title: Determination of phenformin hydrochloride employing a sensitive fluorescent probe.
abstract: A complexation of non-fluorescent phenformin hydrochloride (PFH) with cucurbit [7]uril (CB [7]) in aqueous solution was investigated using the fluorescent probe of palmatine (PAL) coupled with CB [7]. The fluorescent probe of CB [7]-PAL exhibited strong fluorescence in aqueous solution, which was quenched gradually with the increase of PFH. This effect is observed because when PFH was added to the host-guest system of CB [7]-PAL, PFH and PAL competed to occupy the CB [7] cavity. Portions of the PAL molecule were expelled from the CB [7] cavity owing to the introduction of PFH. Based on the significant quenching of the supramolecular complex fluorescence intensity, a fluorescence method of high sensitivity and selectivity was developed to determine PFH with good precision and accuracy for the first time. The linear range of the method was 0.005-1.9 μg mL(-1) with a detection limit of 0.003 μg mL(-1). In this work, association constants (K) of PFH with CB [7] were also determined. KCB [7]-PFH=(2.52±0.05)×10(5) L mol(-1). The ability of PFH to bind with CB [7] is stronger than that of PAL. The results of a density functional theory calculation authenticated that the moiety of PFH was embedded in the hydrophobic cavity of CB [7] tightly, and the nitrogen atom is located in the vicinity of a carbonyl-laced portal in the energy-minimized structure. The molecular modelling of the interaction between PFH and CB [7] was also confirmed by (1)H NMR spectra (Bruker 600 MHz).
authors.affiliation: Analytical and Testing Center, Shanxi Normal University, Shanxi, Linfen 041004, PR China.
authors.forename: Lin
authors.initials: L
authors.lastname: Shi
authors.affiliation: Analytical and Testing Center, Shanxi Normal University, Shanxi, Linfen 041004, PR China.
authors.forename: Jian-Hong
authors.initials: JH
authors.lastname: Xie
authors.affiliation: Analytical and Testing Center, Shanxi Normal University, Shanxi, Linfen 041004, PR China. Electronic address: lmd2004@163.com.
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Du
authors.affiliation: Analytical and Testing Center, Shanxi Normal University, Shanxi, Linfen 041004, PR China.
authors.forename: Yin-xia
authors.initials: YX
authors.lastname: Chang
authors.affiliation: Analytical and Testing Center, Shanxi Normal University, Shanxi, Linfen 041004, PR China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wu
mesh_terms: D001952:Bridged-Ring Compounds / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D007093:Imidazoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D010629:Phenformin / Q000032:analysis* / Q000737:chemistry*; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D001952:Bridged-Ring Compounds; D005456:Fluorescent Dyes; D007093:Imidazoles; D010629:Phenformin; C456276:cucurbit(7)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
keywords: Cucurbit [7]uril; Fluorescent probe; Palmatine; Phenformin hydrochloride