Beta-1,3-glucan polysaccharide can act as a one-dimensional host to create novel silica nanofiber structures

We have demonstrated that the creation of novel silica nanofibers with a uniform diameter is possible by utilizing beta-1,3-glucan polysaccharide as a one-dimensional host for monoalkoxysilane; the finding establishes that beta-1,3-glucan can act not only as a novel one-dimensional host for metal alkoxide polycondensation but also as an interface between inorganic nanofibers and functional organic molecules.     

Beta-1,3-glucan polysaccharide (schizophyllan) acting as a one-dimensional host for creating supramolecular dye assemblies

We have demonstrated that one-dimensional supramolecular dye assemblies with a uniform diameter can be created by utilizing schizophyllan (SPG) as a one-dimensional host. In the supramolecular nanofibers, the dye molecules are assembled into the different aggregation modes depending on the preparation procedures. The findings establish that SPG is useful for creating the supramolecular nanofibers, where temporal superstructures can be stabilized by the SPG-specific helical higher-order structure. [structure: see text].     

Beta-1,3-glucan (schizophyllan) can act as a one-dimensional host for creation of novel poly(aniline) nanofiber structures

We here demonstrate the creation of novel poly(aniline) (PANI) nanofiber structures by a polymer wrapping method using schizophyllan (SPG). Mannose-modified SPG can also wrap PANIs to give nanofibers having a lectin affinity. This interaction is applicable to designing novel PANI/protein composites. The results establish that SPG can act as a novel "host" to assemble PANIs into one-dimensional superstructures. [reaction: see text]     

Click-chemistry as an efficient synthetic tool for the preparation of novel conjugated polymers

The Cu(I)-catalysed 1,3-dipolar "click" cycloaddition is utilised as an efficient reaction for the preparation of novel fluorene-based conjugated polymers.     

Efficient synthesis and characterization of novel bibenzimidazole oligomers and polymers as potential conjugated chelating ligands

[Structure: see text]. A simple and mild condensation route for the synthesis of novel bibenzimidazole oligomers and polymers is reported here using methyl 2,2,2-trichloroacetimidate as a key starting material. The dimer, trimer, tetramer, and polymers of bibenzimidazole were synthesized as a new series of potential conjugated chelating ligands for metallopolymer studies. The polymers show a maximum absorption at around 400 nm. The optical band gap of the polymer was estimated to be 2.68 eV.     

Zeolites as hosts for novel optical and electronic materials

A review of the use of zeolites as hosts for electronically active guest materials is presented. Metal, semiconductor and conductive polymer nanoparticles as electronic and optical material composites are reported with special emphasis on their synthesis.     

Preparation,morphology, and biolabeling of fluorescent nanoparticles based on conjugated polymers by emulsion polymerization

Novel nanoparticles based on conjugated polymer with good fluorescent properties were synthesized by Suzuki coupling reaction using certain surfactants as one kind of special emulsion polymerization. The luminescent properties of the prepared nanoparticles could be controlled by selecting different monomers. Without using substances comprising any heavy metal element, these fluorescent nanoparticles show very good biocompatibility with cells, thus showing potential applications in cell biolabeling, drug delivery tracing, organic light‐emitting diodes, flat displays, and other areas. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

A novel fabrication technique and new conjugated polymers for multilayer polymer light-emitting diodes

We report a novel fabrication technique for multilayer light-emitting diodes composed of new polyoxadiazole, POD, conjugated polymers for the first time. The fabrication technique called vapor deposition polymerization is described. Chemical modification of monomers brought about the enhancement of reactivity and the production of high molecular weight of POD. Emission color with photoexcitation was controllable from violet-blue to green by varying the chemical structures of PODs. It was found that PODs could be employed as either electroluminescent or carrier-injecting layers by the optimization of the device structure. Two types of bilayer devices, which are constructed with POD/tris (8-quinolinoato) aluminum, Alq₃, and with two POD layers with different chemical structures, were investigated. Carrier injection begins in the POD/Alq₃ bilayer device near 7 V, and the device emitted green light from Alq₃. The maximum luminance of the POD/Alq₃ device reached 3500 cd/m². The POD/POD bilayer device emitted blue light with maximum luminance of 21 cd/m². Electroluminescence spectra of the devices coincided with photoluminescence spectra of each emitting material used. © 1997 John Wiley & Sons, Ltd.     

