Controlling the Photofunctionality of a Polyanionic Heteroleptic Copper(I) Photosensitizer for CO2 Reduction Using Its Ion-pair Formation with Polycationic Ammonium in Aqueous Media

A water-soluble trianionic heteroleptic copper(I) photosensitizer having four sulfonate groups ( CuPS ³⁻) was found to afford the 1 : 2 ion-pair adduct with dicationic alkylammonium (hexamethonium) cations ( HM ²⁺) in aqueous media, leading to exhibit excellent photophysical and photocatalytic performances owing to the substantial suppression of water-derived non-radiative decay of the photoexcited state.     

Thermodynamic Control of Intramolecular Singlet Fission and Exciton Transport in Linear Tetracene Oligomers

We newly synthesized a series of homo- and hetero-tetracene (Tc) oligomers to propose a molecular design strategy for the efficient exciton transport in linear oligomers by promoting correlated triplet pair (TT) dissociation and controlling sequential exciton trapping process of individual doubled triplet excitons (T+T) by intramolecular singlet fission. First, entropic gain effects on the number of Tc units are examined by comparing Tc-homo-oligomers [(Tc)_n: n=2, 4, 6]. Then, a comparison of (Tc)_n and Tc-hetero-oligomer [TcF₃-(Tc)₄-TcF₃] reveals the vibronic coupling effect for entropic gain. Observed entropic effects on the T+T formation indicated that the exciton migration is rationalized by number of possible TT states increased both by increasing the number of Tc units and by the vibronic levels at the terminal TcF₃ units. Finally, we successfully observed high-yield exciton trapping process (trapped triplet yield: Φ_TrT=176 %).     

Microwave effect on the surface composition of the Urushibara Ni hydrogenation catalyst and improved reduction of acetophenone

The Urushibara Ni (U-Ni) hydrogenation catalyst and some modified forms, and for comparison Raney-Ni, were subjected to conventional (oil bath) and MW heating, and subsequently characterized by electron dispersive X-ray analysis (EDX), by BET surface area, and by scanning electron microscopy (SEM); yields of the catalyzed hydrogenation of acetophenone to 1-phenylethanol in 2-propanol by one of the modified forms (U-Ni-B) were greatly improved (from 68% to 95%).     

Criteria for pericyclic and pseudopericyclic character of electrocyclization of (Z)-1,2,4,6-heptatetraene and (2Z)-2,4,5-hexatriene-1-imine

The electrocyclic reaction mechanisms of (Z)-1,2,4,6-heptatetraene and (2Z)-2,4,5-hexatriene-1-imine were studied by ab initio MO methods. The activation energy barrier height of the electrocyclic reaction of (Z)-1,2,4,6-heptatetraene is extremely a low energy barrier of 8.58 kcal/mol by a MRMP method. The activation energy barrier height of the electrocyclic ring closure of the trans-type of (2Z)-2,4,5-hexatriene-1-imine is lower by 3.18 kcal/mol than that of (Z)-1,2,4,6-heptatetraene. These low energy barriers come from some orbital interactions relating to allene group. For the reaction of (Z)-1,2,4,6-heptatetraene, the interactions of the vertical and side π orbitals of the allene group with another terminal π orbital are important at the transition state. The interaction of the vertical π orbital of allene group with a lone pair orbital of N atom is dominant at the transition state of the reaction of the trans-type of (2Z)-2,4,5- hexatriene-1-imine. The electrocyclic mechanism of the cis-type of (2Z)-2,4,5-hexatriene-1-imine was also discussed. Contribution of the Mark S. Gordon 65th Birthday Festschrift issue.     

