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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