Two pyrene-based metal−organic frameworks constructed from 1,3,6,8-tetrakis(p-benzoic acid)pyrene: Syntheses, structures and photoelectron performances

Two pyrene-based metal−organic frameworks directed by ionic liquids, [M2(TBAPy)(H2O)2]·(Guests)x (M ​= ​Co 1, Zn 2) based on a tetratopic linker with a π-conjugated pyrene core, i.e. 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy), have been synthesized under the combination of hydro/solvothermal and ionothermal condition. 1 and 2 are isostructural and feature 2D layered porous network based on M2(O2C)4 paddlewheel units with axially coordinated water molecules. The temperature-dependent fluorescence emission clearly demonstrates the varying degree of interchromophoric interaction as a function of temperature within ​1 ​and ​2. Photoelectron measurements reveal that 1 and 2 both display quick response to visible light irradiation, and are capable of repetitive on-off photocurrent switching with a large on-off ratios. The closely spaced TBAPy chromophores and their higher local concentration along with their twisty molecular conformation would facilitate the formation of excimers, photon capture, electron−hole separation, long-range energy transport and delivery.