Department of Chemistry, CB#3290, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
J Am Chem Soc. 2011 Mar 30;133(12):4232-5. doi: 10.1021/ja111197d. Epub 2011 Mar 8.
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).
用一系列不同尺寸的胺作为猝灭剂，研究了由 Ru(bpy)(3)(2+)衍生的桥联配体（MOF-1）构建的磷光金属有机骨架的扩散控制的荧光猝灭。通过模拟随时间变化的荧光猝灭数据来探测胺扩散到充满溶剂的 MOF-1 通道中的动力学，这些数据为胺猝灭剂提供了定量的扩散系数。三乙胺、三丙胺和三丁胺被发现遵循菲克扩散，扩散系数分别为（1.1 ± 0.2）×10(-13)、（4.8 ± 1.2）×10(-14)和（4.0 ± 0.4）×10(-14) m(2)/s。另一方面，二异丙基乙胺（DIPEA）太大而无法进入 MOF 通道。尽管其尺寸较大，但 4-MeOPhNPh(2) 可以通过缓慢、复杂的骨架/客体插层过程进入 MOF 通道，这导致粉末 X 射线衍射揭示了广泛的骨架变形。这项工作代表了对分子扩散进入充满溶剂的 MOF 通道的动力学的首次定量研究。这种关于 MOF 中分子扩散的定量信息对于它们的许多潜在应用（例如，多相催化）至关重要。
