Yuki Morita

Emission amplification by sumanene nanocrystals in an onigiri-type organic-organic assembly

Core-shell assemblies of nanocrystals of sumanene (shell) and sumanenetrione (core) resembling onigiri (filled Japanese rice balls) were fabricated by stepwise reprecipitation. Optical properties of the onigiri-type assemblies showed that emissions from the core sumanenetrione nanocrystals were amplified through energy transfer from the shell sumanene nanocrystals through the nanocrystalline interface.

Liquid crystalline properties of dissymmetric molecules part X: The effect of a terminal nitro group on molecular arrangement in smectic phases in three aromatic ring systems with two ester groups

The smectic A (SmA) layer structure has been examined by X-ray diffraction for four isomeric systems: 4-nitrophenyl 4-(4-alkoxybenzoyloxy)benzoates 1, 4-alkoxyphenyl 4-(4-nitrobenzoyloxy)benzoates 2, 4-(4-alkoxybenzoyloxy)phenyl 4-nitrobenzoates 3, and 4-alkoxyphenyl 4-nitrophenyl terephthalates 4. The phase transition behaviour and layer structure of the SmA phases are notably influenced by the relative orientation of the two ester groups to the terminal groups, by alkoxy chain length, and by temperature. The SmA phase for compounds 1 and 3 has a mainly ‘monolayer’ arrangement, where the layer spacing is 2-5 Å longer than the molecular length. The SmA phase for compounds 2 and 4 consists of a mixed layer structure having monolayer, bilayer, and partially bilayer arrangements, the distribution depending on the relative orientation of the ester groups, the alkoxy chain length, and temperature. It is supposed that the diversity of the SmA phase is related to the polar interaction around the nitro or the nitrobenzene moieties through the smectic layers and reversal of the ester groups causes a subtle change in the entire molecular shape.

Smectic Phase Exhibited by Dissymmetric Liquid Crystals: Effect of a Terminal Fluoromethyl Group on Mesomorphic Properties

This paper describes smetic properties of some liquid crystal materials incorporating a terminal trifluoromethyl, a trifluoromethoxy, or a difluoromethoxy group. These groups tend to promote the appearance of smectic A phase with a characteristic molecular arrangement, and the layer structure is discussed in terms of the physical properties of the molecules.

Synthesis and Physico-Chemical Properties of Polar Liquid Crystal Materials Incorporating a Coumarin Skeleton at the Terminal Position

This paper described the synthesis and physico-chemical properties of homologous series of 2-oxo-2H-chromen-6-yl 6-alkoxy-naphthalene-2-carboxylate (compounds 1-n). Compounds 1-n show a monotropic nematic (N) phase, where the average of the N-isotropic (I) phase transition temperatures is ca. 140°C. The mesomorphic properties were also examined by binary phase diagrams for the mixture of 1-n (n = 4 or 8) and 4-(cyano-4′-octyloxybiphenyl (8 OCB), or 4-heptyloxyphenyl 4-nonyloxybenzoate. The physico-chemical properties for compounds 1-n are compared with the corresponding 4-alkoxybenzoate derivatives (compounds 2-n) and 4-alkoxybiphenyl-4′-carboxylate ones (compounds 3-n). These results are discussed in terms of molecular structures and the electrostatic natures of the molecules.

Physico-Chemical Properties of New Liquid Crystals Incorporating a Lactone Ring

ABSTRACT Synthesis and physico-chemical properties of 4-alkoxyphenyl and 4-alkoxybiphenyl-4′-yl 2H-pyran-2-one-5-carboxylates, 2H-chromen-2-one-6-yl 4-alkoxybenzoates and 4-alkoxybiphenyl-4′-carboxylates, and 2H-chromen-2-one-7-yl 4-alkoxybenzoates and 4-alkoxybiphenyl-4′-carboxylates are described. Terminal 2H-pyran-2-one and chromen-2-one cores are effective in enhancing liquid crystalline properties. The layer structure was examined by a small angle X-ray measurement, and the results are discussed in terms of the molecular structure. The polar effect of the terminal lactone group is recognized in the thermal properties and the layer structure of smectic A (SmA) phase.