Semiconducting nanocrystals,conjugated polymers,and conjugated polymer/nanocrystal nanohybrids and their usage in solar cells

As one of the major renewable energy sources, solar energy has the potential to become an essential component of future global energy production. With the increasing demand in energy, the harvesting of solar energy using inexpensive materials and manufacturing methods has attracted considerable attention. Organic/inorganic (i.e., conjugated polymer/nanocrystal (CP/NC)) nanohybrid solar cell, including both physically mixed CP/NC composites and covalently linked CP-NC nanocomposites, is one of the several most promising alternative, cost-effective concepts for solar-to-electric energy conversion that has been offered to challenge conventional Si solar cells over the past decade. It has low fabrication cost and capability of large-scale production. However, to date, the highest power conversion efficiency (PCE) of organic/inorganic nanohybrid solar cells has been reported to be only 5.5%, which is still lower than the theoretical prediction of more than 10%. Several problems, i. e., microscopic phase separation of semiconducting CPs and NCs, low charge injection, and low carrier collection, have not been well addressed. More research remains to be done to improve the efficiency of CP/NC nanohybrid solar cells. In this review article, the recent advances in solving these problems were discussed. For the CP/NC solar cells prepared by physically mixing electron donating CP and electron accepting NC (i.e., forming CP/NC composites), methods involving the use of solvent mixtures and ligand modification to control the phase separation at the nanoscale are discussed; the implications of intriguing anisotropic NCs as well as their assemblies (i.e., NC arrays) on improving the charge collection are presented. For newly developed CP/NC solar cells prepared by chemically tethering CP chains on the NC surface (i.e., yielding CP-NC nanocomposites, thereby preventing microscopic phase separation of CP and NC and improving their electronic interaction), recent strategies on the synthesis of such nanocomposites and their photovoltaic performance are discussed.     

A novel family of ordered,mesoporous inorganic/organic hybrid polymers containing covalently and multiply bound microporous organic hosts

We have prepared a new family of periodic hybrid polymers containing microporous cavities provided by covalently bound organic hosts. Cyclodextrin (CD) or calixarene (CX) hosts are attached to four or more trialkoxysilyl groups, which are polymerized to form a polysilsesquioxane matrix. Structural integrity is provided by copolymerization with tetraethoxysilane, which produces a polysilicate co-matrix. Periodic order is created by carrying out the polymerization in the presence of a surfactant, cetyltrimethylammonium bromide. The resulting as-synthesized polymers from these three starting materials were characterized by solid-state nuclear magnetic resonance spectroscopy. The (13)C and (29)Si spectra provided evidence for intact polysilsesquioxane, polysilicate, organic host, and surfactant. Removal of the surfactant by washing produced a polymer containing cavities of mesoporous dimensions, in addition to the microporous host cavities. The purpose of introducing mesoporosity is to allow enhanced access of guests to the microporous hosts. Transmission electron microscopy demonstrated that both as-synthesized and solvent-extracted polymers have a periodic structure. All polymers are completely insoluble in water. The as-synthesized CD-containing polymers extracted up to >99% of 4-nitrophenol from aqueous solution, and the solvent-extracted CX-containing polymers extracted up to 67% of Fe(3+) and lesser amounts of other metal cations from aqueous solution, with interesting selectivity patterns. Simple filtration then removes the polymer containing the extracted organic molecule or metal cation. These extraction abilities are superior to previous materials.     

