Determination of the orientation of azathioprine adsorbed on a silver electrode by SERS and ab initio calculations.
Determination of the orientation of azathioprine adsorbed on a silver electrode by SERS and ab initio calculations.
复制标题
通过 SERS 和从头计算确定硫唑嘌呤在银电极上的吸附方向。
DOI：
10.1016/s1386-1425(03)00099-4
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Hosten,CharlesM
中科院分区：
文献类型：
--
作者：
Chen,Shi-Ping;Qiao,Zhuahong;Vivoni,Alberto;Hosten,CharlesM
我们报道了硫唑嘌呤（AZA）在银电极表面的Sers光谱，以及对AZA中6-巯基嘌呤酮（6-MP）组分的经验和从头计算的简正模计算结果。经验计算是用Urey-Bradley力场（UBFF）进行的，从头计算是用STO-3G基组使用UHF，MP2和BLYP方法进行的。从Sers和固体光谱的差异，我们确定AZA通过分子的6-MP组分上的N3位点附接到表面上。银吸附原子-分子模型的UBFF计算再现了Sers光谱中观察到的大部分主要频移。在类似的模型下，从头计算得到的频率偏移与平面内正常模式观察到的方向相同，但平面外正常模式的频率偏移相反。这种现象可能归因于6-MP组分与相邻吸附原子的面对面相互作用，该相互作用通过分子在表面上的倾斜而成为可能。
We report the SERS spectrum of azthioprine (AZA) on a silver electrode surface and the results of normal mode calculations using empirical and ab initio calculations of the 6-mercaptopurione (6-MP) component of AZA. The empirical calculations were done with a Urey-Bradley force field (UBFF) and the ab initio calculations with the STO-3G basis set using the UHF, MP2 and BLYP methods. From the difference between the SERS and solid spectra, we determined that AZA attaches edge-on to the surface through the N3 site on the 6-MP component of the molecule. The UBFF calculation on an Ag adatom-molecule model reproduced most of the main observed frequency shifts in the SERS spectrum. With a similar model, the ab initio calculations yielded frequency shifts in the same direction as the one observed for the in-plane normal modes, but they yielded opposite shifts for the out-of-plane normal modes. This phenomenon may be attributed to a face-on interaction of the 6-MP component with a neighboring adatom made possible by an inclination of the molecule on the surface.