Connectivity patterns and rotamer states of nucleobases determine acid-base properties of metalated purine quartets

Linkage isomers of composition X-M-A-M-A-M-X (M = trans-a2PtII, a = am(m)ine; A = 9-alkyladenine; X = other nucleobase or NH3/amine) display differences in pKa values of the first A to undergo deprotonation at the exocyclic amino group, depending on the central cross-linking pattern and the rotamer state of the adenines.68