3D metal-organic frameworks (MOFs) have gained attention as heterogeneous photocatalysts due to their porosity and unique host-guest interactions. Despite their potential, MOFs face challenges, such as inefficient mass transport and limited light penetration in photoinduced energy transfer processes. Recent advancements in organic photocatalysis have uncovered a variety of photoactive cores, while their heterogenization remains an underexplored area with great potential to build MOFs. This gap is bridged by incorporating photoactive cores into 2D MOF nanosheets, a process that merges the realms of small-molecule photochemistry and MOF chemistry. This approach results in recyclable heterogeneous photocatalysts that exhibit an improved mass transfer efficiency. This research demonstrates a bottom-up synthetic method for embedding photoactive cores into 2D MOF nanosheets, successfully producing variants such as PCN-641-NS, PCN-643-NS, and PCN-644-NS. The synthetic conditions were systematically studied to optimize the crystallinity and morphology of these 2D MOF nanosheets. Enhanced host-guest interactions in these 2D structures were confirmed through various techniques, particularly solid-state NMR studies. Additionally, the efficiency of photoinduced energy transfer in these nanosheets was evidenced through photoborylation reactions and the generation of reactive oxygen species (ROS).

Triphenylphosphine oxide (TPPO, 1) has been adsorbed on neutral alumina by dry grinding of the components in the absence of a solvent. The adsorption proves translational mobility of 1 on the surface of alumina. Different surface coverages from a densely packed monolayer (99% coverage) to a dilute sub-monolayer (25%) have been produced. The samples have been studied by diverse multinuclear ¹H, ¹³C, and ³¹P variable temperature solid-state nuclear magnetic resonance (NMR) techniques. The interactions of 1 with the surface are determined by hydrogen bonding of the P=O group to OH groups on the surface. The ³¹P solid-state NMR spectra prove that even at low temperatures, the molecules of 1 are highly mobile on the surface. Using T₁ and T₂ relaxation time analyses of the ³¹P resonance in the solid state at variable temperatures allowed the identification and quantification of two different modes of mobility. Besides the translational mobility that consists of jumps from one hydrogen-bonding OH site on the surface to an adjacent one, a rotational movement around the axis defined by the P=O group of 1 occurs.