7-羥基香豆素紅外光譜的密度泛函理論研究

賈飛云，蘇 宇，冉 鳴，朱 江，張 波*

1. 川北醫(yī)學(xué)院化學(xué)教研室，四川 南充 637007 2. 四川師范大學(xué)化學(xué)與材料科學(xué)學(xué)院，四川 成都 610066

7-羥基香豆素紅外光譜的密度泛函理論研究

賈飛云1，蘇 宇1，冉 鳴2，朱 江1，張 波1*

1. 川北醫(yī)學(xué)院化學(xué)教研室，四川 南充 637007 2. 四川師范大學(xué)化學(xué)與材料科學(xué)學(xué)院，四川 成都 610066

紅外光譜是化合物結(jié)構(gòu)鑒定的重要信息來源，對天然有機(jī)藥物的分子結(jié)構(gòu)及其生物活性研究意義重大。而隨著理論計(jì)算方法更加合理、計(jì)算精度不斷提高，理論計(jì)算在紅外光譜模擬、振動模式歸屬指認(rèn)等方面優(yōu)勢更加明顯，對紅外光譜解析等實(shí)驗(yàn)研究具有重要參考價(jià)值。本研究利用密度泛函理論(density functional theory, DFT)/B3LYP方法，在6-311G(d,p)基組水平對7-羥基香豆素進(jìn)行了幾何結(jié)構(gòu)優(yōu)化和紅外光譜計(jì)算，得到穩(wěn)定結(jié)構(gòu)及全部振動模式。計(jì)算結(jié)果顯示7-羥基香豆素紅外光譜吸收峰主要分布于波數(shù)3 700～3 500，3 150～3 000，1 750～1 400，1 400～1 000，1 000～50 cm-1幾個(gè)區(qū)域。除波數(shù)3 700～3 500，3 150～3 000 cm-1范圍內(nèi)振動相對獨(dú)立，分別歸屬為O—H伸縮振動和芳環(huán)C—H伸縮振動外，其他幾個(gè)區(qū)域均較為復(fù)雜，譜峰不同程度由多個(gè)振動模式疊加而成。最后，根據(jù)振動模式理論及振動圖像分析，對所有振動模式進(jìn)行了詳細(xì)指認(rèn)。并通過線性回歸方法，利用相關(guān)系數(shù)值r研究了7-羥基香豆素紅外光譜主要吸收峰波數(shù)理論計(jì)算值和實(shí)驗(yàn)數(shù)據(jù)的相關(guān)性。結(jié)果表明，計(jì)算值和實(shí)驗(yàn)值基本吻合，相關(guān)系數(shù)值等于0.998 5，相關(guān)性較好；采用密度泛函理論在該基組水平對7-羥基香豆素紅外光譜的理論計(jì)算較為可靠。

紅外光譜；密度泛函理論；7-羥基香豆素

引 言

香豆素類化合物是具有苯并α-吡喃酮母核天然產(chǎn)物的總稱，結(jié)構(gòu)上可以看成順式鄰羥基桂皮酸脫水而成的內(nèi)酯化合物[1]。具有抗腫瘤、抗艾滋病、抗細(xì)胞增生、抗病毒、抗真菌、抗細(xì)菌、抗血管硬化、抗氧化、增強(qiáng)人體的免疫力等明顯的生物活性[2-7]。天然香豆素中絕大多數(shù)在C7位均連接有含氧官能團(tuán)，故7-羥基香豆素被認(rèn)為是香豆素類化合物的基本母核。紅外光譜作為化合物結(jié)構(gòu)鑒定的重要信息來源[8]，對7-羥基香豆素及其衍生物分子結(jié)構(gòu)和生物活性研究意義重大。而隨著理論計(jì)算方法更加合理、計(jì)算精度不斷提高，理論計(jì)算在紅外光譜模擬、振動模式歸屬指認(rèn)等方面優(yōu)勢更加明顯，對紅外光譜解析等實(shí)驗(yàn)研究具有重要參考價(jià)值。本工作利用密度泛函理論研究了7-羥基香豆素的紅外光譜，并對振動模式進(jìn)行了詳細(xì)指認(rèn)，最后對主要吸收峰波數(shù)理論計(jì)算值與文獻(xiàn)實(shí)驗(yàn)數(shù)據(jù)的相關(guān)性進(jìn)行了研究，結(jié)果表明理論計(jì)算值與實(shí)驗(yàn)數(shù)據(jù)吻合較好。

1 計(jì)算方法

利用密度泛函理論(DFT)/B3LYP方法，在6-311G(d,p)基組水平優(yōu)化了7-羥基香豆素幾何結(jié)構(gòu)，并以相同基組水平計(jì)算紅外光譜，得到7-羥基香豆素穩(wěn)定結(jié)構(gòu)和全部振動模式。因理論計(jì)算未考慮非諧效應(yīng)，故根據(jù)計(jì)算方法和基組水平，采用0.961 3[9]作為頻率修正因子。所有計(jì)算均采用Gaussian09程序完成。

