Structures and photocatalytic performance of two d10 metal-based coordination polymers containing mixed building units

The linker 1,4-bis(2-methyl-imidazole-yl)-butane (bib) was used to construct two coordination polymers, specifically [Cd(bib)(ipa)]_n (1) and [Zn(bib)(tpa)]_n (2), in the presence of isophthalic acid (H₂ipa) and terephthalic acid (H₂tpa), respectively, under solvothermal conditions. Topological analyses reveal that the crystal of complex 1 consists of a 3D threefold interpenetrating network with Schläfli symbol {6⁵.8}, while complex 2 possesses a 2D wavelike layer structure with Schläfli symbol {6⁶}. The photocatalytic properties of both complexes for the degradation of methyl violet have been explored, revealing that complex 2 is a better photocatalyst than 1. A mechanism for the photocatalytic properties of the complexes is proposed, based on the results of density of states (DOS) and partial DOS calculations.

     

Non-isothermal thermogravimetric analysis of pyrolysis kinetics of four oil shales using Sestak–Berggren method

Journal of Thermal Analysis and Calorimetry - In this study, the non-isothermal pyrolysis method was used to investigate the pyrolysis characteristics of oil shale from four areas: namely Nongan,...     

Hydrothermal Synthesis, Crystal Structure and Thermal Stability of [Ni(phen)3]·(C8H12O4)·(H2O)14

One novel complex [Ni(phen)3]·(C8H12O4)·(H2O)14 with hexane dicarboxylic acid and 1,10-phenanthroline has been hydrothermally synthesized and characterized. Crystal data: monoclinic, space group C2/c, a = 2.3475(5), b = 1.2208(2), c = 1.9499(4) nm, β = 114.682(3)o, V = 5.0778(16) nm3, Dc = 1.339 g/cm3, Z = 4, μ(MoKα) = 0.458 mm-1, F(000) = 2168, GOOF = 1.014, R = 0.0401 and wR = 0.0961. The nickel(Ⅱ) center in the title complex is coordinated with six nitrogen atoms of three 1,10-phenanthroline molecules, giving a distorted octahedral coordination geometry. However, the nickel(Ⅱ) ion does not coordinate to the hexane dicarboxylic acid. The complex molecules form a 3D structure through hydrogen bonds. TG analysis shows that the title complex is stable below 240.0 ℃.     

Amino(oligo)thiophene-based environmentally sensitive biomembrane chromophores

There is a growing need for cellular imaging with fluorescent probes that emit at longer wavelengths to minimize the effects of absorption, autofluorescence, and scattering from biological tissue. In this paper a series of new environmentally sensitive hemicyanine dyes featuring amino(oligo)thiophene donors have been synthesized via aldol condensation between a 4-methylpyridinium salt and various amino(oligo)thiophene carboxaldehydes, which were, in turn, obtained from amination of bromo(oligo)thiophene carboxaldehyde. Side chains on these fluorophores impart a strong affinity for biological membranes. Compared with benzene analogues, these thiophene fluorophores show significant red shift in the absorption and emission spectra, offering compact red and near-infrared emitting fluorophores. More importantly, both the fluorescence quantum yields and the emission peaks are very sensitive to various environmental factors such as solvent polarity or viscosity, membrane potential, and membrane composition. These chromophores also exhibit strong nonlinear optical properties, including two-photon fluorescence and second harmonic generation, which are themselves environmentally sensitive. The combination of long wavelength fluorescence and nonlinear optical properties make these chromophores very suitable for applications that require sensing or imaging deep inside tissues.     

One-step synthesis of silver nanoparticles by sonication or heating using amphiphilic block copolymer as templates

Block copolymer-supported Ag Nps (nanoparticles) have either a "cherry"-like or "raspberry"-like morphology [Antonietti, et al., Adv. Mater. 7 (1995) 1000-1005] depending on the amount of silver nitrate loading and the external conditions. Sonication favors silver nitrate and polyethyleneimine diffusion; the nucleation sites are well distributed in the micellar cores, so it is easy to form the cherry-like Ag NP colloids. However, when the amount of silver nitrate is decreased, it is heating that induces the formation of raspberry-like Ag NP colloids. The Ag NP colloids were investigated by transmission electron microscopy to demonstrate the nanosize dimensions and the location of the Ag NPs in the micelles. X-ray diffraction was employed to determine the crystal structure of the Ag NPs. UV-vis spectroscopy was employed for further qualitative characterization of the optical properties of Ag NPs.     

