Latest ArticlesA pyrene-tiaraed pillar[5]arene derivative was synthesized, which showed a concentration-independent intensive excimer emission. Photolysis of the pyrene-tiaraed pillar[5]arene led to a switch from excimer to monomer emission, applicable to photo-writing.
In this communication, a new supramolecualr amphiphile was successfully constructed based on water soluble pillar[5]arene and a unique guest which contain a CO2 responsive tertiary amine unit and a UV responsive coumarin group. When guest molecule 1 dispersed in water, it self-assembled into sheet-like structures. Upon bubbling CO2, 1 transformed into 1H due to the tertiary amine unit was protonated, accompany the nano-sheets transformed into vesicles. Further irradiation of 1H with 365 nm light for 3 h, the coumarin group reacted with each other to form bola-type amphiphie 2H. In this case, vesicles collapsed and re-assembled into nano-tubes. However, when addition of WP5 into the solution of 1H, the vesicles transformed into micelles, this is due to the formation of supramolecular amphiphile WP5&1H. Upon irradiation of WP5&1H with 365 nm light for 3 h, nano-ribbons observed instead of micelles in the solution. Notably, nanotubes from 2H could also transform into nano-ribbons after adding WP5. The self-assembly process and the resultant assemblies were characterized by TEM, SEM, DLS, SAXS and NMR technologies. Due to both CO2 and light are pgreenq for living organisms, we anticipated our system can offer the possibilities in pon demandq drug absorption and release.
Herein, we report the facile conjugation between proteins and water-soluble [60]fullerene derivatives (DC60) under native conditions using SpyTag as a reactive handle. Water-soluble [60]fullerene derivatives were first prepared via sequential Bingel-Hirsch reaction and pclickedq with SpyTag to give DC60-SpyTag for native conjugation with proteins by the highly efficient SpyTag-SpyCatcher chemistry. The bioconjugation was confirmed by MALDI-TOF MS spectra and SDS-PAGE analysis. The TEM and UV-vis spectroscopic study further revealed that the DC60 could alter the optical performance and induce aggregation of the target proteins. It thus provides a general and robust method for modifying proteins with C60 derivatives and could potentially be adapted for native conjugation between proteins and other nonbiological motifs as well.
A metal-organic photoinduced electron transfer (PET) supramolecular nanoarchitecture comprised of Ru(Ⅱ) bis(terpyridine)-modified pillar[5]arene (electron acceptor) and triazole triphenylamine amyl cyanide (electron donor) has been designed and constructed. Through the comparison of diverse solvents and acceptors, the two conditions, i.e., modification of pillar[5]arene to donor and weak polar solvent are benefit for the occurrence of "efficient PET" because of shorter D-A distance in the presence of pillar[5]arene. Crucially, the fluorescence and PET process of the supramolecular assembly could be further modulated by solvent conversion and another competitive guest. The study provides a supramolecular method to design and construct tunable PET systems and PET-based smart materials.
Curcurbit[n]uril (Q[n])-based supramolecular frameworks (QSFs) constructed from the outer surface interaction of Q[n]s (OSIQ) have the characteristic of simplicity, diversity and modulability. Their simplicity is reflected in their simple composition and preparation methods used for QSFs. The diversity of supramolecular organic frameworks (SOFs) is reflected in the synthesis methods and structural characteristics of the as-obtained QSFs, as well as the variety of structural directing agents and basic building blocks used to prepare QSFs. The modulability is reflected by the controllable channel size in the QSFs, which can be adjusted using different sizes of Q[n]s. In this work, the first reported cucurbituril Q[6] was selected as the basic building block and three Q[6]-based supramolecular frameworks were obtained from aqueous HCl solutions in the presence of [CdCl4]2- respectively. The OSIQs are the main driving forces for the formation of these frameworks. This study shows the diversity of the QSFs.
We report herein a new fluorescent probe for the selective recognition and determination of dodine among 20 different pesticides. This fluorescent probe was assembled through host-guest complexation between cucurbit[10]uril (Q[10]) and aminopropyl-1-pyrenebutanamide (PBA) and is designated as PBA@Q[10]. Addition of dodine to PBA@Q[10] results in a dramatic enhancement of fluorescence intensity at 390 nm, accompanied by fluorescence quenching at 488 nm. On this basis, the detection limit is 6.78×10-7 mol/L. The response mechanism is a competitive interaction: dodine occupies the cavity of Q[10] and forces PBA to leave.
Star shape bridged pillar[5]arene trimer (C3-PLT) based on benzene-1,3,5-tricarboxamide (BTAs) was successfully synthesized, which exhibited outstanding guest responsive morphology transition properties. The morphology tuning studies was efficiently achieved with the addition of competitive guest molecules G1 and G2 by various self-assembly mechanisms. C3-PLT itself displays nanofiber morphology through H-type π-π stacking, and this nanofiber morphology can be completely transformed into spherical vesicles by host-guest interaction G1, while upon addition of G2 into C3-PLT by means of "exo-wall" electron-transfer interactions, sheet superstructures can be observed. SEM, 1H NMR, DOSY, fluorescence spectroscopy, and viscosity have verified the formation of supramolecular polymers and morphological transitions between C3-PLT with both guests.
Based on the crystal structures of two cucurbit[6]uril/calix[n]arene-based supramolecular frameworks reported by Long and co-workers, we further investigated the interactions of cucurbit[6]uril with 4-sulfocalix[4]arene and 4-sulfocalix[6]arene using 1H NMR spectroscopy and isothermal titration calorimetry (ITC), respectively. Moreover, solid fluorescent materials were prepared via the adsorption of fluorescent dyes by these porous supramolecular frameworks, which exhibit a selective response to certain volatile organic compounds.
An intramolecular dehydrogenative homo- and hetero-coupling of phenols has been successfully developed for quick preparation of enantiopure axial diphenols under mild Cu(Ⅱ)-mediated conditions, using ((4S, 5S)-2,2-dimethyl-1,3-dioxolane-4,5-diyl)dimethanol as the chiral auxiliary. The commercially available (R)-α-methylbenzylamine was identified as the best amine ligand for Cu(Ⅱ) in the reactions. A variety of homo/hetero bis-dihydroxylbenzoate substrates were examined, affording the corresponding axially chiral diphenols with satisfactory to excellent diastereomeric ratios, and a representative scalable preparation was also attempted. A formal synthesis of natural product (+)-deoxyschizandrin has been achieved in this work using one axially chiral diphenol as the synthetic intermediate.
A Rh(Ⅰ)-catalyzed highly regio- and enantioselective allylic alkylation of Meldrum acid with racemic allylic substrates bearing alkyl groups has been developed. The applying of chiral bisoxazopinephosphine ligand is essential for the high yields and selectivities. This method provides a rapid access to various chiral β-alkyl-λ, δ-unsaturated carboxylic acids and their derivatives.
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