Luminescent Properties of Europium Complexes with Different Long Chains in Langmuir-Blodgett (LB) Films

A series of europium(III) complexes with different chain length, tris [2-m-pyridylmethanamido-5-phenyl- (1,3,4)-oxadiazole] mono [2-(4-n-alkylphenyl)-iminazole (4,5-f)-1,10-phenanthroline] Eu(III) [Eu(PMA)3Nn (n = 6, 10, 14,18)] were synthesized. All of these amphiphilic europium(III) complexes could form stable Langmuir film at air/water interface and could be transferred onto hydrophilic quartz and mica substrates by measurement of UV spectra in which the absorbance of the LB films at about 288 nm scales showed the linearity with the number of layers deposited. In order to investigate relation between fluorescence properties and the arrangement of molecular in LB films, surface topography of monolayer films were observed by atomic force microscopy (AFM). Results showed that the emission spectra have Eu(III) characteristic peaks and strong emission strength. It is interesting that the molecular with looser arrangement in LB films has better monochromacity, which illustrated that energy might transferred more easily from ligand to Eu(III) in loosen structure films.

Electric-field-controlled highly regioselective thiocyanation of N-containing heterocycles

Achieving highly regioselective synthesis in organic chemistry is challenging due to the uncontrollable orientation between reacting partners.External electric fields(EEFs)can influence the reactivity and selectivity of the substrate by causing directional adsorption.However,scalable and efficient techniques for using EEFs as“smart catalysts”have been lacking,hindering their application.In this study,we present a novel method for modifying the regioselectivity of quinoxaline-2(1H)-ones by functionalizing their C7-position using the electric double layer(EDL)theory.This approach led to moderate to good yields of the corresponding C7-thiocyanation products.DFT calculations and control experiments demonstrated that EEFs could reverse the regioselectivity of quinoxaline-2(1H)-ones,allowing the C7-thiocyanation to proceed via a radical reaction mechanism.Additionally,the resulting 7-thiocyano-1-methylquinoxaline-2(1H)-ones exhibited promising AIE properties.Our work showcases a promising strategy for achieving highly regioselective functionalization by aligning the electric field with the desired reaction/bond axis.

Visible-light-promoted tandem decarboxylation coupling/cyclization of N-aryl glycines with quinoxalinones: Easy access to tetrahydroimidazo [1,5-a]quinoxalin-4(5H)-ones

A visible-light-promoted formal[2+2+1]cyclization of N-aryl glycines with quinoxalin-2(1H)-ones to synthesize tetrahydroimidazo[1,5-a]quinoxalin-4(5H)-ones have been developed.The protocol features operational simplicity,mild reaction conditions with blue LED light employing Ru(bpy)3Cl2.6H2O as a photoredox catalyst,a combination of O2 from air and Cu(OAc)2 as the oxidant and broad substrate applicability.

Palladacycle-Catalyzed Carbonylation of Aryl Iodides or Bromides with Aryl Formates

有芳基碘化物或溴化物的芳基甲酸盐的有效催化 palladacycle 的芳香的 carbonylation 反应被开发了。没有外部碳一氧化物的使用，商业地可得到、容易准备的芳基甲酸盐作为羰基来源被采用。现在的催化系统显示出宽广的功能的组忍耐并且负担得起芳基安息香酸盐衍生物在对优秀收益好。

Rhodium(Ⅲ)-catalyzed intermolecular cyclization of anilines with sulfoxonium ylides toward indoles

Rhodium(Ⅲ)-catalyzed synthesis of indole derivatives has been realized via cascade reaction of C -H alkylation/nucleophilic cyclization starting from readily available N-phenylpyridin-2-amines and sulfoxonium ylides. Notably, this transformation could smoothly proceed with high yields, good regioselectivity, and feature broad group tolerance and under redox-neutral condition to avoid external oxidant. The titled products are potentially important building blocks in the organic synthesis through various chemical transformations.

Ring opening [3+2] cyclization of azaoxyallyl cations with benzo[d]-isoxazoles:Efficient access to 2-hydroxyaryl-oxazolines

A selective ring-opening [3+2] cyclization reaction of benzo[d]isoxazoles with 2-bromo-propanamides has been developed.The azaoxyallyl cation intermediates are employed as C^O 3-atom synthon to build oxa-heterocycles via the selectivity of suitable cyclization partners.This transformation provides rapid access to highly functionalized 2-hydroxyaryl-oxazolines under mild conditions and excellent regioselectivity.

Rhodium(Ⅲ)-catalyzed [4+2] annulation of N-arylbenzamidines with1,4,2-dioxazol-5-ones: Easy access to 4-aminoquinazolines via highly selective C-H bond activation

A novel approach for the synthesis of 4-aminoquinazolines has been developed via rhodium(Ⅲ)-catalyzed [4+2] annulation of N-arylbenzamidines with 1,4,2-dioxazol-5-ones.This reaction features excellent regioselectivity,broad substrate scope and high step economy,which would provide the refe rence for the construction of the fused 4-aminoquinazolines with biologically and pharmacologically active compounds.

Water and fluorinated alcohol mediated/promoted tandem insertion/aerobic oxidation/bisindolylation under metal-free conditions:Easy access to bis(indolyl)methanes

A green tandem reaction,including insertion/aerobic oxidation/bisindolylation,starting from indoles and diazo compounds has been developed.The combination of water and fluorinated alcohol plays dual roles as solvent and promoter in this chemical transformation.Molecular oxygen in the air acts as an oxidant.3,3’-Bis(indolyl)methanes with quaternary carbon were produced under metal-free conditions.No any catalyst and additive were required.N2 and water were released as sole by-products.Absence of water and fluorinated alcohol resulted in Wolff rearrangement product.

Ru(Ⅲ)-catalyzed construction of variously substituted quinolines from 2-aminoaromatic aldehydes(ketones)and isoxazoles:Isoxazoles as cyclization reagent and cyano sources

A Ru(Ⅲ)-catalyzed annulation reaction of 2-aminoaromatic aldehydes(ketones)and isoxazoles to afford diverse 3-cyanoquinolines has been developed.Notably,isoxazole acted as a cyclization reagent and nontoxic cyano source via N-O bond cleavage and fragmentation.Variously substituted(especially 6-or 7-substituted)quinolines could be easily afforded.This procedure features wide functional group compatibility,efficiency and avoiding toxic cyano source.Meanwhile,this protocol could be successfully applied to scale-up synthesis.Further chemical transformations of 3-cyanoquinoline could give some valuable skeletons,demonstrating its potential in synthetic application.

Cp^*Co(Ⅲ)-catalyzed C—H amidation of azines with dioxazolones

Cp^*Co(Ⅲ)-catalyzed direct C—H amidation of azines has been developed.This co nversion could proceed smoothly in the absence of external oxidants,acids or bases,with excellent regioselectivity and broad functional group tolerance,CO2 was released as the sole byproduct,thus providing an environmentally benign amidation process.The products obtained are important intermediates in organic synthesis.