The Controversial Orientation of Adenine on Gold and Silver.

In which orientation does adenine adsorb on gold and silver surfaces? This question has been a matter of debate for over 30 years. Since the dawn of surface-enhanced Raman spectroscopy (SERS); it and other techniques such as tip-enhanced Raman spectroscopy (TERS), surface-enhanced infrared absorption spectroscopy (SEIRAS), scanning tunneling microscopy (STM), density functional theory (DFT) simulations, and more, have been used in many attempts to answer this seemingly straightforward, yet controversial, question. Herein, the timeline and recent advances on this topic are explored, and the frequently contradictory findings are put into context and discussed.