Synthesis Of Phenylboronic Acid Derivatives And Their Recognition For Carbohydrate

Ever since the organic boronic acid compounds were synthetized for the first time in 1860,the organic boronic acid compounds have been widely used in organic synthesis and bio medical fields,such as carbohydrates and ion recognition,due to their exceptional atomic configurations,plus their stable and environmentally friendly character.This paper focus on the synthesis of two new organic boronic acid compounds that have not been published before,combine with the research of their ability in carbohydrates recognition.In this paper,two kinds of benzene boronic acid compounds that containing diethyl phosphate substituents were designed and synthetized,and their properties and structures were characterized by IR,1H NMR,and MS among other methods,then the fluorescence spectrum experiments were conducted to recognize carbohydrates,and their binding constants were calculated by Benes-Hildebrand experiments formula,then apply it to a more complex situation to detect fructose in honey.The synthetic experiment is a classic one-pot reaction,using formyl benzene boronic acid(4-formylphenylboronic acid and 2-formylphenylboronic acid)and p-aminobenzoic acid to form Schiff bases compounds that containing boronic acid group,then took these two Schiff bases to react with diethyl phosphite respectively,at last using mixed solvent(water and ethanol)to get the purified compounds 1 and 2that containing phosphate substituent.Both compounds were characterized by IR,1H NMR,and MS the infrared spectrum,one-dimensional hydrogen nuclear magnetic spectrum,mass spectrum,to deducted their structures and make sure they are the products we expected.Then the fluorescence spectrum experiments were conducted accordingly.The qualitative fluorescence spectrum experiments have shown that both compounds are fluorescent in solid and solution state,and after adding different sugar compounds solution,their fluorescence intensity have shown different degrees of enhancement accordingly,and they all have specific recognition for D-fructose.The quantitative fluorescence spectrum experiments have shown that compound1 has excellent combining ability with D-fructose,much better than that of compound2 evidently,with the binding constant for compound 1 is 71.71 to 7.128 for compound2,the reason behind this phenomenon could be that compounds 1 have two free-OH.Using compound 1 with better binding constant as a receptor to detect content of D-fructose in linden honey and sophora flower honey,the experiments results that come from the working curve of mixed sugars,its relative standard deviation of two kinds honey are 0.1260% and 0.4107% respectively,the standard deviation are 0.71%and 1.8% respectively.The results from using D-fructose working curve,its RSD are0.1692% and 0.5750% respectively,the standard deviation are 5.66% and 4.5%respectively.Those results indicate that when the mixed sugars working curve are using rather than D-fructose working curve,can eliminate the influence of other sugars,therefore its results are more accurate.Fluorescence experiment in solid state showed similar results to the ones in solution state: both two compounds itself show faint yellow-green fluorescent,their fluorescence intensity are enhanced visibly after the adding of D-fructose,and the adding of other sugars have no obvious influence on the compounds fluorescence intensity.And the fluorescence enhancement of compounds 1 is much stronger than that of compound 2.Then the influence of different metal salts on the fluorescence intensity of compound 1 and D-fructose mixture(molecule ratio of 3: 1),the adding of ferric chloride(FeCl3)and cobalt chloride(CoCl2)both have strong quenching effect on the compound-fructose mixture,and the adding of other metal salts(CaCl2,CrCl2 MnCl2,CuCl2,ZnCl2)have no such influence on the compounds fluorescence intensity,so the compound-fructose mixture can be used to identify ferric salts and cobalt salts.