4
J. RAMESH & C. ARUNKUMAR
5,15-bis(pentafluorophenyl)-10,20-bis(4′-bromo-
phenyl)porphyrinato zinc(II), MB3a (0.5 g, 4.9 × 10-4
mol) and N,N-dimethylamine hydrochloride (2.12 g,
2.6 × 10-2 mol) were added to a dry round bottomed flask
containing 50 mL of dimethylformamide. The resultant
solution was stirred and refluxed under N2 at 180°C
for 12 h. After that, the reaction mixture was cooled
and extracted with ethyl acetate. Two fractions were
identified, as per TLC, and they were purified by silica
column chromatography using a CHCl3/Hexane (30:70)
mixture. The products MB3b and MB3c were obtained
in 14% and 67% yields respectively. The compounds,
MB3b and MB3c were demetallated using HCl/H2SO4
(5%), purified by column chromatography, giving MB1b
and MB1c in 70–73% yields. Further, metallation of
MB1b and MB1c with Cu(OAc)2 in CHCl3/MeOH
resulted in compounds, MB2b and MB2c quantitatively.
A similar procedure was adopted to make the compounds
DB1b–1c, DB2b–2c and DB3b–DB3c, which were
synthesized from DB3a. UV-vis data of the porphyrins
in CH2Cl2 at 298 K, lmax (log e/M-1 cm-1): MB1b, 417
(5.67), 512 (4.43), 546 (3.97), 588 (3.94), 643 (3.60);
MB1c, 418 (5.66), 512 (4.45), 546 (4.09), 588 (3.97),
643 (3.70); MB2b, 415 (5.52), 538 (4.30); MB2c, 413
(5.60), 537 (4.32); MB3b, 419 (5.65), 546 (4.32); MB3c,
420 (5.58), 547 (4.27); DB1b, 416 (5.69), 511 (4.48) 587
(4.08); DB1c, 418 (5.65), 511 (4.48), 587 (4.08); DB2b,
413 (5.60), 536 (4.36); DB2c, 413 (5.55), 537 (4.32);
DB3b, 419 (5.61), 546 (4.34); DB3c, 420 (5.61), 547
(4.32). 1H NMR data: 400 MHz, CDCl3, d (ppm): MB1b,
8.84–8.72 (m, 8H), 8.01 (d, J = 8.00 Hz, 4H), 7.84 (d,
J = 8.00 Hz, 4H), 3.21(s, 6H), -2.94 (s, 2H); MB1c, 8.86–
8.75 (m, 8H), 8.01 (d, J = 8.00 Hz, 4H), 7.84 (d, J = 8.00
Hz, 4H), 3.21 (s, 12H), -2.90 (d, 2H); MB3b, 9.02–8.89
(m, 8H), 8.09 (d, J = 8.00 Hz, 4H), 7.91 (d, J = 8.00 Hz,
4H), 3.29 (s, 6H); MB3c, 9.01–8.98 (s, 8H), 8.09 (d, J =
8.00 Hz, 4H), 7.91 (d, J = 8.00 Hz, 4H), 3.28 (s, 12H);
DB1c, 9.02–8.92 (m, 8H), 8.33 (s, 4H), 8.13 (s, 2H), 3.29
(s, 12H), -2.88 (s, 2H); DB3b, 8.79–8.76 (m, 8H), 8.13
(s, 4H), 8.07 (s, 2H), 3.24 (s, 12H); DB3c (300MHz),
8.99–8.89 (m, 8H), 8.31 (s, 4H), 8.15 (s, 2H), 2.86 (d,
12H). ESI mass data of MB1b (C46H24Br2F9N5): 977.51
(Calcd.), 978.1474 (Found); MB1c (C48H30Br2F8N6):
1002.59 (Calcd.), 1003.1614 (Found); MB2b (C46H22Br2-
CuF9N5): 1039.04 (Calcd.), 1039.00 (Found); MB2c
(C48H28Br2CuF8N6): 1064.12 (Calcd.), 1065.00 (Found);
MB3b (C46H22Br2F9N5Zn): 1040.88 (Calcd.), 1041.0204
(Found); MB3c (C48H28Br2F8N6Zn): 1065.96 (Calcd.),
1066.0721 (Found); DB1b (C46H22Br4F9N5): 1135.3
(Calcd.), 1135.9261 (Found); DB1c (C48H28Br4F8N6):
1160.38 (Calcd.), 1160.9930 (Found); DB2b (C46H20Br4-
F9N5Cu): 1196.83 (Calcd.), 1197.8522 (Found); DB2c
(C48H26Br4F8N6Cu): 1221.91 (Calcd.), 1220.9563
(Found); DB3b (C46H20Br4F9N5Zn): 1198.68 (Calcd.),
1198.8512 (Found); DB3c (C48H26Br4F8N6Zn): 1223.75
(Calcd.), 1223.9547 (Found). Fluorescence spectral data
of porphyrins in CHCl3 at 298 K (lex at Soret band of
respective compound, MB1b–MB3c and DB1b–DB3c),
em for MB1b: 646 (s), 710 (s); MB1c: 648 (s), 712 (s);
l
MB2b: 653(w), 711(w); MB2c: 649(w), 712(w); MB3b:
597 (s), 643 (s); MB3c: 598 (s), 644 (s); DB1b: 645 (s),
707 (s); DB1c: 648 (s), 711 (s); DB2b: 650(w), 706(w);
DB2c: 650(w), 711(w); DB3b: 592 (w), 641 (s); DB3c:
596 (w), 644 (s).
