Determination of L -Cystine by a New Sensitive Cucurbit[7]uril/palmatine Probe

Abstract

In the presence of cucurbit [7]uril (CB[7]), the CB [7] could react with palmatine, which served as a sensitive fluorescence probe, to form host-guest stable complexes and the fluorescence intensity of the complexes was greatly enhanced. The fluorescence intensity decreased linearly with an increasing number of L-cystine in the inclusion system. The experimental results show that there exists a competition between L-cystine and palmatine for the CB [7] hydrophobic cavity and L-cystine occupies the space of CB [7] cavity, leading palmatine molecules to be forced to reside in the aqueous environment. Based on the fluorescence quenching of the CB [7]/palmatine complexes resulting from complex formation between CB [7] and L-cystine, a spectrofluorimetric method for the determination of L-cystine in aqueous solution in the presence of CB [7] was developed. The linear relationship between the corresponding values of the fluorescence quenching ∆F and L-cystine concentration was obtained in the range of 6.0 to 1.5×10 3 ng•mL -1 , with a correlation coefficient (r) of 0.9996. The detection limit was 2.0 ng•mL -1 . The application of the present method to the determination of L-cystine in tablets gave satisfactory results. This paper also discussed the mechanism of the fluorescence indicator probe.

Fluorescent Dyes and Their Supramolecular Host/Guest Complexes with Macrocycles in Aqueous Solution

“…The structurally related alkaloid derivatives PLM and DHC show a weak binding with CB7; however, a reasonable fluorescence enhancement upon inclusion has been demonstrated . In a recent application, the PLM/CB7 dye/host pair has been used in indicator displacement assays to detect the presence of l -cystine and sotalol in aqueous solution. , The berberine alkaloid (BE) is a particularly interesting dye, because it shows fluorescence enhancement upon binding to all three of the common macrocyclic motifs, namely cucurbiturils, calixarenes, and cyclodextrins. − Furthermore, it has shown an exceptional fluorescence enhancement ( ca. 500) upon its complexation by CB7 (see Figure ).…”

D6h‐Au42 Isomer: A Golden Aromatic Toroid Involving Superatomic π‐Orbitals that Follow the Hückel (4n+2)π rule

“…[41] For example, some ligand-protected gold clusters displaying as ingle superatomic bond involving two clusterc ores have been proposed as superatomic analogues of diatomic molecules. [42] Also, we and other groups explored the occurrence of hybridization in superatoms [43][44][45] leading to hybridized superatomic orbitals, resulting in similarm ulticenter bonds in as ymmetrics patiald isposition,w hich adds to the observed single, double and triples uperatomic bondsi nt he gold clusters. Thus, the superatomc oncept is intimately connected to relevant tools of great chemical significance, such as the Lewis structure model and the VSEPR theory.…”

Simple and fast detection of homocysteine by cucurbit[7]uril fluorescent probe based on competitive strategy

“…uridylcarbonyl portals [26,27]. CB[n] and its derivatives can combine with various guest molecules through hydrogen bonding, hydrophobic interaction, and ion-dipole interaction [26,28,29].…”

“…When Hcy was mixed with the CB[7]-BER system, Hcy and BER contended to occupy the hydrophobic cavity of CB [7]. The electrostatic ion-dipole interaction and hydrophobic interaction between the amine group of Hcy and the carbonyl group of CB [7] portal promote the formation of complexation [27].…”