Terahertz Raman Optical Activity Reveals Emergent Supramolecular Chirality in Mononucleotide G‐quadruplexes

Raman optical activity (ROA) provides unique chiroptical insights into biomolecular structure but suffers from inherently weak signals. A substantial enhancement in the low‐wavenumber/THz region (50–250 cm −1 /1.5–7.5 THz) of ROA spectra upon the formation of mononucleotide G‐quadruplexes (mG4) from guanosine‐5′‐monophosphate (5′rGMP) is reported. Using concentration‐dependent Raman and ROA measurements, a nearly 100‐fold increase in ROA intensity upon aggregation is identified, with spectral features highly sensitive to cation‐mediated structural variations. These effects can be traced to long‐range chiral interactions and distinct stacking arrangements within mG4. While strong terahertz Raman optical activity (THz‐ROA) signals have previously been observed in globular proteins and α‐helical polypeptides, the findings of this study represent the first evidence of this phenomenon in nucleotides, demonstrating that noncovalent self‐assembly into supramolecular helices can give rise to intense low‐frequency chiroptical responses. This establishes THz‐ROA as a powerful background‐free tool for studying supramolecular chirality and nucleotide self‐assembly, with potential applications in characterizing biologically relevant G‐quadruplex structures.