The electron transport system along the Qy axis of the chlorophyll derivatives has attracted considerable attention. Recently, we achieved the first photochemical CO2 reduction using very low energy light (>650 nm) and a synthetic chlorophyll derivative covalently linked with a rhenium bipyridine complex at the Qy axis. This result prompted us to construct an efficient photochemical CO2 reduction system with harvesting red light absorbed by a chlorophyll electron donor. In this study, we discuss the photophysical properties of modified chlorophyll and rhenium bipyridine conjugates comparing with the original one. (C) 2015 Elsevier B.V. All rights reserved.