RESUMO
We developed a strategy for manipulating the binding strength of polycyclic aromatic hydrocarbons (PAHs) via covalent post-assembly modification (PAM) of tetranuclear ruthenium macrocycles containing s-tetrazine ligands. The macrocycles act as efficient receptors for various PAHs. Inverse electron demand Diels-Alder (IEDDA) reaction of the macrocycles was applied to reduce the binding ability significantly.
Assuntos
Compostos Heterocíclicos , Hidrocarbonetos Policíclicos Aromáticos , Reação de Cicloadição , ElétronsRESUMO
The sol-gel polymerization of alkoxysilanes is a convenient and widely used method for the synthesis of silicon polymers and silicon-organic composites. The development of new sol-gel precursors is very important for obtaining new types of sol-gel products. New condensation polymer precursors containing consecutive silicon atoms-decaisopropoxycyclopentasilane (CPS) and dodecaethoxyneopentasilane (NPS)-were synthesized for the preparation of polysilane-polysiloxane material. The CPS and NPS xerogels were prepared by the sol-gel polymerization of CPS and NPS under three reaction conditions (acidic, basic and neutral). The CPS and NPS xerogels were characterized using N2 physisorption measurements (Brunauer-Emmett-Teller; BET and Brunauer-Joyner-Halenda; BJH), solid-state CP/MAS (cross-polarization/magic angle spinning) NMRs (nuclear magnetic resonances), TEM, and SEM. Their porosity and morphology were strongly affected by the structure of the precursors, and partial oxidative cleavage of Si-Si bonds occurred during the sol-gel process. The new condensation polymer precursors are expected to expand the choice of approaches for new polysilane-polysiloxane.
RESUMO
A new class of sila-substituted 1,3,4-oxadiazoles was synthesized and evaluated for antiallergic activity using RBL-2H3 as the in vitro model and the in vivo anaphylactic mouse model. We observed that compound 5c effectively suppressed DNP-HSA-induced mast cell degranulation, compared to carbon analogue 9, and also suppressed the expression of TNF-α mRNA and Akt phosphorylation in antigen-stimulated RBL-2H3 cells. We also studied the effect of 5c in an in vivo passive cutaneous anaphylaxis (PCA) mouse model. The suppression by 5c was more effective than that by diphenylhydramine (DPH), a typical anti-histamine drug.
Assuntos
Antialérgicos/química , Antialérgicos/farmacologia , Oxidiazóis/química , Oxidiazóis/farmacologia , Anafilaxia Cutânea Passiva/efeitos dos fármacos , Silício/química , Anafilaxia/tratamento farmacológico , Anafilaxia/enzimologia , Anafilaxia/genética , Anafilaxia/imunologia , Animais , Antialérgicos/uso terapêutico , Linhagem Celular , Regulação da Expressão Gênica/efeitos dos fármacos , Imunoglobulina E/imunologia , Masculino , Camundongos , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Oxidiazóis/uso terapêutico , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Prata/química , Fator de Necrose Tumoral alfa/genética , beta-N-Acetil-Hexosaminidases/metabolismoRESUMO
Chlorotrisylsilylenoid reacted with both acetophenone and benzil to give the corresponding 2,5-dioxasilolanes and silylethers, respectively.
Assuntos
Cetonas/química , Compostos de Organossilício/química , Acetofenonas/química , Cristalografia por Raios X , Conformação Molecular , Fenilglioxal/análogos & derivados , Fenilglioxal/química , Silício/químicaRESUMO
A highly active and durable fumed silica-supported heterogeneous molybdenum(VI) catalyst was applied to ring closing alkyne metathesis and cyclooligomerization reactions to give high yields of metathesis products near room temperature conditions.
RESUMO
A highly active alkyne metathesis catalyst is realized by replacing the amide ligands of a molybdenum(VI) trisamide alkylidyne complex with silanol groups from incompletely condensed POSS (polyhedral oligomeric silsesquioxane) ligands. This catalyst serves as an effective homogeneous mimic of an amorphous silica-supported catalyst. Reactivities of various catalytic mixtures are reported along with an X-ray structure of the aniline-coordinated amidodisiloxymolybdenum(VI) alkylidyne complex.
RESUMO
Halosilylenoids, stable at room temperature (Tsi)X(2)SiLi (Tsi=C(SiMe(3))(3), X=Br, Cl), were synthesized from the reaction of TsiSiX(3) with lithium naphthalenide. Bromosilylenoid reacted with tBuOH and MeI both at -78 degrees C and at room temperature to give (Tsi)HSiBr(2) and (Tsi)MeSiBr(2), respectively, in high yields; this clearly shows its nucleophilicity. In the reaction of bromosilylenoid with methanol, 2-propanol, and 2,3-dimethyl-1,3-butadiene, the corresponding products, (Tsi)HSi(OMe)(2), (Tsi)HSi(OiPr)Br, and bromo(Tsi)silacyclopent-3-ene, were obtained in high yields; this demonstrates its amphiphilic property, as if bromosilylene would be trapped. Chlorosilylenoid also exhibited both nucleophilic and amphiphilic properties. The (29)Si chemical shifts for (Tsi)Br(2)SiLi, (Tsi)Br(2)SiK, and (Tsi)Cl(2)SiLi were 106, 70, and 87 ppm, respectively.