C3‐vinyl and C13‐keto‐carbonyl groups of methyl pyropheophorbide‐a, a chlorophyll‐a derivative, were systematically modified to investigate the substituent effects along the y‐axis of chlorin macrocycles. C131 deoxygenation resulted in blueshifts of the Qy absorption maxima and a large reduction of their redox potentials, whereas introduction of the dicyanomethylene group at the 131‐position caused the opposite effect on both optical and electrochemical properties. Among the nine chlorins examined, the Qy peak positions could be varied from 647 to 736 nm by the cooperative effects of the diagonal substituents' combinations.

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