Surface-Catalyzed Photodissociation of (E)-4′,4‴-(Diazene-1, 2-diyl)bis(([1,1′-biphenyl]-4-carbonitrile)) Investigated by Surface-Enhanced Raman Scattering and Quantum Chemical Calculations

Aromatic azo compounds display properties crucial for important chemical applications and have been subjected to experimental and theoretical studies based on the findings of plasmon-driven azo coupling of aminobenzene derivatives. To provide spectroscopic data for plasmon-driven azo coupling of 4′-aminobiphenyl-4-carbonitrile (4AB4CN), (E)-4′,4‴-(diazene-1,2-diyl)bis(([1,1′-biphenyl]-4-carbonitrile)) (DDBBC) was synthesized by coupling of 4AB4CN and 4′-nitroso-[1,1′-biphenyl]-4-carbonitrile in acetic acid with 40% yield. Then, the ordinary Raman and surface-enhanced Raman scattering spectra of DDBBC were measured using a 632.8 nm excitation laser and were analyzed using quantum chemical calculations for the first time. The five characteristic peaks associated with the N═N bond in the measured spectra revealed that DDBBC is adsorbed on the Ag surface via interactions between the surface and the N═N and C≡N bonds, resulting in flat orientation on the surface. Remarkably, in an acidic solution, surface-cata...