Photosensitization of bioinspired thymine-containing polymers

Here, we report a sensitization study on a family of water-soluble photopolymers based on thymine. The goal of this study was to determine whether the presence of sensitizer molecules would promote photocrosslinking/immobilization of the polymers using low-energy irradiation (520 nm) as compared to the UV irradiation (approximately 280 nm) necessary for the standard photoinduced process to take place. With the aid of Eosin Y Spirit Soluble (EY) as a sensitizer, water-soluble polystyrene copolymers of vinylbenzylthymine-vinylbenzyltriethylammonium chloride (VBT-VBA) were immobilized after exposure to visible irradiation. By exciting the sensitizer molecule in the presence of VBT copolymers at a wavelength where absorption by the latter does not occur, the triplet state of the sensitizer is generated in high yields, and consequently, polymer photocross-linking takes place. UV-vis spectroscopy has been used to study the effect of irradiation dose, copolymer composition, and sensitizer concentration on the photoreactivity of VBT polymers. These studies demonstrate the feasibility of using Eosin Y as a sensitizer to achieve the thymine photodimer formation, resulting in immobilization of VBT-VBA-EY films on PET substrate. This provides complementary information on photoinduced immobilization of VBT-VBA films that are crucial for developing new classes of environmentally benign materials and new energy-saving methods.     

A new HPLC-UV validated method for therapeutic drug monitoring of tyrosine kinase inhibitors in leukemic patients

Development and validation of simple, rapid, and reliable high-performance liquid chromatography (HPLC)-UV method for quantification of major tyrosine kinase inhibitors, imatinib, dasatinib, and nilotinib, in human plasma is presented. Chromatographic separation of the drugs is achieved on an RP-C(18) column at flow rate of 0.9 mL/min at 35°C; eluate is monitored at 267 nm. Mean intra-day and inter-day precision for all compounds are 2.5 and 13.3%; mean accuracy is 13.9%; extraction recovery ranges within 40.24 and 81.81%. Calibration curves range from 10 to 0.005 μg/mL. Limits of detection are 10 ng/mL for imatinib and nilotinib, 50 ng/mL for dasatinib; limits of quantitation are 50 ng/mL for imatinib and nilotinib, 100 ng/mL for dasatinib. Although this method allows the detection of dasatinib, levels found in patients plasma are close to the limit of detection, then below the limit of quantitation. Quantification with HPLC-mass spectrometry, then, is required for dasatinib to give a correct evaluation. In conclusion, the sensitivity of this new method is sufficient to perform therapeutic monitoring and pharmacokinetic studies of imatinib and nilotinib but not dasatinib in CML patients.     

Selective organic functionalization of graphene bulk or graphene edges

Graphene sheets have been functionalized with a PAMAM dendron, finding that graphene can be efficiently functionalized all over the surface, or only at the edges, depending on the reactions used in the functionalization process.     

Predicting the UV spectrum of polyoxometalates by TD‐DFT

UV absorption spectra of the Lindqvist polyoxometalate [W₆O₁₉]^2? were predicted by relativistic time‐dependent density functional theory with several combinations of density functional and basis set. Hybrid functionals with frozen‐core Slater basis sets were found to provide the best agreement with experiment while keeping reasonable computational demand. The approach was extended to [W₁₀O₃₂]^4? and [PW₁₂O₄₀]^3?, suggesting that it can be applied to the polyoxometalates family. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011     

Mesoporous materials incorporating a zinc(II) complex: Synthesis and direct luminescence quantum yield determination