Circular DNA and DNA/RNA hybrid molecules as scaffolds for ricin inhibitor design

Ricin Toxin A-chain (RTA) catalyzes the hydrolytic depurination of A4324, the first adenosine of the GAGA tetra-loop portion of 28S eukaryotic ribosomal RNA. Truncated stem-loop versions of the 28S rRNA are RTA substrates. Here, we investigate circular DNA and DNA/RNA hybrid GAGA sequence oligonucleotides as minimal substrates and inhibitor scaffolds for RTA catalysis. Closing the 5'- and 3'-ends of a d(GAGA) tetraloop creates a substrate with 92-fold more activity with RTA (kcat/Km) than that for the d(GAGA) linear form. Circular substrates have catalytic rates (kcat) comparable to and exceeding those of RNA and DNA stem-loop substrates, respectively. RTA inhibition into the nanomolar range has been achieved by introducing an N-benzyl-hydroxypyrrolidine (N-Bn) transition state analogue at the RTA depurination site in a circular GAGA motif. The RNA/DNA hybrid oligonucleotide cyclic GdAGA provides a new scaffold for RTA inhibitor design, and cyclic G(N-Bn)GA is the smallest tight-binding RTA inhibitor (Ki = 70 nM). The design of such molecules that lack the base-paired stem-loop architecture opens new chemical synthetic approaches to RTA inhibition.     

Synthesis and characterization of novel conjugated polymers based on 3-cyclobutene-l,2-dione moiety

Three novel conjugated polymers bearing 3,4-bis(4-hexylthiophen-2-yl)-3-cyclobutene-1,2-dione unit in their main chain have been synthesized successfully in good yields through Suzuki or Stille coupling reaction.Their molecular structures have been confirmed by FT-IR,~1H NMR and ~(13)C NMR.All these copolymers exhibit broad and strong absorption bands in UV-vis region,and their optical band gaps are calculated to be 1.6-2.0 eV.suggesting that they have good coverage with the solar spectrum.These polymers...     

A structure and magnetic properties of one-dimensional manganese/cobalt coordination polymers with 5-nitro-1,3-benzenedicarboxylic acid and imidazole

One-dimensional manganese(II) complex, [Mn₂(5-nbdc)₂(imH)₆] · 2H₂O (1) (5-nbdcH₂ = 5-nitro-1,3-benzenedicarboxylic acid and imH = imidazole), has been hydrothermally synthesized and structurally characterized by X-ray crystallography with the following data: orthorhombic, space group Pna2(1), M _r = 972.63 for Mn₂C₃₄H₃₄N₁₄O₁₄, a = 13.3391(12) Å, b = 16.4657(15) Å, c = 18.2177(16) Å; V = 4001.3(6) ų, Z = 4, D _calcd 1.615 g cm^?3, µ = 0.718 mm^?1, the final R = 0.0490 and wR = 0.1277 for 7278 observed reflections (I > 2σ(I)). Complex 1 exhibits very weak intra-chain ferromagnetic coupling (J k^?1 = 0.001 K) with g = 1.930. The magnetism of a one-dimensional cobalt(II) complex [Co(5-nbdc)₂(imH)₂] _n (2) indicates weak intra-chain anti-ferromagnetic coupling (J k^?1 = ?0.067 K) with g = 2.0791.     

Tetracationic Bis-Triarylborane 1,3-Butadiyne as a Combined Fluorimetric and Raman Probe for Simultaneous and Selective Sensing of Various DNA,RNA, and Proteins

