Synthesis of maremycins A and D1 via cycloaddition of a nitrone with (E)-3-ethylidene-1-methylindolin-2-one

A concise synthesis of maremycins A and D1 has been accomplished via cycloaddition of a chiral cyclic nitrone with ( E)-3-ethylidene-1-methylindolin-2-one as a key step. This synthesis clarifies the stereochemistry of the maremycins and is suitable for large-scale synthesis for biological screening.     

Efficiency of numerical basis sets for predicting the binding energies of hydrogen bonded complexes: evidence of small basis set superposition error compared to Gaussian basis sets

Binding energies of selected hydrogen bonded complexes have been calculated within the framework of density functional theory (DFT) method to discuss the efficiency of numerical basis sets implemented in the DFT code DMol3 in comparison with Gaussian basis sets. The corrections of basis set superposition error (BSSE) are evaluated by means of counterpoise method. Two kinds of different numerical basis sets in size are examined; the size of the one is comparable to Gaussian double zeta plus polarization function basis set (DNP), and that of the other is comparable to triple zeta plus double polarization functions basis set (TNDP). We have confirmed that the magnitudes of BSSE in these numerical basis sets are comparative to or smaller than those in Gaussian basis sets whose sizes are much larger than the corresponding numerical basis sets; the BSSE corrections in DNP are less than those in the Gaussian 6-311+G(3df,2pd) basis set, and those in TNDP are comparable to those in the substantially large scale Gaussian basis set aug-cc-pVTZ. The differences in counterpoise corrected binding energies between calculated using DNP and calculated using aug-cc-pVTZ are less than 9 kJ/mol for all of the complexes studied in the present work. The present results have shown that the cost effectiveness in the numerical basis sets in DMol3 is superior to that in Gaussian basis sets in terms of accuracy per computational cost.     

Regioselectivity Control in Lipase‐Catalyzed Polymerization of Divinyl Sebacate and Triols

Lipase‐catalyzed regioselective polymerization of divinyl sebacate and triols has been performed in bulk. NMR analysis of the product obtained by the polymerization of divinyl sebacate and glycerol using Candida antarctica lipase at 60°C showed that 1,3‐diglyceride was a main unit and a small amount of the branching unit (triglyceride) was contained. The polymerization of divinyl sebacate with 1,2,4‐butanetriol or 1,2,6‐hexanetriol at 60°C produced a branched polymer. In polymerization at a lower temperature, the regioselectivity was perfectly controlled to give a linear polymer consisting of the α,ω‐disubstituted unit exclusively. The lipase origin and feed ratio of monomers greatly affected the microstructure of the polymer; under selected conditions, regiospecific polymerization was achieved.     

In vitro photodynamic activity of chloro(5,10,15,20-tetraphenylporphyrinato)indium(III) loaded-poly(lactide-co-glycolide) nanoparticles in LNCaP prostate tumour cells

In(III)-meso-tetraphenylporphyrin (InTPP) was encapsulated into nanoparticles (smaller than 200 nm) of poly(d,l-lactide-co-glycolide) (PLGA) using the emulsification–evaporation technique. The photodynamic efficacy of InTPP-loaded nanoparticles and its cellular uptake was investigated with LNCaP prostate tumour cells, in comparison with the free InTPP. The effects of incubation time (1–3 h), drug concentration (1.8–7.7 μmol/L) and incident light dose (15–45 J/cm²) with both encapsulated and free InTPP were studied. The type of cell death induced by the photochemical process using both encapsulated and free InTPP was also investigated. Cell viability was reduced more significantly with increasing values of these effects for InTPP-loaded nanoparticles than with the free drug. The cellular death induced by both encapsulated and free InTPP was preponderantly apoptotic. Confocal laser scanning microscopy data showed that the InTPP-loaded nanoparticles, as well free InTPP, were localized in the cells, and always in the perinuclear region. Encapsulated InTPP was measured by the intensity of fluorescence intensity of cell extracts and was three times more internalized into the cells than was the free InTPP. Electron paramagnetic resonance experiments corroborated the participation of singlet oxygen in the photocytotoxic effect of nanoparticles loaded with InTPP.     

Superconducting properties of gold powder mixed Bi−Pb−Sr−Ca−Cu−O composites

Two kinds of Au powder having different particle size were mixed with a Bi–Pb–Sr–Ca–Cu–O superconductor, purpose being to improve the superconducting characteristics, especiallyJ _c. By conventional Au powder addition,J _c appreciably increased and a maximumJ _c of 900 A/cm² was obtained on the Au 30 wt% mixed composite. On the contrary,J _c decreased by mixing with ultra fine Au powder. ThisJ _c deterioration was predominantly ascribed to the formation of microcracks and poses by the segregation of Au ultra fine powder.     

Photochemical and photoelectrochemical behaviour of chlorophyll a-smectite conjugate

Chlorophyll a was adsorbed onto smectite to form chlorophyll-smectite conjugate, which became photostable against light illumination. The chlorophyll-smectite conjugate caused the photoreduction of nitro blue tetrazolium, NBT, through the formation of superoxide anion, and the conjugate retained the photosensitive activity even after 20 hour illumination. Furthermore, the conjugate deposited on SnO₂ electrode caused electron transfer under light illumination. The anodic photocurrent rose at ?200 mV versus Ag/AgCl electrode (KCl saturated) and reached a maximum level at approximately +100 mV. The photocurrent spectrum was in good agreement with the absorption spectrum of chlorophyll-smectite conjugate in an aqueous solution and the quantum efficiency was approximately 1% at 670 nm.     

A Cell‐Targeted Non‐Cytotoxic Fluorescent Nanogel Thermometer Created with an Imidazolium‐Containing Cationic Radical Initiator

A cationic fluorescent nanogel thermometer based on thermo‐responsive N‐isopropylacrylamide and environment‐sensitive benzothiadiazole was developed with a new azo compound bearing imidazolium rings as the first cationic radical initiator. This cationic fluorescent nanogel thermometer showed an excellent ability to enter live mammalian cells in a short incubation period (10 min), a high sensitivity to temperature variations in live cells (temperature resolution of 0.02–0.84 °C in the range 20–40 °C), and remarkable non‐cytotoxicity, which permitted ordinary cell proliferation and even differentiation of primary cultured cells.