A palladium complex confined in a thiadiazole-functionalized porous conjugated polymer for the Suzuki-Miyaura coupling reaction.

Porous organic polymers (POPs) with well-distributed and tunable functional groups acting as ligands for specific reactions are promising supports for confining useful novel metals such as Pd, Au, and Pd. Herein, a thiadiazole-containing POP has been successfully synthesized and used for immobilizing Pd species. Pd immobilized inside the micropores (2.3 nm) of the POP material is easily prepared owing to a large amount of the strong anchoring group, thiadiazole, which is intrinsically distributed in the as-prepared POP. The rigid thiadiazole-containing polymer can stabilize the central metal rather than poisoning it. The as-prepared catalyst shows excellent catalytic activity in Suzuki-Miyaura coupling reactions under mild reaction conditions and low catalyst loading. Importantly, the intrinsically distributed thiadiazole ligands can stabilize the Pd moiety, preventing aggregation and leaching, and afford excellent catalytic lifetimes. Consequently, the catalyst can be reused 10 times without a significant loss of its catalytic activity.

Nanogap Engineering for Enhanced Transmission of Wire Grid Polarizers in Mid-Wavelength Infrared Region.

Wire-grid polarizers (WGPs) have been widely used in various fields, such as polarimetry, imaging, display, spectroscopy, and optical isolation. However, conventional WGPs used in diverse mid-wavelength infrared (MWIR) applications show high reflection losses, which intrinsically arise from high refractive indices of their IR-transmitting substrates, such as silicon (Si) and germanium (Ge). This study demonstrated the enhanced transmittance of a transverse magnetic (TM) wave that surpassed ~80% over the entire MWIR range from 3000 to 5000 nm in a narrow air gap of a WGP, where aluminum (Al) was selectively deposited on a nanopatterned Si substrate using an oblique angle deposition method. Moreover, a higher TM wave transmittance was achieved by reducing the air gaps of the WGPs in the nanopatterns, which were distinctly different from the traditional WGPs comprising metal wires patterned directly on a flat substrate. A finite-difference time-domain simulation was performed to investigate optical properties of the proposed WGPs, which showed that the electric field in the air nanogap was remarkably enhanced. The characteristic performances were further investigated using a combination of an effective medium approximation and an admittance diagram, revealing that the broadband transmission enhancement could be attributed to a combined effect of a strong electric field and a better admittance matching. The approach and results described in this paper hold promise for the design and the fabrication of high-quality WGPs, as well as their numerous applications.

Highly enantioselective aryl transfer to aldehydes: a remarkable effect of sulfur substitution in amino thioacetate ligands.

Chiral amino thioacetate ligands were prepared from the corresponding amino alcohols and used as catalysts for enantioselective aryl transfer reaction. The amino thioacetates were remarkably superior to the corresponding amino alcohols. Low catalyst loadings of only 1-2.5 mol % were sufficient to achieve excellent enantioselectivity as well as high conversion in short reaction time. The results reveal that the thioacetoxy moiety of the amino thioacetates has a surprisingly beneficial effect in enhancing the asymmetric induction.

Encapsulation of Pd complex in ionic liquid on highly ordered mesoporous silica MCM-41.

Palladium acetate was encapsulated onto highly ordered mesoporous silica MCM-41 with the aid of ionic liquid. The immobilized Pd complex can efficiently catalyze Heck coupling reactions of activated and non-activated aryl halides with acrylates. The Pd catalyst exhibited remarkably high catalytic activity and outstanding stability. Moreover, the immobilized palladium acetate could be recycled at least six times without significant loss of activity.

Highly enantioselective Pd-catalyzed allylic alkylation using new chiral ferrocenylphosphinoimidazolidine ligands.

New ferrocenylphosphinoimidazolidines containing central chirality and planar chirality were found to act as highly effective chiral ligands in Pd-catalyzed asymmetric allylic alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate.

Amino-functionalized SBA-15 type mesoporous silica having nanostructured hexagonal platelet morphology.

Amino-functionalized SBA-15 type mesoporous silicas having unique hexagonal platelet morphologies with short channels (100-300 nm) running parallel to the thickness of the nanostructured hexagonal platelet type morphologies have been directly synthesized by co-condensation of aminopropyltriethoxysilane (APTES) and sodium metasilicate as a silica source in the presence of Pluronic P123 triblock copolymer as a structure directing agent.

An extremely active and general catalyst for Suzuki coupling reaction of unreactive aryl chlorides.

ß-Diketiminatophosphane Pd complex 2a acted as a powerful catalyst which allows easy access to the Suzuki coupling reaction of less reactive aryl chlorides under mild conditions. A wide range of sterically hindered and deactivated aryl chlorides could be efficiently coupled at a low catalyst loading of 0.1 mol %. Furthermore, this catalytic system also proved to be highly effective in one-pot multiple couplings.

An efficient and general method for the Heck and Buchwald-Hartwig coupling reactions of aryl chlorides.

The ß-diketiminatophosphane Pd complex acted as a powerful catalyst for the Heck coupling of aryl chlorides with alkenes. Various aryl and heteroaryl chlorides were coupled efficiently under relatively mild conditions. Furthermore, this catalytic system also proved to be highly active in the Buchwald-Hartwig coupling of deactivated and sterically hindered aryl chlorides at room temperature.

General and highly active catalyst for mono and double Hiyama coupling reactions of unreactive aryl chlorides in water.

A new ß-diketiminatophosphane Pd catalyst was found to be highly effective in the mono and double Hiyama coupling reactions of unactivated aryl chlorides in water.

Room temperature Stille cross-coupling reaction of unreactive aryl chlorides and heteroaryl chlorides.

Phosphanyl-beta-ketoiminate Pd complexes serve as highly effective catalysts in the Stille coupling reaction of aryl chlorides and heteroaryl chlorides with organostannanes at room temperature.