RESUMO
Precise revealing the mechanisms of excited-state intermolecular proton transfer (ESPT) and the corresponding geometrical relaxation upon photoexcitation and photoionization remains a formidable challenge. In this work, the compound (E)-4-(((4H-1,2,4-triazol-4-yl)imino)methyl)-2,6-dimethoxyphenol (TIMDP) adopting a D-π-A molecular architecture featuring a significant intramolecular charge transfer (ICT) effect has been designed. With the presence of perchloric acid (35 %), TIMDP can be dissolved through the formation of a HClO4 -H2 O-OH(TIMDP)-N(TIMDP) hydrogen-bonding bridge. At the ground state, the ICT effect is dominant, giving birth to crystals of TIMDP. Upon external stimuli (e.g., UV light irradiation, electro field), the excited state is achieved, which weakens the ICT effect, and significantly promotes the ESPT effect along the hydrogen-bonding bridge, resulting in crystals of [HTIMDP]+ â [H2 O]â [ClO4 ]- . As a consequence, the mechanisms of the ESPT can be investigated, which distorted the D-π-A molecular architecture, tuned the emission color with the largest Stokes shift of 242â nm, and finally, high photoluminescence quantum yields (12 %) and long fluorescence lifetimes (8.6â µs) have achieved. These results not only provide new insight into ESPT mechanisms, but also open a new avenue for the design of efficient ESPT emitters.
RESUMO
By using in-site generated formate, 2D HOFs of TCPP, with excellent stability and permanent porosity (BET surface area larger than 560 m2 g-1), have been obtained. The constructed 2D square-like TCPP-HCO2 grid sheets have shown considerable in-plane stability that comparable to the TCPP-based 2D MOFs, that can be exfoliated into atomically thin 2D nanosheets with efficient photocatalytic activity in aqueous system. These results are expected to shed light on the application-orientated one-pot synthesis for new kinds of multi-dimensional HOFs.