A photochromic metal–organic framework with a rare 3D self-interpenetrated architecture and an ultrahigh MnO4− sensing ability

Abstract

Photochromic materials have shown a wide range of applications. However, the development of new photochromic materials is still a great challenge. In this work, a photochromic functional ligand, 9,10-bis(di(pyridine-4-yl)methylene)-9,10-dihydroanthracene (L), was selected to construct a photochromic LMOF, [Ni₂L(OBA)₂(H₂O)_1.5·3.5i-PrOH]_n (1) (LMOF = luminescent metal–organic framework; H₂OBA = 4,4′-oxybisbenzoic acid; i-PrOH = isopropanol). 1 is composed of 4-connected Ni²⁺, 4-connected L and OBA²⁻ bridges and exhibits a rare three-dimensional (3D) (4,4)-connected self-interpenetrated architecture and excellent water, pH and thermal stabilities. 1 and 1′ (1 after photochromism) can sense MnO₄⁻ in H₂O by luminescence quenching effects. More importantly, this material after photochromism exhibits ultrahigh sensitivity for detecting MnO₄⁻ (the second highest K_sv of 6.11 × 10⁵ M⁻¹ and the nearly lowest LOD of 3.96 × 10⁻⁸ M) and can very efficiently recognize MnO₄⁻. The sensing mechanism was explored in detail.