Joo Sang-Woo, Kim Wan-Joong, Yun Wan Soo, Hwang Sungu, Choi Insung S
Department of Chemistry, Soongsil University, Seoul 156-743, Korea.
Appl Spectrosc. 2004 Feb;58(2):218-23. doi: 10.1366/000370204322842968.
The adsorption structure and binding of phenyl isocyanide (PNC), 2,6-dimethyl phenyl isocyanide (DMPNC), and benzyl isocyanide (BZI) on gold nanoparticle surfaces have been studied by means of surface-enhanced Raman scattering (SERS). PNC, DMPNC, and BZI have been found to adsorb on gold assuming a standing geometry with respect to the surfaces. The presence of the nu(CH) band in the SERS spectra denotes a vertical orientation of the phenyl ring of PNC, DMPNC, and BZI on Au. The lack of a substantial red shift and significant band broadening of the ring breathing modes implied that a direct ring pi orbital interaction with metal substrates should be quite low. For PNC, the band ascribed to the C-NC stretching vibration was found to almost disappear after adsorption on Au. On the other hand, the C-NC band remained quite strong for DMPNC after adsorption. This result suggests a rather bent angle of C-N[triple bond]C: for the nitrogen atom of the NC binding group on the surfaces, whereas a linear angle of C-N[triple bond]C: should be more favorable on gold surfaces due to an intramolecular steric hindrance of its two methyl groups. SERS of BZI on gold nanoparticles also supports a bent angle of :C[triple bond]N-CH2 for its nitrogen atom, suggesting a preference of sp3 (or sp2) hybridization for the nitrogen atom.
通过表面增强拉曼散射（SERS）研究了异氰基苯（PNC）、2,6-二甲基异氰基苯（DMPNC）和苄基异氰（BZI）在金纳米颗粒表面的吸附结构和结合情况。已发现PNC、DMPNC和BZI以相对于表面垂直的几何构型吸附在金上。SERS光谱中ν(CH)带的存在表明PNC、DMPNC和BZI的苯环在金上呈垂直取向。环呼吸模式缺乏显著的红移和明显的谱带展宽，这意味着与金属基底的直接环π轨道相互作用应该相当低。对于PNC，吸附在金上后，归属于C-NC伸缩振动的谱带几乎消失。另一方面，吸附后DMPNC的C-NC谱带仍然很强。这一结果表明，对于表面上NC结合基团的氮原子，C≡N的夹角相当弯曲；而由于其两个甲基的分子内空间位阻，C≡N的线性夹角在金表面应该更有利。金纳米颗粒上BZI的SERS也支持其氮原子的:C≡N-CH₂夹角弯曲，表明氮原子更倾向于sp³（或sp²）杂化。
