Synthesis and characterization of 1,4-dihydropyridine-substituted metallophthalocyanines

Article abstract of DOI:10.1016/j.mencom.2013.07.016

New phthalocyanines bearing 1,4-dihydropyridine fragments were synthesized by cyclotetramerization of phthalonitrile derivatives and the corresponding metal salts.

Full text of DOI:10.1016/j.mencom.2013.07.016

Mendeleev
Communications
Mendeleev Commun., 2013, 23, 224–225
Synthesis and characterization of 1,4-dihydropyridine-
substituted metallophthalocyanines
Ali Reza Karimi,* Fatemeh Bagherian and Meysam Sourinia
Department of Chemistry, Faculty of Science, Arak University, Arak 38156-8-8349, Iran.
Fax: +98 861 417 4006; e-mail: a-karimi@araku.ac.ir
DOI: 10.1016/j.mencom.2013.07.016
New phthalocyanines bearing 1,4-dihydropyridine fragments were synthesized by cyclotetramerization of phthalonitrile derivatives
and the corresponding metal salts.
Phthalocyanines bearing heterocyclic group have received consi-
derable attention due to their chemistry, biochemistry and photo-
chemistry.1 Among them phthalocyanines with xanthenes,2
NC
NC
OH
CN
CN
K2CO3
DMF
O
+
l-prolinol,3 imidazole,4 bis(indolyl)methane,5 thiophene,6 pyridine 7
,
triazol8 etc. are known. These compounds showed interesting
electrical, electrochemical and electrochromic properties.9 Thus,
synthesis of phthalocyanines bearing other heterocycles, with
the aim to develop new bioactive molecules is an active area of
research.
1,4-Dihydropyridines (DHPs) and their derivatives have
attracted strong interest for the treatment of cardiovascular
diseases, such as angina pectoris10 and hypertension.11 They
are also an interesting class of photochromic materials, for
example, the coloured form of DHP in the solid state is very
stable.12 Recently, 1,4-dihydropyridines were reported as com-
pounds possessing ability to scavenge 1O2.13
NO2
H
O
3
1
2
C(O)H
O
O
O
O
2
2
p-TSA,
EtOH,
reflux
Me Me
Alum, DMF,
MW irradiation
+
Me Me
+
H2N
NH4OAc
R1
NC
NC
In continuation of our previous work on the synthesis of
heterocycle-functionalized phthalocyanines2,4,5 and 1,4-dihydro-
pyridines14 and due to the resultant pharmacological interest in
compounds which belong to these families, here we describe the
synthesis and characterization of a new class of metallophthalo-
cyanines containing DHPs (Scheme 1).
NC
O
NC
O
O
O
O
O
Phthalonitrile derivatives 6a–c were synthesized in two steps.†
The first involves the nucleophilic aromatic nitro substitution in
4-nitrophthalonitrile under the action of 4-hydroxybenzaldehyde
in the presence of anhydrous K2CO3 as the base in DMF.5 The
Me
Me
Me
Me
Me
Me
N
H
N
Me
Me
6c
Zn(OAc)2,
DBU, DMAE,
N2, reflux
†
General procedure for the preparation of 6a,b. A solution of 4-(4-formyl-
henoxy)phthalonitrile 3 (1 mmol), dimedone (2 mmol) andAlum (0.1 mmol),
R1
p
in 1 ml DMF was stirred at room temperature. Then 4-methylaniline (1 mmol)
or 4-chloroaniline (1 mmol) was added and the mixture was irradiated in
a microwave oven at 300 W for 4 min. After completion of the reaction,
the mixture was cooled to room temperature. Ethanol (2 ml) and water
(1 ml) were added to the reaction mixture, the resulting precipitate was
separated and washed with hot water and ethanol.
