Photoinitiated subnanosecond electron transfer within covalently linked electron donor-acceptor molecules can result in the formation of a spin-correlated radical pair (SCRP) with a well-defined initial singlet spin configuration. Subsequent coherent mixing between the SCRP singlet and triplet m(s) = 0 spin states, the so-called zero quantum coherence (ZQC), is of potential interest in quantum information processing applications because the ZQC can be probed using pulse electron paramagnetic resonance (pulse-EPR) techniques. Here, pulse-EPR spectroscopy is utilized to examine the ZQC oscillation frequencies and ZQC dephasing in three structurally well-defined D-A systems. While transitions between the singlet and triplet m(s) = 0 spin states are formally forbidden (Delta m(s) = 0), they can be addressed using specific microwave pulse turning angles to map information from the ZQC,onto observable, single quantum coherences. In addition, by using structural variations to tune the singlet-triplet energy gap, the ZQC frequencies determined' for this series of molecules indicate a stronger dependence on the electronic g-factor than on electron-nuclear hyperfine interactions.