NEW METHOD FOR GENERATION OF t-BUTYL PERFLUOROALKYL NITROXIDES

Electron transfer reactions between O-benzoyl t-butylhydroxyl- amine,t-BuNHOCOPh(1)and perfluorodiacyl peroxides(RfCO_2)_2(2)may serve as a novel method for generating useful t-hutyl perfluoroalkyl nitroxldes at room temperature in CFCl2-CF2Cl.

An Efficient Method for the Synthesis of Aliphatic α-Organothio Aldoximes

A new and simple procedure for the synthesis of aliphatic α-organothio aldoximes wasreported. The aliphatic aldoxime was chlorinated by t-BuOCl, the resulting hydroxime acidchloride was treated with triethylamine and alkyl mercaptan in a one pot procedure to get the targetcompounds. The method is very efficient with high yield and good purity.

Role of the Notch Signaling Pathway in Fibrosis of Denervated Skeletal Muscle

In order to investigate the role of the Notch signaling pathway in skeletal muscle fibrosis after nerve injury, 60 Sprague-Dawley rats were selected and divided randomly into a control and two experimental groups. Group A served as controls without any treatment. Rats in groups B were injected intraperitoneally with 0.2 mL PBS and those in group C were injected intraperitoneally with 0.2 mL PBS+100 ymol/L, 0.2 mL N-[N-(3,5-difluorophenacetyl)-l-alanyl]- S-phenylglycine t-butyl ester (DAPT, a gamma-secretase inhibitor that suppresses Notch signaling) respectively, on postoperative days 1, 3, 7, 10, and 14 in a model of denervation-induced skeletal muscle fibrosis by right sciatic nerve transection. Five rats from each group were euthanized on postoperative days 1, 7, 14, and 28 to collect the right gastrocnemii, and hematoxylin and eosin (HE) staining, immunohistochemistry test, real-time PCR, and Western blotting were performed to assess connective tissue hyperplasia and fibroblast density as well as expression of Notch 1, Jagged 1, and Notch downstream molecules Hes 1 and collagen I (COL I) on day 28. There was no significant difference in HE-stained fibroblast density between group B and C on postoperative day 1. However, fibroblast density was significantly higher in group B than in group C on postoperative days 7, 14, and 28. Notch 1, Jagged 1, Hes 1, and COL I proteins in the gastrocnemius were expressed at very low levels in group A but at high levels in group B. Expression levels of these proteins were significantly lower in group C than in group B (P<0.05), but they were higher in group C than in group A (P<0.05) on postoperative day 28. We are led to conclude that locking the Notch signaling pathway inhibits fibrosis progression of denervated skeletal muscle. Thus, it may be a new approach for treatment of fibrosis of denervated skeletal muscle.

NANOSTRUCTURES OF FUNCTIONAL BLOCK COPOLYMERS

Nanostructure fabrication from block copolymers in my group normally involves polymer design, synthesis, self-assembly, selective domain crosslinking, and sometimes selective domain removal. Preparation of thin films withnanochannels was used to illustrate the strategy we took. In this particular case, a linear triblock copolymer polyisoprenc-block-poly(2-cinnamoylethyl methacrylate)-block-poly(t-butyl acrylate), PI-b-PCEMA-b-PtBA, was used. Films, 25 to50 μm thick, were prepared from casting on glass slides a toluene solution of PI-b-PCEMA-b-PtBA and PtBA homopolymer,hPtBA, where hPtBA is shorter than the PtBA block. At the hPtBA mass faction of 20% relative to the triblock or the totalPtBA (hPtBA and PtBA block) volume fraction of 0.44, hPtBA and PtBA formed a seemingly continuous phase in the matrixof PCEMA and Pl. Such a block segregation pattern was locked in by photocrosslinking the PCEMA domain. Nanochannelswere formed by extracting out hPtBA with solvent. Alternatively. larger channels were obtained from extracting out hPtBAand hydrolyzing the t-butyl groups of the PtBA block. Such membranes were not liquid permeable but had gas permeabilityconstants ～6 orders of magnitude higher than that of low-density polyethylene films.

Does Ethanol Play a Pro-Oxidant Role during Oxidative Stress in the Liver?

Oxidative stress has been implicated in the pathophysiology of liver injury during xenobiotic and alcohol metabolism, ischemia/reperfusion injury. In this study we examined if ethanol acted as a pro-oxidant making cells become more sensitive to tert-butylhydroperoxide (tBH) killing. Cell viability was determined in a rat hepatoma cell line (FTO2B) and rat primary hepatocytes in culture in the presence or absence of ethanol pretreatment. To elucidate the contribution of labile iron, deferoxamine (DF, an iron chelator) or lipid free radicals, N,N-diphenyl-p-phenylenediamine (DPPD, a lipid scavenger) were added to the ethanol tBH co-treatment. The levels of glutathione (GSH) and glutathione disulfide (GSSG) in the hepatocytes were also measured. Ethanol treatment (both pretreatment and co-treatment during the 3-hr tBH exposure) increased cell killing dramatically in both FTO2B cells and primary rat hepatocytes. Both DF and DPPD decreased ethanol-enhanced tBH cell killing in hepatocytes. These results demonstrated that co-treatment of FTO2B cells and primary rat hepatocytes with ethanol and tBH increased cell killing. The GSH level was dramatically reduced while GSSG level rose. Both DFP and DPPD reversed or protected the cells from this insult, indicating that ethanol was a pro-oxidant.

