Hachiro Nakanishi

Photodimerization of 1,4-dicinnamoylbenzene crystal via a topochemical process

Abstract 1,4-Dicinnamoylbenzene crystals photodimerize readily via a double [2+2] cycloaddition into the corresponding tricyclic dimer, which consists of two cyclobutane rings and a macro ring bridged by two phenylene linkages.

Merocyanine-p-toluenesulfonic acid complex with large second-order nonlinearity

Merocyanine - p-toluenesulufonic acid complex was investigated for the crystal structure and the optical properties. The molecules are crystallized in the space group P1 so that the crystal exhibits a large optical nonlinearity . The second order nonlinear optical coefficient d11 measured by means of the Maker Fringe ifiethod is 314pm/V as a pristine data and 500pm/V after the correction of scattering and is greater than d11 of 2-inethyl-4-nitroaniline.

Organic Nanocrystals for Nanomedicine and Biophotonics

In this chapter, we will describe the advanced methodology for opening the new gate of nanomedicine and bioimaging using organic nanocrystals formulation, which is free from organic solvent and nano carrier. The organic nanocrystals aqueous dispersion is prepared by our originally developed technique, the reprecipitation method. The importance of the contribution of nanotechnology to biomedical application has been greatly increased in few decades. Especially the current scientific endeavours on the researches of nanotechnology based nanomedicine and bioimaging have been giving us the novel and important information of biological events in vitro and in vivo. When focusing bioimaging and nanomedicine, we definitely treat the fluorescent dyes and drugs. However, currently used numerous organic compounds including drugs and fluorescent dye probes are hydrophobic in nature. Therefore, for their using in drug administration to human and animals or in dye staining imaging in living cells in vitro and in vivo, organic solvents are widely used for their increasing water solubility. However, organic solvent has not only the problems of causing systemic toxicity and cytotoxic activity, but also disturb obtaining accurately the biological experimental data, which may be modified by the influence of organic solvent. Many researchers have been making the scientific endeavour to clear these problems. Using nano carrier such as liposome, nanocapsule, nanosphere, dendrimer, emulsion, and surfactant have concluded successfully in some part of increasing water solubility of drugs and dyes. However, these carries still suffer from systemic toxicity and cytotoxic activity caused by their own. Additionally, the nano carriers have disadvantage of low amount loading of drugs and dyes in carrier and of their leakage. To overcome these problems, recently the organic solvent and carrier free method for photodynamic cancer therapy and for bioimaging of living cells in vitro using organic nanocrystals are reported including our group (Baba et al., 2007 and 2009). Organic nanocrystals were prepared by the reprecipitation method (details are described in the flowing section 2). Employing these anticancer drug and fluorescent dye nanocrystals are superior in anticancer function and excellent fluorescent cell imaging, which are at least comparable with conventional manner. The crystals are most densely packed structure of molecules and nanocrystals are too. Therefore, the amounts of molecules in nanocrystals, which consist of 100% of molecules, are higher than that of the same size of nano carriers, 14

Crystals of stilbazolium p-toluenesulfonate for second-order nonlinear optics

Abstract Crystal growth of 1-methyl-4-(2-(4-methoxyphenyl)vinyl)pyridinium 4-toluenesulfonate (methoxystilbazolium p-toluenesulfonate) was performed by slow evaporation method and two different crystals were found. Crystals grown from methanol solution were second-harmonic generation (SHG) active. On the other hand, crystals grown from water solution were SHG inactive. X-ray crystal structure analysis revealed that in the latter case, the chiral-handle character of p-toluenesulfonate (pTS) anion is obstructed by the hydrogen bonding between two pTS anions and water molecules incorporated during crystallization. The effective d value of SHG active crystals attained on the (010) plane was, as a preliminary result, 190 pm/V at the pumping wavelength of 1064 nm.

Functional Organic Nanocrystals

The topic in this chapter concerns organic nanocrystals. Numerous scientific researches of nanocrystals are focusing on inorganic compounds such as a metal and a semiconductor. The research related to organic nanocrystals is relatively new compared to that of inorganic nanocrystals. Nearly two decades ago, our research team had developed a novel preparation method of organic nanocrystals, what we call the reprecipitation method. Since then, we have been leading the research area of organic nanocrystals. The reprecipitation method has bottom-up type with a wet process procedure to prepare organic nanocrystals, and organic nanocrystals are obtained as their water dispersion. Numerous numbers of organic compounds are allowed to be a candidate for a targeting of organic nanocrystals by means of using the reprecipitation method. Functional organic nanocrystals have been attracted in a scientific and technological area of materials. In this chapter, first we mention the research back ground of organic nanocrystals, and then introduce the preparation method of organic nanocrystals, i.e. the reprecipitation method, and their improved ones. Then, several kinds of functional organic nanocrystals relating to optoelectrical materials, nanomedicine, and biophotonics are mentioned. Recent topics of organic nanocrystals achieved by several groups are briefly introduced. In this chapter, the topics are proceeding as follows: 1. Back ground of the research of organic nanocrystals 2. Preparation method of organic nanocrystals 3. Several functional organic nanocrystals 4. Recent topics of organic nanocrystals achieved by several groups

Polydiacethylenes with directly bound aromatic substituents for the enlarged third-order nonlinearity

In order to obtain the polydiacetylenes with aromatic substituents directly bound to the polymer backbone, many of unsymmetrical diacetylene derivatives with aromatic rings at one side and carbazolylmethyl at the other side of diacetylene moiety have been synthesized. Among them, 1-(3,5-bis(trifluoromethyl)phenyl)-5- (N-carbazolyl)-1,3--pentadiyne (DFCP) was found to be topochemically polymerized with complete conversion into the polymer single crystals. Spectroscopies and X- ray crystal structure analysis revealed that the fr-conjugation between the polymer backbone and the phenyl ring of this polymer are in the similar extent to those of the so-far prepared poly(diphenyldiacetylene)s in spit çf mono- aromatic-substituted polydiacetylene. Nearly the same magnitude of as the largest reported for polydiacetylenes was evaluated from third harmonic generation.

Application 42 – Fabrication technique of organic nanocrystals and their optical properties and materialization

Abstract Organic nanocrystals are, for the definition, crystals of nanometer order of an organic compound. Organic nanocrystals are the nanomaterials that have been attracting attention in recent years because they show some interesting characteristics for basic science, and many applications using organic nanocrystals are expected as well.

X-ray photoacoustic absorption spectra of CuInSe2

The X-ray photoacoustic absorption spectrum (Cu K-edge) of CuInSe 2 , which has a chalcopyrite structure and applications to solar cells, has been measured together with that of pure Cu metal as a reference, using synchrotron radiation. It is shown that the information derived from X-ray absorption near edge structure (XANES) is also included in the photoacoustic X-ray absorption spectrum which reflects heat generation processes in material. The first energy peak value in the XANES region in CuInSe 2 shifts to lower energy than that of pure Cu metal, indicating a chemical shift in CuInSe 2 .