A Hierarchical Self-Assembly System Built Up from Preorganized Tripodal Helical Metal Complexes.

The hierarchical organization strategy has realized elaborate supramolecular structures that are difficult to achieve by a one-pot thermodynamically driven self-assembly. Self-assembly via Schiff base formation of the preorganized tripodal helical unit 2(2+), which is composed of the tris(bipyridyl) ligand 1 and octahedral metal ion (Ru(II) and Fe(II)), lead to two supramolecular structures, i.e., a macrobicyclic dimer and an interlocked helicate. Notably, the interlocked helicate had a unique motif with an elongated shape (∼ 58 Å) and linearly aligned metal centers with homochiral configurations (all-Δ or all-Λ), which shows potential for allosteric regulation based on the long-range transmittance of the structural information.

Amounts and compositional analysis of glycosaminoglycans in the tissue of fish.

We isolated GAGs from the inedible parts; head, skin, internal organs, fins, scales and spine, of atlantic mackerel (Scomber scombrus), japanese jack mackerel (Trachurus japonicus), pacific bluefin tuna (Thunnus orientalis), yellowfin sole (Limanda aspera), broadbanded thornyhead (Sebastolobus macrochir), golden threadfin bream (Nemipterus virgatus), and nile tilapia (Oreochromis niloticus). We also investigated deep-sea fish, eelpouts (Bothrocara hollandi, Lycodes toyamensis, and Lycodes nakamurae), rough snailfish (Careproctus trachysoma), and squids (Watasenia scintillans, Enoploteuthis chunii, and Berryteuthis magister). Enzymatic digestion of the GAGs enabled a compositional analysis of CS, DS, and HA including the sulfation patterns of CS and DS, as well as the amount of each GAG. The molecular weights and distributions of these GAGs were also examined. The amounts of GAGs contained in the tissues and CS/DS ratios differed remarkably among the fish. The dorsal fin of the yellowfin sole contained more than 1300mg of CS-DS per 100g of defatted-dry tissue. Although the fish generally contained A-type rich CS-DS, bottom fish and deep-sea fish often possessed C-type CS-DS in larger ratios. Squid characteristically had E-type CS-DS which was normally less common in fish except in cartilaginous fish. These analytical results had no relation to the biological classification.

Effect of packing on orientation and cis-trans isomerization of azobenzene chromophore in Langmuir-Blodgett film.

Photoactive film material of long-chain azobenzene derivative, p-(omega-trimethylammoniodecyloxy)-p'-octyloxyazobenzene bromide (TAOAB), was fabricated into a Langmuir-Blodgett (LB) film by a polyion-complex technique using poly(sodium 4-styrenesulfonate) as a polyanion. To investigate the effect of the packing state of the azobenzene chromophore on its orientation and cis-trans isomerization, TAOAB was mixed with methyl stearate in the LB film matrix at various mole fractions (X(TAOAB)), and structural characterizations were subsequently carried out by means of Fourier transform infrared and ultraviolet-visible spectroscopies, X-ray diffraction analysis, and atomic force microscopy. The results obtained show that as the degree of packing increases, both the azobenzene chromophores and the hydrocarbon chains orient more perpendicularly to the surface of the LB film. In addition, reversible cis-trans photoisomerization of TAOAB took place upon alternate irradiation with UV and visible light even in a mixed LB film with the chromophores in a dense lateral packing state. In the process of thermal cis-to-trans isomerization, we found that the reaction rate is strongly affected by the packing state of TAOAB at 20 degrees C, reflecting the differences in steric hindrance among LB films of various X(TAOAB). In addition, higher activation energy was obtained for thermal cis-to-trans isomerization when the free volume around the chromophores became smaller.