Chemical trend of Ln-M exchange couplings in heterometallic complexes with Ln = Gd, Tb, Dy, Ho, Er and M = Cu, V

The 4f-3d exchange couplings were definitively and precisely determined in the dinuclear complexes (Ln-M) involving double μ-oxo-bridges, by means of combined high-frequency electron paramagnetic resonance and pulsed-field magnetization techniques, revealing a monotonic decrease of ferromagnetic J(Ln-Cu) in the order of the atomic number, (64)Gd to (68)Er.     

Design and synthesis of new chiral phosphorus-olefin bidentate ligands and their use in the rhodium-catalyzed asymmetric addition of organoboroxines to N-sulfonyl imines

Novel chiral phosphorus-olefin bidentate ligands have been synthesized in a few steps from a readily available enantiopure compound. These ligands have been applied to a rhodium-catalyzed asymmetric addition of organoboroxines to N-sulfonyl aldimines, achieving high yield and enantioselectivity.     

Exploring the thermochromism of sulfite-embedded polyoxometalate capsules

The Dawson-type polyanion [α-Mo(18)O(54)(SO(3))(2)](4-), with two SO(3)(2-) templates embedded inside a polyoxomolybdate(vi) cage, exhibits thermochromism over an exceptionally wide temperature range (～500 K). The temperature dependence of the cluster structure, established from X-ray crystallography, IR and Raman spectroscopy and DFT calculations, is related to a decreasing HOMO-LUMO gap in the near UV with increasing temperature. We postulate this is due to geometrical changes that affect both the occupied and unoccupied frontier molecular orbitals of this cluster anion.     

Effects of pressure and temperature on the survival rate of adherent A-172 cells

Preservation of cells under high pressure is an important alternative to cryopreservation. We studied the effect of temperature (4, 25, 37°C) and pressure (0.1–350 MPa) on the survival rate of A-172 glioblastoma cells. The survival rate was not changed by brief (10 min) pressurization of up to 150 MPa, but the survival rate began to decrease from 150 MPa, and most of the A-172 cells died when treated with over 200 MPa. Lengthy pressurization (4 days) at lower pressure (upto 20.1 MPa) without medium exchange showed complex results. The survival rate of cells preserved at 25°C showed two maxima at 1.6 and 20.1 MPa. After preservation, cells adhered and proliferated in the same way as normal cells when cultured at 37°C in a CO₂ incubator. The other two temperatures, 4° and 37°C, showed no maximum survival rate. Therefore, a high survival rate can be maintained with high pressure treatment.     

Oxidative coupling polymerization of 2,3‐dihydroxynaphthalene with dinuclear‐type copper(II) catalyst

The oxidative coupling polymerization of 2,3‐dihydroxynaphthalene with the novel dinuclear‐type copper(II) catalysts successfully produced poly(2,3‐dihydroxy‐1,4‐naphthylene). For example, the MeOH‐insoluble polymer with a number average molecular weight of 4.4 × 10³ from the polymerization using the complex of CuCl₂ and N,N′‐bis(2‐morpholinoethyl)‐p‐xylylenediamine ( p ‐ 1 ) at room temperature under an O₂ atmosphere followed by acetylation of the hydroxyl groups was obtained in 63% yield. The structures of the tetraamine ligands and the counter anion of the copper(II) salts significantly influenced the catalyst activity. The polymerization of 2,2′‐dimethoxy‐1,1′‐binaphthalene‐3,3′‐diol with the 2CuCl₂‐ p ‐ 1 catalyst, however, resulted in a lower yield. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1635–1640, 2005     

Structure comparison between Th2Zn17-type and TbCu7-type Sm–Fe intermetallic compounds and their nitrides by means of 57Fe-Mössbauer spectroscopy

Samarium–iron intermetallic compounds were prepared by a melt spinning method with low and high wheel speeds, which resulted in a Th₂Zn₁₇-type and a TbCu₇-type structure, respectively. Structure comparison between these types was investigated for Sm–Fe intermetallic compounds and their nitrides by ⁵⁷Fe-Mössbauer spectroscopy.     

Diversity of Ligularia kanaitzensis in sesquiterpenoid composition and neutral DNA sequences

Twenty-six eremophilane-type sesquiterpenoids, including six new compounds, were isolated from the title species. One of the new compounds, kanaitzensol, suggested the presence of an enzyme for the conversion of eremophil-7(11)-en-8-one derivative to furanoeremophilanes. The plant was collected at 15 locations in Yunnan Province of China and found to be diverse with respect to its sesquiterpenoid composition. DNA sequencing also revealed a large intraspecific diversity of the plant.