General procedure for preparation of 6c. A solution of 4-(4-formyl-
phenoxy)phthalonitrile 3 (1 mmol), dimedone (2 mmol), p-TSA (0.1 mmol),
ammonium acetate (1.5 mmol) in ethanol (20 ml) was refluxed at 80°C
for 12 h. Then to the resulting solution some water was added to precipitate
the product. The resulting solid residue was filtered off and washed with
hot water and hot ethanol.
6a R1 = Me
6b R1 = Cl
10
X
Metal salt, DBU,
DMAE, N2, reflux
7–9
N
N
N
N
N
M
N
Me
Me
X
N
X
O
O
N
4-{4-[3,3,6,6-Tetramethyl-10-(4-methylphenyl)-1,8-dioxo-1,2,3,4,5,
6,7,8,9,10-decahydro-9-acridinyl]phenoxy}phthalonitrile 6a: yield 83%.
O
N R
X =
IR (KBr, nmax/cm–1): 3043, 2928, 2960, 2231, 1641, 1574, 1498, 1359,
7 M = Zn, R = Me
8 M = Co, R = Me
9 M = Zn, R = Cl
10 M = Zn, R = H
1
1621, 850, 570. H NMR (300 MHz, DMSO-d6) d: 7.65 (d, 1H, Harom
,
X
J 8.4 Hz), 7.46 (d, 2H, Harom, J 8.4 Hz), 7.29 (d, 2H, Harom, J 6.0 Hz),
7.22 (s, 1H, Harom), 7.15 (d, 1H, Harom, J 8.1 Hz), 7.06 (d, 2H, Harom
Me
Me
,
J 6.0 Hz), 6.91 (d, 2H, Harom, J 8.1 Hz), 5.24 (s, 1H, CH), 2.44 (s, 3H,
Me), 2.20–1.83 (m, 8H, CH2), 0.94 (s, 6H, Me), 0.77 (s, 6H, Me).
Scheme 1
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Mendeleev Commun., 2013, 23, 224–225
0.8
0.7
0.6
0.5
0.4
0.3
0.2
product of this step was reacted with 2 equiv. of dimedone and
4-methylaniline, 4-chloroaniline or ammonium acetate to access
6a–c. The desired metallophthalocyanines 7–10 were obtained by
cyclotetramerization of dinitrile compounds 6a–c (3 mmol) in
the presence of anhydrous metal salts [CoCl2 and Zn(OAc)2]
(1 mmol) using DBU as a base in 2-(dimethylamino)ethanol
(DMAE) under reflux.‡ These complexes showed good thermal
stability (Table S1, Online Supplementary Materials). The primary
weight loss is related to the residual solvent and water which is a
typical of a TGA heating run. The initial decomposition tempe-
ratures of the compounds are in the order: 9 > 7 > 10 > 8.
Phthalocyanine 7 is soluble in THF, chloroform and DMF,
phthalocyanine 8 is soluble in chloroform and DMF, whereas
phthalocyanines 9, 10 show good solubility in DMSO and DMF.
The UV-VIS spectra of compounds 7–10 in DMF are shown in
Figure 1.
3
2
1
0.1
0.0
190
290
390
490
l/nm
590
690
790
890
Figure 2 Absorption spectra of complex 7 in DMF at concentrations of
(1) 10, (2) 20 and (3) 30 mmol dm–3
.
0.8
The aggregation behaviour of phthalocyanines 7–10 at five
concentrations (50, 40, 30, 20 and 10 mmol dm–3) in DMSO,
DMF, chloroform and THF was studied. The intensity of the
absorption bands was increased with growing concentration
and there were no new bands due to the aggregated species. So,
phthalocyanines 7–10 did not form aggregates in these solvents
at different concentrations. Phthalocyanine 7 did not show aggre-
gation in THF, DMF and CHCl3 (Figure 2). The aggregation
behaviours of synthesized compounds were initiated at concetra-
tion of 500 mmol dm–3.
0.7
7
0.6
0.5
0.4
0.3
8
0.2
9
0.1
10
In conclusion, we have synthesized and characterized four
new metallophthalocyanines 7–10 which possess good solubility
and do not undergo aggregation in DMF, DMSO, THF and
CHCl3.
