黄烷酮及其羟基衍生物的荧光性质研究

黄烷酮类化合物是天然药物的重要活性成分，也是有机合成的研究热点之一，但此类化合物的荧光性质尚缺乏研究。研究了黄烷酮及其6种羟基衍生物的荧光性质，发现黄烷酮(Flavanone，FV)、7-羟基黄烷酮(7-Hydroxyflavanone，7HF)和6-羟基黄烷酮(6-Hydroxyflavanone，6HF)的水溶液有荧光，而2’-羟基黄烷酮(2’-Hydroxyflavanone，2’HF)、4’-羟基黄烷酮(4’-Hydroxyflavanone，4’HF)、柚皮素(4’,5,7-三羟基黄烷酮，Naringenin)和乔松素(5,7-二羟基黄烷酮，Pinocembrin)的水溶液基本无荧光。在三维荧光图谱中，FV的荧光激发波长(λ_ex)为235，265和340 nm，发射波长(λ_em)为386 nm;7HF的λ_ex为230，276和315 nm，λ_em为391 nm;6HF的λ_ex为260和356 nm，λ_em为482 nm。研究了pH对FV，7HF和6HF荧光的影响，从分子结构的角度讨论了pH对荧光产生影响的原因。研究了7HF和6HF在不同pH条件下的紫外吸收光谱，用pH-光度法测得7HF和6HF的羟基质子电离常数pK_a分别为7.26±0.05和9.90±0.02。研究了溶剂(甲醇)对FV，7HF和6HF荧光光谱的影响，发现FV和7HF在甲醇溶液中的荧光比在水中减弱，而6HF在甲醇中的荧光显著增强。在有序介质(SDS，CTAB，β-CD)中，FV和7HF的荧光减弱，而6HF在β-CD或CTAB中的荧光增强。以硫酸奎宁或L-色氨酸为参比，测得FV和7HF水溶液的荧光量子产率分别为0.057和0.012;6HF在甲醇中和在β-CD浓度为1.62 mg·mL-1的水溶液中的荧光量子产率分别为0.064和0.012。

Study on Fluorescence Properties of Flavanone and Its Hydroxyl Derivatives

Flavanone derivatives are important active ingredients of natural medicine ,so the synthesis of these compounds is one of the research hotspots of organic synthesis .Nevertheless ,there is little research on fluorescence properties of these compounds up to now .Fluorescence properties of flavanone and 6 kinds of hydroxyl derivatives are studied in this paper .It is found that aqueous solutions of flavanone (FV) ,7‐hydroxyflavanone (7HF) and 6‐hydroxyflavanone (6HF) have fluorescence ,but aqueous solutions of 2’‐hydroxyflavanone (2’HF) ,4’‐hydroxyflavanone (4’HF) ,naringenin and pinocembrin basically have no fluores‐cence .In three dimensional fluorescence spectra ,excitation wavelengths λex of FV are located at 235 ,265 and 340 nm ,emission wavelength λem is at 386 nm ;λex of 7HF are at 230 ,276 and 315 nm ,λem is at 391 nm ;λex of 6HF are at 260 and 356 nm ,em is at 482 nm .Influences of pH on fluorescence of FV ,7HF and 6HF are studied ,and the reasons of pH affects on fluorescence are discussed from the viewpoint of molecular structure .The UV‐absorption spectra of 7HF and 6HF at different pH are studied , and the proton ionization constants (pKa) of 7HF and 6HF are determined respectively to be 7.26 ± 0.05 and 9.90 ± 0.02 ,by a pH‐absorption method .Influences of solvent (methanol) on fluorescence of FV ,7HF and 6HF are studied ,and find that the fluorescence of FV and 7HF in methanol are weaker than that in water ,but the fluorescence of 6HF in methanol is much stron‐ger .In ordered media (SDS ,CTAB andβ‐CD) ,fluorescence of FV and 7HF decreased than that in water ,but the fluorescence of 6HF enhanced in the media of β‐CD or CTAB .Using quinine sulfate or L‐tryptophane as reference ,fluorescence quantum yields of FV and 7HF aqueous solutions are measured to be 0 .057 and 0.012 ,respectively ;fluorescence quantum yields of 6HF in methanol or in aqueous solution containing 1.62 mg · mL -1 β‐CD are measured to be 0.064 or 0.012 ,respectively .