A bis-triarylborane tetracation (4-Ar₂B-3,5-Me₂C₆H₂)-C≡C−C≡C-(3,5-Me₂C₆H₂-4-BAr₂ [Ar=(2,6-Me₂-4-NMe₃-C₆H₂)⁺] ( 2⁴⁺ ) shows distinctly different behaviour in its fluorimetric response than that of our recently published bis-triarylborane 5-(4-Ar₂B-3,5-Me₂C₆H₂)-2,2′-(C₄H₂S)₂–5′-(3,5-Me₂C₆H₂-4-BAr₂) ( 3⁴⁺ ). Single-crystal X-ray diffraction data on the neutral bis-triarylborane precursor 2 N confirm its rod-like dumbbell structure, which is shown to be important for DNA/RNA targeting and also for BSA protein binding. Fluorimetric titrations with DNA/RNA/BSA revealed the very strong affinity of 2⁴⁺ and indicated the importance of the properties of the linker connecting the two triarylboranes. Using the butadiyne rather than a bithiophene linker resulted in an opposite emission effect (quenching vs. enhancement), and 2⁴⁺ bound to BSA 100 times stronger than 3⁴⁺ . Moreover, 2⁴⁺ interacted strongly with ss-RNA, and circular dichroism (CD) results suggest ss-RNA chain-wrapping around the rod-like bis-triarylborane dumbbell structure like a thread around a spindle, a very unusual mode of binding of ss-RNA with small molecules. Furthermore, 2⁴⁺ yielded strong Raman/SERS signals, allowing DNA or protein detection at ca. 10 nm concentrations. The above observations, combined with low cytotoxicity, efficient human cell uptake and organelle-selective accumulation make such compounds intriguing novel lead structures for bio-oriented, dual fluorescence/Raman-based applications.     

Octahydrogenated retinoic acid‐conjugated glycol chitosan nanoparticles as a novel carrier of azadirachtin: Synthesis,characterization, and in vitro evaluation

Environment‐friendly and controlled release formulation is highly promising for reducing environmental pollution and achieving the most effective utilization of pesticides. As a novel “green” nanocarrier of pesticides, amphiphilic self‐assembled nanoparticles were prepared by chemical conjugation of octahydrogenated retinoic acid (OR) to the backbone of glycol chitosan (GC). In aqueous media, the synthesized OR‐GC conjugates formed nanosized particles with a diameter of 257 nm. Hydrophobic azadirachtin (AZA) was efficiently loaded into the OR‐GC nanoparticles at a feed weight ratio of up to 1:4 using a simple dialysis method, the maximum drug‐loading efficiency of which was 74%. AZA‐OR‐GC (25 wt %) nanoparticles also showed sustained release of the incorporated AZA (65% of the loaded dose was released in 7 days at 27 °C in phosphate‐buffered saline; pH 7.2). Cytotoxicity tests and cell cycle arrest assays confirmed that OR‐GC exhibits good biocompatibility; AZA‐OR‐GC (25 wt %) nanoparticles also showed favorable inhibition of cell proliferation in Sl‐1 cells compared with free AZA in organic solvents. Overall, controlled release AZA‐OR‐GC may be a promising environment‐friendly formulation for integrated pest management. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3932–3940     

A novel one-pot, two-step synthesis of N-acyl-1,3-thiazolidines and N-acyl-1,3-oxazolidines as potential double prodrugs of formaldehyde

A convenient and general one-pot, two-step protocol to prepare both N-acyl-1,3-thiazolidines and N-acyl-1,3-oxazolidines from formaldehyde, fatty acyl chlorides, and natural α-amino acids has been performed for the peculiar case of formaldehyde. In the presence of triethylamine to promote both the ring-forming process and the amide bond formation, subsequent addition of the acyl donor proved to be efficient to trap the preformed stable formaldehyde-derived 1,3-thiazolidine or the transient 1,3-oxazolidine using an appropriate ratio of formaldehyde.     

Halogenated benzothiadiazole-based conjugated polymers as efficient photocatalysts for dye degradation and oxidative coupling of benzylamines

Donor-acceptor(D-A) conjugated polymers are widely used in photovoltaic applications and heterogeneous catalysis due to their tunable building block and pre-designable structures. Here, a series of adjustable Donor-acceptor(D-A) benzothiodiazole-based conjugated polymers were designed and synthesized. The photocatalytic performance could be improved by fine-tuning the chemical structure by halogen substitution(F or Cl). The polymers exhibited excellent optoelectronic properties and were effectiv...     

