Organic microcrystals ranging from several tens nm to µm in size of chromophores were successfully prepared by simply dispersing ethanol solutions compounds into stirred water, i.e. a reprecipitation method. The was found depend on concentration solutions, conditions, temperature and so on.

Perylene microcrystals with different sizes from about 50 nm to 200 were prepared using the reprecipitation method. Their excitonic absorption peaks found shift high energy side decreasing crystal size, that is say, shifts of bulk 500 cm -1 and 1420 for microcrystals, respectively. Moreover, strong fluorescence free-exciton level in was observed even at room temperature, which not usually crystals.

A method for preparing nanoparticles of a water-insoluble drug that are suitable administration to the human body has been established. reprecipitation was used fabricate 50 nm dimerized SN-38, an anticancer camptothecin derivative, form stable aqueous dispersions and can penetrate into cancer cells inhibit cell proliferation more potently than irinotecan.

Abstract Controlling or switching the optical signal from a large collection of molecules with minimum photons represents an extremely attractive concept. Promising fundamental and practical applications may be derived such photon‐saving principle. With this aim in mind, we have prepared fluorescent photochromic organic nanoparticles (NPs), showing bright red emission, complete ON–OFF contrast full reversibility, excellent fatigue resistance. Most interestingly, upon successive UV visible...

Topochemical [2 + 2] cycloaddition polymerization of methyl p-phenylenediacrylate and 2,5-distyrylpyridine in nanocrystals, prepared by the reprecipitation method, were investigated comparison with those bulk crystals. The single crystals, larger than 1 μm size, broke into microcrystals variety size shape course polymerization. Interestingly, however, these nanocrystals show single-crystal-to-single-crystal transformation.

Abstract In this study, we found that, in perylene microcrystals, luminescence peak position from free-exciton state was gradually shifted to high energy side with reducing the crystal size, even if microcrystals were fabricated by different kinds of preparation techniques. The life time self-trapped exciton became shorter when size reduced. main reason estimated be based on change lattice state.

Abstract The crystal growth of α-perylene microcrystals in the reprecipitation method was studied using light-scattering technique and absorption spectroscopy. A certain model for microcrystallization has been established. relationship between conditions size clarified on basis this model. Especially, water temperature confirmed to be one most important parameters used control method. apparent activation energy perylene estimated 68 kJ mol−1.

Polyimide (PI) is a candidate material that showing promise for use in wide range of applications several advanced technologies. In this study, we employed the reprecipitation method and subsequent imidization to prepare unique hollow PI nanoparticles (NPs) by blending suitable polymer porogen with precursor form individual NPs. The structures were induced through phase separation between porogen, process was influenced compatibility two polymers. We then assembled multilayered films...

Porous polyimide (PI) nanoparticles were fabricated using the reprecipitation method, with a second polymer as porogen, and subsequent imidization. Poly(acrylic acid) was suitable porogen for generating unprecedented PI having superficial nanopores, sizes of which in range 20−70 nm. The porous morphology affected mainly by molecular weight content poly(acrylic acid). After thermal imidization, almost no remained inside nanoparticles. Infrared spectroscopy thermogravimetric analysis indicated...

The preparation of fullerene fine crystals with uniform size and shape would permit the control their specific electronic energy levels fabrication materials completely new properties. To this end, we have successfully fabricated, for first time, shape- size-controlled C60 using a reprecipitation method developed in our laboratory. obtained were clearly monodisperse came an interesting diversity shapes such as spherical, rodlike, fibrous, disk, octahedral. We able to selectively these sizes...

We have fabricated well-defined nanostructures such as SiO2-coated Ag nanoparticles (NPs) connected with quantum dots (QDs) (Ag/SiO2-QDs) so to control the fluorescence enhancement induced by localized surface plasmon resonance. Namely, distance between NP and QD should be noted a controllable model investigate effect. Actually, highly monodispersed core was first coated five thicknesses of SiO2 shell, then QDs were specifically adsorbed onto amino-functionalized NPs. As result, intensity...

Aiming at the preparation of nanometer-size polydiacetylene microcrystals, crystallization process during reprecipitation method was investigated using electron micrographs and light-scattering technique. We found that an amorphous nanoparticle formed initially subsequently crystallized. conclude nanoparticles must be sufficiently small in order to achieve crystals.

