The use of earth-abundant metals for the direct C-H activation through a heterogeneous protocol would allow reaching appealing sustainability for the synthesis and derivat-ization of fine chemicals since this approach would enable at the same time (i) the use of accessible resources, (ii) a beneficial atom- and step-economy of non-activated substrates, and (iii) the ability to reuse the catalyst and to easily separate it from products.1 To change the paradigm of molecular catalytic processes for fine chemical synthesis, we introduced recently the concept of solid porous macroligand for heterogenized molecular catalysis.2 Here we show the heterogenization of an earth-abundant molecular nickel complex within the structure of a bipyridine bipyridine-based POP, namely BpyMP-1, used as a porous macroligand.3 To assess the actual coordination of the nickel to the bpy sites within the porous polymer and the molecular nature of the heterogenized Ni(bpy) catalyst, we correlate both typical ssNMR signals and IR bands of bipyridines to the nickel content determined by ICP-OES analysis. DFT calculations on molecular cluster models of the binding site futher confirm the dependence of this band intensity to the bipyridine nickelation. We then explored the catalytic potential of Ni@BpyMP-1 for the direct C-H arylation of benzothiophene in the presence of lithium bis(trimethylsilyl)amide (LiHMDS) in toluene. The 2-phenylbenzothiophene was obtained with 50% yield and 100% regioselectivity for the arylation of benzothiophene at the C2 position using 1wt%Ni@BpyMP-1 catalyst, determined to be the best from a series. The heterogenous Ni@BpyMP-1 was found to be applicable to other aryl electrophiles as well as other heteroarenes (Figure 1a). Further improvement was made through heterogenization of Ni catalyst within BpyMP-1 for free NH indole arylation with 41% yield in 3-phenyl-indole and 62% C3 selectivity over N-arylation when the Ni@BpyMP-1 catalyst was used compard to homogeneous reaction (Figure 1b). Then, we evaluated the ability of Ni@BpyMP-1 solids to be recycled in the C2 arylation of benzothiophene. The TON reaches approx. 44 per run using 1wt%Ni@BpyMP-1 in the presence of NaBH4 (Figure 1c). After seven consecutive catalytic runs, a cumulative TON of 316 was reached. This corresponds to a total productivity of 12 grams of 2-phenylbenzothiophene per gram of catalyst. Taking into account their robustness and their potential processability, the porous organic polymers used as macroligands for molecular catalysts further pave the way to molecularly defined and robust heterogeneous systems for a more sustainable synthesis of fine chemicals. This work has been carried out within the H-CCAT project that has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 720996. References 1.Mohr, Y. et al. Green Chem. 22, 3155–3161 (2020). 2.Wisser, F. M. et al. Acs Catal. 8, 1653–1661 (2018). 3.Mohr, Y. et al. ACS Catal. 11, 3507–3515 (2021).