title: Binding of aromatic isocyanides on gold nanoparticle surfaces investigated by surface-enhanced Raman scattering.
abstract: 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.
authors.affiliation: Department of Chemistry, Soongsil University, Seoul 156-743, Korea. sjoo@ssu.ac.kr
authors.forename: Sang-Woo
authors.initials: SW
authors.lastname: Joo
authors.forename: Wan-Joong
authors.initials: WJ
authors.lastname: Kim
authors.forename: Wan Soo
authors.initials: WS
authors.lastname: Yun
authors.forename: Sungu
authors.initials: S
authors.lastname: Hwang
authors.forename: Insung S
authors.initials: IS
authors.lastname: Choi