New Organic Sensitizer for Stable Dye-Sensitized Solar Cells with Solvent-Free Ionic Liquid Electrolytes

We report a high molar extinction coefficient metal-free sensitizer composed of a triarylamine donor in combination with the 2-(2,2'-bithiophen-5-yl)acrylonitrile conjugation unit and cyanoacrylic acid as an acceptor. In conjugation with a volatile acetonitrile-based electrolyte or a solvent-free ionic liquid electrolyte, we have fabricated efficient dye-sensitized solar cells showing a corresponding 7.5% or 6.1% efficiency measured under the air mass 1.5 global sunlight. The ionic liquid cell exhibits excellent stability during a 1000 h accelerated test under the light-soaking and thermal dual stress. Intensity-modulated photocurrent and photovolatge spectroscopies were employed along with the transient photoelectrical decay measurements to detail the electron transport in the mesoporous titania films filled with these two electrolytes.

Energy-Level and Molecular Engineering of Organic D-pi-A Sensitizers in Dye-Sensitized Solar Cells

A series of organic D-pi-A sensitizers composed of different triarylamine donors in conjugation with the thienothiophene unit and cyanoacrylic acid as an acceptor has been synthesized at a moderate yield. Through tuning the number of methoxy substituents on the triphenylamine donor, we have gradually red-shifted the absorption of sensitizers to enhance device efficiencies.

One-pot synthesis of silver nanoplates and charge-transfer complex nanofibers

We describe a facile one-pot process to synthesize Ag nanoplates by reducing silver nitrate with 3,3',5,5'-tetramethylbenzidine (TMB) at room temperature. The silver nanoplates were highly oriented single crystals with (111) planes as the basal planes. TMB can be readily oxidized to charge-transfer (CT) complex between TMB, as a donor, and (TMB)(2+), as an acceptor. The pi-pi interaction of the neutral amine (TMB) and diiminium structure (dication, TMB2+) result in the formation of one-dimensional CT complex nanofiber.

Surface potential images of polycrystalline organic semiconductors obtained by Kelvin probe force microscopy

P-type copper phthalocyanine (CuPc) and n-type hexadecafluorophthalocyanina-tocopper (F16CuPc) polycrystalline films were investigated by Kelvin probe force microscopy (KPFM). Topographic and corresponding surface potential images are obtained simultaneously. Surface potential images are related with the local work function of crystalline facets and potential barriers at the grain boundaries (GBs) in organic semiconductors. Based on the spatial distribution of surface potential at GBs, donor- and acceptor-like trapping states in the grain boundaries (GBs) of p-CuPc and n-F16CuPc films are confirmed respectively.

Entangled metal-organic frameworks modulated by N-donor ligands of different conformations

Based on the aromatic dicarboxylic acid and N-donor ligands with different conformations, four Zn(II) metal-organic frameworks, namely [Zn(mfda)(L-1)](1), [Zn-2(mfda)(2)(L-2)]center dot DMF center dot H2O (2), [Zn-2(mfda)(2)(L-3)(H2O)]center dot DMF (3) and [Zn-2(mfda)(2)(L-4)] (4) have been synthesized (mfda = 9,9-dimethylfluorene-2,7-dicarboxylate anion, L-1 = 1,10-phenanthroline, L-2 = 4,4 '-bipyridine, L-3 = 2,5-bis(4-pyridyl)-1,3,4-ocadiazole and L-4 = 1,4-bis(imidazol-1-ylmethyl)benzene). Single-crystal X-ray diffraction has revealed that all compounds exhibit entangled structures. Compound 1 is composed of 1D zigzag chains that are entangled through the pi-pi stacking interactions to generate a three-fold interpenetrating diamond-like networks.

Simple and Efficient Near-Infrared Organic Chromophores for Light-Emitting Diodes with Single Electroluminescent Emission above 1000 nm

A series of NIR organic chromophores with donor-pi-acceptor-pi-donor structure are synthesized. Good thermal stability and strong photoluminescence in solid state render them suitable for application in light-emitting diodes. Exclusive near-infrared emission at 1080 nm with external quantum efficiency of 0.28% is obtained from the nondoped OLEDs. The longest electroluminescence wave-length is 1220 nm.

Dye-Sensitized Solar Cells Based on Organic Sensitizers with Different Conjugated Linkers: Furan, Bifuran, Thiophene, Bithiophene, Selenophene, and Biselenophene

Six organic dyes with different conjugated linkers such as furan, bifuran, thiophene, bithiophene, selenophene, and biselenophene have been prepared in combination with the dihexyloxy-substituted triphenylamine donor and the cyanoacrylic acid acceptor. In conjunction with an acetonitrile-based electrolyte and a solvent-free ionic liquid electrolyte, these dyes exhibit 6.88-7.77% and 6.39-7.00% efficiencies, respectively. We have demonstrated that furan and selenophene can be employed as building blocks of sensitizers in stable solar cells for the first time. We have also studied the influence of heteroatoms on photocurrents and photovoltages with the aid of quantum calculations and transient photoelectrical decay measurements. Temperature-dependent electrical impedance experiments have shown that a relatively low external quantum efficiency of the dye with biselenophene linker is not related to the charge collection yield in the case of an acetonitrile electrolyte.

