The paper describes technology and principal results concerning the studies of hybrid photovoltaic devices possessing layers of ZnO nanocrystals with different sizes. The presented studies have shown that better photovoltaic efficiency is achieved for the ZnO nanocrystals with smaller sizes. The physical origin of the observed effects is observed.

Results of a study on the application of a copolymer of fluorine as acceptor and 1H-pyrazolo[3,4-b]quinoxaline as a donor in bulk heterojunction solar cells are given. To the best of our knowledge, 1H-pyrazolo[3,4-b]quinoxaline co-polymers were not applied in organic photovoltaic devices yet. Organic photovoltaic devices as well as devices of active layers with TiO2 nanocrystals of different crystallite size were investigated. The methods of polymer and TiO2 nanocrystllites synthesis are presented and their physical properties are given. The fabricated photovoltaic structures possess high values of U oc voltage as as well as relatively high parameters of I sc currents. The maximally achieved parameters corresponded to open circuit voltage U oc  = 1.13[V], and short current density Isc = 33.49[μA] under illumination 1,3 [μW cm−2], which correspond to energy conversion efficiency equal to about 0.80 %. The TiO2 nanocrystallites play a crucial role in the photovoltaics parameters.

The complex studies of photoinduced absorption, second harmonic generation and third harmonic generation were performed for TiO2 films of different morphology. In particular we have studied the influence of a bicolor laser beam treatment by a 300mW green cw laser emitting at 532nm on changes of absorption, birefringence and third harmonic generation on TiO2 films. We have performed the corresponding measurements using as a photoinducing light a glass erbium 10ns pulsed laser with a fundamental wavelength of about 1540nm together with its second harmonic generation (SHG) at 770nm using the method of bicolor laser treatment and a frequency repetition of about 10Hz. Varying the power density ratios between the fundamental and its SHG we have established the optimal conditions to achieve maximal photoinduced changes of absorption, birefringence and third harmonic generation (THG). We have detected changes of the birefringence and of the THG immediately after the laser treatment. We study an influence of the nanoparticle's sizes on the observed changes of the optical features. Additionally we have studied the role of different chemical treatment on the structural and optical parameters.

Domoic acid (DA) is a water-soluble marine neurotoxin produced and released by certain species of the diatom genus Pseudo-nitzschia. Present in coastal waters, it can be a threat to public health and marine life, and can result in severe economic losses to the molluscan shellfish and crustacean harvesting industries. Here we report on the efficiency of nanocrystalline (NC) titania (TiO2) thin films used as a photocatalyst in the ultraviolet light photodegradation of DA. Titanium dioxide thin films produced by a sol-gel dip-coating method in the presence of polyethylene glycol of different molecular weights (200, 400 and 600) were deposited on glass substrates and crystallised at 90°C. The films were characterised using spectroscopic ellipsometry, Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. The photocatalytic activity measurements were carried out by immersing the NC TiO2 films in a DA solution (2500 ng ml−1) and then exposing them for various times at room temperature to UVA irradiation (λ = approximately 350 nm). The degradation of DA, quantified by HPLC analysis, was not significant when using daylight or ultraviolet light irradiation alone, whereas the NC TiO2 films prepared at low temperature proved to be a very efficient photocatalyst when used in conjunction with UVA light. The effectiveness of the photodegradation was improved by increasing molecular weight of polyethylene glycol, which increased the thickness of the film. The presence, transformation and degradation of three DA isomers were observed. The approach may eventually be practical for destroying DA in seawater used by aquaculture industry depuration facilities.

Iron tungstate (FeWO4) and cobalt tungstate (CoWO4) nanostructures were prepared by the hydrothermal method using sodium tungstate (Na2WO4·2H2O), ferrous ammonium sulfate [(NH4)2Fe(SO4)2·6H2O] and cobalt chloride (CoCl2·6H2O) solutions as precursors. The crystal structure and morphology of the as-prepared tungstates were characterized by X-ray diffraction analysis and transmission electron microscopy. The above characterizations render that the products obtained belong to the monoclinic crystal system and P2/a space group, with average sizes of nanoparticles of about 150nm and 70nm in the case of FeWO4 and CoWO4, respectively. Electronic properties of the FeWO4 and CoWO4 tungstates were studied using several X-ray spectroscopy methods, mainly X-ray photoelectron spectroscopy (XPS), X-ray emission spectroscopy (XES) and X-ray absorption spectroscopy (XAS). The XPS valence-band and core-level spectra, the XAS W LIII edges (unoccupied W d-like states) as well as the XES bands reflecting the energy distribution of the valence W d- and O p-like states were recorded. The present XPS and XAS results reveal that the as-prepared FeWO4 and CoWO4 tungstates are in a composition close to a stoichiometric one. The XES results render that the W 5d- and O 2p-like states contribute throughout the whole valence-band region of the FeWO4 and CoWO4 tungstates, however maximum contributions of the O 2p-like states occur in the upper, whilst the W 5d-like states in the lower portions of the valence band, respectively.

