Synthesis Of A Functional Organic Molecule Containing Boric Acid And Naphthalene As Well As Sugar Sensor Research

The saccharide exists in the body of animals and plants widely, which consists to the body of organism as well as be an essential energy and physiological substance of life. In addition, it has an external signal transmission and identifying function. Therefore, establish sensitive and selective methods of the sugar recognition play significant roles in the fields of medicine, cellular, biological science. In recent years a large number of fluorescence sensors based on boric acid have been investigated. The detection methods maintained the fluorescence spectroscopy, the circular dichroism spectroscopy and the absorption spectroscopy. The fluorescence spectroscopy was the most widely used way. Boric acid and saccharides or hydroxyl compounds which have cis-1, 2- or 1, 3-diols can form five- or six-membered rings, respectively. Therefore boric acid can be used as the receptor to recognize the reducing sugars in the body which can be acting as the substrate. More over, it also can be applied to medical research about controlling and detecting a number of diseases such as diabetes, heart disease, kidney failure, gangrene and so on. At the same time it can be used for establishing self-regulating drug delivery systems or adjusting some life activities related to sugars.This paper is based on this research thinking. Naphthyl-1-amine, 1, 6-dibromohexane and 4-methylphenylboronic acid are major raw materials. The functional organic monomer: dimethyl5-(6-(N-(4-dihydroxy boryboryl -benzyl)hexyloxy)-naphthalen-1-ylamino)benzene-1,3-dioate which contains rigid fluorescent group of naphthalene and boric acid which can recognize the sugars was synthesized. Then using this monomer: dimethyl5-(6-(N-(4- dihydroxyboryboryl-benzyl)-naphthalen-1-ylamino)hexyloxy)benzene-1,3-dioate and PEG600 to get the polymer named poly-[(polyoxyethylene-600)-oxy- 5-(6-(N-(4-dihydroxyboryborylbenzyl)-naphthalen-1-ylamino)hexyl)-isophthaloyl] by melt poly-condensation.We studied the recognition between the receptor (the functional organic monomer) and the substrate ( the sugars ).First, we learned the fluorescence intensities and stocks changes on differentΦscales. The stocks changes shifted about 20 nm from 440nm to 420nm whenΦvalues changed from 0.1 to 1.Besides, the fluorescence intensities were growing whenΦvalues varied from 0.1 to 0.5; then in the process ofΦvalues altered from 0.5 to 1, the fluorescence intensities fell off. We believe that the main reason of the blue stocks-shift was mainly due to charge-transfer effect (CT-effect). In generally, with reducing of the polarity of the solution, the stocks-shift will shift to blue. And the diversification of fluorescence intensities caused byΦvalue changes was dominated by the kinetic effects. WhenΦvalue was in weak polar region (Φvalue from 1 to 0.5), the solution was controlled by the negative kinetic effect, then the fluorescence intensity increased when the polarity of the solution rose .After theΦvalue decreased further (Φvalue from 0.5 to 0.1), the fluorescence intensities fell away with the increase of polarity which influenced by the positive kinetic effect .But the corresponding displacement of absorption spectra was not particularly significant, we believe that this was due to its main peak of absorption spectra located close to 220 nm.Second, in order to study the relationship between the structure change of the monomer and the fluorescence, we studied the influence of PH to the fluorescence intensity. It had the similar changes to fluorescence within sugars and without sugars in the solution. In the process of the PH value transfer from the strong acid to strong alkaline,the main peak of the fluorescence peak shifted from approximate 350 nm to 430 nm .And with enlarging the PH value, the fluorescence intensities of 350 nm were gradually smaller and the fluorescence intensities of 430 nm were gradually larger. In the situation of PH <4.0, its fluorescence intensities were decreased with adding the sugar. When PH = 4.0, the fluorescence intensity was quenched entirely. The former situation was linked to the tetrahedral structure of nitrogen in the monomer. The latter situation was associated with the neutral structure of the monomer. Thus, we believe that both structures were the weak fluorescence constructions. In addition, because of the infection coming from its carboxylic acid group, the PH value of the monomer'neutral was 4.0 which was different from the normal compounds that neutral PH values were physical PH. When PH> 4.0, particularly in the neutral and alkaline conditions, after the identification was coming true between boric acid and sugar, that boron's SP2 was turning into SP3 can be considered. In our opinion, the emergence of boron's tetrahedral structure was the reason why the peak at 430 nm appeared. And because this structure could lower nitrogen's PET effect to naphthalene, we thought that was a strong fluorescence structure.Meanwhile, we studied the recognition between the monomer and the reducing sugars. We chose fructose, glucose and ribose as reducing sugars; sucrose and maltose as disaccharides. We found that the identification between reducing sugars (particularly the fructose) were fast and effective. We also discovered that there were three main reasons that led the impossible identification happen: 1)the force between the boric acid and the hydroxyl was weak; 2)the hydrolysis of the disaccharides were affected by environment; 3)the rigid structure of the disaccharides.Makes the compound dimethyl 5-(6-(N-(4-dihydroxyboryborylbenzyl) -naphthalen-1-ylamino) hexyloxy)benzene-1,3-dioate to be assembled in the membrane of Aurum by electrostatic assembly, then forms a self-assembly membrane (SAMs), which will let it come into being a sensor devices to the saccharide recognition. We realized that the absorption peak was shifting after forming self-assembly membrane. This proved the feasibility of the former design ideas.In short, synthesized a monomer which could be use as a fluorescent sensor:dimethyl5-(6-(N-(4-dihydroxyboryborylbenzyl)-naphthalen-1-ylamino)benzene-1,3-dioate.We did a series of studies about recognition between this system and saccharide which could give to some useful experience not only to the future research about the self-administration medical system but also to fluorescence sensors which could be used to detect the reducing sugars in the human body.