The synthesis and spectroscopic characterization of a series of luminescent platinum meso-tetrakis {3,5-di[(N-carbazyl) n-alkyloxyphenyl]} porphyrin (Pt-8Cn-TPP, n-alkyl = (CH2)(n), n = 4, 6, and 8) are presented. The protonated platinum porphyrins ([Pt-8Cn-TPPH8](8+)) were assembled with mesoporous silica MCM-48 resulting in the assembly materials [Pt-8Cn-TPPH8](8+)/MCM-48. The luminescence of [Pt-8Cn-TPPH8](8+)/MCM-48 can be extremely quenched by molecular oxygen with very high sensitivity (I-0/ I-100 > 5000) and rapid response time (0.04 s) suggesting that the [Pt-8C n-TPPH8](8+)/MCM-48 system can be employed to develop high performance oxygen sensors. Among this assembly system, [Pt-8C8-TPPH8](8+)/ MCM-48 exhibits the highest sensitivity. Even if the concentration of oxygen is 0.1%, the luminescence intensity of [Pt-8C8-TPPH8](8+)/ MCM-48 can be quenched by 86%.