9,1 8,27,3 6-Tetrakis[meso-(4-carboxypheny1)]-tetrabenzoporphyrinatozinc(II) (TCPBP, as a sodium salt) was prepared in order to compare its photoinduced electron-transfer behavior toward unsaturated cluster Pd-3(dppm)(3)(CO)(2+) ([Pd-3(2+)]; dppm = Ph2PCH2PPh2 as a PF6- salt) with that of 5,10,15,20-tetrakis[meso-(4-carboxyphenyl)]porphyrinatozinc(II) (TCPP) in non-luminescent assemblies of the type dye center dot center dot center dot[Pd-3(2+)] (x = 0-4; dye = TCPP and TCPBP) using femtosecond transient absorption spectroscopy. Binding constants extracted from UV-vis titration methods are the same as those extracted from fluorescence quenching measurements (static model), and both indicate that the TCPBP center dot center dot center dot[Pd-3(2+)](x) assemblies (K-14 = 36000 M-1) are slightly more stable than those for TCPP center dot center dot center dot[Pd-3(2+)](x) (K-14 = 27000 M-1). Density functional theory computations (B3LYP) corroborate this finding because the average ionic Pd center dot center dot center dot O distance is shorter in the TCPBP center dot center dot center dot[Pd-3(2+)] assembly compared to that for TCPP center dot center dot center dot[Pd-3(2+)]. Despite the difference in the binding constants and excited-state driving forces for the photoinduced electron transfer in dye*center dot center dot center dot[Pd32+] -> dye center dot+center dot center dot center dot[Pd-3(center dot+)], the time scale for this process is ultrafast in both cases (<85 fs). The time scales for the back electron transfers (dye(center dot+)center dot center dot center dot[Pd-3(center dot+)] -> dye center dot center dot center dot[Pd-3(2+)) occurring in the various observed species (dye center dot center dot center dot[Pd-3(2+)](x); x = 0-4) are the same for both series of assemblies. It is concluded that the structural modification on going from porphyrin to tetrabenzoporphyrin does not greatly affect the kinetic behavior in these processes.