Cationic conjugated polyelectrolyte/molecular beacon complex for sensitive, sequence-specific, real-time DNA detection

A new fluorescence method has been developed for DNA detection at room temperature in a sensitive, selective, economical, and real-time manner that interfaces the superiority of a molecular beacon in mismatch discrimination with the light-harvesting property of water-soluble conjugated polyelectrolytes. The probe solution contains a cationic conjugated polyelectrolyte (PFP-NMe3+), a molecular beacon with a five base pairs double-stranded stem labeled at the 5'-terminus with fluorescein (DNA P-Fl), and ethidium bromide (EB, a specific intercalator of dsDNA). The electrostatic interactions between DNA P-Fl and PFP-NMe3+ keep them in close proximity, facilitating the fluorescence resonance energy transfer (FRET) from PFP-NMe3+ to fluorescein. Upon adding a complementary strand to the probe solution, the conformation of DNA P-Fl transits into dsDNA followed by the intercalation of EB into the grooves. Two-step FRET, from PFP-NMe3+ to DNA P-Fl (FRET-1), followed by FRET from DNA P-Fl to EB (FRET-2) takes place. In view of the observed fluorescein or EB emission changes, DNA can be detected in aqueous solution. Because the base mismatch in target DNA inhibits the transition of DNA P-Fl from the stem-loop to duplex structure, single nucleotide mismatch can be clearly detected.     

Synthesis, crystal structure and magnetism study on novel one-dimensional Cu(II) coordination polymers with 2,5-dimethylpyrazine-1,4-dioxide as bridging ligand

A novel one-dimensional coordination polymer [Cu(μ _1,6-dmpzdo)(dmpzdo)₂]·(ClO₄)₂ (dmpzdo = 2,5-dimethylpyrazine-1,4-dioxide) has been synthesized and its crystal structure determined by X-ray crystallography. In the complex each Cu1 atom is located in a square planar coordination environment with two oxygen atoms O2 and O2A from two dmpzdo terminal ligands, and two other oxygen atoms O3 and O3A from two μ _1,6-dmpzdo bridging ligands. The one-dimensional chain is constructed by the coordination of a μ _1,6-dmpzdo bridging ligand and Cu(II) ions. The data of the variable temperature (4–300 K) magnetic susceptibilities were fitted by using the one-dimensional chain fitting formula, which gave the magnetic coupling constants 2J = −98.88 cm⁻¹.     

Design and synthesis of monofunctionalized, water-soluble conjugated polymers for biosensing and imaging applications

Water-soluble conjugated polymers with controlled molecular weight characteristics, absence of ionic groups, high emission quantum yields, and end groups capable of selective reactions of wide scope are desirable for improving their performance in various applications and, in particular, fluorescent biosensor schemes. The synthesis of such a structure is described herein. 2-Bromo-7-iodofluorene with octakis(ethylene glycol) monomethyl ether chains at the 9,9'-positions, i.e., compound 4, was prepared as the reactive premonomer. A high-yielding synthesis of the organometallic initiator (dppe)Ni(Ph)Br (dppe = 1,2-bis(diphenylphosphino)ethane) was designed and implemented, and the resulting product was characterized by single-crystal X-ray diffraction techniques. Polymerization of 4 by (dppe)Ni(Ph)Br can be carried out in less than 30 s, affording excellent control over the average molecular weight and polydispersity of the product. Quenching of the polymerization with [2-(trimethylsilyl)ethynyl]magnesium bromide yields silylacetylene-terminated water-soluble poly(fluorene) with a photoluminescence quantum efficiency of 80%. Desilylation, followed by copper-catalyzed azide-alkyne cycloaddition reaction, yields a straightforward route to introduce a wide range of specific end group functionalities. Biotin was used as an example. The resulting biotinylated conjugated polymer binds to streptavidin and acts as a light-harvesting chromophore to optically amplify the emission of Alexa Fluor-488 chromophores bound onto the streptavidin. Furthermore, the biotin end group makes it possible to bind the polymer onto streptavidin-functionalized cross-linked agarose beads and thereby incorporate a large number of optically active segments.