Self-assembly of a polymer pair through poly(lactide) stereocomplexation

A polymer pair composed of poly( N-isopropylacrylamide-co-2-hydroxyethyl methacrylate terminated oligo( L-lactide)) ( poly( NIPAAm-co-HEMAOLLA)) graft random copolymer and poly( D-lactide) ( PDLA) homopolymer was self-assembled into micelles with a diameter around 100 nm through the stereocomplexation between the OLLA branches of the graft copolymer and the PDLA homopolymer. The specific intermolecular stereocomplexation was considered as the powerful ordered aggregation force in the micelle cores. The shell's component of poly( NIPAAm-co-HEMA) and its thermosensitivity were proved by H-1 nuclear magnetic resonance ( NMR) and dynamic light scattering ( DLS), respectively. The incorporation of PDLA homopolymer into the graft copolymer affected the micelle size and the critical micelle concentration ( CMC). The incorporation of even a small quantity ( 11 wt%) of PDLA into the graft copolymer micelles resulted in a great decrease of the micelle size. For the graft copolymer with low per cent grafting of 18%, the size of the corresponding micelles decreased slightly even if the PDLA content increased up to 33 wt%. For the graft copolymer with high per cent grafting of 58%, with the further increase of PDLA content, the size of the corresponding micelles at first decreased further and then began to increase. The molecular weight of the PDLA did not significantly affect the micelle size.

Phenylthiolate as a sigma- and pi-donor ligand: synthesis of a 3-D organometallic coordination polymer [K2Fe(SPh)(4)](n)

The synthesis and crystal structure of the first mixed-metal organometallic polymer network containing phenylthiolato ligands, [K2Fe(SPh)(4)](n), are investigated. The simple phenyl-thiolate acts as a sigma- and pi-donor ligand to give a 3-D potassium iron coordination polymer with both metal-carbon and metal-sulfur coordination interactions.

In vitro study on the binding of neutral red to bovine serum albumin by molecular spectroscopy

In this paper, the binding of neutral red (NR) to bovine serum albumin (BSA) under physiological conditions has been studied by spectroscopy method including fluorescence, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. The Stern-Volmer fluorescence quenching constant (K-SV), binding constant (K-b) and the number of binding sites (It) were measured by fluorescence quenching method. Fluorescence experiments were also performed at different ionic strengths. It was found K-SV was ionic strength dependent, which indicated the electrostatic interactions were part of the binding forces. The distance r between donor (BSA) and acceptor (NR) was obtained according to Foster's non-radiative energy transfer theory. CD spectroscopy and FT-IR spectroscopy were used to investigate the structural information of BSA molecules on the binding of NR, and the results showed no change of BSA conformation in our experimental conditions.

Synthesis, characterization, photoluminescent and electroluminescent properties of new conjugated 2,2 '-(arylenedivinylene)bis-8-substituted quinolines

A series of new PPV oligomers containing 8-substituted quinoline, 2,2'-(arylenedivinylene) bis-8-quinoline derivatives, were designed and synthesized via a Knoevenagel condensation reaction of quinaldine, 8-hydroxy-or 8-methoxy-quinaldine with aromatic dialdehydes. These PPV oligomers were characterized by H-1 and C-13-NMR, X-ray diffraction, elemental analysis, UV-visible and fluorescence spectroscopies. The X-ray diffraction investigation showed that there are intermolecular pi...pi interactions in the solid state in 1 and 3. The optical and photoluminescent properties study demonstrated that the emission color of the resulting materials varies from blue to yellow and is dependent on the substituents (pi-donor and pi-acceptor groups) on both sides of the conjugated molecules and the aromatic core in the middle of the conjugated backbones. The electroluminescent devices using compounds 1-4 as the emitters and electron-transporting layers were fabricated with the structure ITO/NPB/emitter/LiF/Al. The best device performance with the maximum brightness of 5530 cd m(-2) and the luminous efficiency of 2.4 cd A(-1) is achieved by using compound 4, with intramolecular charge transfer character, as the emitter; these values represent a more than 5-fold improvement in brightness and efficiency compared to compound 3 without methoxy groups on the phenyl rings.

Ammonium 4-nitrophenylarsonate

In the crystal structure of the title compound, (NH4)[AsO2 (OH)(C6H4NO2)], the 4-nitrophenylarsonate anions and ammonium cations are linked through hydrogen bonds to form infinite chains along the b axis. The hydroxyl O atom of the 4-nitrophenylarsonate anion acts as both an acceptor and a donor of hydrogen bonds. All atoms are located in general positions.

