Adsorption of (S)-histidine on Cu(110) and oxygen-covered Cu(110), a combined Fourier transform reflection absorption infrared spectroscopy and force field calculation study
Adsorption of (S)-histidine on Cu(110) and oxygen-covered Cu(110), a combined Fourier transform reflection absorption infrared spectroscopy and force field calculation study
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DOI：
10.1021/jp035355u
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发表时间：
2003-10-02
影响因子：
3.3
通讯作者：
Pradier, CM
中科院分区：
文献类型：
--
作者：
Marti, EM;Methivier, C;Pradier, CM
通过反射吸收红外光谱 (RAIRS) 研究了 (S)-组氨酸在 Cu(110) 上的吸附以及吸附氧修饰的 Cu(110)。组氨酸分子的分子形式和方向是从实验RAIRS数据推导出来的；此外，通过分子力学力场（MMFF）计算来模拟振动光谱，以解决振动模式和吸附物的几何形状。该分子优先以其 HHis(-) 分子形式结合到表面。在金属Cu(110)表面上，通过距表面等距的两个氧原子和咪唑基团的脱氢氮发生吸附；后者相对于铜表面采取直立位置。氨基（NH2）可能保持在靠近表面的位置，从而促进与金属的相互作用。铜表面上氧气的预吸附（θ 大约为 0.3）会引起分子取向的微小变化：与没有氧气时相比，环往往不那么直立；该环现在通过 RAIRS 和 MMFF 计算推导出的 NH 基团相互作用。分子不会随着氧覆盖度的增加而重新定向（θ接近0.6），并且氧吸附时没有观察到表面阻塞；当氧覆盖率增加时，组氨酸的方向和数量仅略有变化。
Adsorption of (S)-histidine on Cu(110), and Cu(110) modified by adsorbed oxygen, has been studied by reflection absorption infrared spectroscopy (RAIRS). The molecular form and the orientation of the histidine molecule were deduced from experimental RAIRS data; moreover, vibrational spectra were simulated with a molecular mechanics force field (MMFF) calculation to address vibrational modes and the geometry of the adsorbate. The molecule preferentially binds to the surface in its HHis(-) molecular form. On the metallic Cu(110) surface, the adsorption occurs via the carboxylate group (COO-), with the two oxygen atoms equidistant from the surface, and via the dehydrogenated nitrogen of the imidazole group; the latter adopts an upright position with respect to the copper surface. The amino group (NH2) is likely to be maintained close to the surface, thus facilitating the interaction with the metal. Preadsorption of oxygen(theta approximate to 0.3) on the copper surface induces minor changes in the molecular orientation: the ring tends to be less upright than in the absence of oxygen; the ring now interacts via its NH group as deduced from RAIRS and MMFF calculations. The molecule does not reorient with increasing oxygen coverage (theta approximate to 0.6), and no surface blocking was observed upon oxygen adsorption; both the orientation and the amount of histidine only slightly vary when the oxygen coverage is increased.