Pore functionalization, single-crystal transformation and selective CO2 adsorption in chemical stable pillared-layer Co(II) based metal–organic framework

Abstract

The high-efficiency CO2 separation using metal–organic frameworks (MOFs) is crucial in CO2 capture and subsequent conversion for green carbon cycling, yet challenged by rational optimizing the size, shape, sorption site and microenvironment of the pores. The new MOFs with formula [Co2(btd)2(dpbt)2]·3DMF (1) is constructed from two matched long linkers of 4,4′-(benzoic[i1,2,5]thiadiazole-4,7-diyl)dibenzoic (H2btd) and 4,7-di(4-pyridyl)-2,1,3- benzothiadiazole) (dpbt) under solvothermal condition. The compound processes 3-fold interpenetrated pillared-layer frameworks, generating 1D channels sized at 10.8 × 8.2 Å2 and with exposed thiadiazole groups for improved CO2 sorption. The framework is quite rigid confirmed by quite limited changes in crystallographic parameters during solvent exchange and guest removal in single-crystal-to-single-crystal (SC-SC) fashion. The Co(II)-MOF exhibits unprecedented good chemical stability in aqueous solution with pH ranging from 1 to 12, retaining unchanged PXRD patterns for more than 24 h. The activated MOFs show better adsorption for CO2 over N2 with selectivity of 18.8 at 273 K, benefitted from the merits of narrow 1D channels and appending Lewis basic sites on the pore surface.