Convergent assembly of highly potent analogues of bryostatin 1 via pyran annulation: bryostatin look-alikes that mimic phorbol ester function

Highly potent bryostatin analogues which contain the complete bryostatin core structure have been synthesized using a pyran annulation approach as a key strategic element. The A ring pyran was assembled using a pyran annulation reaction between a C1-C8 hydroxy allylsilane and an aldehyde comprising C9-C13. This pyran was transformed to a new hydroxy allylsilane and then coupled with a preformed C ring aldehyde subunit in a second pyran annulation, with concomitant formation of the B ring. This tricyclic intermediate was elaborated to bryostatin analogues which displayed nanomolar to subnanomolar affinity for PKC, but displayed properties indistinguishable from a phorbol ester in a proliferation/attachment assay.     

Effect of lithium iodide addition on poly(ethylene oxide)-poly(vinylidene fluoride) polymer-blend electrolyte for dye-sensitized nanocrystalline solar cell

The effect of lithium iodide concentration on the conduction behavior of poly(ethylene oxide)-poly(vinylidene fluoride) (PEO-PVDF) polymer-blend electrolyte and the corresponding performance of the dye-sensitized solar cell (DSSC) were studied. The conduction behavior of these electrolytes was investigated with varying LiI concentration (10-60 wt % in polymer blend) by impedance spectroscopy. A "polymer-in-salt" like conduction behavior has been observed in the high salt concentration region. The transition from "salt-in-polymer" to "polymer-in-salt" conduction behavior happened at the salt content of 23.4 wt %, which is much lower than 50 wt % as generally reported. The electrolyte shows the highest ionic conductivity (approximately 10(-3) S cm(-1)) at the salt concentration above 23.4 wt %. From the evaluation of salt effect on the performances of corresponding DSSC, we find that increasing LiI concentration leads to increased short-circuit photocurrent density (Jsc) caused by enhanced I3(-) diffusion up to an LiI content of 28.9 wt %. Above this limitation, the Jsc decreases as a result of increased charge recombination caused by the further increased I3(-) concentration. The open-circuit voltage (Voc) increases gradually with LiI concentration owing to the enhanced I(-) content in DSSC. The optimized conversion efficiency is obtained at a salt content of 28.9 wt % in the "polymer-in-salt" region, with high ionic conductivity (1.06 x 10(-3) S cm(-1)). Based on these facts, we suggest that the changes of conduction behavior and the changes of I3(-) and I(-) concentrations in the electrolytes contribute to the final performance variation of the corresponding DSSC with varying LiI concentration.     

Adsorption of metal anions of vanadium(V) and chromium(VI) on Zr(IV)-impregnated collagen fiber

The metal anions of vanadium (V) and chromium (VI) in aqueous solution can be effectively adsorbed by Zr(IV)-impregnated collagen fiber (ZrICF). The maximum adsorption capacity of V(V) takes place within the pH range of 5.0 to 8.0, while that of Cr(VI) is within the pH range of 6.0 to 9.0. When the initial concentration of metal ions was 2.00 mmol L⁻¹ and the temperature was 303 K, the adsorption capacity of V(V) on Zr-ICF was 1.92 mmol g⁻¹ at pH 5.0, and the adsorption capacity of Cr(VI) was 0.53 mmol g⁻¹ at pH 7.0. As temperature increased, the adsorption capacity of V(V) increased, while that of Cr(VI) was almost unchanged. The adsorption isotherms of the anionic species of V(V) and Cr(VI) can be fit by the Langmuir equation. The adsorption rate of V(V) follows the pseudo-first-order rate model, while the adsorption rate of Cr(VI) follows the pseudo-second-order rate model. Furthermore, ZrICF shows high adsorption selectivity to V(V) in the mixture solution of V(V) and Cr(VI). Practical applications of ZrICF could be expected in consideration of its performance in adsorption of V(V) and Cr(VI).