JOURNAL OF CHEMICAL RESEARCH 2007 391
Table 1 Yields of various metallo-porphyrins
Species no.
R
Mn(OAc)2
Cu(OAc)2
28%
Zn(OAc)2
24%
Pb(OAc)2
11%d
In absence of
metal acetatea
1
OH
OMe
8%c
21%
2
3
Cl
25%
28%
24%
25%
21%
22%
OMe
CH3
4
5
25%
15%
26%
14%
22%
12%b
Cl
N
aFrom ref.9
bFrom ref.10.
c8% is the Mn(II) porphyrin and remaining 12% is corresponding free-base porphyrin. d11% is the Pb(II) porphyrin and remaining
10% is the corresponding free-base porphyrin.
In conclusion, we have developed a one-flask synthesis of
metallo-porphyrins in good yields when compared to the
Rothemund and Adler–Longo methods for the synthesis of
porphyrins.
Synthesis of [meso-tetrakis(2-chloroquinolin-3-yl)porphyrinato]
zinc(II) (5Zn-II): A mixture of 2-chloro-6-methoxyquinoline-
3-carboxaldehyde (1b) (443 mg, 2 mmol), freshly distilled
pyrrole (134 mg 2 mmol) and zinc acetate (220 mg) was
dissolved in propionic acid (50 ml) and refluxed for 4 h with
stirring. After usual workup, the compound was obtained 14%
yield. Anal. calcd. for C56H28N8Cl4Zn: C, 66.0; H, 2.75; N,
11.0. Found: C, 66.0; H, 2.7; N, 11.0%. FAB-MS m/z 1019 (M
+ 1)+ requires 1018. UV: λmax nm (CHCl3) (log x): 435 (5.54),
General procedure
A mixture of vaniline (3.04 g, 0.02M), pyrrole (1.34 g,
0.02M) and zinc acetate (2.2 g, 0.01M) in freshly distilled
propionic acid (60 ml) was refluxed for four hours in open air.
The excess of propionic acid was distilled under vacuum and
the residue was neutralised with sodium bicarbonate solution.
The black coloured precipitate obtained was filtered and dried.
The residue was purified by passage through a flash column
using chloroform:methanol (98:2) as solvent to get a dark red
coloured compound [meso-tetrakis(3-methoxy-4-hydroxy-
phenyl)porphyrinato]zinc(II) (1.04 g, 24%). M.p. > 300°C.
Anal. calcd. for C48H36N408Zn: C, 67.05; H, 4.2; N, 6.5.
Found: C, 67.5; H, 4.2; N, 6.5%. FAB-MS m/z 861 (M + 1)+,
requires 860. UV: λmax nm (CHCl3) (log e): 428(5.218), 550
1
5.60 (4.67). H NMR (CDCl3 + DMSO- d6) d ppm: 9.06 (m,
8H, pyrrole β-protons), 8.65 (s, 4H, quinoline C4-H), 8.06 (m,
8H, quinoline C5 & C8-H), 7.82(m, 4H, quinoline C6-H), 7.60
(m, 4H, quinoline C7-H), -2.63 (s, 2H, porphyrin N-H).
M. Amaravathi is very grateful to DST for sanctioning
the project Women Scientist Scheme-A and L. Giribabu is
thankful to IICT for providing infrastructural facilities.
1
(4.19). H NMR (CDCl3 + d6-DMSO) d ppm: 8.92 (m, 8H,
Received 8 May 2007; accepted 10 July 2007
pyrrole β-protons), 7.74 (d, 4H, Ar–H), 7,59 (s, 4H, Ar–H),
7.25, 7, 22 (d, 4H, Ar–H), 3.94 (s, 12H, 4x O–CH3). IR (KBr)
cm-1: 3492–2500 (s, broad, O-H stretch), 1595, 1508, 1461,
1416 (m, aromatic C=C, C=N ring stretch), 928 (s, porphyrin
macrocyclic bend), 803, 776 (m, aromatic C=C-H out-of plane
bend). E1/2: -1.05; 0.80, 1.00, 1.22 V vs. SCE
Synthesisof[meso-tetrakis(2-chloroquinolin-3-yl)porphyrinato]
copper(II) (5Cu-II): A mixture of 2-chloro-6-methoxy-
quinoline-3-carboxaldehyde (1b), (443 mg, 2 mmol) freshly
distilled pyrrole (134 mg, 2 mmol) and copper acetate (200
mg) was dissolved in propionic acid (50 ml) and refluxed for 4
h with stirring. After usual workup, the compound is obtained
15% yield. Anal. calcd. for C56H28N8Cl4Cu: C, 66.1; H, 2.75;
N, 11.0. Found: C, 66.0; H, 2.8; N, 11.0%. FAB-MS m/z 1018
(M + 1)+ requires 1017. UV: λmax nm (CHCl3) (log x): 425
(5.76), 545 (4.91).
Paper 07/4637 doi: 10.3184/030823407X228227
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K.M. Kadish, K.M. Smith and R. Guilard (eds), The Porphyrin Handbook:
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PAPER: 07/4637