Synthesis And Application Of Fluorescent Probes Based On Chromene Pyrazoline

As an optical detection technique,fluorescent probes play an important role in the field of chemistry,environment and life sciences.Some heterocyclic compounds such as chromen,pyrazoline and?,?-unsaturated chalcone,etc.They have been widely reported as fluorescent probe in ion recognition because of their excellent fluorescence properties.In this paper,fluorescent probes based on chromene were designed and synthesized to apply to ion recognition.We pay attention to the study of optical property and applied to detect ions in cells.The detailed contents are summarized as follows:1.Synthesis,characteristics and application of 1-?3-?2-Hydroxyphenyl?-5-?2-phenyl-2H-chromen-3-yl?-4,5-dihydro-1H-pyrazol-1-yl?ethanone as fluorescent probe for Zn²⁺Firstly,2-phenyl-2H-chromen-3-aldehyde was synthesized by domino oxo-Michael/aldol reaction between salicylaldehyde and cinnamaldehyde.2-phenyl-2H-chromen-3-aldehy-de was reacted with acetophenone and 2-hydroxyacetophenone using NaOH base in ethanol solvent at room temperature and provided chalcone in good yield,respectively.Then,chalcone reacted with hydrazine hydrate under reflux in acetic acid.The corresponding pyrazoline compounds are 1-?3-Phenyl-5-?2-phenyl-2H-chromen-3-yl?-4,5-dihydro-1H-pyra zol-1-yl?ethanone and 1-?3-?2-Hydroxyphenyl?-5-?2-phenyl-2H-chromen-3-yl?-4,5-dihydro-1H-pyrazol-1-yl?ethanone?L?.The structures were confirmed by ¹H NMR,¹³C NMR and HRMS spectra.Their optical properties were studied by absorption and fluorescence spectra.The compound L can be used to determine Zn²⁺with high selectivity and sensitivity among a series of cations in aqueous ethanol-water solution.In contrast to L compound,which has no hydroxyl group in the phenyl ring did not revealed any significant changes in absorption and fluorescence emissions upon addition to Zn²⁺,which indicates the importance of a phenolic group as a binding site at the 3-position of the pyrazoline ring.The stoichiometric between the probe L and Zn²⁺was determined by Job's plot and found to be 1:1.Probe L was successfully applied to the detection of Zn²⁺in living BHK-21 cells,indicating that the compound has good membrane permeability.2.Synthesis,characteristics and application as Cu²⁺probe of 1-?3-?2-hydroxynaphthalen-1-yl?-5-?2-phenyl-2H-chromen-3-yl?-4,5-dihydro-1H-pyrazol-1-yl?ethanoneA fluorescent probe based on naphthalene pyrazoline fluorophore for Cu²⁺wasdesigned and synthesized.The structure of the probe was characterized by¹H NMR,¹³C NMR and HRMS spectra.The probe can induce a significant quenching after Cu²⁺was added and exhibits high sensitivity and selectivity for response to Cu²⁺in CH₃CH₂OH:H₂O?V:V=1:1,HEPES=10 mM,pH=7.4?solution.This process shows a noticeable change in color from a colorless to pale yellow color that can achieve“naked-eye”recognition.The binding ratio of this probe and Cu²⁺was determined to be 1:1 based on the Job's plot and the Cu²⁺titration result.The binding constant?Ka?of the complex was calculated to be 3.14×10⁴ M^-1 and the detection limit of the probe for Cu²⁺was 8.85×10^-7 M.The fluorescent image was returned by adding an appropriate amount of PPi.This probe can be employed to selectively monitor Cu²⁺in living PK-21 cells.3.Synthesis of chalcone-based fluorescent probe and its application as an identification of F^-To gain the target,we synthesized 2-phenyl-2H-benzopyran-3-aldehyde by using salicylaldehyde and cinnamaldehyde,then,reacted with 2-hydroxyacetophenone under reflux in ethanol solution.And the structure of the compound was characterized by ¹H NMR,¹³C NMR and elemental analysis.Its binding properties investigated in the CH₃CH₂OH:H₂O?V:V=1:1?solution by fluorescence spectroscope showed that it can selectively bind F^-with fluorescence enhancement,and formed 1:1 stoichiometry complex with F^-.The detection limit of the probe for F^-was 2.64×10^-5 M.The fluorescent probe C can detect F^-efficiently and sensitively.