Efficient copper-catalyzed S-vinylation of thiols with vinyl halides

The synthesis of vinyl sulfides through the coupling reaction of thiols with vinyl iodides, bromides, and chlorides is described. The thiols can couple with aryl iodides in the presence of only 0.5 mol % Cu(2)O without the need for an ancillary ligand. In the presence of 5 mol % of Cu(2)O and 10 mol % 1,10-phenanthroline as the ligand, the more challenging alkyl vinyl bromides can also be coupled with thiols, giving the vinyl sulfides in good to excellent yields.     

Direct Spectroscopic Evidence of the Influence of Chamber Wall Condition on Oxide Etch Rate

The drift of TEOS etch rate has been observed during MERIE oxide etch for the damascene process. The etch rate typically fluctuates between 5300 Å/min and 6000 Å/min. Studies using fluorocarbon-based chemistry show a normal TEOS etch rate when the chamber wall is heavily coated with polymer deposition. On the other hand, a lower etch rate appears when the chamber has less deposition. Hysteresis behavior has been observed during the etch rate of TEOS, as well as emission intensity trends of F, CF _x (x=1~3), and SiF. From the observed emission intensity variation of F, CF _x , and SiF, a model is proposed to explain the impact of chamber wall polymer deposition on the etch rate of TEOS. This model includes a mechanism of etch rate enhancement by embedding oxygen in the chamber wall polymer. From the correlation between etch rate and emission intensity, it clearly shows that F is directly responsible for the etch of TEOS. Compared to F, CF _x plasma chemistry has a closer link to chamber wall polymer formation, but contributes less in the etch of TEOS.     

Bidirectional iterative synthesis of alternating benzene-furan oligomers towards molecular wires

Reaction of propargylic dithioacetal 2a with BuLi gives the sulfur-substituted allenyllithium 3a which is allowed to react with a dialdehyde to yield the corresponding alternating benzene-furan oligoaryls 6. Functional group transformation converts the ester groups in 6 to dialdehyde 8 which can be used for the synthesis of higher homologues towards molecular wires. A combination of this furan annulation, Heck reaction and Sonogashira coupling leads to a variety of benzene-furan-alkene/alkyne conjugated oligomers of precise length.     

Nickel-catalyzed decarboxylative coupling of an alkynyl carboxylic acid with aryl iodides

A decarboxylative coupling reaction with an alkynyl carboxylic acid and aryl iodides in the presence of a nickel catalyst was developed. When the reaction was conducted with NiCl₂ (10 mol%), Xantphos (15 mol%), Mn (1.0 equiv), and Cs₂CO₃ (1.5 equiv), the desired diaryl alkynes were formed in moderated to good yields. Furthermore, this method does not produce the diyne, which is formed in the homocoupling of alkynyl carboxylic acids.     

Synthesis of alkenyl sulfides through the iron-catalyzed cross-coupling reaction of vinyl halides with thiols

We report here the iron-catalyzed cross-coupling reaction of alkyl vinyl halides with thiols. While many works are devoted to the coupling of thiols with alkyl vinyl iodides, interestingly, the known S-vinylation of vinyl bromides and chlorides is limited to 1-(2-bromovinyl)benzene and 1-(2-chlorovinyl)benzene. Investigation on the coupling reaction of challenging alkyl vinyl bromides and chlorides with thiols is rare. Since the coupling of 1-(2-bromovinyl)benzene and 1-(2-chlorovinyl)benzene with thiols can be performed in the absence of any catalyst, here we focus on the coupling of thiols with alkyl vinyl halides. This system is generally reactive for alkyl vinyl iodides and bromides to provide the products in good yields. 1-(Chloromethylidene)-4-tert-butyl-cyclohexane was also coupled with thiols, giving the targets in moderate yields.     

Highly regioselective synthesis of aryl chalcogenides through C-H functionalization of arenes

We report here the regioselective synthesis of aryl chalcogenides through the iridium-catalyzed meta C-H borylation followed by copper-catalyzed C-S coupling reaction with chalcogenide sources in one pot, giving the 3,5-disubstituted aryl chalcogenides with high regioselectivity and good yields.     