New luminescent inorganic–organic hybrid materials incorporating the luminescent zinc(II) complex ZnL₂ (λ_em = 457 nm and Φ_em = 4.4% reference values for ZnL₂; HL = chelating ligand resulting from the reaction between salicylaldehyde and 3-aminopropyltriethoxysilane), covalently bonded to different types of mesoporous silica hosts (namely MCM-41, MCM-48 and SBA-15), were prepared via both the methods of grafting post-synthesis (GPS) and one-pot synthesis (OPS). The products obtained, which form the GPS [(GPS)(Zn/MCM-41), (GPS)(Zn/MCM-48), (GPS)(Zn/SBA-15)] and the OPS [(OPS)(Zn/MCM-41), (OPS)(Zn/MCM-48), (OPS)(Zn/SBA-15)] series, contain the ZnL₂ guest covalently bonded to the silica framework through silicon–oxygen bonds formed when the silane group is placed at the periphery of the Zn(II) coordination sphere. GPS and OPS materials were characterized by powder X-ray diffraction, N₂ adsorption/desorption, thermogravimetric analysis (TGA) and UV/vis spectroscopy. For the new mesoporous materials the emission quantum yield (EQY) was measured by means of an integrating sphere combined with a spectrofluorimeter. The ZnL₂ loading (measured by the ZnL₂/SiO₂ ratio calculated from TGA data) for MCM-41 appears to be independent of the synthesis procedure, whereas, for both MCM-48 and SBA-15, the ZnL₂/SiO₂ ratio of the materials obtained via OPS is about four times higher than products obtained from GPS. The ZnL₂ loaded GPS and OPS series show λ_em maxima at about 485 and 455 nm, respectively. Moreover, with reference to EQY (GPS)(Zn/SBA-15) and (OPS)(Zn/SBA-15), although featuring ZnL₂/SiO₂ ratios of 0.13 and 0.45, respectively, they showed similar EQY values: 2% and 5%. On the contrary, (GPS)(Zn/MCM-41) and (OPS)(Zn/MCM-41) which give similar ZnL₂/SiO₂ ratios (0.09 and 0.14) exhibit very different EQY, i.e. 2% and 22%, respectively.     

Templated Synthesis of Copper(II) Azacyclam Complexes Using Urea as a Locking Fragment and Their Metal‐Enhanced Binding Tendencies towards Anions

Copper(II) azacyclam complexes 3 ²⁺ and 4 ²⁺ were obtained through a metal‐templated procedure involving the pertinent open‐chain tetramine, formaldehyde and a phenylurea derivative as a locking fragment. Both metal complexes can establish interactions with anions through the metal centre and the amide NH group. Equilibrium studies in DMSO by a spectrophotometric titration technique were carried out to assess the affinity of 3 ²⁺ and 4 ²⁺ towards anions. While the NH group of an amide model compound and the metal centre of the plain Cu^II(azacyclam)²⁺ complex do not interact at all with anions, 3 ²⁺ and 4 ²⁺ establish strong interactions with oxo anions, profiting from a pronounced cooperative effect. In particular, 1) they form stable 1:1 and 1:2 complexes with H₂PO₄^? ions in a stepwise mode with both hydrogen‐bonding and metal–ligand interactions, and 2) in the presence of CH₃COO^?, they undergo deprotonation of the amido NH group and thus profit from axial coordination of the partially negatively charged carbonyl oxygen atom in a scorpionate binding mode.     

Use of SPME-GC-MS in the study of time evolution of the constituents of saffron aroma: modifications of the composition during storage

The effect of storage on the composition of saffron aroma is studied. Six samples of saffron from different areas of Italy are analyzed by solid-phase microextraction-gas chromatography-mass spectrometry. Samples 1, 2, and 3 are derived from cultivations of Crocus sativus in the zone of Salerno (Southern Italy) from 2000 to 2002. Samples 4, 5, and 6 are derived from cultivations in Sardinia, Italy (from 1998, 2000, and 2001, respectively). In all samples, 3,5,5-trimethyl-2-cyclohexen-1-one; 3,5,5-trimethyl-2-cyclohexen-1,4-dione; safranal; and 2,4,4-3,5,5-trimethyl-2-cyclohexen-1,4-dione; safranal; and 2,4,4-trimethyl-6-hydroxy-3-carboxaldehyde-2,5-cyclohexadien-1-one are found. 5,5-Dimethyl-2-methylene-1-carboxaldehyde-3-cyclohexene; 3,5,5-trimethyl-1,4-cyclohexandione; and beta-ionone are found with nonanal, dihydro-beta-ionone, and 2,6-di-t-butylphenol. Safranal is the main component in all of the samples. The most important changes are in the presence of alcohols and aldehydes and oxidation products of the major terpenoids components. Furthermore, the presence of safranal--the most important constituent of the flavor--changes during the time, increasing during 3 years, then decreasing after 5 years.     

Enzymatic Approach to and Odor Description of the Twelve Enantiomerically Pure Isomers of Pelargene®

Pelargene^® is a commercial fragrance sold as a mixture of three regioisomeric pyran derivatives ( 1 – 3 ). The enantiomers of each of the two possible diastereoisomers of 1 – 3 were prepared by means of a biocatalyzed approach, and the odor properties of the twelve isolated stereoisomers were evaluated.