FLUORESCENT TRICYCLIC BETA-AZAVINAMIDINE - BF2 COMPLEXES

Boron trifluoride reacted with dipyrid-2-ylamine 6, its N-methyl and 6,6'-dimethyl derivatives 8 and 10, and 3,3',5,5'-tetraphenyl-6-azapyrromethene 13 to give fluorescent beta-azavinamidine (1,3,5-triazapenta-1,3-diene) dyes: 10-azapyridomethene-BF2 complex 5 (lambda(f) 422 nm, lambda(las) 426 nm), its quaternary 10-methyl tetrafluoroborate and 4,6-dimethyl derivatives 9 (lambda(f) 362 nm) and 11 (lambda(f) 416 nm), and 1,3,5,7-tetraphenyl-8-azapyrromethene-BF2 complex 17 (lambda(f) 696 nm). Treating 3,3',4,4'-tetraphenyl-5,5',6-trimethylpyrromethene (prepared in situ from ethyl 3,4-diphenyl-5-methylpyrrole-2-carboxylate in a reaction with acetyl chloride) with boron trifluoride, gave 1,2,6,7-tetraphenyl-3,5,8-trimethylpyrromethene-BF2 complex 21. Absorption for the vinamidine chromophore differed from that for the beta-azavinamidine chromophore by a hypsochromic shift of 86 nm in a comparison of pyridomethene-BF2 complex 3 with its 10-aza derivative 5 and by a bathochromic shift of 105 nm in a comparison of the pyrromethene-BF2 complex 20 with the 8-azapyrromethene-BF2 complex 17.