A Cost-effective Approach for 2-（t-Butyl）-6-methyl-4H-pyrone-A Key Intermediate Toward the Synthesis of Red-emitting Dyes for OLED Applications

In the interest of driving down the cost of DCM-type light emitting materials, we have found a new approach to prepare 2-（t-butyl）-6-methy1-4H-pyrone, which is cost effective and more amenable to large scale production than the reported method. Furthermore, three new DCM-type dyes, N,N-bis-[p-（2-（4-dicyanomethylene-6-t-butyl-4H- pyran-2-yl）-vinyl）-phenyl]-4-t-butyl-aniline （BDCM-BA）, N,N-bis-[p-（2-（4-dicyanomethylene-6-t-butyl-4H-pyran- 2-yl）-vinyl）-phenyl]aniline （BDCM-A） and N,N-bis-[p-（2-（4-dicyanomethylene-6-t-butyl-4H-pyran-2-yl）-vinyl）- phenyl]-4-methoxyl-aniline （BDCM-MA） were synthesized in good yields using 2-（t-butyl）-6-methyl-4H-pyrone as starting material. They can be utilized in OLEDs as nondoped red emitting materials as the result of the restricted concentration quenching effect.

Effect of Different Salts on the Solubilities of Benzene and Diphenyl in t-Butyl Alcohol-Water Mixture and Hydrophobic Interaction

The solubilities of benzene and diphenyl in mixed solvents of t-butyl alcohol(TBA) and water with different salts have been determined at T = 298.15, 303.15, 308.15 and 313.15K. The molar fraction of TBA [x(TBA)] in mixed solvent is 0.045, and the molality of the salts (m_s)in mixed solvents are 0.000, 0.250, 0.500, 0.750 and 1.000 mol/kg, respectively. The standard Gibbsenergies of solution of benzene and diphenyl in the mixed solvents have also been calculated basedon the solubility data. The effects of different salts on the hydrophobic interaction (HI) forbenzene-benzene pair in the systems were discussed.

Solubilities of benzene, toluene and diphenyl in the t-butyl alcohol+water mixtures and hydrophobic interaction

The solubilitices of benzene, toluene and diphenyl in mixed solvents of t-butyl alcohol (TBA) and water at 283.15, 288.15, 293.15 and 298.15 K have been determined by spectrophotometry. The mole fraction of TBA [x (TBA)] in the mixed solvent are 0.000, 0.010, 0.020, 0.030, 0.040, 0.045, 0.050, 0.060, 0.080 and 0.100, respectively. The standard Gibbs energies of solution of benzene, toluene and diphenyl in the mixed solvent have also been calculated based on the solubility data. The hydrophobic interactions (HI) for the pairs of benzene-benzene, methane-benzene and methane-methane in the mixed solvent were calculated and discussed.

Design, Synthesis, and Evaluation of 3-（（4-（t-Butyl）-2-（2- benzylidenehydrazinyl）thiazol-5-yl）methyl）quinolin- 2（1H）-ones as Neuraminidase Inhibitors

A series of novel 3-（（4-（t-buty-）-2-（2-benzylidenehydrazinyl）thiazol-5-yl）methyl）quinolin-2（1H）-ones （7a--7z） were designed, synthesized and evaluated for their ability of inhibiting neuraminidase （NA） of influenza H1N1 virus. Some compounds displayed moderate influenza NA inhibitory activity. Compound 71 with the scaffold of 2-（2-（2-methoxybenzylidene）hydrazinyl）thiazole was the best one, exhibiting moderate NA inhibitory activity with ICs0 of 44.66 ~tmol/L. Structure-activity relationship showed that compounds with methoxy or hydroxy groups at the ortho position, fluorine and nitro groups at the meta position and chlorine and bromine groups at the para posi- tion of phenyl ring were more active. Docking study indicated that compound 71 has important interactions with some key residues （including Asp151, Glu119, Arg292, Tyr406, and Asn347） and binds to 430-cavity adjacent to NA active site.

The spin delocalization substituent parameter σ(?)——6.The spin-delocalizing abilities of the thiomethyl,cyclopropyl and t-butyl groups.Synthesis of three substituted trifluorostyrenes

Three substituted α,β,β-trifluorostyrenes(TFS's),i.e.,p-thiomethyltrifluorostyrene(4), p-cyclopropyltrifluorostyrene(5)and p-t-butyltrifluorostyrene(6),have been synthesized.The rate constants(k_2)of the thermal cyclodimerization of these compounds have been measured in the tem- perature range 120—160℃.The polar parameters σ_(mb) of these TFS's calculated from ^(19)F NMR chemi- cal shifts are:for p-thiomethyl,-0.18;p-cyclopropyl,-0.31 and p-t-butyl,-0.22.The spin delo- calization substituent parameters σ'_T(140°)of p-thiomethyl,cyclopropyl and t-butyl groups are 0.59, 0.27 and 0.30 respectively.Thus all of these groups act as electron-donating groups which can also effectively stabilize a spin.