Surface-enhanced Raman scattering and DFT investigation of 1,5-diphenylcarbazide and its metal complexes with Ca(II), Mn(II), Fe(III) and Cu(II)

• 1,5-diphenylcarbazide and its Ca, Mn, Fe and Cu complexes were investigated.
• A reliable assignment of vibrational spectra for DPC and DPC-metal complex was done.
• Characteristic SERS features were evidenced for each DPC-metal complex.
• SERS spectroscopy is demonstrated as a useful method for metal ions detection.

In recent years, surface-enhanced Raman scattering (SERS) has become an increasingly viable method for the detection of metal ions, evidenced by the existing studies on metal complexes. In this study, 1,5-diphenylcarbazide (DPC) and its Ca(II), Mn(II), Fe(III) and Cu(II) complexes were investigated by FTIR/ATR, FT-Raman and surface-enhanced Raman spectroscopies. The hybrid B3LYP exchange–correlation functional was used for the molecular geometry optimizations, molecular electrostatic potential (MEP) distribution and vibrational frequencies calculations of the DPC molecule and its complexes. Based on experimental and theoretical data, we were able to accurately identify unique and representative features for each DPC–metal complex, features that enable the detection of said metal complexes in millimolar concentrations.

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