Design and synthesis of phthalimide-based fluorescent liver x receptor antagonists

Based on our structure-activity relationship study of liver X receptor (LXR) ligands, we designed and synthesized fluorescent LXR antagonists containing an unsubstituted or substituted amino group on a phthalimide unit.     

Flow-injection spectrophotometric determination of acetyl-coenzyme A with immobilized phosphotransacetylase

Phosphotransacetylase (PTA) is immobilized on AF-Tresyl TOYOPEARL 650 gel and used on-line in a stainless-steel column (10 × 4 mm i.d.). CoA-SH liberated enzymatically from acetyl-CoA is reacted with Ellman's reagent [5,5′-dithiobis(2-nitrobenzoic acid)] in the carrier stream. The calibration graph for acetyl-CoA is linear from 4 × 10^?6 to 4 × 10^?4 M and the detection limits is 8 × 10^?7 M. The immobilized enzyme can be employed for over 4 months without any significant decrease in activity. The enzyme retains its activity in methanol even though the initial rate of reaction is decreased.     

Synthesis of the enantiomers of cis-2-methyl-5-hexanolide,the major component of the sex pheromone of the carpenter bee

(2R,5S)-2-Methyl-5-hexanolide and its antipode were synthesized in highly optically pure state (?98–99% e.e.) starting from ethyl (S)-lactate and the enantiomers of methyl β-hydroxyisobutyrate. The specific rotations of our samples were [α]_D±91.0-93.5° (CHCl₃), while the reported values of the samples prepared by resolution or asymmetric synthesis were ±64.5–65.6°.     

A novel selenium-mediated spiroannelation : one-step preparation of d1-theaspirane fron α-dihydroionol

d1-Theaspirane (1) was prepared by the selenium-mediated electrochemical oxidation of α-dihydroionol (3), via a novel selenium-mediated spiroannelation.     

Macroscopic wall number analysis of single-walled, double-walled, and few-walled carbon nanotubes by X-ray diffraction

The layer number is of great importance for nanocarbon materials, such as carbon nanotubes (CNTs) and graphene. While simple optical methods exist to evaluate few-layer graphene, equivalent analysis for CNTs is limited to transmission electron microscopy. We present a simple macroscopic method based on the (002) X-ray diffraction peak to evaluate the average wall number of CNTs in the range from single- to few-walled. The key was the finding that the (002) peak could be decomposed into two basic components: the intertube structure (outer-wall contacts) and the intratube structure (concentric shells). Decomposition of the peaks revealed a linear relationship between the average wall number and the ratio of the intertube and intratube contributions to the (002) peak. Good agreement with CNTs having average wall numbers ranging from 1 to ～5 demonstrated this as a macroscopic method for average wall number analysis.     

Rotationally correlated reactivity in the CH (v = 0, J, F(i)) + O2 → OH (A) + CO reaction

The rotational-state-selected CH (v = 0, J, F(i)) beam has been prepared by using an electric hexapole and applied to the crossed beam reaction of CH (v = 0, J, F(i)) + O(2) → OH (A) + CO at different O(2) beam conditions. The rotational state selected reactive cross sections of CH (RSSRCS-CH) turn out to depend remarkably on the rotational state distribution of O(2) molecules at a collision energy of ～?0.19 eV. The reactivity of CH molecules in the N = 1 rotational states (namely ∣J = 1∕2, F(2)> and ∣J = 3∕2, F(1)> states, N designates the angular momentum excluding spin) becomes strongly enhanced upon a lowering of the rotational temperature of the O(2) beam. The RSSRCS-CH in these two rotational states correlate linearly with the population of O(2) molecule in the specific K(O(2)) frame rotation number states: CH(|J = 1/2,F(2)>) with O(2)(|K(O(2)) = 1>);CH(|J = 3/2,F(1)>) with O(2)(|K(O(2)) = 3>). These linear correlations mean that the rotational-state-selected CH molecules are selectively reactive upon the incoming O(2) molecules in a specific rotational state; here, we use the term "rotationally correlated reactivity" to such specific reactivity depending on the combination of the rotational states between two molecular reactants. In addition, the steric asymmetry in the oriented CH (∣J = 1∕2,?F(2),?M = 1∕2>) + O(2) (|K(O(2)) = 1>) reaction turns out to be negligible (< ±1%). This observation supports the reaction mechanism as theoretically predicted by Huang et al. [J. Phys. Chem. A 106, 5490 (2002)] that the first step is an intermediate formation with no energy barrier in which C-atom of CH molecule attacks on one O-atom of O(2) molecule at a sideways configuration.     

First total synthesis of (±)-adunctin B

The first total synthesis of (±)-adunctin B (1), a natural product isolated from Piper aduncum (Piperaceae) and having antibacterial activity, was achieved in 1.26% overall yield in 15 steps from 5,7-dimethoxycoumarin-3-carboxylate (8).     

Time-resolved fluorescence study on the photomerocyanine form of spiropyran and its derivative with azobenzene

The excited state dynamics of the photomerocyanine (PMC) form originating from spirobenzopyran and the bi-functional photochromic compound spirobenzopyran–azobenzene (SpAz), containing typical photochromic molecules of spirobenzopyran (Sp) and azobenzene (Az), were investigated using picosecond time-resolved fluorescence measurements in solution at 200 and 285 K and in a PMMA polymer film at 298 K. While the fluorescence lifetimes of PMC were about twice as long as those of SpAz under all experimental conditions, both lifetimes showed similar strong dependence on viscosity rather than temperature. These results suggest that non-radiative decay to an intermediate state could be accompanied by a significant conformational change. The effect of the Az moiety in this relaxation process is also discussed. It is unlikely that an energy transfer from the PMC moiety to the Az moiety occurs. It was concluded that the PMC moiety in the bi-functional SpAz is independent from the Az moiety.     

Polybenzimidazole block sulfonated poly(arylene ether sulfone) ionomers

Novel ionomers based on polybenzimidazole block sulfonated poly(arylene ether sulfone) show excellent thermal properties. The ionic aggregation of sulfonic acid groups leads to well-developed phase separated morphology and thus high proton conductivity at wide humidity range, up to 65 mS cm(-1) at 90% relative humidity.