Diffusion-Controlled Luminescence Quenching in Metal−Organic Frameworks

Abstract

Diffusion-controlled luminescence quenching of a phosphorescent metal-organic framework built from the Ru(bpy)(3)(2+)-derived bridging ligand (MOF-1) was studied using a series of amines of different sizes as quenchers. The dynamics of amine diffusion into solvent-filled MOF-1 channels was probed by modeling time-dependent luminescence quenching data, which provide quantitative diffusion coefficients for the amine quenchers. Triethylamine, tripropylamine, and tributylamine were found to follow Fickian diffusion with a diffusivity of (1.1 ± 0.2) × 10(-13), (4.8 ± 1.2) × 10(-14), and (4.0 ± 0.4) × 10(-14) m(2)/s, respectively. Diisopropylethylamine (DIPEA), on the other hand, was found to be too large to enter the MOF channels. Despite its size, 4-MeOPhNPh(2) can enter the MOF channels via a slow, complicated framework/guest intercalation process to result in extensive framework distortion as revealed by powder X-ray diffraction. This work represents the first quantitative study of the dynamics of molecular diffusion into solvent-filled MOF channels. Such quantitative information on molecular diffusion in MOFs is of fundamental importance to many of their potential applications (e.g., heterogeneous catalysis).

Metal–Organic Frameworks as A Tunable Platform for Designing Functional Molecular Materials

“…Lin et al quantitatively determined molecular diffusion coefficients in solvent-filled MOF channels for the first time. By monitoring luminescence quenching as a result of quencher diffusion into MOFs, 50 Lin and co-workers probed the dynamics of amine diffusion into a MOF built from the Ru(bpy) 3 2+ –derived bridging ligand. Modeling of time-dependent luminescence quenching data provided quantitative diffusion coefficients for the amine quenchers.…”

Fe/Ni Metal–Organic Frameworks and Their Binder-Free Thin Films for Efficient Oxygen Evolution with Low Overpotential

“…20−22 Further the isoreticular expansion and functionalization of these frameworks can be readily achieved without altering their underlying topologies and the accessible pores or open channels in MOFs can also facilitate the diffusion and ad/desorption of the reactants and products during catalysis. 23,24 Recently, the multivariate synthesis method and the postsynthetic exchange/substitution reactions 25,26 have been applied to fabricate multivariate MOFs (MTV-MOFs) 27 and mixed-metal MOFs (MM-MOFs) 28 with heterogeneity and emergent properties, which all show great potential for heterogeneous catalysis reactions. 29−36 For most heterogeneous catalytic reactions, the catalysts are often processed into granules or films to enhance the reactivity and help the catalyst recovery.…”

Liquid- and Gas-Phase Diffusion of Ferrocene in Thin Films of Metal-Organic Frameworks

“…The diffusion of various gas molecules in different MOF structures has been intensively studied, e.g., references [6,7,8,9,10]. On the other hand, the diffusion of the guest molecules from the liquid phase has only been investigated in a few publications [11,12,13]. So far, a comparison of the mass transfer properties in the MOF pores in the liquid and the gas phase is lacking.…”