Two Functional Two-Dimensional Photochromic Zn-MOFs Derived from the Viologen-Carboxylate Ligands

In this work, two functional two-dimensional (2D) Zn(II) metal–organic frameworks (Zn-MOFs), {[Zn(NDC)(CEbpy)]·H2O}n (1) and {[Zn(HBTC)(CV)0.5(H2O)]·0.5(CV)·6H2O}n (2), were synthesized using two viologen-carboxylate ligands (CEbpy = 1-carboxyethyl-4,4′-bipyridine; CV = N,N′-4,4′-bipyridiniodipropionate) in the presence of secondary linkers (H2NDC = 1,4-naphthalenedicarboxylic acid; H3BTC = 1,3,5-benzenetricarboxylic acid). Owing to the successful construction of the donor–acceptor (D–A) system, both Zn-MOFs exhibited excellent electron-transfer photochromic properties, and their photoproducts remained stable in air for several days. Additionally, compounds 1 and 2 exhibited potential for photocontrolled luminescence and demonstrated clear and legible printing capabilities, making them suitable for use as light-controlled switch and inkless erasable printing media.