Domoic acid (DA) is a water-soluble marine neurotoxin produced and released by Pseudo-nitzschia species. It is remarkably pervasive in North American coastal waters, where it is a threat to public health and some marine life, and has resulted in severe economic losses in the shellfish and crustacean harvesting industry. In this paper we report on the development of nanocrystalline titania thin films that were used as photocatalyst in the UV photodegradation of DA. TiO2 thin films produced by a sol–gel dip-coating method in the presence of polyethylene glycol (PEG) of different molecular weights (200, 400 and 600), were deposited on glass and fused quartz substrates, and crystallized at different temperatures (90, 500 and 900°C). The films were characterized using UV–vis, FTIR, SEM, XRD, and Raman spectroscopy. For the photocatalytic activity measurements, the TiO2 films were immersed in a DA solution (2500ng/mL) and exposed for various times at room temperature to UV irradiation (λ∼350nm). DA analysis was carried out by HPLC, and the photocatalytic activity was quantified as the rate of disappearance of DA. The photocatalytic activity of the TiO2 thin films was studied as a function of their crystallization temperature, type of PEG content, and thickness. The films prepared at low temperature proved to be very efficient photocatalysts. They showed a higher photocatalytic activity than those produced at high temperature. Also, using PEG of higher molecular weight in the TiO2 coating solutions increased the effectiveness of the degradation. When using UV irradiation alone, without photocatalyst, the degradation of DA was not significant. The presence, transformation, and degradation of various DA isomers were observed during the photodegradation process, and a photodegradation mechanism is proposed.

[reaction: see text] The challenging structural features and important biological activity of (+)-compactin (1) explain the substantial synthetic interest that it has generated. We report a novel enantioselective approach to the advanced intermediate 2a, which constitutes a formal synthesis of (+)-1. The sequence utilizes MacMillan's organocatalytic Mukaiyama-Michael reaction, which stereoselectively adds the silyloxyfuran 6 to alpha,beta-unsaturated aldehyde 7. The chirality generated in this reaction guides the formation of the other three consecutive stereocenters found in 2a.

Raman studies were performed on titania thin films prepared by polyethylene glycol (PEG) assisted, low-temperature, sol-gel method. The Raman spectra of the films show a systematic blue shift in the peak position and a broadening in the full width at half-maximum (FWHM) when compared with those of the bulk anatase TiO2 powder. Several reports have appeared indicating this kind of peak shift and broadening of FWHM, which were attributed to the confinement of phonons in the anatase nanocrystallites. In this paper, we report an analysis of quantum size effect in the Raman spectra of nanocrystalline TiO2 thin films performed by utilizing the phonon dispersion relation of the anatase phase which has been obtained from a work based on density functional perturbation theory (DFPT). For comparison purposes the quantum size effect calculations have also been done utilizing the dispersion relations of the rutile phase. There is good agreement between the crystallite sizes evaluated from the equally weighted Raman line intensity of the dispersion relations obtained from the DFPT and those determined by X-ray diffraction. Copyright (C) 2006 John Wiley & Sons, Ltd.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A new series of nonpeptidic cathepsin K inhibitors that are based on a beta-substituted cyclohexanecarboxamide motif has been developed. Lead optimization yielded compounds with sub-nanomolar potency and exceptional selectivity profiles against cathepsins B, L, and S. Use of fluorine atoms to block metabolism on the cyclohexyl ring led to compounds with excellent pharmacokinetic properties. Considering the well-established role of cathepsin K in osteoclast-mediated bone turnover, compounds such as (-)-34a (hrab Cat K IC50 0.28 nM; > 800-fold selectivity vs Cat B, L, and S; PK data in dogs: F 55%, t(1/2) = 15 h) exhibit great potential for development as an orally bioavailable therapeutic for treatment of diseases that involve bone loss.

