Modification of β-Octaethylporphyrin via Insertion of Amino and Azino Groups into meso-Positions

Abstract

The functionalization of Ni(II) β-octaethylporphyrin was performed by introducing various amino and azino groups into meso-positions. Amino, n-propylamino, and trifluoromethylacetylamino groups were used as electron donor substituents, while azino group was inserted as an electron acceptor. The azine fragment was inserted through formylation followed by reaction with hydrazine and then with aromatic aldehydes, and the corresponding azine derivatives of p-nitrophenylbenzaldehyde and methyl pyropheophorbide d were obtained. It was found that under the conditions of formylation of meso-(trifluoroacetamido)-β-octaethylporphyrin, the amide fragment was oxidized to form hydroxamic acid. As a result of substitution of meso-positions of β-octaethylporphyrin, new functionalized porphyrin derivatives with significantly altered electron-optical properties were obtained. In particular, the azine bridged conjugate of β-octaethylporphyrin with methyl pyropheophorbide d was synthesized, the electronic absorption spectrum of which contains bathochromically shifted long-wavelength bands. The resulting compounds could be of interest as potential photosensitizers, sensor dyes and biologically active compounds. in vacuum. The residue was puri fied by the column chromatography with eluent CH 2 Cl 2 - n -hexane (1 : 1) yielding 15 mg (65 %) of the compound 5 (R f = 0.55). 1 H NMR (600 MHz, CDCl 3 , 303 K) d ppm: 1.77 (24H, m, CH 2 C H 3 ), 3.86 (16H, m, C H 2 CH 3 ), 9.56 (3H, m, 10, 15, 20-CH), 9.90 (1H, s, NH). UV-Vis (CH 2 Cl 2 ) l max (A rel ) nm: 400 (1.00), 526 (0.06), 563 (0.13). LDI TOF m/z : found 702.48, calc. for [M+H] + C 38 H 45 F 3 N 5 NiO 702.29. General procedure of insertion of azine group into Ni(II) β-octaethylporphyrin. Ni(II) 5-((trifluoromethylacetyl)amino)-2,3,7,8,12,13,17,18-octaethylporphyrin ( 5 ) (40 mg, 0.057 mmol) was dissolved in 15 mL of CH 2 Cl 2 , then Vilsmeier reagent (freshly prepared from DMF (0.7 mL, 9.06 mmol) and POCl 3 (0.7 mL, 7.51 mmol)) was added dropwise to the solution, and the reaction mixture was stirred for 1 hour at reflux. Then