發(fā)布時間：2018-04-14 16:36

  本文選題：胸腺嘧啶 + 密度泛函理論��； 參考：《曲阜師范大學(xué)》2017年碩士論文

【摘要】：胸腺嘧啶是DNA中A-T堿基對(腺嘌呤-胸腺嘧啶)的組成部分,它們之間彼此配對,通過氫鍵作用,使DNA雙螺旋結(jié)構(gòu)變得更加穩(wěn)定。胸腺嘧啶是遺傳物質(zhì)的重要構(gòu)成部分,也是許多抗疾病藥物的關(guān)鍵合成成分,無論是在生物遺傳學(xué)還是在醫(yī)藥學(xué)上,都具有十分重要的作用。因此胸腺嘧啶分子的結(jié)構(gòu)特性具有較高的研究價值。本文通過密度泛函理論(DFT)分別對胸腺嘧啶與水分子團(tuán)簇的基態(tài)結(jié)構(gòu)、紅外振動光譜,以及胸腺嘧啶在銀團(tuán)簇表面上的表面增強(qiáng)拉曼光譜做了充分的研究。本文共有五個章節(jié):第一部分:講述了胸腺嘧啶分子的重要性質(zhì)和廣泛的用途,敘述了氫鍵的作用以及紅外光譜的應(yīng)用,介紹了表面增強(qiáng)拉曼光譜的相關(guān)增強(qiáng)機(jī)理。第二部分:分別對量子化學(xué)的計算方法、Gaussian系列軟件、密度泛函的相關(guān)理論、AIM軟件等進(jìn)行了介紹,同時也對拉曼散射強(qiáng)度的計算進(jìn)行了說明。第三部分:主要應(yīng)用Gaussian09W程序中密度泛函理論(DFT)B3LYP方法,在6-311++G(d,p)基組水平上,研究了C5H6N2O2?(H2O)n(n=1~4)分子團(tuán)簇的基態(tài)結(jié)構(gòu)以及它們的紅外光譜。通過對C5H6N2O2?(H2O)n(n=1~4)分子團(tuán)簇的結(jié)構(gòu)進(jìn)行優(yōu)化,獲得了團(tuán)簇最穩(wěn)定的結(jié)構(gòu)。AIM程序分析表明:分子團(tuán)簇間形成了氫鍵,而且電子密度?的強(qiáng)弱也反映了紅移和藍(lán)移的大小。之后使用Veda4軟件對C5H6N2O2?(H2O)n(n=1~4)分子團(tuán)簇紅外光譜的振動頻率進(jìn)行了分析,并對振動頻率進(jìn)行了比較。最后,通過分析四種最穩(wěn)定結(jié)構(gòu)的分子團(tuán)簇的紅外光譜,我們發(fā)現(xiàn)O H…O和N H…O氫鍵的形成使得O H和N H原子之間伸縮頻率減小,即發(fā)生了紅移;同樣的,O H…N氫鍵使O H原子之間的彎曲振動頻率變大,即發(fā)生了藍(lán)移。第四部分:應(yīng)用DFT的B3LYP方法,在6-311++G(d,p)(C,H,O)/Lan L2DZ(Ag)基組上,優(yōu)化得到胸腺嘧啶分子與Ag團(tuán)簇形成的復(fù)合物C5H6N2O2-Agn(n=1~6)的最穩(wěn)定結(jié)構(gòu)。同時計算了C5H6N2O2-Agn(n=2,4,6)三種復(fù)合物的表面增強(qiáng)拉曼光譜(SERS)和預(yù)共振拉曼光譜(SERRS),其結(jié)果與實驗值相一致,證明了理論方法的合理性和精確性。復(fù)合物的SERS中,大部分振動模式?jīng)]有明顯增強(qiáng),但其中C=O的彎曲振動和O Ag的伸縮振動有明顯的增強(qiáng),是由復(fù)合物結(jié)構(gòu)極化率的改變而引起的,屬于靜化學(xué)增強(qiáng)。進(jìn)一步采用含時密度泛函理論(TDDFT)方法計算得到了復(fù)合物的吸收光譜,分別選擇385 nm、417 nm和388 nm作為入射光,計算得到了它們的共振拉曼光譜。在SERRS中,O Ag的伸縮振動增強(qiáng)了104左右,是由電荷轉(zhuǎn)移引起的共振增強(qiáng),且轉(zhuǎn)移模式都是電子在Ag團(tuán)簇向胸腺嘧啶分子的π*鍵軌道轉(zhuǎn)移躍遷。其增強(qiáng)模式屬于選擇性增強(qiáng),證明復(fù)合物的SERRS是化學(xué)增強(qiáng)。第五部分:對全文進(jìn)行綜合性總結(jié)與展望。
[Abstract]:Thymidine is a component of A-T base pairs (adenine thymine) in DNA. They pair with each other and make the double helix structure of DNA more stable by hydrogen bonding.Thymine is an important component of genetic material and a key synthetic component of many anti-disease drugs. It plays an important role in both biogenetics and medicine.Therefore, the structural properties of thymidine molecules are of high value.In this paper, the ground state structure, infrared vibrational spectrum and surface-enhanced Raman spectra of thymine and water clusters on the surface of silver clusters have been studied by density functional theory (DFT).There are five chapters in this paper: in the first part, the important properties and wide applications of thymidine are described, the function of hydrogen bond and the application of infrared spectroscopy are described, and the mechanism of surface enhanced Raman spectroscopy is introduced.In the second part, the calculation methods of quantum chemistry are introduced, such as Gaussian series software, density functional theory and