Solvent-dependent formation of di- and trinuclear rhodiurn and iridium complexes bridged by N,N '-donor ligands

Reactions of Rh and Ir hydrido complexes. [Rh(H)(2)(PPh3)(2)(solv)(EtOH)]ClO4 (solv = Me2CO, 1a; EtOH, 1b) and [Ir(H)(2)(PPh3)(2)(Me2CO)(2)]BF4 (2), with various N,N'-donor bridging ligands, such as pyrazine (pyz), 4,4'-trimethylenedipyridine (tmdp) and di(4-pyridyl) disulfide (dpds), in some solvents were examined, and their reaction products were characterized by X-ray crystal structure analysis. IR, H-1 NMR and UV-vis spectra. Rh hydrido complexes, la or 1b, formed a dinuclear Rh complex, [Rh-2(PPh3)(2) {(eta(6)-C6H5PPh2}(2)] (ClO4)(2).6CH(2)Cl(2) (3.6CH(2)Cl(2)), in dichloromethane with a reductive elimination of hydrogen. The reactions of 1a or 1b with the pyz ligand in dichloromethane and tetrahydrofuran gave triangular Rh-3 complexes, [Rh-3(PPh3)(6)(pyz)(3)](ClO4)(3).CH2Cl2 (5.CH2Cl2) and [Rh-3(PPh3)(6)(pyz)(3)](ClO4)(3).EtOH (5.EtOH), respectively, in contrast to the formation of a dinuclear Rh hydrido complex, [Rh-2(H)(4)(PPh3)(4)(Me2CO)(2)(pyz)](ClO4)(2).EtOH A-EtOH). in acetone. The reactions of la or 1b with the tmdp ligand in dichloromethane and 3-methyl-2-butanone also afforded dinuclear Rh complexes, [Rh-2(PPh3)(4)(tmdp)(2)](ClO4)(2) (6) and [Rh-2(PPh3)(4)(tmdp)(2)](ClO4)(2).4MeCOCHMe(2) (6.4MeCOCHMe(2)), respectively. On the other hand, Ir hydrido complex 2 reacted with pyz and dpds ligands in dichloromethane to afford dinuclear Ir complexes, [Ir-2(H)(4)(PPh3)(4)(Me2CO)(2)(pyz)]- (BF4)(2).3CH(2)Cl(2) (7.3CH(2)Cl(2)) and [Ir-2(H)(4)(PPh3)(4)(dpds)(2)](BF4)(2).3CH(2)Cl(2).H2O (8.3CH(2)Cl(2).H2O), respectively, without any reductive elimination of hydrogen. Based on structural studies in solution and in the solid state. it was demonstrated that various Rh and Ir complexes were selectively produced depending on the choice of solvents and N,N'-donor bridging ligands.

Synthesis, crystal structure and luminescence studies of a lanthanide coordination polymer with a new double betaine ligand

A novel europium(III) coordination polymer with a new double betaine derivative, {[Eu(L')(NO3)(H2O)(3)](NO3)(2). 3.5H(2)O}(n) (L-1 = 1,3-bis(pyridinio-4-carboxylato)-propane) has been synthesized and its structure determined. Its luminescence properties have also been studied. The title metal carboxylate coordination polymer contains centrosymmetric dimeric units in which each pair of metal ions is linked by a pair of syn-anti carboxylato-O,O' groups, and each pair of such dimeric units is bridged by the backbones of L-1 ligands to form infinite double chains in the b direction. These metal carboxylate chains are further cross-linked by hydrogen bonds among both coordinated and discrete nitrate anions, aqua ligands and lattice water molecules to form a three-dimensional network. Luminescent data show that the L-1 ligand is a good energy donor and the complex has a relatively long luminescent lifetime.

Effect of lanthanum ions on tRNA(Phe) structure: Imino proton NMR spectroscopy

The effect of lanthanum ions on the structural and conformational change of yeast tRNA(Phe) was studied by H-1 NMR. The results suggest that the tertiary base pair (G-15)(C-48), which was located in the terminal in the augmented dihydrouridine helix (D-helix), was markedly affected by adding La3+ and shifted 0.33 downfield. Based pair (U-8)(A-14), which is associated with a tertiary interaction, links the base of the acceptor stem to the D-stem and anchors the elbow of the L structure, shifted 0.20 upfield. Another imino proton that may be affected by La3+ in tRNA(Phe) is the tertiary base pair (G-19)(C-56). The assignment of this resonance is tentative since it is located in the region of highly overlapping resonances between 12.6 and 12.2. This base pair helps to anchor the D-loop to the T psi C loop.