Herein, we report the targeted synthesis and solid state assembly of a novel triazine-based [4+6] organic molecular cage. The tetrahedral cage features a large cavity (∼2070 Å(3)), and after desolvation, the resultant material exhibits a high Brunauer-Emmett-Teller surface area of 1181 m(2) g(-1) and also features selective adsorption of CO2 over N2.