The　development　of　efficient　and　yet　economic　photocatalysts　that　can　utilize　solar　light　is　crucial　for　the　sustainable　future.　We　report　a　simple　approach　to　introduce　a　bidentate　type　of　metal　coordination　site　in　polymeric　carbon　nitride　(PCN)　by　an　in　situ　keto　enol　cyclization　route　of　acetylacetone　and　urea　to　incorporate　a　metal　chelating　pyrimidine　derivative　into　the　molecular　framework　of　PCN.　The　resulting　new　metal　coordination　sites　provide　both　N-　and　O-complexing　ligands　unlike　the　unmodified　PCN　that　has　N-ligands　only.　As　a　proof-of-concept　experiment,　we　introduced　Al3+　ions　into　these　coordination　sites,　which　induced　significant　enhancements　in　visible　light　photocatalytic　activities　for　organic　pollutant　degradation　and　H-2　evolution　as　compared　to　those　of　bulk　PCN　and　the　conventional　＂nitrogen　pot＂　metal　coordinated　PCN.　The　optimized　Al　loading　was　as　low　as　0.32　wt　%.　The　photocatalytic　activities　sensitively　depended　on　the　Al　incorporation,　and　the　Al-incorporated　sample　demonstrated　an　excellent　stability　in　water　with　showing　little　sign　of　metal　leaching.　While　the　aluminum　ions　complexed　in　the　nitrogen　pot　little　influenced　the　photocatalytic　activity,　Al3+　ions　complexed　by　both　N　and　O　ligands　in　the　alternative　coordination　sites　significantly　enhanced　the　photocatalytic　activity　of　PCN.　This　study　demonstrates　a　facile　and　scalable　synthesis　of　PCN　with　alternative　metal　coordination　sites　for　efficient　solar　energy　conversion.