School of Chemistry and Environment, Beihang University, Beijing 100191, China.
Chemphyschem. 2011 Sep 12;12(13):2468-75. doi: 10.1002/cphc.201100187. Epub 2011 Jul 6.
We present a detailed analysis of the surface-enhanced Raman scattering (SERS) of adenine and 2'-deoxyadenosine 5'-monophosphate (dAMP) adsorbed on an Ag(20) cluster by using density functional theory. Calculated Raman spectra show that spectral features of all complexes depend greatly on adsorption sites of adenine and dAMP. The complexes consisting of adenine adsorbed on the Ag(20) cluster through N3 reproduce the measured SERS spectra in silver colloids, and thus demonstrated that adenine interacts with the silver surface via N3. We also investigate the SERS spectrum of adenine at the junction between two Ag(20) clusters and demonstrate that adenine can bind to the clusters through N3 and the external amino group, while dAMP can be adsorbed on the cluster in an end-on orientation with the ribose and phosphate groups near to or away from the silver cluster. In contrast to the adenine-Ag(20) complexes, the dAMP-Ag(20) complexes produce new and strong bands in the low- or high-wavenumber region of the Raman spectra, due to vibrations of the ribose and phosphate groups. Furthermore, the spectrum of dAMP bound to the Ag(20) cluster via N7 approaches the experimental SERS spectra on silver colloids.
我们通过使用密度泛函理论，对吸附在 Ag(20) 团簇上的腺嘌呤和 2'-脱氧腺苷 5'-单磷酸(dAMP)的表面增强拉曼散射(SERS)进行了详细分析。计算得到的拉曼光谱表明，所有配合物的光谱特征都很大程度上取决于腺嘌呤和 dAMP 的吸附位置。通过 N3 吸附在 Ag(20)团簇上的腺嘌呤复合物再现了银胶体中的测量 SERS 光谱，因此表明腺嘌呤通过 N3 与银表面相互作用。我们还研究了两个 Ag(20)团簇之间的腺嘌呤 SERS 光谱，并证明腺嘌呤可以通过 N3 和外部氨基与团簇结合，而 dAMP 可以以端到端的方式吸附在团簇上，核糖和磷酸基团靠近或远离银团簇。与腺嘌呤-Ag(20)复合物不同，由于核糖和磷酸基团的振动，dAMP-Ag(20)复合物在拉曼光谱的低波数或高波数区域产生新的和强的谱带。此外，通过 N7 与 Ag(20)团簇结合的 dAMP 谱接近银胶体上的实验 SERS 光谱。
