SPECTROSCOPIC CHARACTERIZATION OF FREE-BASE HYDROXY(ARYLETHYNYL)PORPHYRINS IN ACIDIC
683
pyridine-d5;Me4Si):δH,ppm0.58(18H,s,−Si(CH3)3),4.11
(6H, s, −OCH3), 7.29 (4H, m, Ph), 8.05 (4H, m, Ph),
8.85 (4H, d, pyrrole-H), 9.60 (4H, d, pyrrole-H). Anal.
calcd. for C44H40N4O2Si2Zn: C, 67.89; H, 5.18, N,
7.20%. Found: C,68.25; H, 5.47, N, 6.75.
quenched upon the addition of triethylamine (2.0 mL).
The organic layer was washed with 2 × 200 mL satu-
rated Na2CO3, dried over MgSO4, and concentrated
under reduced pressure to yield the free-base porphyrin
(0.0667g, 82%).1H NMR (400 MHz; CDCl3; Me4Si): δH,
ppm -1.88 (2H, s, pyrrole –NH), 3.95 (6H, s, −OCH3),
4.12 (6H, s, −OCH3), 7.11 (4H, m, Ph), 7.33 (4H, m,
Ph), 7.95 (4H, m, Ph), 8.10 (4H, m, Ph), 8.84 (4H, d,
pyrrole-H), 9.65 (4H, d, pyrrole-H). Anal. calcd. for
C52H38N4O4⋅1/2 H2O: C, 78.87; H, 4.96 N, 7.08%. Found,
C, 78.87; H, 4.91; N, 7.10.
[5,15-Bis(ethynyl)-10,20-dimethoxyphenylpor-
phinato]zinc(II) (6a). 5a (0.806 g, 1.04 mmol) was dis-
solved in CH2Cl2 (125 mL) and the solution was degassed
with a stream of Ar for 15 min after which tetrabuty-
lammonium fluoride (2 mL, 1 M solution in THF) was
added. After 30 min the reaction was quenched with
acetic acid (115 μL) and concentrated under reduced
pressure. The product was recrystallized from MeOH/
CH2Cl2 to yield a dark blue solid (0.622 g, 95%). 1H NMR
(400 MHz; CDCl3, pyridine-d5; Me4Si): δH, ppm 4.10
(6H, s, −OCH3), 4.14 (2H, s, terminal alkyne H), 7.28
(4H,m,Ph),8.05(4H,d,Ph),8.88(4H,d,pyrrole-H),9.65
(4H, d, pyrrole-H). Anal. calcd. for C38H24N4O2Zn⋅1/2
H2O: C, 70.98; H, 3.92; N, 8.71%. Found: C, 71.28; H,
4.09; N, 8.73.
5,15-Bis(ethynylphenyl)-10,20-dimethoxyphenyl-
porphyrin (8c). 7c (0.1282 g, 0.1630 mmol) was dis-
solved in CHCl3 (150 mL) and 20 drops of concentrated
HCl were added. After 10 min, the reaction was quenched
upon the addition of triethylamine (3.5 mL). The organic
layer was washed with 2 × 200 mL saturated Na2CO3,
dried over MgSO4, and concentrated under reduced pres-
sure to yield the free-base porphyrin (0.1179 g, 78%).1H
NMR (300 MHz; CDCl3; Me4Si): δH, ppm -1.92 (2H, s,
pyrrole –NH), 4.15 (6H, s, −OCH3), 7.35 (4H, m, Ph),
7.54 (6H, m, Ph), 8.05 (4H, m, Ph), 8.13 (4H, m, Ph),
8.89 (4H, d, pyrrole-H), 9.70 (4H, d, pyrrole-H). Anal.
[5,15-Bis(ethynylmethoxyphenyl)-10,20-dimetho-
xyphenylporphinato]zinc(II) (7a). A solution of triethy-
lamine (1.0 mL), 4-iodoanisole (0.0970 g, 0.414 mmol),
and dry THF (30 mL) was degassed with a stream
of Ar for 10 min after which 6a was added (0.0958 g,
0.1511 mmol). Tetrakis(triphenylphosphine)palladium
(0) (0.0187g, 0.0162 mmol) and copper(I) iodide
(0.0095 g, 0.050 mmol) were then added and the mix-
ture was heated at reflux overnight. The mixture was
concentrated under reduced pressure and purified by
column chromatography (silica, 7:3 hexanes/THF) to
yield a dark green solid (0.0910 g, 71%).1H NMR (400
MHz; CDCl3, pyridine-d5; Me4Si): δH, ppm 3.92 (6H, s,
−OCH3), 4.11 (6H, s, −OCH3), 7.09 (4H, m, Ph), 7.29
(6H, m, Ph), 7.93 (4H, m, Ph), 8.07 (4H, m, Ph), 8.86
(4H, d, pyrrole-H), 9.67 (4H, d, pyrrole-H). Anal. calcd.
