The　development　of　efficient,　robust　and　earth-abundant　catalysts　for　photocatalytic　conversions　has　been　the　Achilles’　heel　of　solar　energy　utilization.　Here,　we　report　on　a　chemical　approach　based　on　ligand　designed　architectures　to　fabricate　unique　structural　molecular　catalysts　coupled　with　appropriate　light　harvesters　(e.g.,　carbon　nitride　and　Ru(bpy)3　2+)　for　photoredox　reactions.　The　“Co4O4”　cubane　complex　Co4O4(CO2Me)4(RNC5H4)4　(R　=　CN,　Br,　H,　Me,　OMe),　serves　as　a　molecular　catalyst　for　the　efficient　and　stable　photocatalytic　water　oxidation　and　CO2　reduction.　A　comprehensive　structure–function　analysis　emerged　herein,　highlights　the　regulation　of　electronic　characteristics　for　a　molecular　catalyst　by　selective　ligand　modification.　This　work　demonstrates　a　modulation　method　for　fabricating　effective,　stable　and　earth-abundant　molecular　catalysts,　which　might　facilitate　further　innovation　in　the　function-led　design　and　synthesis　of　cubane　clusters　for　photoredox　reactions.　©　2018　Luo　et　al.