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 Having molecularly-defined active sites, porous macroligands have been found to drive the activity and the selectivity of heterogenized catalytic processes on a similar way as molecular ligands but with the advantage of the structuration in a three-dimensional framework3 and the confinement within a porous nanospace.4 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.5 The molecularly-defined Ni@BpyMP-1 heterogeneous catalyst allows the C2-selective arylation of benzothiophene and thiophene and, to the best of our knowledge, the first heterogeneous C2-selective arylation of selenophene. First, 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 heteroarens. For thiophene and 2-methylthiophene, the corresponding arylation products could be isolated in average to good yields. More scarcely studied selenophene, an attractive motif for optoelectronics19 and bioactive compounds, could also be successfully arylated (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. A simple reuse of Ni@BpyMP-1 catalyst led only to traces of product. Since the molecular benzothiophene C-H arylation is proposed to occur through a redox pathway (believed to involve Ni(I)/Ni(III) species, even if a Ni(0)/Ni(II) redox catalysis cannot be ruled out),1 we also postulate an irreversible nickel oxidation as deactivation pathway in the heterogeneous system. In order to reactivate the Ni species, we thus tested reducing agents such as sodium borohydride (NaBH4). 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. We demonstrate here the heterogeneously catalyzed direct and fully regioselective C2-H arylation of various het-eroarenes, including benzothiophene as an important building block for APIs. We also report the first proof-of-principle protocol for its efficient regeneration. The optimized heterogeneous catalytic system has been reused for at least seven times with a total TON of ca. 300 and a productivity of 12 grams of 2-phenylbenzothiophene per gram of catalyst without significant Ni leaching. The applicability of this novel heterogeneous system was further demonstrated by success-fully arylating other heterocycles like thiophenes, selenophene and indole. 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.