A fluorescent probe for detection of Hg²⁺ ions constructed by tetramethyl cucurbit[6]uril and 1,2-bis(4-pyridyl)ethene

Abstract

In this paper, tetramethyl cucurbit[6]uril (TMeQ[6]) and 1,2-bis(4-pyridyl)ethene (G) were used to construct a supramolecular fluorescent probe G@TMeQ[6]. The host–guest interaction between TMeQ[6] and G was investigated using 1H NMR spectroscopy, single-crystal X-ray diffraction and various experimental techniques. The results show that TMeQ[6] and G form an inclusion complex with a host–guest ratio of 1:1 and the equilibrium association constant (Ka) was 2.494 × 104 M−1. The G@TMeQ[6] fluorescent probe can sensitively recognize Hg2+ ions by fluorescence enhancement. The linear range is 0.33 × 10−5–1.65 × 10−5 mol·L−1, R2 = 0.9926, and the limit of detection is 4.12 × 10−8 mol·L−1. The fluorescent probe can be used to detect the concentration of Hg2+ ions in aqueous solution, and provides a theoretical basis for the development of new fluorescent probes for detecting heavy metal ions.

Study on the host–guest interactions between tetramethyl cucurbit[6]uril and 2-heterocyclic-substituted benzimidazoles

“…The hydrophobic effect of the cavity and the negative charge of the port are two essential characteristics of Q[ n ]s that aid in forming various host–guest compounds due to their exceptional selectivity and affinity for particular molecules. 7–11 These unique properties of Q[ n ]s have led to their widespread use in ion recognition, 12,13 supramolecular catalysis, 14,15 drug carriers, 16,17 and luminescent materials. 18,19 However, Q[6, 8, 10] have inferior solubility due to their highly symmetrical spatial structure, which can be improved and modified by introducing substituents on the waist of the Q[ n ]s. A series of modified cucurbit[ n ]urils have been reported, such as methyl, hydroxyl, cyclopentyl, and cyclohexyl substituted Q[ n ]s. 20–24 Tetramethyl cucurbit[6]uril (TMeQ[6]) exhibits superior water solubility and greater affinity compared to Q[6].…”