The fascinating story of olefin (or alkene) metathesis (eq
1) began almost five decades ago, when Anderson and
Merckling reported the first carbon-carbon double-bond
rearrangement reaction in the titanium-catalyzed polymerization of norbornene. Nine years later, Banks and Bailey reported “a new disproportionation reaction . . . in which olefins are converted to homologues of shorter and longer carbon chains...”. In 1967, Calderon and co-workers named this metal-catalyzed redistribution of carbon-carbon double bonds olefin metathesis, from the Greek word “μeτάθeση”, which means change of position. These contributions have since served as the foundation for an amazing research field, and olefin metathesis currently represents a powerful transformation in chemical synthesis, attracting a vast amount of interest both in industry and academia.

https://core.ac.uk/download/pdf/4884240.pdf

Ruthenium-based heterocyclic carbene-coordinated olefin metathesis catalysts.

: The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Large-scale applications of transition metal-catalyzed couplings for the synthesis of pharmaceuticals.

In recent years, olefin cross metathesis (CM) has emerged as a powerful and convenient synthetic technique in organic chemistry; however, as a general synthetic method, CM has been limited by the lack of predictability in product selectivity and stereoselectivity. Investigations into olefin cross metathesis with several classes of olefins, including substituted and functionalized styrenes, secondary allylic alcohols, tertiary allylic alcohols, and olefins with α-quaternary centers, have led to a general model useful for the prediction of product selectivity and stereoselectivity in cross metathesis. As a general ranking of olefin reactivity in CM, olefins can be categorized by their relative abilities to undergo homodimerization via cross metathesis and the susceptibility of their homodimers toward secondary metathesis reactions. When an olefin of high reactivity is reacted with an olefin of lower reactivity (sterically bulky, electron-deficient, etc.), selective cross metathesis can be achieved using fee...

A General Model for Selectivity in Olefin Cross Metathesis

A mean-field phase diagram for conformationally symmetric diblock melts using the standard Gaussian polymer model is presented. Our calculation, which traverses the weak- to strong-segregation regimes, is free of traditional approximations. Regions of stability are determined for disordered (DIS) melts and for ordered structures including lamellae (L), hexagonally packed cylinders (H), body-centered cubic spheres (QIm3m), close-packed spheres (CPS), and the bicontinuous cubic network with Ia3d symmetry (QIa3d). The CPS phase exists in narrow regions along the order−disorder transition for χN ≥ 17.67. Results suggest that the QIa3d phase is not stable above χN ∼ 60. Along the L/QIa3d phase boundaries, a hexagonally perforated lamellar (HPL) phase is found to be nearly stable. Our results for the bicontinuous Pn3m cubic (QPn3m) phase, known as the OBDD, indicate that it is an unstable structure in diblock melts. Earlier approximation schemes used to examine mean-field behavior are reviewed, and compa...

Unifying Weak- and Strong-Segregation Block Copolymer Theories

Provided are sulfonamide-containing compositions, topcoat polymers, and additive polymers for use in lithographic processes that have improved static receding water contact angles over those known in the art. The sulfonamide-containing topcoat polymers and additive polymers of the present invention include sulfonamide-substituted repeat units with branched linking group as shown in Formula (I):

Sulfonamide-Containing Topcoat and Photoresist Additive Compositions and Methods of Use

The life of ceramic SPF dies can be enhanced significantly by plasma spray application of a cordierite glaze on the forming surface. The preferred glaze has a coefficient of thermal expansion close to or matching with the ceramic of the die, and, typically, is a 2•2•5 MAS system including 2-10 mol % TiO 2 (or above 8 wt %).

Glaze for ceramic superplastic forming (SPF) dies

Extensive pattern customization will be necessary to realize viable circuit patterns from line-space arrays generated by
block copolymer directed self assembly (DSA). In pattern customization with regard to chemical epitaxy of lamellar
block copolymers, quantitative and precise knowledge of DSA-feature registration to the chemical prepattern is critical.
Here we measure DSA pattern placement error for spatial frequency tripling and quadrupling indexed to specific lines in
the chemical prepattern. A range of prepattern line widths where minimal DSA placement error can be expected is
identified, and a positive correlation between DSA placement accuracy and prepattern uniformity is shown. Considering
the experimental non-idealities present in the chemical prepatterns used in this work that arise from using electron-beam
lithography, we anticipate that 3σ DSA placement errors will be at a minimal level if highly uniform chemical
prepatterns produced by optical lithography are used.

Measurement of placement error between self-assembled polymer patterns and guiding chemical prepatterns

Field effect transistors (FETs) composed of discrete silicon (Si) active regions or ‘fins,’ referred to as finFETs, have superior electrostatic properties compared to planar devices (see Figure 1).1 As a result, they are likely to play a role in further miniaturization of electronic devices.2 However, density requirements for fin patterning have exceeded what can be achieved through direct printing by 193nm immersion (193i) lithography. Consequently, sublithographic patterning techniques that can extend the resolution of 193i to the sub-80nm pitch regime (i.e., where the distance between identical features is less than 80nm) are now of vital importance. Sidewall image transfer (SIT) is now commonly used to manufacture 22nm-node finFET-based technology (meaning the transistor is 22nm across).2 The SIT process doubles the spatial frequency of a template or mandrel shape printed by a conventional lithography through a sequential deposition and etch process. This forms a feature along the sidewalls of the template shape similar to an offset spacer in a CMOS transistor. By removing the template shape selectively, the remaining sidewall features can be used for further pattern transfer. Coupled with 193i, SIT can be used to fabricate grating-like features with a minimum full pitch of 40nm. A further lithography step can be used to customize the grating pattern into a circuit pattern provided it obeys certain design rule restrictions determined by the SIT process. Extending SIT to the sub-40nm pitch regime requires us to reduce the template pitch to less than 80nm. This can be achieved using multiple interleaved 193i exposures or a higher resolution lithography, such as extreme ultraviolet or electron beam lithography. Another option is to perform a further iteration of the SIT process, resulting in a tripling or quadrupling of pitch. While these approaches can all lead to finer pitch patterning, Figure 1. A 3D schematic of a finFET device. Because the gate wraps around the channel region between source and drain of a finFET, the same level of gate control can be achieved with a shorter gate length. Dfin: Fin width. Hfin: Fin height. Lg: Gate length.

Directed self-assembly for ever-smaller printed circuits

Linear or branched functionalized polycarbosilanes having an absorbance less than 3.0 μm−1 at 193 nm and a relatively high refractive index are provided. The functionalized polycarbosilanes contain at least one pendant group that is acid labile or aqueous base soluble. Also disclosed are photoresists formulations containing the functionalized polycarbosilanes that are suitable for use in lithography, e.g., immersion lithography.

Daniel P. Sanders

Papers

Sulfonamide-Containing Topcoat and Photoresist Additive Compositions and Methods of Use

Glaze for ceramic superplastic forming (SPF) dies

Measurement of placement error between self-assembled polymer patterns and guiding chemical prepatterns

Directed self-assembly for ever-smaller printed circuits

Functionalized carbosilane polymers and photoresist compositions containing the same