Cucurbit[n]uril Assisted Nitrogen-doped Carbon Dots:synthesis And Properties

Carbon dots(CDs),Because of its high chemical stability,low cytotoxicity,unique tunable photoluminescence and other excellent physical and chemical properties,carbon dots have attracted widely attention in the fields of bioimaging,light-emitting diodes and son on.However,most CDs show relatively poor luminescence properties,such as short emission and low quantum yield(QY),which are often insufficient for bioimaging and other optical materials.Recent research results indicate that through host-guest interactions,for example,blue-emitting?-cyclodextrin-derived carbon dots are encapsulated in polymer micelles can be used as fluorescent probes with red emission^[1],which provides an important example of macrocycle in CDs.Against this research background,two different atom-doped CDs in the assistant of cucurbit[n]uril(Q[n])based host-guest interaction were synthized.Detailed studies are in following:1.The Q[n]-CDs were synthesized from pure tobias acid(TBA)in the presence Q[n]s in acidic water using a conventional hydrothermal route.Q[7]-CDs emit blue fluorescent emission,Q[8]-CDs emit yellow fluorescent emission,and no fluorescent emission was observed in CDs.TEM image indicated that the Q[n]-CDs were spherical with the particle diameter of 2-6 nm in well-resolved lattice fringes.FTIR,¹H NMR and XPS spectra results suggested that the Q[n]-CDs not only retain the rigid cavity of Q[n]s,but also form a new chemical bond such as N=S bond.Meanwhile,Q[7]-CDs exhibited a long fluorescence lifetime(96 ns)and a high quantum yield(56.75%),and tunable fluorescence emission from the dynamic host–particle interaction of Q[8]-CDs,which can be further exploited as biosensors for amino acids and 1-adamantanamine.In addition,An MTT assay showed that these CDs displayed low cytotoxicity and acted as a bioimaging reagent.2.(3-Aminophenyl)boronic acid(3-AB)and Q[n]s as the starting materials,CDs appeas different pH responses were synthesized.transmission electron microscopy(TEM),scanning electron microscopy(SEM),and atomic force microscopy AFM,X-ray powder diffraction(X-ray),X-ray photoelectron spectroscopy(XPS),UV-vis absorption,fluorescence emission spectra,and ¹H NMR spectra were exploited to characterize the properties of CDs and its properties.Experimental results suugested that various host-guest complex were formed between the Q[n]s and 3-AB,and which leading to the formation of CDs with different sizes.SXQ[7]-1 can be used as fluorescent probe for tungstate ions and dichromate ions.At the same time,the Q[n]-CDs formed under strong acid showing lower toxicity in PC3 cell experiment,and can be used for multi-channel cell imaging.