm eine Anbindung der fluorierten Membrananker an den N-Terminus eines an fester Phase aufgebauten mucinanalogen Glycopeptids als antigene Einheit zu ermöglichen, wurde ein entsprechendes Ankersystem auf Basis von Glutaminsäure entwickelt. Dabei wurden an diese Verbindung neben dem TN-Antigen noch weitere komplexe tumorassoziierte Kohlenhydrat-antigene des Mucintyps angebunden, wobei der Aufbau der resultierenden amphiphilen Glycolipopeptide vollständig an der festen Phase gelang. Insgesamt konnten so mithilfe des teilfluorierten Lysinankers und des zweifach perfluorierten Glutaminsäureankers erste amphiphile Glycopeptid-Konjugate hergestellt werden, deren antigene Kopfgruppe aus einer 20 Aminosäuren umfassenden Wiederholungseinheit des Mucins MUC1 mit TN-, T- bzw. STN-Antigen-Seitenkette besteht. Derartige Verbindungen stellen reizvolle Bausteine für die Tumordiagnostik und für die Entwicklung von stabilen liposomalen Tumorvakzinen dar, da die verwendeten Perfluoralkylanker die Antigenpräsentation nicht wesentlich beeinflussen und die Bindung des Antikörpers nicht behindern. rn