A 2D Metal‐Free Inorganic Covalent Framework: Synthesis, Crystal Structure, and Room‐Temperature Phosphorescence

Abstract

AbstractThe synthesis, crystal structure and room‐temperature phosphorescence (RTP) of a 2D metal‐free inorganic covalent framework ((H2en) [B5O8(OH)], named as CityU‐12, and en represents for ethylenediamine) are reported. The precise structure information of CityU‐12 has been disclosed through both single‐crystal X‐ray diffraction (SCXRD) analysis and low‐dose high‐resolution transmission electron microscopy (LD‐HRTEM) study. The SCXRD results show that CityU‐12 composes of 2D anionic B─O‐based covalent inorganic frameworks with protonated ethylenediamine locating in the pore sites of 2D B─O layers while LD‐HRTEM suggests that CityU‐12 has an interplanar distance of 0.60 nm for (00) crystal plane and 0.60 nm for (10) crystal plane. The optical studies show that CityU‐12 is an excellent nonconventional RTP material with the emission peak at 530 nm and a lifetime of 1.5 s. The quantum yield is 84.6% and the afterglow time is as long as 2.5 s. This work demonstrates that metal‐free B─O frameworks can be promising nonconventional phosphors for RTP.