[reaction: see text] The challenging structural features and important biological activity of (+)-compactin (1) explain the substantial synthetic interest that it has generated. We report a novel enantioselective approach to the advanced intermediate 2a, which constitutes a formal synthesis of (+)-1. The sequence utilizes MacMillan's organocatalytic Mukaiyama-Michael reaction, which stereoselectively adds the silyloxyfuran 6 to alpha,beta-unsaturated aldehyde 7. The chirality generated in this reaction guides the formation of the other three consecutive stereocenters found in 2a.

Compactin inhibits HMG-CoA reductase, the rate-controlling enzyme in choles­terol biosynthesis. The synthesis of an advanced intermediate diol J towards the synthesis of (+)-Compactin features MacMillan’s organocatalytic Mukaiyama-Michael reaction to introduce the first stereocenter which then controls the formation of the remaining three chiral centers.

[reaction: see text] The challenging structural features and important biological activity of (+)-compactin (1) explain the substantial synthetic interest that it has generated. We report a novel enantioselective approach to the advanced intermediate 2a, which constitutes a formal synthesis of (+)-1. The sequence utilizes MacMillan's organocatalytic Mukaiyama-Michael reaction, which stereoselectively adds the silyloxyfuran 6 to alpha,beta-unsaturated aldehyde 7. The chirality generated in this reaction guides the formation of the other three consecutive stereocenters found in 2a.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Sesquiterpenoids (+)-trans-dracuncuflifoliol (1) and (+)-4-hydroxyoppositan-7-one (2) were prepared stereoselectively from enantiomerically pure (7aR)-7a-methyl-1,2,5,6,7,7a-hexahydro-4H-inden-4-one ((−)-6), whose synthesis was described herein. Conjugate addition of the organocopper (I) reagent 10 to (−)-6, followed by epimerization of the ring junction, generated 3 of the 4 contiguous chiral centers of both natural products.

The trifluoroethylamine group found in cathepsin K inhibitors like odanacatib can be replaced by a difluoroethylamine group. This change increased the basicity of the nitrogen which positively impacted the logD. This translated into an improved oral bioavailability in pre-clinical species. Difluoroethylamine compounds exhibit a similar potency against cathepsin K and selectivity profile against other cathepsins when compared to trifluoroethylamine analogs.

Titanium dioxide (TiO2) films, composed mainly of anatase nanocrystallites, have been obtained from a low temperature poly(ethylene glycol) (PEG) modified sol-gel method. The maximum process temperature in this method is around 90° C. An addition of PEG in the films accelerates the formation of anatase nanocrystallites. In order to better understand the nature of the influence of PEG on film crystallization, sol-gel solutions were prepared with PEG of different molecular weights (200, 400 and 600). The reference solution without PEG was also prepared. In addition, the influence of different PEG chain lengths on the films' phase transition from anatase to rutile was studied by means of Raman spectroscopy and XRD. Anatase was found to be stable up to 900-1000° C, depending on the molecular weight of the PEG used in the films.

Prior reports from our laboratories have identified the nonpeptidic inhibitor 2 as a potent and selective Cathepsin K (Cat K) inhibitor. Modelling studies suggested that the introduction of a NH linker between the P3 aryl and P2 leucinamide moieties would allow the formation of a H-bond with the Gly66 residue of Cat K, hopefully increasing potency. Aniline 4 was thus synthesized and showed improved potency over its predecessor 2. Further modelling concluded that a 2-substituted five membered ring could more adequately place the P3 moiety of 4 into the S3 pocket of Cat K. The synthesis of the 2-substituted thiophene 5 confirmed this hypothesis by displaying a slight increase in potency against Cat K (>10-fold increase in potency vs 2) and a good selectivity profile against Cathepsins B, L, and S. This rationally designed inhibitor 5 also displayed increased potency in a functional bone resorption assay (10 nM) versus 2 (95 nM).

A large-scale, chromatography-free synthesis of a potent and selective Cathepsin K inhibitor 1 is reported. The key asymmetric center was installed by addition of (R)-pantolactone to the in situ-generated ketene 4a. The final step of the convergent synthesis of 1 was completed via Suzuki coupling of aryl bromide 7a with unprotected aryl piperazine boronic acid 13. Residual palladium and iron generated in the Suzuki coupling were efficiently removed from crude 1 via a simple extractive workup using lactic acid.