Biomedical subjects
Publications and source records attributed to Daoben Zhu.
The fluorescence of a triad with TTF and anthracence units can be reversibly modulated by sequential oxidation and reduction. Thus, a new redox fluorescence switch can be established on the basis of this new triad. [structure: see text]
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The influence of polyanilines (PANIs) as hole conductors on the photovoltaic behaviors of dye-sensitized solar cells is studied. The current-voltage (I-V) characteristics and the incident photon to current conversion efficiency (IPCE) curves of the devices are determined as the function of different conductivities and morphologies of PANIs. The results show that the conductivity of PANIs affects the performance of the devices greatly, and PANI with the intermediate conductivity value (3.5 S/cm) is optimum. In addition, the effects of both the film formation property and the cluster size of polyanilines on the photovoltaic behaviors of the devices are also discussed.
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A C60-pyrrolidine derivative with a hydrophobic-hydrophilic-hydrophobic structure (2-{3,4-di{2-[2-(2-decyloxyethoxy)ethoxy]ethoxy}}phenyl-3,4-fulleropyrrolidine, DTPF) has been synthesized and well-characterized. This compound could form stable nanospheres by simply injectingits tetrahydrofuran (THF) solution into water and then removing THF by purging gaseous nitrogen in sequence. Novel nanoassemblies of DTPF nanospheres and gold nanoparticles were obtained through in situ photoreduction of aqueous HAuCl4 in the presence of DTPF nanospheres, which were confirmed by UV-visible, transmission electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy methods. It is proposed that the interaction between the positively charged nitrogen atom and the gold nanoparticles is the main driving force for the formation of the nanoassemblies.
The fluorescence of 1-imino nitroxide pyrene can be significantly enhanced only under the combined actions of Cys and CF(3)COOH; such spectral change upon the actions of two chemical inputs mimics the performance of an "AND" gate.
By pyrolysis of CdS powder in inert gas, single-crystalline cadmium nanotubes growing in the form of a heap, were produced for the first time in high yield.
Remarkable surface wettability transition occurs with an inducement of ultraviolet (UV) for aligned ZnO nanorod films. The inorganic oxide films, which show super-hydrophobicity (left), become super-hydrophilic (right) when exposed to UV illumination. After the films are placed in the dark, the wettability evolves back to super-hydrophobicity. This reversible effect is ascribed to the cooperation of the surface photosensitivity and the aligned nanostructure. Such special property will greatly extend the applications of ZnO films.
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A novel, water-soluble, cationic PPV derivative poly[(2,5-bis(3-bromotrimethylammoniopropoxy)-phenylene-1,4-divinylene)-alt-1,4-(2,5-bis(2-(2-hydroxyethoxy)ethoxy))phenylene vinylene] (BH-PPV) has been synthesized by a Heck coupling reaction. Multilayered assemblies of the BH-PPV and the sodium salt of hexa(sulfobutyl)fullerenes (C(60)-HS) were fabricated successfully by an alternate deposition technique. The multilayer structures were studied by UV/Vis spectroscopy, small angle X-ray diffraction, and atomic force microscopy. The photoinduced charge transfer property of the self-assembled multilayer film was also measured by a three-electrode cell technique. A steady and rapid cathodic 5.5 microA cm(-2) photocurrent response was measured as the irradiation of the multilayer film was switched on and off. Importantly, the response of on/off cycling is prompt and reproducible. A possible mechanism for the electron-transfer process is proposed.
Three-dimensional anisotropic aligned carbon nanotube microstructures were constructed by the chemical vapor deposition method on silicon templates with well-defined structure. It brought about new properties of wettability. Superhydrophobic (contact angle > 150 degrees ) and very hydrophilic (contact angle < 30 degrees ) properties can both be achieved by a simple change of structural parameter.
Bis(2-(2-hydroxyphenyl)benzothiazolate)zinc (Zn(BTZ)(2)) is one of the best white electroluminescent materials used in organic light-emitting diodes (LEDs). Despite a large number of studies devoted to this complex, very little is known about its basic molecular and electronic structures and electron transport properties in LEDs. Therefore, we investigate the structures and electroluminescent properties. The unsolvated single crystal of Zn(BTZ)(2) was grown and its crystalline structure was determined from X-ray diffraction data. The crystal is triclinic, space group P-1, a = 9.4890(19) A, b = 9.5687(19) A, c = 11.685(2) A, alpha = 84.38(3) degrees, beta = 78.94(3) degrees, gamma = 83.32(3) degrees. The structure of the chelate is dimeric [Zn(BTZ)(2)](2) with two isotropic Zn(2+) ion centers having five-coordinate geometry. The present study provides direct evidence for the sole existence of dimeric structure in the powder and the thin film. The dimer is energetically more stable than the monomer. Analysis of the electronic structure of [Zn(BTZ)(2)](2) calculated by density functional theory reveals a localization of orbital and the distribution of four orbital "tetrads". The structural stabilities of both anion and cation and the distribution of the hole in the cation and that of the excess electron in the anion are discussed in terms of theoretical calculations. Strong intermolecular interaction may be expected to enable good electron transport properties as compared with tris(8-hydroxyquinolinato)aluminum.
