Fig. 4
Characterization and multimode reversible transformations of porous structures of 8PN. a CO2 (195 K) and N2 (77 K) adsorption/desorption isotherms for 8PN-THF. b Differential scanning calorimetry (DSC) curve of 8PN-THF. c Variable-temperature powder X-ray diffraction (PXRD) patterns of 8PN-THF. d Electrostatic potential (ESP) diagram of the pore constructed by four TPE-4pn molecules in 8PN-THF indicating the nitro groups inside the pore present the less electron density (in yellow color) than the nitro groups outside the pore (in red color). The potential energy range is −4.8 × 10−2 to 4.8 × 10−2. e Emission spectra of 8PN excited at 365 nm. f Photographs of 8PN taken under UV-light irradiation (365 nm). g Illustration of the multimode reversible structural transformations realized in 8PN including transitions between various porous phases as well as transitions between nonporous and porous states in response to different kinds of external stimuli. Source data are provided as a Source Data file