Non-amine-based furan-containing oligoaryls as efficient hole transporting materials

A new class of highly stable furan-based hole transporting oligomeric materials, synthesized from the corresponding propargylic dithioacetals, serve as efficient hole transporting materials in electroluminescent devices. The performance of the devices using these furan materials is comparable with or somewhat better than those employing the conventional triarylamines (e.g. alpha-NPD).     

Monolayer structures of highly photoluminescent furan oligoaryls: an approach to improve packing crystallinity of dithiolated aromatics

We demonstrated that mono- and dithiolated furan-containing oligoaryls (II-IV, see Chart 2) can be successfully synthesized via a one-pot strategy starting from propargylic dithioacetals. IRAS (infrared reflection-absorption spectroscopy) and STM (scanning tunneling microscopy) experiments revealed that single-component monolayers of II, III, and IV are essentially disordered, an important property that prevents excited photoluminescent molecules from self-quenching in the organic layers of an OLED device. Surprisingly, localized lattice packing of crystalline dithiolated furan oligoaryls on Au(111) can be assembled by immersing preadsorbed n-dodecanethiol SAMs in the corresponding deposition solutions. The discrepancy in the formation of disordered or localized crystalline structures is discussed. For single-component monolayers, the facile formation of S-Au bonds generates chaotically distributed monolayers in which the arched molecules hinge each other and block the desorptive pathways. The absence of crystalline packing is mainly attributed to the difficulty for the dithiols to simultaneously break two S-Au bonds, to desorb, and then to readsorb, the key step to improve the intermolecular attractions for crystalline SAMs. By preassembling n-dodecanethiol SAMs, the space for dithiolated compounds III and IV to adsorb is limited to domain boundaries or packing defects where crystalline packing of III and IV can grow.     

Synthesis, structure, and dynamic properties of hybrid organic-inorganic rotaxanes

The synthesis and characterization of a series of hybrid organic-inorganic [2]rotaxanes is described. The ring components are heterometallic octa- ([Cr(7)MF(8)(O(2)C(t)Bu)(16)]; M = Co, Ni, Fe, Mn, Cu, Zn, and Cd) nuclear cages in which the metal centers are bridged by fluoride and pivalate ((t)BuCO(2)(-)) anions; the thread components feature dialkylammonium units that template the formation of the heterometallic rings about the axle to form the interlocked structures in up to 92% yield in conventional macrocyclization or one-pot 'stoppering-plus-macrocyclization' strategies. The presence in the reaction mixture of additives (secondary or tertiary amines or quaternary ammonium salts), and the nature of the stoppering groups (3,5-(t)Bu(2)C(6)H(3)CO(2)- or (t)BuCONH-), can have a significant effect on the rotaxane yield. The X-ray crystal structures of 11 different [2]rotaxanes, a pseudorotaxane, and a two-station molecular shuttle show two distinct types of intercomponent hydrogen bond motifs between the ammonium groups of the organic thread and the fluoride groups of the inorganic ring. The different hydrogen bonding motifs account for the very different rates of dynamics observed for the heterometallic ring on the thread (shuttling slow; rotation fast).     

FTIR Analysis of Plasma Damage of Kapton

Recently, Kapton (polyimide) has been used in the reduction of dust particles in plasma etching chambers. However, it is found that there is a limit of lifetime for Kapton in trapping particles. Beyond this time limit, particle contamination becomes serious and even causes defect on wafers. In this study, two plasma etching recipes were used to test the particle/polymer trapping efficiency of Kapton. A Fourier Transform Infrared (FTIR) spectrometer was used to examine the functional groups change of the Kapton surface after plasma etching. The increase of IR absorption of CF_x (x = 2, 3) indicates the growth of fluorocarbon polymer on the Kapton surface. The Kapton surface was damaged as indicated by the change of C=O, -NH₂, and C - H IR intensities. IR Spectroscopic data show that Kapton has a very good particle/polymer reduction efficiency when using high-polymer recipe but not very efficient with oxygen-rich recipe. It has drawn our attention that when testing metal contamination of the processed wafers using chambers with Kapton coating, the concentration of aluminum was always high as compared to those without using Kapton. It can be ascribed to the plasma damage of Kapton, as supported by the surface chemical analysis with energy dispersion spectroscopy (EDS). Data collected from FTIR and EDS are correlated to interpret the mechanisms of plasma damage of Kapton.