Since the discovery of carbon nanotubes by lijima in 1991, various carbon nanotubes with either a single- or multilayered graphene cylinder(s) have been produced, along with their noncarbon counterparts (for example, inorganic and polymer nanotubes). These nanostructured materials often possess size-dependent properties and show new phenomena related to the nanosize confinement of the charge carriers inside, which leads to the possibility of developing new materials with useful properties and advanced devices with desirable features for a wide range of applications. In particular, carbon nanotubes have been shown to exhibit superior properties attractive for various potential applications, ranging from their use as novel electron emitters in flat-panel displays to electrodes in electrochemical sensors. For many of the applications, it is highly desirable to have aligned/patterned forms of carbon nanotubes so that their structure/property can be easily assessed and so that they can be effectively incorporated into devices. In this Review, we present an overview on the development of aligned and micropatterned nanotubes, with an emphasis on carbon nanotubes.
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The synthesis of anthracene (AN) nanowires and perylene (PY) nanorods on the basis of solid-phase organic reactions under controlled conditions is discussed, and the structures are confirmed by SEM, TEM, and XRD. The dimension-dependent emission properties of the AN nanowires and PY nanorods is observed. This approach is expected to form a new general route for the controlled morphosynthesis of organic molecular materials in restricted dimensions, with controlled size and shape, the solid-state physical properties of which are of great interest. It should have outstanding potential in providing customized 1D nanomaterials for a broad range of applications for molecule devices and nanoscience and is expected to be applicable other functionalized nanomaterials (i.e., organic, inorganic, and polymer).
The present paper investigated the molecular configurations of the two novel amphiphiles with Schiff base moiety as headgroup in LB films. FTIR-ATR spectra and UV-vis electronic absorption spectra revealed the different isomers between the two amphiphiles LB film. Since z.sbnd;OH groups situate in different position of the aromic rings in Schiff base amphiphiles, the proton transfer by different ways leads to different isomers, which were reflected by monolayer and LB films behavior.
The photoinduced interaction of fluorescein ester derivatives, fluorescein's butyl ester (FL4) and fluorescein's anthraquinone-methyl ester (FL-AQ), and colloidal CdS was examined by absorption, fluorescence spectroscopy, and photoinduced ESR spectroscopy. It is found that FL4 and FL-AQ molecules are adsorbed on the surfaces of CdS colloid by an electrostatic interaction forming the surface complex of the type CdS-FL4 or CdS-FL-AQ. The apparent association constant (K(app)) and the degree of association (alpha) of CdS-FL4 obtained from absorption spectra are 2.25 x 10(4) M(-1) and 0.78, respectively. The values of K(app) and alpha of CdS-FL4 as determined from fluorescence spectra are 1.54 x 10(4) M(-1) and 0.82, respectively, which matches well with that determined from the absorption spectra changes. And the values of K(app) and alpha of CdS-FL-AQ obtained from absorption spectra are 4.18 x 10(4) M(-1) and 0.83, respectively. These data indicate that there is a strong interaction between the dye and the CdS particle surface. But there was no evidence for interfacial electron transfer from FL4 or FL-AQ to colloidal CdS by photoinduced ESR experiments. The fluorescence quenching is due to the formation of a nonfluorescent complex. The related phenomena are discussed in this paper.
A new dyad 1 with two spiropyran units as the photochromic acceptors and one fluorescein unit as the fluorescent donor was synthesized and characterized. External inputs (ultraviolet light, visible light, and proton) induce the reversible changes of the structure and, concomitantly, the absorption spectrum of dyad 1 due to the presence of two spiropyran units. Only the absorption spectrum of the ME form of the spiropyran units in dyad 1 has large spectral overlap with the fluorescence spectrum of the fluorescein unit. Thus, the fluorescence intensity of dyad 1 is modulated by reversible conversion among the three states of the photochromic spiropyran units and the fluorescence resonance energy transfer (FRET) between the ME form and the fluorescein unit. Based on the fact that dyad 1 could "read out" three external input signals (ultraviolet light, visible ligh,t and proton) and "write" a compatible specific output signal (fluorescence intensity), dyad 1 described here can be considered to perform an integrated circuit function with one OR and one AND interconnected logic gates. The present results demonstrate an efficient strategy for elaborating and transmitting information at the single molecular level.