The structural parameters and average molecular structures of the asphaltenes obtained from the Aguacate oilfield, located in the Golden Lane of Mexico, have been investigated combining experimental analysis and molecular simulation. The average molecular structural parameters of the polycyclic aromatic hydrocarbon (PAH) region, average number of fused aromatic rings (nFAR), average structural isomers in the polydispersity of the PAH core, average architecture, average molecular weight, and substituents in the PAH core have been determined by means of ¹³C single-pulse excitation (SPE) nuclear magnetic resonance (NMR) in combination with ¹³C distortionless enhancement by polarization transfer (DEPT)-135° experiments, ¹H NMR, X-ray photoelectron spectroscopy, fluorescence emission, and matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry. The total energy of the PAH isomers and their fluorescence emission are calculated with density functional theory and ZINDO/S, respectively. The PAH region structural parameters determined are (a) Y-carbons (C_Y) or internal triple bridgehead aromatic carbons, (b) external peripheral aromatic carbon atoms at the junction of two fused rings (C_AP3), (c) aromatic carbon atoms bonded to hydrogen atoms (C_AH), (d) aromatic carbon atoms bonded to heteroatom (C_AX), (e) aromatic carbon atoms bonded to hydrogen at the β position with respect to the heteroatom (C_AHβX), and (f) substituted aromatic carbon atoms (C_A-Caliph). The ¹³C NMR chemical shift ranges used for the different structural carbon atoms in the PAH core were obtained from our previous study [Ruiz-Morales, Y.; Miranda-Olvera, A. D.; Portales-Martı́nez, B.; Domı́nguez, J. M. Determination of ¹³C NMR Chemical Shift Structural Ranges for Polycyclic Aromatic Hydrocarbons (PAHs) and PAHs in Asphaltenes: An Experimental and Theoretical Density Functional Theory Study. Energy Fuels 2019, 33 (9), 7950−7970, DOI: 10.1021/acs.energyfuels.9b00182]. There is overlapping of the ¹³C SPE NMR signals of C_AH, C_Y, and C_AP3; therefore, quantitative ¹³C DEPT-135° NMR is necessary to determine the average C_AH, and this value is subtracted from the quantitative ¹³C SPE NMR spectrum, where the signals overlap, to obtain the average number of bridgehead carbons (C_Y and C_AP3). It is concluded that island is the predominant architecture of the Aguacate asphaltene, in accordance with the Yen–Mullins model. The PAH region contains nine fused aromatic rings (9FAR), where one of the rings is a thiophenic ring.

中文翻译：

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确定墨西哥Golden Lane（Faja de Oro）原油平均沥青质结构的实验和理论方法

结合实验分析和分子模拟研究了从位于墨西哥黄金巷的阿瓜特油田获得的沥青质的结构参数和平均分子结构。多环芳烃（PAH）区的平均分子结构参数，稠合芳环的平均数目（n FAR），PAH核多分散性中的平均结构异构体，平均结构，平均分子量和PAH核中的取代基已通过¹³ C单脉冲激发（SPE）核磁共振（NMR）与通过极化转移（DEPT）-135°实验进行的¹³ C无畸变增强相结合来确定，¹1 H NMR，X射线光电子能谱，荧光发射和基质辅助的激光解吸/电离飞行时间（MALDI-TOF）质谱。PAH异构体的总能量及其荧光发射分别通过密度泛函理论和ZINDO / S计算。确定的PAH区域结构参数为（a）Y碳（C _Y）或内部三桥头芳族碳，（b）两个稠环（C _AP3）交界处的外围芳族碳原子，（c）芳族碳原子键与氢原子（C _AH）结合，（d）与杂原子（C _AX）结合的芳族碳原子，（e）在相对于杂原子（_CAHβX）的β位置与氢结合的芳族碳原子）和（f）取代的芳族碳原子（_CA-Caliph）。PAH核中不同结构碳原子所用的¹³ C NMR化学位移范围是从我们先前的研究中获得的[Ruiz-Morales，Y。米兰达-奥尔维拉（AD）Portales-Martınez，B。多米·恩格斯（JM）沥青质中多环芳烃（PAHs）和PAHs的¹³ C NMR化学位移结构范围的确定：实验和理论密度泛函理论研究。能源燃料 2019，33（9），7950-7970，DOI：10.1021 / acs.energyfuels.9b00182]。C _AH，C _Y和C _AP3的¹³ C SPE NMR信号重叠; 因此，需要使用定量¹³ C DEPT-135°NMR来确定平均C _AH，并将此值从定量^13中减去C SPE NMR谱图（信号重叠）获得桥头碳的平均数（C _Y和C _AP3）。结论是，根据Yen-Mullins模型，岛屿是Aguacate沥青质的主要建筑。PAH区包含9个稠合的芳环（9FAR），其中一个环是噻吩环。