The 19F NMR spectra of zinc(II) derivatives of parent
trans-porphyrins (MB3a and DB3a), mono-aminated
porphyrins (MB3b and DB3b) and di-aminated
porphyrins (MB3c and DB3c) showed three, five and two
signals respectively. 19F NMR data: 470 MHz, CDCl3, d
(ppm): MB3a, -136.97 – -137.11 (br, d, 4F, F′), -152.24 –
-152.56 (br, d, 2F, F′′′), -161.89 – -162.05 (br, d, 4F, F′′);
MB3b, -137.04 – -137.11 (m, 2F, F′), -140.52 – -140.58
(m, 2F, F′sub), -152.22 – -152.28 (m, 2F, F′′sub), -152.79 (t,
J = 21 Hz, 1F, F′′′), -162.14 – -162.24 (m, 2F, F′′); MB3c,
-140.52 (d, J = 24 Hz, 4F, F′sub), -152.31 (d, J = 19 Hz,
4F, F′′sub). DB3a, -136.95 – -137.12 (m, 4F, F′), -152.18
(t, J = 21 Hz, 2F, F′′′), -161.79 – -161.90 (m, 4F, F′′);
DB3b, -136.90 – -137.10 (m, 2F, F′), -140.44 – -140.60
(m, 2F, F′sub), -152.13 – -152.19 (m, 2F, F′′sub), -152.45 (t,
J = 19 Hz, 1F, F′′′), -161.94 - -162.05 (m, 2F, F′′); DB3c,
-140.52 (d, J = 14 Hz, 4F, F′sub), -152.23 (s, 4F, F′′sub).
RESULTS AND DISCUSSION
Using MB3a/DB3a with dimethylamine hydrochlo-
ride, the mono-aminated meso-tetraarylporphyrins,
M(TF5)(TF4DMA)D(4-/3,5-BrP)P (MB1b–3b and
DB1b–3b)/di-aminated meso-tetraaryl trans‑porphyrins,
MB(TF4DMA)D(4-/3,5-BrP)P (MB1c–3c and DB1c–3c)
were synthesized [M = 2H, Cu(II) and Zn(II)]. All the
synthesized porphyrins (Scheme 1) were isolated, purified
by column chromatography and characterized by UV-vis,
1
fluorescence, H NMR spectroscopic methods and mass
spectrometry. Several attempts were made to synthesize
the cationic porphyrin derivatives (N-trimethylated por-
phyrins), however the results were unsuccessful.
The electronic absorption data of the synthesized
porphyrins are dominated by an intense Soret (B) band
which can be attributed to spin allowed p–p transition in
the range of 412–420 nm and a medium intensity two or
four visible (Q) bands in the range of 509–643 nm [25].
The overlaid UV-vis spectra of MB1a–1c are shown in
Fig. 2a. It has been noted that the introduction of mono-/
di-aminated groups at the porphyrin periphery does
not influence the electronic properties of the resultant
compounds and shows a marginal red shifted Soret band
of only 1–3 nm compared to that of the free ligand. The
fluorescent spectral pattern of free ligands DB1a–1c is
similar to its tetraphenylporphyrin analogue (H2TPP). On
excitation at the Soret band, all the porphyrins exhibit
two emission bands (weak or strong) in the range of
590–656 nm and 639–712 nm corresponding to S1 → S0
transitions (Fig. 2b).
Copyright © 2018 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2018; 22: 4–12