Graphitic　carbon　nitride　(g-CN)　is　a　promising　heterogeneous　metal-free　catalyst　for　organic　photosynthesis,　solar　energy　conversion,　and　photodegradation　of　pollutants.　Its　catalytic　performance　is　easily　adjustable　by　modifying　texture,　optical,　and　electronic　properties　via　nanocasting,　doping,　and　copolymerization.　However,　simultaneous　optimization　has　yet　to　be　achieved.　Here,　a　facile　synthesis　of　mesoporous　g-CN　using　molecular　cooperative　assembly　between　triazine　molecules　is　reported.　Flower-like,　layered　spherical　aggregates　of　melamine　cyanuric　acid　complex　(MCA)　are　formed　by　precipitation　from　equimolecular　mixtures　in　dimethyl　sulfoxide　(DMSO).　Thermal　polycondensation　of　MCA　under　nitrogen　at　550°C　produces　mesoporous　hollow　spheres　comprised　of　tri-s-triazine　based　g-CN　nanosheets　(MCA-CN)　with　the　composition　of　C3N4.14H1.98.　The　layered　structure　succeeded　from　MCA　induces　stronger　optical　absorption,　widens　the　bandgap　by　0.16　eV,　and　increases　the　lifetime　of　photoexcited　charge　carriers　by　twice　compared　to　that　of　the　bulk　g-CN,　while　the　chemical　structure　remains　similar　to　that　of　the　bulk　g-CN.　As　a　result　of　these　simultaneous　modifications,　the　photodegradation　kinetics　of　rhodamine　B　on　the　catalyst　surface　can　be　improved　by　10　times.　Simple　molecular　engineering　of　triazine　precursors　enables　simultaneous　optimization　of　the　texture　and　photoelectric　properties　of　graphitic　carbon　nitride　(g-CN).　Thermolysis　of　flower-like　supramolecular　aggregates　of　melamine　and　cyanuric　acid　yields　the　formation　of　mesoporous　g-CN　hollow　spheres　with　the　typical　nanosheet-type　structure　preserved　in　the　microspheres.　Such　structures　are　highly　active　in　the　photocatalytic　degradation　of　organic　pollutants.　Copyright　©　2013　WILEY-VCH　Verlag　GmbH　&　Co.　KGaA,　Weinheim.