0.0
190
290
390
490
l/nm
590
690
790
890
Figure 1 Absorption spectra of complexes 7–10 in DMF (C = 30 mmol dm–3).
We gratefully acknowledge the financial support from the
Research Council of Arak University.
4-{4-[10-(4-Chlorophenyl)-3,3,6,6-tetramethyl-1,8-dioxo-1,2,3,4,5,
6,7,8,9,10-decahydro-9-acridinyl]phenoxy}phthalonitrile 6b: yield 78%.
IR (KBr, nmax/cm–1): 3086, 3047, 2962, 2935, 2879, 2231, 1641, 1593, 1487,
Online Supplementary Materials
Supplementary data associated with this article can be found
in the online version at doi:10.1016/j.mencom.2013.07.016.
1361, 1284, 850, 524. 1H NMR (300 MHz, DMSO-d6) d: 7.66 (d, 2H, Harom
,
J 7.5 Hz), 7.48 (m, 2H, Harom), 7.19 (m, 4H, Harom), 6.91 (m, 3H, Harom),
5.48 (s, 1H, CH), 1.99 (m, 8H, CH2), 0.95 (s, 6H, Me), 0.78 (s, 6H, Me).
4-[4-(3,3,6,6-Tetramethyl-1,8-dioxo-1,2,3,4,5,6,7,8,9,10-decahydro-
9-acridinyl)phenoxy]phthalonitrile 6c: yield 68%. IR (KBr, nmax/cm–1):
3313, 3205, 3061, 3040, 2985, 2931, 2872, 2231, 1628, 1593, 1485, 1423,
References
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1392, 572, 524. H NMR (300 MHz, DMSO-d6) d: 11.94 (s, 1H, NH),
7.70 (d, 1H, Harom, J 8.4 Hz), 7.30 (d, 2H, Harom, J 2.1 Hz), 7.18 (m, 2H,
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1.23 (s, 6H, Me), 0.89 (s, 6H, Me).
‡
General procedure for preparation of metallophthalocyanines 7–10.
A mixture of compound 6 (3 mmol), metal salt [anhydrous Zn(OAc)2 or
CoCl2] (1 mmol), DBU (3 drops) and DMAE (10 ml) was refluxed under
nitrogen for 12 h. The reaction mixture was then cooled to room tem-
perature. Ethanol was then added and the product was filtered under
suction. The green solid was washed several times with hot ethanol.
Zinc(ii) phthalocyanine 7: yield 42%. IR (KBr, nmax/cm–1): 3055, 2957,
2872, 1716, 1639, 1601, 1502, 1473, 1363, 1300, 1261, 1224, 1165, 1122,
954, 846. 1H NMR (300 MHz, DMSO-d6) d: 7.56–6.95 (m, 44H, Harom),
5.29 (4H, CH), 2.45 (12H, Me), 2.25–1.90 (m, 32H, CH2), 0.99–0.84
(48H, Me). MS (MALDI-TOF), m/z: 2392 (M+).
Cobalt(ii) phthalocyanine 8: yield 39%. IR (KBr, nmax/cm–1): 2957,
2918, 2850, 1641, 1500, 1471, 1363, 1222, 1097, 1016, 956, 848, 729.
MS (MALDI-TOF), m/z: 2385 (M+).
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2874, 1714, 1635, 1599, 1491, 1473, 1394, 1365, 1228, 1163, 1091, 1014,
943, 746. MS (MALDI-TOF), m/z: 2474 (M+).
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Zinc(ii) phthalocyanine 10: yield 45%. IR (KBr, nmax/cm–1): 3383, 3261,
3043, 2951, 1714, 1602, 1504, 1473, 1394, 1369, 1232, 1176, 1085, 945,
837. 1H NMR, d: 7.70–7.19 (m, 4H + 28H, NH + Harom), 5.40 (4H, CH),
2.50–2.09 (32H, CH2), 1.04–0.98 (48H, