Spectroscopic probe on N–H⋯N, N–H⋯O and controversial C–H⋯O contact in A–T base pair: A DFT study

• Experimental spectroscopic results serve as a benchmark for computational study.
• Computational results help in interpreting and guiding experiments.
• C–H⋯O contact in A–T base pair as a hydrogen bond?
• IR and NMR spectroscopic results for A–T base pair using DFT functional.

DNA base pair A–T has been investigated by IR and NMR spectroscopy using DFT methods. The results have been analyzed in terms of infrared vibrational frequencies and 1H NMR chemical shifts. Different types of interactions N–H⋯N, N–H⋯O and C–H⋯O types have been investigated in DNA base pairs. Although, previous reports argued about the third C–H⋯O type interaction in A–T base pair, such typical interaction has been analyzed thoroughly by IR and NMR spectroscopy using DFT methods. Our results show that the CH⋯O interaction in the A–T base pair is a weak interaction compared to normal hydrogen bond interactions.

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