Size Effect of Arylenediimide π-Conjugate Systems on the Photoresponsive Behaviors in Eu 3+ -Based Coordination Polymers.

Various arylenediimides (ADIs) have been applied to construct photoresponsive coordination polymers (CPs), while the size effect of ADI π-conjugate systems on the photoresponsive behaviors in CPs has been overlooked in the past few years. Herein, we emphasize the size effect of ADI π-conjugate systems on photoinduced electron transfer (ET) in CPs, taking two Eu 3+ -based CPs, [Eu(H 2 BINDI)(BINDI) 0.5 (H 2 O) 2 ]·NH 2 (CH 3 ) 2 ·8H 2 O ( 1 ) and [Eu 2 (BIPMDI)(DMF) 4 (NO 3 ) 2 ]·H 2 O·2DMF ( 2 ) [H 4 BINDI = N , N '-bis(5-isophthalic acid)naphthalenediimide; H 4 BIPMDI = N , N '-bis(5-isophthalic acid)pyromellitic diimide; DMF = N , N -dimethylformamide], as a case. Both 1 and 2 display ET-based photochromic behaviors with distinct photoresponsive rates and coloration contrast, which can contribute to the size effect of diimide cores on the interfacial contacts of electron donors/acceptors. Meanwhile, ET between the neighboring larger NDI cores of the H 4 BINDI ligands can block ligand-to-metal charge transfer and quench luminescence of the Eu 3+ metal center in 1 . Therefore, this work will provide a theoretical basis for the development and exploration of photoresponsive materials.