Biomedical subjects
Publications and source records attributed to Huibiao Liu.
The syntheses of N-confused phlorins are provided by reactions of N-confused porphyrins with nitrilimines and with dialkyl acetylenedicarboxylate. Both reactions involve zwitterionic intermediates and proceed through an addition/cyclization pathway.
Novel dibenzocoronenetetracarboxylic acid diimide analogues and naphthoperylenetetracarboxylic acid diimide analogues containing imidazole, 1,2,4-triazole, and pyrazole rings embedded as functional constituents within the parent hydrocarbon backbone have been synthesized. The pi-rich and pi-poor heterocycles have different influences on the physical properties of the parent benzocoronenetetracarboxylic acid diimide and naphthoperylenetetracarboxylic acid diimide systems. The pi-rich 3 was able to self-assemble into one-dimensional nanostructures through strong pi-pi stacking, whereas the pi-poor 8 lacked the one-dimensional self-assembly capability, thus offering the potential to control the self-assembly capability of the pi-conjugated perylene core by decoration with N-heterocycles.
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[reaction: see text] A facile method for the synthesis of pyrrolidin-2-one fused N-confused calix[4]phyrins is provided by reactions of 5,10,15,20-tetraaryl-2-aza-21-carbaporphyrin with acyl chlorides in the presence of triethylamine. The (1)H NMR and UV-vis spectra of products indicate their loss of macrocyclic aromaticity.
[structure: see text] New perylene bisimide dyes bearing 3,5-bis(2-hydroxyphenyl)-1,2,4-triazole receptor units with different spacers have been synthesized and characterized. The fluorescence and electronic properties of these compounds have been studied. MALDI-TOF, UV-vis, and fluorescence titration experiments proved that monotopic perylene bisimide ligands could be assembled into dimmers by Fe(III) coordination. The coordination properties of the ditopic perylene bisimide ligands have also been studied preliminarily. Furthermore, the SEM images indicated that well-defined nanoscale structures could be fabricated by self-assembly due to metal ion coordination and pi-pi stacking interactions of perylene rings with the help of a proper spacer.
[reaction: see text] A novel [2]rotaxane, containing pyrene and perylene bisimide as both stoppers and photoactive units, has been prepared. The shuttling of the protonated macrocycle switched the energy transfer (EN) from a pyrene moiety to a perylene moiety, which resulted in changes of fluorescence of the perylene moiety.
The paper described here concerns a challenge of general interest for producing a novel structure of a polymer aggregate, the achievement of nanowires with controlled diameters. We provide a strategy for fabricating a supramolecular polymer, in which ordered polydiacetylene nanowires can be obtained by associated self-polymerization and self-assembly processes. The polymer nanowire film shows excellent field emission properties with the turn-on field of 8.2 V/mum at 10 muA/cm2 and the maximum current density of 5 mA/cm2 at an applied field of 15 V/mum.
An ultrathin nanoscopic multilayer film has been fabricated through the electrostatic layer-by-layer self-assembly of negatively charged 5,10,15,20-tetrakis(3,4,5-trihydroxyphenyl)porphyrin (DHP) and oppositely charged polyethylenimine (PEI). UV-vis spectra showed a continuous and uniform deposition process of PEI and DHP. The film structure was characterized by small-angle X-ray diffraction measurement and AFM images. The nonlinear optical properties of ultrathin film were studied by Z-scan technique with laser duration of 8 ns at a wavelength of 532 nm. The film sample exhibited strong nonlinear saturated absorption and a self-defocusing effect. The nonlinear absorption coefficient and refractive index of the self-assembly ultrathin film are -9.7 x 10(-5) m/W and -7.56 x 10(-12) m(2)/W, respectively.
