Investigation of coordination properties of isolated adenine to copper metal: A systematic spectroscopic and DFT study

•Vibrational modes involving copper, coordinated to N9 atom of adenine is observed.•Coordination of copper to adenine explained in terms of FTIR and Raman Peak shift.•Redistribution of charges gives clear signature of complex formation.

The coordination properties of copper with adenine have been studied by the analyzing the changes in Fourier Transform Infra-red (FTIR) and Raman spectra of adenine and adenine–copper complex. The geometry of adenine and adenine copper complex were optimized and theoretical Infra-red and Raman spectra of the optimized structures were calculated using Density Functional Theory (DFT). During synthesis of adenine–copper complex specific procedure was adopted to attach the Cu atom with particular N-atom of adenine (N9). The results of Raman and DFT confirmed the attachment. The Raman bands at 625, 330 and 230 cm−1 of adenine–copper complex contain significant contribution of the vibrational motions of Cu metal coordinated to N9 and Cl atoms. The DFT calculations give additional vibrational modes containing the Cu, N9 and N9∗ atoms, which are not observed in FTIR and Raman spectra. The Raman, IR and DFT study confirm that Cu metal has good binding affinity to the isolated adenine base.

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