Theoretical studies on the photochemical reaction mechanisms of o-xylylene. Effects of phenyl group for electrocyclic reaction mechanism

The potential energy surfaces (PESs) of the electrocyclic reactions of o-xylylene at the ground and the lowest excited states are calculated by CASSCF molecular orbital and MRMP2 methods. The lowest excited state geometry of o-xylylene has C(2v) symmetry and is about 65 kcal mol(-1) in energy above the ground state. The PESs in the vicinity of the conical intersection are different from those of the electrocyclic reaction of cis-butadiene. In the vicinity of the conical intersection, the transition state at the ground state relating to methylene-cycloheptadienyl carbene is located. The transition state is only 4.3 kcal mol(-1) lower in energy than the conical intersection at the CASSCF(10,10)/6-31G(d) level and 0.5 kcal mol(-1) lower at the MRMP2/6-311+G(d,p) level. The transition state corresponding to benzocyclobutene does not locate in the vicinity of the conical intersection because of the resonance energy between benzene ring and methylene group.     

An integrated microfluidic system for long-term perfusion culture and on-line monitoring of intestinal tissue models

Conventional cell-based assays in life science and medical applications can be difficult to maintain functionally over long periods. Microfluidics is an emerging technology with potential to provide integrated environments for cell maintenance, continuous perfusion, and monitoring. In this study, we developed an integrated microfluidic device with on-chip pumping and detection functionalities. The microfluidic structure in the device is divided into two independent channels separated by a semipermeable membrane on which cells are inoculated and cultured. Perfusion and fluorescence measurements of culture media for each channel can be conducted by the on-chip pumping system and optical fiber detection system. Performance of the device was examined through long-term culture and monitoring of polarized transport activity of intestinal tissue models (Caco-2 cells). The cells could be cultured for more than two weeks, and monolayer transport of rhodamine 123 was successfully monitored by on-line fluorescent measurement. This device may have applications in toxicity testing and drug screening.     

Biphenylene-substituted ruthenocenylphosphine for Suzuki-Miyaura coupling of aryl chlorides

High activity in the palladium-catalyzed Suzuki-Miyaura reactions of aryl chlorides with arylboronic acids was furnished using biphenylene-substituted di- tert-butylruthenocenylphosphine (R-Phos) as a supporting ligand. Substrate combinations even for the construction of highly hindered tetra- ortho-substituted biaryls can be achieved in good to excellent yields with low catalyst loadings in short reaction times.     

Miuraenamides: Antimicrobial Cyclic Depsipeptides Isolated from a Rare and Slightly Halophilic Myxobacterium

Marine myxobacteria are rare culture‐resistant microorganisms, several strains of which have been identified by research groups in Asia. Paraliomyxa miuraensis, a slightly halophilic myxobacterium discovered in Japan, produces the cyclic hybrid polyketide–peptide antibiotics known as miuraenamides A and B, whose taxonomical and biological characteristics have been reported previously. Herein, we describe the chemical characterization of these two miuraenamides and introduce four new members of the miuraenamide family. We carried out the complete structural analysis of miuraenamides A and B on the basis of NMR spectroscopic analysis and elucidated the absolute configuration of miuraenamide A by chemical derivatization and subsequent use of the modified Mosher method or the Marfey method. Miuraenamides C–F were isolated from the same strain of the bacterium as miuraenamides A and B. The structure–antimicrobial‐activity relationships of the six natural metabolites and four chemically derived compounds demonstrated the importance of both the macrocyclic structure and the β‐methoxyacrylate moiety.     

Critical behavior and the limit distribution for long-range oriented percolation. I

We consider oriented percolation on ${\mathbb{Z}}^d\times{\mathbb{Z}}_+$ whose bond-occupation probability is pD( · ), where p is the percolation parameter and D is a probability distribution on ${\mathbb{Z}}^d$ . Suppose that D(x) decays as |x|^?d?α for some α > 0. We prove that the two-point function obeys an infrared bound which implies that various critical exponents take on their respective mean-field values above the upper-critical dimension $d_c=2(\alpha\wedge2)$ . We also show that, for every k, the Fourier transform of the normalized two-point function at time n, with a proper spatial scaling, has a convergent subsequence to $e^{-c|k|^{\alpha\wedge2}}$ for some c > 0.