Trifluoromethanesulfonic acid tfsa

4,5-Diazofluoren-9-one (DAFO) was synthesized in our laboratory following the synthetic route described in the literature [38 (link)] and modified by us [39 (link)]. The detailed synthesis of DAFO is described in the S1 Section in the Supporting Information. The 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA, 99% of purity) was supplied by TCI Europe (Zwijndrecht, Belgium), and it was purified by sublimation at 220 °C under high vacuum prior to use. The 2,2′-bis(4-aminophenyl)hexafluoropropane (6FpDA, 99% of purity) and 2,4,6-trimethyl-m-phenylenediamine (TMPD, 96% of purity) were purchased from Cymit Química (Barcelona, Spain) and Sigma-Aldrich (St. Louis, MO, USA), respectively, and purified by sublimation at 220 °C and 110 °C before use. Matrimid 5218 was kindly gifted by Huntsman. Chlorotrimethyl silane (CTMS, >98% of purity) and N,N-dimethylaminopyridine (DMAP, ≥99% of purity) were purchased from TCI. Anhydrous dimethylacetamide (DMAc, 99.8% of purity), anhydrous pyridine (Py, 99.5% of purity), acetic anhydride (97% of purity), and 1,3,5-triphenylbenzene (135TPB, >99% of purity) were purchased from Alpha Aesar (Haverhill, MA, USA). The trifluoromethanesulfonic acid (TFSA, 99% of purity) was purchased from Fluorochem (Glossop, UK).

N-methyl pyrrolidine (98%, Alfa Aesar, Haverill, MA, USA), N-methyl piperidine (99%, Alfa Aesar, Haverill, MA, USA), 1,5 dibromopentane (98%, Alfa Aesar, Haverill, MA, USA), potassium carbonate (K₂CO₃, 99%, Merck, Rowe, NJ, USA), biphenyl (99%, Alfa Aesar, Haverill, MA, USA), 2,2,2-trifluoroacetophenone (98%, Alfa Aesar, Haverill, MA, USA), isatin (98%, Alfa Aesar, Haverill, MA, USA), trifluoroacetic acid (TFA, 99%, Alfa Aesar, Haverill, MA, USA), trifluoromethanesulfonic acid (TFSA, 99%, Fluorochem, Derbyshire, UK), potassium hydroxide (+85% pellets, Merck, Rowe, NJ, USA), acetonitrile, (99.5%, Scharlab, Quezon City, Philippines), dimethylsulfoxide (DMSO, Scharlab, Quezon City, Philippines), N-methyl pyrrolidone (NMP, Scharlab, Quezon City, Philippines) acetone (Scharlab, Quezon City, Philippines), diethyl ether (Sigma Aldrich, St. Louis, MO, USA), methanol (Sigma Aldrich, St. Louis, MO, USA), dichloromethane (DCM, Scharlab, Quezon City, Philippines), dmso-d₆ (99.80 atom% Deutero, Kastellaun, Germany) were all used as received.