.
calcd. for C50H34N4O2 H2O: C, 81.06; H, 4.90; N, 7.56%.
Found, C, 81.16; H, 4.77; N, 7.59.
General procedure for the deprotection
of methoxy groups
The corresponding methoxyphenyl porphyrin (~0.1
mmol) was dissolved in dry CH2Cl2 (7 mL) and degassed
with a stream of Ar for 10 min at -78°C. Boron tribro-
mide (5:1 mol ratio BBr3/-OCH3 substituent, 1M solu-
tion in CH2Cl2) was added drop wise and the mixture
was stirred for 20 min then allowed to come up to room
temperature and stirred for an additional 4 h. The reac-
tion was quenched upon addition of methanol (5 mL),
concentrated under reduced pressure, and extracted with
ethyl acetate (50 mL). The organic layer was then washed
with 2 × 25 mL deionized water, dried over MgSO4, and
recrystallized from ethyl acetate/hexanes to yield a dark
blue solid (54−74%).
.
for C52H36N4O4Zn H2O: C, 72.26; H, 4.43; N, 6.48%.
Found C, 72.48; H, 4.74; N, 6.28.
[5,15-Bis(ethynylphenyl)-10,20-dimethoxy-
phenylporphinato]zinc(II) (7c). A solution of trieth-
ylamine (2.0 mL), iodobenzene (0.16 g, 0.80 mmol),
and dry THF (65 mL) was degassed with a stream
of Ar for 10 min after which 6a was added (0.1999 g,
0.310 mmol). Tetrakis(triphenylphosphine) palladium (0)
(0.0392 g, 0.0339 mmol) and copper (I) iodide (0.0154 g,
0.0809 mmol) were then added and the mixture was
heated at reflux overnight. The mixture was concentrated
under reduced pressure and purified by column chroma-
tography (silica, 7:3 hexanes/THF) to yield a dark green
solid (0.1422 g, 58%).1H NMR (400 MHz; CDCl3, pyri-
dine-d5; Me4Si): δH, ppm 4.11 (6H, s, −OCH3), 7.30 (4H,
m, Ph), 7.55 (6H, m, Ph), 8.01 (4H, m, Ph), 8.08 (4H, d,
Ph), 8.89 (4H, d, pyrrole-H), 9.71 (4H, d, pyrrole-H).
5,15-Bis(ethynylmethoxyphenyl)-10,20-dimethoxy-
phenylporphyrin (8a). 7a (0.0721 g, 0.0852 mmol) was
dissolved in CHCl3 (100 mL) and 10 drops of concen-
trated HCl were added. After 10 min, the reaction was
5,15-Bis(ethynylhydroxyphenyl)-10,20-dihydroxy-
1
phenylporphyrin (1). H NMR (300 MHz; DMSO-d6;
Me4Si): δH, ppm -1.96 (2H, s, pyrrole –NH), 7.03 (4H,
m, Ph), 7.24 (6H, m, Ph), 8.00 (8H, m, Ph), 8.86 (4H, d,
pyrrole-H), 9.70 (4H, d, pyrrole-H), 10.03 (2H, s, −OH),
10.16 (2H, s, −OH). Anal. calcd. for C48H30N4O4 ⋅ꢀ2H2O:
C 75.58, H 4.49, N 7.34; found, C 75.30, H 4.37, N 7.10.
MALDI-TOF: 727.1 (m/z MH+ calcd.), 727.1 (obsd.).
UV-VIS (DMF): 450 (305,000 M-1.cm-1), 614 (45,800),
704 (28,900).
5,15-Bis(ethynylhydroxyphenyl)-10,20-diphenyl-
porphyrin (2). 1H NMR (300 MHz; DMSO-d6; Me4Si):
δH, ppm -1.96 (2H, s, pyrrole –NH), 7.02 (4H, m, Ph),
7.87 (6H, m, Ph), 7.97 (4H, m, Ph), 8.22 (4H, m, Ph),
8.79 (4H, d, pyrrole-H), 9.72 (4H, d, pyrrole-H), 10.17
Copyright © 2017 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2017; 21: 683–691