Artificial stepwise light harvesting system in water constructed by quadruple hydrogen bonding supramolecular polymeric nanoparticles

Stepwise energy transfer is ubiquitous in natural photosynthesis,which greatly promotes the widespread use of solar energy.Herein,we constructed a supramolecular light harvesting system based on sequential energy transfer through the hierarchical self-assembly of M,which contains a cyanostilbene core flanked by two ureidopyrimidinone motifs,endowing itself with both aggregation-induced emission behavior and quadruple hydrogen bonding ability.The monomer M can self-assemble into hydrogen bonded polymers and then form supramolecular polymeric nanoparticles in water through a mini-emulsion process.The nanoparticles were further utilized to encapsulate the relay acceptor ESY and the final acceptor NDI to form a two-step FRET system.Tunable fluorescence including a white-light emission was successfully achieved.Our work not only shows a desirable way for the fabrication of efficient two-step light harvesting systems,but also shows great potential in tunable photoluminescent nanomaterials.

Metal-free direct C(sp^(3))-H functionalization of 2-alkylthiobenzoic acid to access 1,3-benzooxathiin-4-one

Metal-free direct α-C(sp^(3))-H intramolecular cyclization of 2-alkylthiobenzoic acid in the presence of Selectfluor is described.This novel strategy provides a facile and efficient method to access important 1,3-benzooxathiin-4-one derivatives with good functional groups tolerance and yields.

Preparation of a fixed-tetraphenylethylene motif bridged ditopic benzo-21-crown-7 and its application for constructing AIE supramolecular polymers

Benzo-21-crown-7(B21 C7)is one of the most important crown ethers,which not only shows excellent physicochemical properties but also exhibits promising binding capability with dialkylammonium salts.In this paper,we designed and synthesized a fixed-tetraphenylethylene(FTPE)motif bridged ditopic benzo-21-crown-7 molecule(H).The fixed tetraphenylethylene motif endows H with aggregation induced emission(AIE)prope rty.In the presence of a ditopic dialkylammonium salt guest molecule(G),a fluorescent supramolecular polymer with golden luminescent property could be fabricated.This B21 C7-based host-guest supramolecular polymer with golden fluorescence may have potential application in dynamic luminescent materials.

Supramolecular interaction controlled and calix[4]arene ligand assisted Pd-catalyzed C(sp3)-H arylation of aliphatic aldehydes

A calix[4]arene ligand assisted directβ-C-H arylation of tertiary aliphatic aldehydes has been developed via a Pd-catalyzed C(sp3)-H functionalization process.This strategy exhibited good functional group compatibility and C-H bond site-selectivity.Mechanism studies have shown that both synergistic effect and cationic-πsupramolecular interaction between calixarene cavity and transition-metal catalytic center may play an important role in this catalytic cycle.This complementary method would be used in organic and medical chemistry due to the importance of tertiary aliphatic aldehydes.

Asymmetric Michael addition reactions catalyzed by a novel upper-rim functionalized calix[4]squaramide organocatalyst

A novel upper-rim functionalized calix[4]squaramide organocatalyst bearing bis-squaramide and cyclohexanediamine scaffolds was designed and prepared to catalyse a serial of asymmetric Michael addition of 1,3-dicarbo nyl compounds to a,β-unsaturated carbonyl compounds in high yields(up to 99%)and good to excellent enantiomeric excesses(up to 99%ee).The comparative experiments indicated that the cooperative effect between calixarenes cavitives and chiral catalytic centers on this calix[4]squaramide catalyst could promote these reactions.Moreover,this strategy also provides valuable and easy access to chiral chromene,naphthoquinone and acetylacetone derivatives,which are important skeletons in biological and pharmaceutical compounds.

NFSI-catalyzed S–S bond exchange reaction for the synthesis of unsymmetrical disulfides

The metal-free S–S bond exchange reaction of symmetrical disulfides catalyzed by NFSI is described. This novel protocol provides a facile and efficient approach to accessing important unsymmetrical disulfides.Furthermore, this strategy could also be utilized in the late-stage functionalization of amino acids, drugs,and natural products. The broad substrate scope, good functional group tolerance and easy accessibility of catalyst indicate that this strategy affords a green and practical complementary method to various unsymmetrical disulfides.