Synthesis and dissipative particle dynamics simulation of cross-linkable fluorinated diblock copolymers: self-assembly aggregation behavior in different solvents.

Developing microstructures, such as low molecular aggregates, spherical micelles and multi-compartment micelles, is an expanding area of research in Materials Science. By applying an atom transfer radical polymerization (ATRP) process to cross-linkable fluorinated diblock copolymers and analyzing the data we are able to demonstrate the potential for developing films with different micro-structures for additional biological research. Applying the Dissipative Particle Dynamic (DPD) Method, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) techniques to cross-linkable fluorinated diblock copolymers of (methyl methacrylate-co-hydroxyethyl methacrylate-co-butyl methacrylate)-b-2-(perfluoroalkyl)ethyl methacrylate (MMA-co-HEMA-co-BMA-b-FMA) we were able to analyze the structures and their relationships to the aggregation of various microstructure formations through the use of various solvents in the process. For the self-assembly of the cross-linkable diblock copolymer in solutions, the DPD simulation results are only in qualitative agreement with experimental data of aggregate morphologies and sizes. This suggests an improved approach to creating materials and methods necessary for studying microstructures in films used in other research areas. Our work examines whether using selective solvents can be easily extended to prepare aggregates with different morphologies, which is an effective shortcut to obtain films with different microstructures. DPD simulation can be considered as an adjunct to experiments and provides other valuable information for the experiment.

Synthesis and optical properties of two novel stilbene derivatives containing 1,3,4-oxadiazole moiety.

Two novel stilbene derivatives containing 1,3,4-oxadiazole moiety were synthesized and characterized by elemental analyses, (1)H NMR, MS. The photophysical processes of the title compounds were investigated by UV-vis absorption and fluorescence emission spectra in different solutions. The fluorescence quantum yield (Phi) of 1a and 1b in THF is 0.65 and 0.69, respectively. The influence of the solution on the fluorescence intensities was also discussed. Under ultraviolet light excitation, the two compounds exhibit strong blue fluorescence emission. They may serve as potential applications in organic electroluminescent materials.

N'-(4-Fluoro-benzyl-idene)-3,4,5-trimethoxy-benzohydrazide.

The title compound, C(17)H(17)FN(2)O(4), is of inter-est due to its potential pharmaceutical and agrochemical activity. All three meth-oxy groups are twisted with respect to the attached aromatic ring [C-C-O-C torsion angles = 10.43 (18), 97.38 (14), -19.34 (17)°] and the phenyl ring makes a dihedral angle of 40.6 (2)° with the plane through the remaining atoms in the mol-ecule. Inter-molecular N-H⋯O hydrogen bonds link the mol-ecules into chains running along the c axis.

N'-(2-Chloro-benzyl-idene)-3,4,5-tri-methoxy-benzohydrazide methanol solvate.

In the title compound, C(17)H(17)ClN(2)O(4)·CH(4)O, the dihedral angle between the benzene ring planes is 5.29 (6)°. Inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a chain along the a axis.

Inhibitory kinetics of paeonol on the activity of mushroom tyrosinase oxidizing L-dopa.

AIM: To evaluate the effect of paeonol on the activity of tyrosinase and provide experimental evidence for the treatment of hyperpigmentation disorders. METHODS: Tyrosinase activity was estimated by measuring the oxidation rate of L-3,4-dihydroxyphenylalanine (L-Dopa). The inhibitory effects of paeonol on the activity of mushroom tyrosinase and Michaelis-Menten kinetics were deduced from the Lineweaver-Burk plots. RESULTS: The inhibitory concentration of paeonol leading to 50% enzyme activity lost (IC50) was estimated to be 0.60 mmol x L(-1). The inhibition constants for paeonol binding free enzyme, K(I), and substrate-enzyme, K(IS), are 0.084 and 0.12 mmol x L(-1), respectively. CONCLUSION: Paeonol is a potential mixed inhibitor of mushroom tyrosinase. The mixed inhibition function may originate from its ability to form a Schiff base with a primary amino group and to chelate copper at the active site of tyrosinase.

Synthesis, fluorescence properties and applications of two novel oxadiazole-based stilbene optical brighteners as UV protectants for insect baculovirus.

Two novel symmetrical stilbene optical brighteners based on 1,3,4-oxadiazole bearing sodium sulfonate unit were synthesized. The two target compounds were characterized by NMR and elemental analysis. The photophysical processes of the target compounds were investigated by UV-Vis absorption and fluorescence emission spectra in different solutions. The two optical brighteners were tested as radiation protectants for the Spodoptera litura nuclear polyhedrosis virus (SINPV) against 2nd-instar S. litura larvae. The results indicate that the two compounds exhibit strong blue fluorescence emission, and the fluorescence quantum yield in DMF is 0.86 and 0.75, respectively. The insecticidal effect of SINPV is increased by the addition of the two compounds and especially the compound 3b shows more obvious synergy effect.