A theoretical study on the interaction of aromatic amino acids with graphene and single walled carbon nanotube
A theoretical study on the interaction of aromatic amino acids with graphene and single walled carbon nanotube
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DOI：
10.1063/1.3079096
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发表时间：
2009-03-28
影响因子：
4.4
通讯作者：
Kawazoe, Yoshiyuki
中科院分区：
文献类型：
--
作者：
Rajesh, Chinagandham;Majumder, Chiranjib;Kawazoe, Yoshiyuki
在这项研究中，我们研究了苯丙氨酸(Phe)、组氨酸(His)、酪氨酸(Tyr)和色氨酸(Tryp)分子与石墨烯和单壁碳纳米管(CNTs)的相互作用，以了解曲率对非共价相互作用的影响。计算采用密度泛函理论和原子轨道-分子轨道线性组合(LCAO-MO)方法中的Moller-Plesset二阶微扰理论(MP2)。利用这些方法，发现这些配合物的平衡构型非常相似，即氨基酸的芳环倾向于平行于底物平面定向，具有弱pi-pi相互作用的特征。紧跟潮流的是：His<；Phe<；Tyr<；Tryp。虽然平面石墨烯和轧制纳米管结构结合能的变化趋势基本相似，但在绝对大小上有所不同。对于纳米管，这些分子的结合强度被发现比石墨烯薄片弱。为了深入了解这些相互作用的性质，我们计算了氨基酸的芳香族基序的极化率。值得注意的是，我们发现极化率与相互作用的强度之间有很好的相关性；极化率越高，结合强度越大。此外，我们还分析了氨基酸部分吸附前后的态光谱电子密度。结果表明，游离碳纳米管的费米能级因氨基酸的吸附而发生红移，其程度与这些分子的极化率的变化趋势一致。
In this study we have investigated the interaction of phenylalanine (Phe), histidine (His), tyrosine (Tyr), and tryptophan (Tryp) molecules with graphene and single walled carbon nanotubes (CNTs) with an aim to understand the effect of curvature on the non-covalent interaction. The calculations are performed using density functional theory and the Moller-Plesset second-order perturbation theory (MP2) within linear combination of atomic orbitals-molecular orbital (LCAO-MO) approach. Using these methods, the equilibrium configurations of these complexes were found to be very similar, i.e., the aromatic rings of the amino acids prefer to orient in parallel with respect to the plane of the substrates, which bears the signature of weak pi-pi interactions. The binding strength follows the trend: His < Phe < Tyr < Tryp. Although the qualitative trend in binding energy is almost similar between the planar graphene and rolled nanotube structure but they differ in terms of the absolute magnitude. For the nanotube, the binding strength of these molecules is found to be weaker than the graphene sheet. To get an insight about the nature of these interactions, we have calculated the polarizability of the aromatic motifs of the amino acids. Remarkably, we find excellent correlation between the polarizability and the strength of the interaction; the higher the polarizability, greater is the binding strength. Moreover, we have analyzed the electronic densities of state spectrum before and after adsorption of the amino acid moieties. The results reveal that the Fermi level of the free CNT is red-shifted by the adsorption of the amino acids and the degree of shift is consistent with the trend in polarizability of these molecules.