Physicochemical Studies of Demetalation of Light-harvesting Bacteriochlorophyll Isomers Purified from Green Sulfur Photosynthetic Bacteria

Demetalation kinetics of bacteriochlorophylls (BChls) c, d and e from green sulfur photosynthetic bacteria were studied under weakly acidic conditions. Demetalation rate constants of BChl e possessing a formyl group at the 7-position were significantly smaller than those of BChls c and d , which had a methyl group at this position. The activation energy of demetalation of 3¹ R -8,12-diethyl([E,E])-BChl e was 1.5-times larger than that of 3¹ R -[E,E]-BChl c . ¹⁵N-labeled 3¹ R -[E,E]-BChls c and e were purified from cells of green sulfur bacteria grown in a medium containing ¹⁵NH₄Cl, and their ¹⁵N NMR spectra were measured. The chemical shifts of N₂₁, N₂₂ and N₂₃ atoms of 3¹ R -[E,E]-BChl e were lower-field shifted than those of 3¹ R -[E,E]-BChl c , respectively, and especially the difference in chemical shifts of N₂₂ was significantly large. These results suggest that the electron-withdrawing formyl group at the 7-position of BChl e affected an electronic state of the chlorin macrocycle and caused BChl e to be more tolerant for removal of the central magnesium compared with BChls c and d .     

Radioprotection by DMSO in nitrogen-saturated mammalian cells exposed to helium ion beams

The contribution of OH radical-mediated indirect action by particle beams under hypoxic irradiation condition was investigated by using a radical scavenger. V79 cells were irradiated with 150 MeV/nucleon helium ions at an LET of 2.2 keV/μm in the presence or absence of DMSO, and their colony survivals were determined. The contribution of indirect action to cell killing under hypoxic condition was estimated to be 52±9%. We conclude that OH radical-mediated indirect action still has a half in total contribution on cell killing under hypoxic condition.     

Organocatalytic activity of 4-hydroxy-prolinamide alcohol with different noncovalent coordination sites in asymmetric Michael and direct aldol reactions

4-Hydroxy-prolinamide alcohol with different noncoordination sites as a molecule showed excellent asymmetric catalytic activity in both the Michael reaction (up to 98% ee) and the direct aldol reaction (up to >99% ee), and the catalyzing reactions with high enantioselectivity are supported by a DFT theoretical study of their transition state.     

A note on stability spectrum of generic structures

We show that if a class K of finite relational structures is closed under quasi‐substructures, then there is no saturated K ‐generic structure that is superstable but not ω ‐stable (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of enantiopure 1-substituted, 1,2-disubstituted, and 1,4,5-trisubstituted imidazoles from 1,2-amino alcohols

A highly versatile method for the preparation of enantiopure 1-substituted, 1,2-disubstituted, and 1,4,5-trisubstituted imidazoles was developed by using the cyclocondensation reaction of a 1,2-dicarbonyl compound, an aldehyde, a 1,2-amino alcohol, and ammonium acetate.     

Fluorescence lifetime imaging microscope consisting of a compact picosecond dye laser and a gated charge-coupled device camera for applications to living cells.

An inverted microscope was combined with a compact dye laser with a pulse width of <190 ps and an intensified charge-coupled device (ICCD) camera with a minimum gate width of 200 ps. The resulting fluorescence lifetime imaging microscope, which has a temporal resolution of 340 ps, was used to measure the fluorescence lifetime of polymer microspherers. The results indicated a fluorescence lifetime of 0.9 ns. The present analytical instrument was also employed in an evaluation of biological cells after labeling them with SYTO 13, a fluorescent dye.     

Synthesis of π‐conjugated network polymers based on fluoroarene and fluorescent units via direct arylation polycondensation and their porosity and fluorescent properties

In this study, we report the synthesis of π‐conjugated network polymers including unique fluorescent units via palladium‐catalyzed direct (C? H) arylation polycondensation of 1,2,4,5‐tetrafluorobenzene with tetrabromoarenes. The obtained polymers, including tetraphenylethene (TPE) or pyrene (PYR) units, had microporous structures with the specific Brunauer–Emmett–Teller (BET) surface areas at 508 and 824 m² g^?1, respectively. These polymers possessed narrow pore distributions (<15 nm). These analyses supported that π‐conjugated microporous polymers (CMPs) were synthesized by the direct arylation. Similar to the result of BET surface areas, carbon capture capacity of CMP based on PYR unit was higher than that of CMP based on TPE unit. Because the nitrogen capture capacity of these CMPs was low (≈ 0), selectivity of carbon dioxide adsorption was very high. TPE is a typical aggregation‐induced emission unit but PYR is an aggregation‐caused quenching (ACQ) molecule. The incorporation of TPE unit into the microporous polymer gave green‐colored fluorescence (Φ = 0.12). The polymer including PYR units also showed the green‐colored fluorescence (Φ = 0.05) even though the ACQ property. These synthesized CMPs exhibited characteristic solvatofluorochromism. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3862–3867