Gelation of 1-Alkoxy-4-(2-Perfluoroalkyl)Ethoxybenzenes in Organic Solvents

ABSTRACT This paper describes preparation and physico-chemical properties of 1-alkoxy-4-(2-perfluoroalkyl)ethoxybenzenes (FmOOCn). For FmOOCn, 4-F(CF2)mCH2CH2O-phenyl-O-(CH2)nH, three homologues, m = 8 (n = 1, 2) and m = 10 (n = 1) reveal monotropic smectic A and unidentified smectic phases, respectively. Simultaneously, most of the homologous are possible to gelatinize various organic solvents such as octane, cyclohexane, DMF, ethanol, and so on. The gelation ability increases with increasing the carbon number of the perfluoroalkyl chain. The formed gel is transparent, semitransparent or opaque, and the phase transition between the gel phase and the isotropic fluid is thermally reversible. The images of gel observed with scanning electron microscope (SEM) show gathered fibrous aggregates.

Synthesis and Thermal Properties for 4-(4-Alkoxyphenoxycarbonyl)phenyl 3-Alkoxy-2-X-benzoates

ABSTRACT Some derivatives of 4-(4-alkoxyphenoxycarbonyl)phenyl 3-alkoxy-2-X-benzoates (X = F, Cl, Br, or CF3) were synthesized by means of an ortho-directed lithiation followed by an electrophilic aromatic substitution reaction, as a key step, and their thermal properties of liquid crystals were examined. These results are discussed in terms of molecular structure and electrostatic effects.

LIQUID CRYSTALLINE PROPERTIES OF DISSYMMETRIC MOLECULES, PART XI: THE EFFECT OF ESTER AND LATERAL NITRO GROUPS ON THE MOLECULAR ARRANGEMENT IN SMECTIC PHASES IN THREE AROMATIC-RING SYSTEMS CONNECTED BY TWO ESTER GROUPS

The phase transition behavior and layer structure of 4-octyloxyphenyl 4-(4-alkoxy-3-X-benzoyloxy)benzoates and 4-(4-octyloxybenzoyloxy)phenyl 4-alkoxy-3-X-benzoates (X=H or NO2) were examined by thermal, microscopic, and small-angle X-ray diffraction measurements. The homologs of the former (X=H) exhibit nematic, smectic A, and Smectic C (Sm A and C, respectively) phases, and the layer spacing shows a notable change near the Sm C–Sm A transition point, while in contrast the layer spacing for the homologs (X=NO2) is almost independent of the phase transition and temperature. For the homologs of the latter (X=H and NO2), on the other hand, the layer spacing is fairly narrow compared with the calculated molecular length, and it remains constant through the Sm A and Sm C phases. These results are discussed in terms of the layer structure of the Sm A and Sm C phases, and the molecular properties are obtained by a semi empirical molecular orbital calculation.

4-Perfluoroalkylbutoxybenzene derivatives as liquid crystalline organogelators based on phase-selective gelators†

4-Perfluoroalkylbutoxybenzene derivatives 1(n) have been prepared as a new class of thermotropic liquid crystalline organogelators incorporating a perfluoroalkyl group without a hydrogen bonding group. Significantly, compounds 1(n) at room temperature act as efficient and rapid phase-selective gelators in a kind of method appropriate for water purification.

Beam-induced graphitic carbon cage transformation from sumanene aggregates

We found that electron-beam irradiation of sumanene aggregates strongly enhanced their transformation into a graphitic carbon cage, having a diameter of about 20 nm. The threshold electron dose was about 32 mC/cm2 at 200 keV, but the transformation is still induced at 20 keV. The transformation sequence suggested that the cage was constructed accompanied by the dynamical movement of the transiently linked sumanene molecules in order to pile up inside the shell. Thus, bond excitation in the sumanene molecules rather than a knock-on of carbon atoms seems to be the main cause of the cage transformation.