Herein we report a robust primitive cubic (pcu)-topology metal metalloporphyrin framework (MMPF), MMPF-18, which was constructed from a ubiquitous secondary building unit of a tetranutlear zinc cluster, Zn-4(mu(4)-O)(-COO)(6), and a linear organic linker of 5,15-bis(4-catboxyphenyl)porphyrin (H(2)bcpp). The strong pi-pi stacking from porphyrins and the lengthy H(2)bcpp ligand affords a 4-fold-interpenetrating network along with reduced void spaces and confined narrow channels. Thereby, MMPF-18 presents segmented pores and high-density metalloporphyrin centers for selective CO2, uptake over CH4 and size-selective chemical transformation of CO2, with epoxides forming cyclic carbonates under ambient conditions.