A Novel Fluorescent Probe Based on Pyrazole-Pyrazoline for Fe (III) Ions Recognition

Firstly, a novel pyrazole-pyrazoline fluorescent probe was developed and synthesized. The probe can be used to determine Fe³⁺ ions in a series of cations in tetrahydrofuran aqueous solution with high selectivity and high sensitivity. After the addition of iron ions, the fluorescence intensity is significantly reduced, Its structure was characterized by ¹H NMR, ¹³C NMR and HR-ESI-MS. UV absorption spectra and Fluorescence spectroscopy were used to study the selective recognition of probe M on metal ions. The probe M can selectivity and sensitivity to distinguish the target ion from other ions through different fluorescence phenomena. In addition, the binding modes of M with Fe³⁺ were proved to be 1:1 stoichiometry in the complexes by Job's plot, IR results. The combination of probe M and iron ions is 1:1, and the detection limit is 3.9 × 10^-10 M. The binding mode and sensing mechanism of M with Fe³⁺ was verified by theoretical calculations using Gaussian 09 based on B3LYP/6-31G(d) basis.

The extraordinary richness of the reaction between diazomethane and tetracyanoethylene: can computational calculations shed light on old papers?

In the quest of the structure of the intermediate between Δ¹- and Δ²-pyrazolines, the reactivity of these molecules tetrasubstituted by cyano groups in adjacent positions (3,3,4,4 or 4,4,5,5) has been explored in their neutral and protonated forms.

NMR spectroscopic elucidation of the structure and stereochemistry of tricyclic 3-styrylpyrazolines

Diastereomeric mixtures of tricyclic 3-styrylpyrazolines have been prepared by the reaction of 3-cynnamylidenechroman-4-ones and their 1-thio analogs with hydrazine in hot acetic acid or propionic acid solutions. The diastereomeric mixtures were separated by column chromatography to obtain the pure diastereomers. The elucidation of their structure and stereochemistry and complete (1)H and (13)C assignments have been performed by a combination of various one- and two-dimensional NMR experiments.