Synthesis, characterizations, and photophysical properties of new photoactive dyads and triads containing perylenetetracarboxylic diimide (PIm) and porphyrin (free-base porphyrin (H(2)P) and zinc porphyrin (ZnP)), in which both entities were connected with a short ether bond, were examined with the aim of using these systems for molecular photonics. The porphyrin(P)-PIm systems absorbed strongly across the visible region, which greatly matched the solar spectrum. The geometric and electronic structures of the dyads and triads were probed using density function theory method at the B3LYP/3-21G level. It was revealed that the majority of the highest-occupied molecular orbital was located on the porphyrin entity, while the lowest-unoccupied molecular orbitals were entirely on the PIm entity. The excited-state electron-transfer processes were monitored by both steady-state and time-resolved emission as well as transient-absorption techniques in polar solvent benzonitrile. Upon excitation of the P (H(2)P and ZnP) moieties, efficient fluorescence quenching of the P moiety was observed, suggesting that the main quenching paths involved charge separation from the excited singlet porphyrin ((1)P) to the PIm moiety. Upon excitation of the PIm moiety, fluorescence quenching of the (1)PIm moiety was also observed. The nanosecond transience of spectra in near-IR region revealed the charge separation process from the P moieties to the PIm moiety via their excited singlet states. The lifetimes of the charge-separated states were evaluated to be 7-14 ns, depending on the solvent polarity. Photosensitized electron mediation systems were also revealed in the presence of methyl viologen and sacrificial electron donor.
In this contribution, large-area organic charge-transfer complex (AgTCNQ and CuTCNQ) nanowires were synthesized by organic vapor-solid-phase reaction at mild experimental conditions. These nanowires were facilitated on the surface of Cu and Ag foils or different kinds of substrates coated with a layer of silver and copper on a large scale. The excellent field emission properties were observed in the as-grown AgTCNQ and CuTCNQ nanowires. They should have great potential in vacuum device applications.
An ultrathin composite film containing anionic Ag-His complexes (His: L-Histidine) and oppositely charged BH-PPV was fabricated by means of the electrostatic layer-by-layer self-assembly technique. UV/Vis spectra showed a continuous deposition process of Ag-His complexes and BH-PPV. The film structure was characterized by using small-angle X-ray diffraction, AFM, and SEM. The nonlinear optical properties of the ultrathin film were studied by using the Z-scan technique with a laser duration of 8 ns at a wavelength of 532 nm. The film sample exhibited a strong nonlinear saturated absorption, with an alpha2 value of -3.9 x 10(-5) mW(-1) and a self-defocusing effect with an n2 value of -4.78 x 10 (-12) m2W(-1).
A class of bis-urea compounds with perylene bisimide was synthesized and characterized successfully. (1)H NMR and fluorescence spectra confirmed that strong hydrogen-bonding interactions between neighboring urea groups were formed. Interestingly, the photocurrent measurement showed that the self-assembled films of bis-urea compounds could produce steady and rapid anodic photocurrent responses. The TEM images indicated that well-defined nanoscale rods with uniform diameter distribution could be fabricated by self-assembly of hydrogen-bonding interactions and pi-pi stacking interactions of perylene rings.
A supramolecular system of a perylene derivative containing bis(2,6-diacylaminopyridine) units and a perylene bisimide bound through three hydrogen-bonds was synthesized and characterized. 1H NMR spectra confirmed the existence of hydrogen-bonding interactions between the perylene derivative (3) and the perylene bisimide (7). The photocurrent generation of the self-assembled 3.7 film was measured, and a cathodic photocurrent response was obtained. SEM images indicated that well-defined long fibers could be fabricated by self-assembly, by exploiting the hydrogen bonding interactions and pi-pi stacking interactions of perylene rings.
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.
Aligned organic nanotubes of perylene with uniform diameters, lengths and wall thicknesses were fabricated via a simple immersion technique using a porous alumina membrane as the template.
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).
In this contribution we have developed a useful and experimentally easy way to use C60 powder to directly fabricate C60 nanotubes with a mondisperse size distribution and uniform orientation. The structure of C60 nanotubes was confirmed by SEM, TEM, and FT-IR.
[structure: see text] Three novel fullerene derivatives bearing a 2,6-bis(acylamino) pyridine unit as a hydrogen bonding motif displaying a dimerization tendency were synthesized and characterized by the cycloaddition reaction of alkyl azide to [60]fullerene. An SEM image of the dimerization system of compound 1 indicated spherical particles having a mean diameter of 15 nm with a rather narrow size distribution.