Plasmon induced and pH controlled semiconductive conformation of 1H-2(phenylazo) imidazole on silver nanoparticles

• A pH dependent SERS study of 1H-2(phenylazo) imidazole (PaiH) is reported.
• Chemical, biological and electronic significance of PaiH molecule is discussed.
• Different conformations on colloidal silver nanoparticles are observed.
• The conformation is plasmon induced and pH controlled.
• The HOMO–LUMO gap of PaiH is significantly reduced in acidic pH.

A pH controlled SERS study of 1H-2(phenylazo) imidazole (PaiH) is reported. A combination of different conformations is evident; majority preferring a particular conformation at a given pH. PaiH is in cis-form at concentrations 10−6–10−5 M at pH = 7 which undergoes azo to hydrozone conformation in alkaline pH whereas the azo-Ns participate in the electronic interaction at acidic pH. Significant reduction of HOMO–LUMO gap indicates the possibility of PaiH of being an organic semiconductor.

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