ABSTRACT
We report here the first step by step anchoring of a W(≡CtBu)(CH2tBu)3 complex on a highly crystalline and mesoporous MOF, namely Zr-NU-1000, using a Surface Organometallic Chemistry (SOMC) concept and methodology. SOMC allowed us to selectively graft the complex on the Zr6 clusters and characterize the obtained single site material using state of the art experimental methods including extensive solid-state NMR techniques and HAADF-STEM imaging. Further FT-IR spectroscopy revealed the presence of a WâO moiety arising from the in situ reaction of the W≡CtBu functionality with the coordinated water coming from the 8-connected hexanuclear Zr6 clusters. All the steps leading to the final grafted molecular complex have been identified by DFT. The obtained material was tested for gas phase and liquid phase olefin metathesis and exhibited higher catalytic activity than the corresponding catalysts synthesized by different grafting methods. This contribution establishes the importance of applying SOMC to MOF chemistry to get well-defined single site catalyst on MOF inorganic secondary building units, in particular the in situ synthesis of WâO alkyl complexes from their W carbyne analogues.
ABSTRACT
Minimal edge-transitive nets are regarded as suitable blueprints for the successful practice of reticular chemistry, and par excellence ideal for the deliberate design and rational construction of highly coordinated metal-organic frameworks (MOFs). We report the systematic generation of the highly connected minimal edge-transitive related nets (transitivity [32]) from parent edge-transitive nets (transitivity [21] or [11]), and their use as a guide for the deliberate design and directional assembly of highly coordinated MOFs from their associated net-coded building units (net-cBUs), 12-connected (12-c) double six-membered ring (d6R) building units. Notably, the generated related nets enclose the distinctive highly coordinated d6R (12-c) due to the subsequent coordination number increase in one node of the resultant new related net; that is, the (3,4,12)-c kce net is the (4,6)-c soc-related net, and the (3,6,12)-c kex and urx nets are the (6,6)-c nia-related nets. Intuitively, the combination of 12-connected hexagonal prismatic rare-earth (RE) nonanuclear [RE9(µ3-O)2(µ3-OH)12(O2C-)12] carboxylate-based clusters with purposely chosen organic or organic-inorganic hybrid building units led to the formation of the targeted highly coordinated MOFs based on selected minimal edge-transitive related nets. Interestingly, the kex-MOFs can alternatively be regarded as a zeolite-like MOF (ZMOF) based on the zeolite underlying topology afx, by considering the dodecacarboxylate ligand as a d6R building unit, delineating a new avenue toward the construction of ZMOFs through the composite building units as net-cBUs. This represents a significant step toward the effective discovery and design of novel minimal edge-transitive and highly coordinated materials using the d6Rs as net-cBUs.