2 結(jié)果與討論

2.1 幾何構(gòu)型

Fig.1 Optimized molecular structure of 7-Hydroxycoumarin

Table 1 Some geometrical parameters of 7-Hydroxycoumarin

2.2 紅外光譜分析

圖2表示在B3LYP/6—311G(d,p)水平理論計(jì)算得到的7-羥基香豆素紅外光譜圖。圖3給出了實(shí)驗(yàn)測得的7-羥基香豆素的紅外光譜圖。由圖2可知，7-羥基香豆素紅外光譜吸收峰主要分布于波數(shù)3 700～3 500，3 150～3 000，1 750～1 400，1 400～1 000，1 000～50 cm-1幾個(gè)區(qū)域。除波數(shù)3 700～3 500，3 150～3 000 cm-1范圍內(nèi)振動相對獨(dú)立，分別歸屬為O—H伸縮振動和芳環(huán)C—H伸縮振動外，其他幾個(gè)區(qū)域均較為復(fù)雜，譜峰不同程度由多個(gè)振動模式疊加而成。

Fig.2 Calculated infrared spectum of 7-Hydroxycoumarin

Fig.3 Experimental infrared spectum of 7-Hydroxycoumarin*

為了更為直觀地表示紅外光譜理論計(jì)算數(shù)據(jù)與實(shí)驗(yàn)數(shù)據(jù)的相關(guān)性，以理論值為x軸、實(shí)驗(yàn)值為y軸，做出7-羥基香豆素紅外光譜主要吸收峰波數(shù)的相關(guān)圖，并進(jìn)行了線性回歸，相關(guān)系數(shù)值r=0.998 5。結(jié)果表明，7-羥基香豆素紅外光譜主要吸收峰理論計(jì)算值與實(shí)驗(yàn)值相關(guān)性較好，r值為0.998 5。由此進(jìn)一步表明，采用密度泛函理論在B3LYP/6-311G(d,p)基組水平對7-羥基香豆素紅外光譜的理論計(jì)算較為可靠。

Fig.4 Correlation of calculated and experimental data for 7-Hydroxycoumarin

Table 2 Comparation of the theoretical vibrational modes and experimental IR for 7-Hydroxycoumarin

3 結(jié) 論

利用密度泛函理論DFT/B3LYP方法在6-311G(d,p)基組水平對7-羥基香豆素進(jìn)行了結(jié)構(gòu)優(yōu)化和紅外光譜計(jì)算，并根據(jù)振動模式理論圖形分析，對所有振動模式進(jìn)行了詳細(xì)指認(rèn)。最后通過線性回歸方法，利用相關(guān)系數(shù)值r研究了7-羥基香豆素紅外光譜主要吸收峰波數(shù)理論計(jì)算值和實(shí)驗(yàn)數(shù)據(jù)的相關(guān)性。結(jié)果表明，計(jì)算值和實(shí)驗(yàn)值基本吻合，相關(guān)性較好；采用密度泛函理論在該基組水平對7-羥基香豆素紅外光譜的理論計(jì)算較為可靠。

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*Corresponding author

The Study on Infrared Spectra of 7-Hydroxycoumarin by Density Functional Theory

JIA Fei-yun1, SU Yu1, RAN Ming2, ZHU Jiang1, ZHANG Bo1*

1. Teaching and Research Group of Chemistry, North Sichuan Medical College, Nanchong 637007, China

2. Department of Chemistry and Material Science, Sichuan Normal University, Chengdu 610066, China

Infrared spectroscopy is an important source of information for the identification of the compounds structure and it is great significant for biological activity research of natural and organic drug molecules. With the theoretical calculation method is more reasonable and calculation accuracy continues to improve, Theoretical calculate advantage is more obvious in the infrared spectrum simulation and vibration modes attributable identified. And it has important reference value for experimental study of infrared spectral analysis. Using density functional theory, geometry optimizations and frequencies calculation of 7-Hydroxycoumarin were performed at the level of B3LYP/6-311G(d,p), the stable structure and all vibration modes of 7-Hydroxycoumarin were attained. The results show that the infrared absorption peak of 7-hydroxycoumarin is mainly distributed in the several regions in wave number of 3 700～3 500, 3 150～3 000, 1 750～1 400, 1 400～1 000, 1 000～50 cm-1. In addition to the vibration in a wave number range of 3 700～3 500, 3 150～3 000 cm-1is relatively independent, and were attributed to OH stretching vibration and benzene ring CH stretching vibration, the other several vibration regions are more complex, the different degree of spectral peaks is composed of multiple vibration modes. Finally, based on the theoretical analysis of the vibration mode, the vibration modes of 7-Hydroxycoumarin molecule were assigned, and in order to discuss the reliability of theoretical calculation method, the correlation diagram of the main absorption peak of 7-hydroxyl group was drawn from the theoretical value ofXaxis and the experimental value ofYaxis, the correlation between experimental IR data and calculated IR data of 7-Hydroxycoumarin was analyzed through the linear regression method. Results show that they have good correlation, correlation coefficient values “r” equals 0.998 5，and the theory calculation of 7-Hydroxycoumarin IR by density functional theory at the base set level is reliable.

Infrared spectra; Density functional theory; 7-Hydroxycoumarin

Sep. 29, 2014; accepted Feb. 10, 2015)

2014-09-29，

2015-02-10

國家自然科學(xué)基金項(xiàng)目(21172025)，四川省教育廳科研項(xiàng)目(14ZB0193)，四川省中醫(yī)藥管理局中醫(yī)藥科學(xué)技術(shù)研究專項(xiàng)項(xiàng)目(2014K042)資助

賈飛云，1976年生, 川北醫(yī)學(xué)院化學(xué)教研室副教授 e-mail: cloud7612@163.com *通訊聯(lián)系人 e-mail: zhangbo6606@163.com

O657.6

A

10.3964/j.issn.1000-0593(2016)01-0060-04