AIM software, and the calculation of Raman scattering intensity is also explained.Part three: the ground state structure and infrared spectra of C _ 5H _ 6N _ 2O _ 2 H _ 2O _ N _ 2 O _ 2 H _ 2O _ n _ (1) N _ (1) O _ (4) clusters have been studied by using the density functional Theory (DFT) B3LYP method at the level of 6-311 G ~ (2 +) base set in the Gaussian09W program.By optimizing the structure of C _ 5H _ 6N _ 2O _ 2H _ 2O _ 2 H _ 2O _ N _ N _ N _ 4) clusters, the most stable structure of the clusters is obtained. AIM program shows that hydrogen bonds are formed among the clusters, and the electron density?The magnitude of the red shift and the blue shift is also reflected in the magnitude of the red shift and the blue shift.The frequency of infrared spectra of C _ 5H _ 6N _ 2O _ 2 and H _ 2O _ n _ (1) O _ (4) molecular clusters was analyzed by Veda4 software, and the vibrational frequencies were compared.Finally, by analyzing the IR spectra of the four most stable molecular clusters, we found that O _ (H) 鈥�O and N...The formation of O hydrogen bond reduces the stretching frequency between O H and N H atoms, that is, red shift occurs.The N hydrogen bond increases the frequency of the bending vibration between O and H atoms, that is, the blue shift occurs.Part IV: using DFT's B3LYP method, the most stable structure of the complex C _ 5H _ 6N _ 2O _ 2-Agnn ~ (1 /) formed by thymidine and Ag clusters was optimized on the 6-311 G ~ (11) G ~ (-1) B3LYP group.At the same time, the surface-enhanced Raman spectra (SERS) and pre-resonance Raman spectra (SERRSs) of C _ 5H _ 6N _ 2O _ 2-Agnn _ (2) O _ (2) O _ (4)) complexes are calculated. The results are in agreement with the experimental data, which proves the rationality and accuracy of the theoretical method.In the SERS of the composite, most of the vibration modes are not obviously enhanced, but the flexural vibration and the stretching vibration of O-Ag are obviously enhanced, which is caused by the change of the polarizability of the complex structure and belongs to the static and chemical enhancement.Furthermore, the absorption spectra of the complexes were calculated by time-dependent density functional theory (TDDFT) method. 385nm and 388nm were selected as incident light respectively, and their resonance Raman spectra were calculated.In SERRS, the stretching vibration of Ag increases by about 104, which is due to the resonance enhancement caused by charge transfer, and the transfer mode is the transition of electrons from Ag cluster to the 蟺 * bond orbital of thymidine molecule.The enhancement mode is selective enhancement, which proves that the SERRS of the complex is chemically enhanced.Part V: a comprehensive summary and prospect of the full text.
【學(xué)位授予單位】：曲阜師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：Q526.1;O657.3

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