The invention is an inorganic-organic hybrid, microporous, sorbent material for the selective postcombustion capture of carbon dioxide from flue gas. The material is ideal for post-combustion capture as the microporosity is most beneficial in low-pressure applications. The make-up of post-combustion flue gas is primarily nitrogen with low concentrations of C02 (15%) and other gases. The invention selectively interacts with carbon dioxide over nitrogen through strong covalent interactions (exothermic process) at exposed metal sites in the sorbent. This enables the technology to be used at the low concentrations present in flue gas. Additionally, the exposed cationic metal sites are incorporated in the material as synthesized and require no post-processing for activation. This is in contrast to other similar sorbent materials.