Nitrogen-doped　microporous　carbon,　which　features　a　uniquely　tunable　porosity,　exhibits　promisingly　high　adsorption　prospects　in　the　greenhouse　gas　capture　and　water　treatment.　Herein,　we　propose　a　series　of　novel　N-doped　microporous　carbons　(CMPAn-C1000),　and　precisely　tune　their　porosities　via　a　direct　pyrolysis　of　rigid　conjugated　microporous　poly(aniline)s　(CMPAn,　n　=　1,　2,　3)　with　pore　size　difference　in　a　molecular　level,　as　achieved　by　simply　tuning　their　linkers　with　varying　sizes,　planarity,　and　symmetry.　The　CMPA3-C1000,　with　a　satisfactory　amount　of　nitrogen　heteroatoms,　high　SBET　of　∼800　m2　g−1,　and　large　ultra-micropore　volume　of　0.25　cm3　g−1,　has　excellent　CO2　capture　ability　(i.e.,　5.1　mmol　g−1　at　273　K,　1　atm)　and　Hg(II)　adsorption　performance　(i.e.,　Qe　=　571　mg　g−1;　k2　=　0.0031　g　mg−1　min−1),　respectively.　CMPA3-C1000　might　perform　chemisorption　towards　Hg(II),　according　to　calculations　using　density　functional　theory　and　experimental　data;　nitrogen　atoms　in　porous　carbon　contributed　to　this　excellent　Hg(II)　adsorption.　©　2023　Elsevier　B.V.