本文選題：銀納米粒子 + 光化學(xué)還原��； 參考：《江蘇科技大學(xué)》2017年碩士論文

【摘要】：近年來手性銀納米材料由于在手性催化、手性識(shí)別、光學(xué)領(lǐng)域等方面的應(yīng)用而受到廣泛的關(guān)注。本文選用不同的手性小分子作為手性誘導(dǎo)劑和修飾劑,采用光化學(xué)還原和液相化學(xué)還原法制備出具有手性的銀納米粒子,對制備的銀納米粒子進(jìn)行紫外-可見吸收光譜(UV-vis)、圓二色譜(CD)、透射電鏡(TEM)的表征,并對銀納米粒子手性形成機(jī)理進(jìn)行了初步探討。采用光化學(xué)還原法,在硝酸銀和脫氧膽酸鈉的混合溶液的pH=10條件下,以AgNO_3溶液為前驅(qū)體,脫氧膽酸鈉為手性誘導(dǎo)劑和穩(wěn)定劑,以紫外燈為光源,還原銀離子制備了脫氧膽酸鈉包覆的銀納米粒子。當(dāng)脫氧膽酸鈉/Ag+摩爾比為6:1時(shí),制備出的銀納米粒子手性信號(hào)最強(qiáng)。當(dāng)脫氧膽酸鈉/Ag+摩爾比低時(shí),還原反應(yīng)速率比較慢,生成的銀納米粒子的表面等離子共振吸收峰位于455 nm左右,半峰寬較寬,粒子的尺寸較大,且尺寸分布較寬。隨著摩爾比增大,還原反應(yīng)速率比較快,在體系中生成的銀納米粒子尺寸分布均勻,粒子的尺寸較小,半峰寬變窄。采用液相化學(xué)還原法,以AgNO_3溶液為前驅(qū)體,檸檬酸鈉與NaBH4的混合溶液為還原劑,還原銀離子制備了黃綠色的銀納米溶膠,通過配體交換反應(yīng),制備脫氧膽酸鈉修飾的銀納米粒子。隨著脫氧膽酸鈉的濃度增大,銀納米溶膠的SPR吸收峰的強(qiáng)度逐漸增大,半峰寬逐漸減小,銀納米溶膠的SPR吸收峰的最大吸收峰峰位置出現(xiàn)藍(lán)移現(xiàn)象。向銀納米溶膠中加入NaCl能促進(jìn)納米粒子的聚集。隨著氯化鈉的加入量增多,銀納米粒子在400 nm左右的SPR吸收峰的峰強(qiáng)逐漸減弱,SPR吸收峰的最大吸收峰的位置發(fā)生紅移,銀納米粒子的半峰寬逐漸變窄,并且在600 nm左右出現(xiàn)新的SPR吸收峰。向銀納米溶膠中加入適量的HCl溶液能夠促進(jìn)納米粒子的聚集,并且增強(qiáng)銀納米粒子的手性信號(hào)。采用液相化學(xué)還原法,以AgNO_3溶液為前驅(qū)體,檸檬酸鈉與NaBH4的混合溶液為還原劑,還原銀離子制備了黃綠色的銀納米溶膠,通過配體交換反應(yīng),制備L-組氨酸修飾的銀納米粒子。L-組氨酸是一種以內(nèi)鹽的形式存在的氨基酸,質(zhì)子化的氨基和羧基之間存在靜電相互作用,會(huì)誘導(dǎo)組氨酸修飾的銀納米粒子聚集。當(dāng)L-組氨酸的濃度比較低,銀納米粒子的聚集程度較低,粒子有序聚集,引起局域電磁場增強(qiáng),從而使CD信號(hào)增強(qiáng)。當(dāng)L-組氨酸的濃度繼續(xù)增大時(shí),會(huì)引起粒子聚集程度增強(qiáng),導(dǎo)致粒子無序聚集,使粒子的CD信號(hào)減弱。向銀納米溶膠中加入適量的NaCl時(shí)能促進(jìn)納米粒子的聚集,從而增強(qiáng)銀納米粒子的CD信號(hào)。
[Abstract]:In recent years, chiral silver nanomaterials have attracted wide attention due to their applications in chiral catalysis, chiral recognition and optics. In this paper, chiral silver nanoparticles were prepared by photochemical reduction and liquid chemical reduction with different chiral molecules as chiral inducers and modifiers. The silver nanoparticles were characterized by UV-Vis absorption spectra, circular dichroism (CD), transmission electron microscopy (TEM), and the mechanism of chiral formation of silver nanoparticles was discussed. Under the condition of pH=10 of mixed solution of silver nitrate and sodium deoxycholate, AgNO_3 solution was used as precursor, sodium deoxycholate as chiral inducer and stabilizer, ultraviolet lamp as light source. Silver nanoparticles coated with sodium deoxycholate were prepared by reducing silver ions. When the molar ratio of deoxycholate to silver is 6:1, the chiral signal of silver nanoparticles is strongest. When the molar ratio of deoxycholate to Ag is low, the reduction rate is relatively slow. The surface plasmon resonance absorption peak of the silver nanoparticles is about 455nm, the width of the half-peak is wider, the size of the particles is larger and the size distribution is wider. With the increase of molar ratio, the reduction reaction rate is faster, the size distribution of silver nanoparticles in the system is uniform, the particle size is smaller, and the width of the half peak becomes narrower. The yellowish green silver nanosol was prepared by liquid-phase chemical reduction using AgNO_3 solution as precursor and the mixed solution of sodium citrate and NaBH4 as reducing agent. Silver nanoparticles modified with sodium deoxycholate were prepared. With the increase of the concentration of sodium deoxycholate, the intensity of the SPR absorption peak and the half width of the silver nano-sol gradually increased, and the blue shift phenomenon appeared in the position of the largest absorption peak of the SPR absorption peak of the silver nano-sol. Adding NaCl to silver nanoparticles can promote the aggregation of nanoparticles. With the addition of sodium chloride, the peak intensity of the SPR absorption peak of silver nanoparticles at about 400nm gradually weakened and the position of the maximum absorption peak of the SPR absorption peak shifted red, and the half peak width of silver nanoparticles gradually narrowed. A new SPR absorption peak appeared at about 600nm. Adding appropriate amount of HCl solution to silver nanoparticles can promote the aggregation of nanoparticles and enhance the chiral signals of silver nanoparticles. The yellowish green silver nanosol was prepared by liquid-phase chemical reduction using AgNO_3 solution as precursor and the mixed solution of sodium citrate and NaBH4 as reducing agent. L- histidine modified silver nanoparticles. L- histidine is an amino acid in the form of salt. There is electrostatic interaction between protonated amino groups and carboxyl groups, which induces the aggregation of silver nanoparticles modified by histidine. When the concentration of L- histidine is low, the aggregation degree of silver nanoparticles is lower, and the ordered aggregation of silver nanoparticles leads to the enhancement of local electromagnetic field and the enhancement of CD signal. When the concentration of L- histidine continues to increase, the particle aggregation will be enhanced, resulting in the disordered aggregation of particles, and the CD signal of particles will be weakened. Adding appropriate amount of NaCl to silver nanoparticles can promote the aggregation of silver nanoparticles and enhance the CD signal of silver nanoparticles.
【學(xué)位授予單位】：江蘇科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TB383.1;TQ131.22

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