Synthesis And Spectroscopic Properties Of Pyridyl-β-diketones And Their Derivatives

β–Diketone compound is a special organic compounds. It exists in two forms: the keto andthe enol, Which makes them extremely attractive as intermediates and chemistry ofmetallocomplexes. β–Diketone compounds in the UV protection, pharmaceutical and pesticideintermediates, luminescence, catalyzer, atomic absorption spectrometry and other fields have awide range of application prospects.In this paper, we designed and synthesized a series of β–diketone derivatives and reviewedresearch progress of the pyridyl β–diketone ligands in recent years. Ten pyridyl β–diketones,thirty1H–pyrazoles derivatives, Ten boron difluoride pyridyl–β–diketonate derivatives weresynthesized.The main work is as follows:1. Ten pyridyl β–diketones were synthesized by Claisen condensation of ethylisonicotinate (nicotinate) with various aryl methyl ketones in benzene in the presence of sodiumamide as the base and characterized using FTIR,1H NMR, elemental analysis and massspectrometry. The UV vis absorption spectra show that they are a kind of good absorbents inUV region from320to400nm.1H NMR results show that β–diketones have two forms andpredominately exist in the enol form in chloroform.2. The1H–pyrazoles were synthesized by cyclization of the β–diketones with hydrazinemonohydrate in ethanol. Their structures are established by FTIR,1H NMR, mass spectrometry,elemental analysis and the crystal structure of10b was determined.3. The N-acyl-3-pyridyl-5-aryl-pyrazoles were obtained by N–acylation of the1H–pyrazoles with acyl chloride, benzoyl chloride in the presence of triethylamine. Theirstructures were well supported by FTIR,1H NMR, mass spectrometry and elemental analysis.The preliminary structure activity relationship analysis revealed that the pyrazole derivativeswith electron–withdrawing substituent had better antimicrobial activity than that ofelectron–donating substituent.4. The boron difluoride pyridyl β–diketonate derivatives were synthesized bycomplexation of pyridyl β–diketones with boron trifluoride diethyl etherate. Their compositions and structures were confirmed by FTIR,1H NMR, mass spectrometry and elemental analysis.Their optical properties were determined by UV–vis absorption, fluorescence spectroscopy andquantum yield. The results indicated that the longest absorption maxima of compounds1e–10eare red shifted about20–45nm as compared to those of compounds1a–10a. These boroncomplexes exhibited intense fluorescence in the blue-green region (400500nm) with arelatively high quantum yield.