Second-order hyperpolarizabilities (β), electron distribution, dipole moment, and excitation energy together with oscillator strength of stilbazolium cations have been investigated by a semiempirical calculation PM3 parametrization the MNDO Hamiltonian. Since stilbazoliums were found to generally several times larger β value than nitrostilbene derivatives similar experimental absorption maximum wavelength, such ionic species are concluded be advantageous create new second-order nonlinear...

We have investigated size-dependent optical properties of poly-1,6-di(N-carbazolyl)-2,4-hexadiyne (poly-DCHD) nanocrystals in ensemble and a single particle level. Our experimental results demonstrate that far-field microscopy coupled with an AFM setup is reliable approach for investigating organic nanoparticles. Single poly-DCHD show resonant Rayleigh scattering spectra lower resonance energy peak having larger cross-section against its long axis. also examined the extinction Raman their...

We found that monodispersed C60 micro/nanocrystals (M/NCs) with unique multibranched structures can be fabricated by reprecipitation method, using m-xylene and 2-propanol as good poor solvents, respectively. The resulting M/NCs had a hexagonal crystal structure was to kind of solvates in which the molar ratio 3:2. seem important nanoparts an integrated device.

Polythiophene films were synthesized by electrolytic polymerization, and the synthetic parameters their thermoelectric properties, i.e., Seebeck coefficient electric conductivity, investigated in detail. The tended to decrease with increasing conductivity. However, power factor increased was 1.03×10-5 W·m-1·K-2 at 23 µV·K-1 201 S·cm-1. This value is large compared those of other conductive polymers, figure merit reached one thirty against Bi–Te system. In addition, elaborated surface...

Abstract Nano eye-drops are a new type of ophthalmic treatment with increased potency and reduced side effects. Compounds in conventional barely penetrate into the eye because cornea, located at surface eye, has strong barrier function for preventing invasion hydrophilic or large-sized materials from outside. In this work, we describe utility nano utilising brinzolamide, commercially available glaucoma drug, as target compound. Fabrication nanoparticles brinzolamide prodrug increases...

Abstract We have presented a simple technique for the fabrication of nanocrystals organic molecules and polymers shown that it is possible, using liquid‐phase technique, to fabricate ranging in size from 10 nm 1 μm by manipulating preparative conditions. In particular, poly(4‐BCMU) 20 350 were prepared controlling preparation The main advantages are practicality suitability wide range materials. nanocrystals, though at very early stage, seems promising approach producing low‐dimensional...

Abstract The microcrystals formation process of diacetylene (DCHD) in the reprecipitation method has been investigated by SEM and light scattering. Amorphous DCHD particles were confirmed to be formed first, then crystallize. size control monomer could achieved controlling such amorphous particles, which depended on concentration injected solution. solid-state polymerization was carried out UV-irradiation, resulting poly-DCHD 50 nm 150 nm. unchanged during polymerization. By adding SDS...

The controlled release of an anticancer agent from drug nanoparticles could be successfully achieved by optimizing the chemical structure dimeric compounds as prodrug.

Abstract Effective control of drug release from “nano-prodrugs”, which are nanoparticles composed water-insoluble prodrug compounds is one the most important determinants balance between efficacy and side effects. However, chemical behaviors nano-prodrugs in relation to poorly characterized. We created using a series fatty acid ester (C2–C18) derivatives 7-ethyl-10-hydroxycamptothecin (SN-38) found that their vitro cytotoxic activities decreased as length chain increased. The cytotoxicities...

A series of five fluorescent and ionic dimethylamino stilbazolium homologues with increasing conjugation length (from ethenyl to decapentaenyl) is investigated by high-frequency, amplitude-modulated femtosecond hyper-Rayleigh scattering at 1300 nm. hyperpolarizability value that not overestimated the presence a multiphoton fluorescence contribution obtained from Fourier analysis signal. The demodulation curve (decrease amplitude versus modulation frequency) characterized both decay...

Photoinduced charge separation and recombination processes in fine particles of octathiophene-C60 dodecathiophene-C60 dyad molecules were investigated by the subpicosecond laser photolysis method. Sizes particle samples estimated to be 60−140 nm using SEM observation dynamic light scattering measurements. Charge separated states generated within 1 ps upon 150 fs excitation both molecules. Generation yields about a half those corresponding polar solvents, indicating existence competitive...