Both the triazine-and thiophene-containing SNP-BDT1 and SNP-BDT2 polymers have characteristic signals at 167-169 ppm in solid-state C CP-MAS spectra which belong to C3N3ring carbons. Signals in the range from 110-150 ppm are attributed to sp 2 -hybridised carbon atoms within aromatic phenyl and thiophene units (Figure ). The sulfur-containing polymer, SP-BTT, shows three distinct signals at 136, 131 and 118 ppm, which correspond to quaternary carbons in thiophene and phenyl rings, and to tertiary thiophene carbons. Details of the bulk analysis of the as-received polymers are found in the SI (Table , S4-S7, Figure ). For all polymer systems, we detect residual Pd-content (0.03 to 1.05 wt%) and P atoms (0.09 to 0.36 wt%) trapped in the polymer matrix after the cross-coupling reaction, as well as Sn (0.39 to 1.07 wt%) and halogen atoms (Cl: 0.57 to 3.72 wt%, Br: 2.25 to 5.74 wt%) arising from unreacted end-groups. These findings correlate with results from TGA measurements under an oxidative atmosphere that show a residual content of non-combustible inorganics between 3 and 7 wt% (Figure ). Irrespective, the high degree of cross-linking we achieve in all networks confers high thermal stability up to 750 °C under an inert atmosphere (Figure ). Powder X-ray diffraction (PXRD) shows that the SNP-BDT1, SNP-BDT2 and SP-BTT networks are -just like the previously reported SNPs -amorphous with broad features at around 10 and 25° 2θ which correlate with in-plane distances between aromatic building blocks and π-stacking distances of approx. 3.6 Å, 11 respectively (Figure ). Scanning electron microscopy (SEM) images of SNP-BDT1 and SNP-BDT2 networks confirm a 'cauliflower'-like morphology typical for nucleation-growth polymers, while the SP-BTT polymer grows in rodlike aggregates of 20 to 100 μm length (Figure ). Transmission electron microscopy (TEM) and selected-area electron-diffraction (SAED) for these three polymers confirm a similar degree of internal, microscopic structure as seen in PXRD data with visible, concentric rings indicative of polycrystalline materials (Figure ). Cross-linking of C2 and C3 symmetric building blocks suggests a regular bonding pattern with hexagonal, "honeycomb"-shaped pores on paper, and the low number of unreacted end-groups in our polymers suggests just that. However, as structural analysis reveals and as we established previously, Pd-catalyzed Stille cross-coupling favors the formation of the disordered, kinetic product, presumably with some degree of interpenetration of adjacent pore structures. We investigated these pore channels by nitrogen gas adsorption/desorption analysis performed at 77 K. All polymers show Type I isotherms with a pronounced hysteresis indicative of micro-and mesopores (Figure ). The guest accessible surface area was calculated according to Brunauer-Emmett-Teller (BET) and varies in the range from 79 to 698 m 2 g -1 (Table ).