Dipyridamole and its derivatives modify the kinetics of the electron transport in reaction centers from Rhodobacter sphaeroides

Quenching of Singlet Molecular Oxygen, O2(1Δg), by Dipyridamole and Derivatives

“… *Obtained from the oxidation potential vs Ag/Ag + 0.01 m Ag + in ACN in Refs. (17) and (18) by adding 0.27 V vs SCE. DIP = dipyridamole; ACN = acetonitrile. …”

“…Redox potential values throughout this paper are taken from Refs. (17) and (18) and are relative to SCE in ACN. The final term in () is the energy of the Coulombic interaction between the two ions formed after the electron transfer with internuclear distance a in the encounter complex: a = r + + r − , where r + is the molecular radius of the quencher (for the DIP r + = 8 Å), and r − is the radius of the electron acceptor, which is 1.73 Å for O 2 ; as it is very small, the last term in the () was neglected.…”

“…Redox potential values throughout this paper are taken from Refs. (17) and (18) and are relative to SCE in ACN. The final term in (Eq.…”

“…The electrooxidation of DIP in ACN is characterized by two almost reversible voltammetric waves, corresponding to two consecutive one‐electron processes (15–18). In the first process, the formation of a stable radical cation DIP •+ occurs ( E 1/2 = 0.30 V vs SCE), and a dication anion is formed in the second process ( E 1/2 = 0.60 V vs SCE) (16).…”

“…The oxidation potential of the appropriate redox couple can be related to the thermodynamics of the electron‐transfer reaction, and electrochemical studies may provide valuable insights to evaluate the above hypothesis. For this reason, in recent years we studied the electrochemical properties of DIP aiming to obtain more information, which could be useful in explaining its antioxidant activity (15–18).…”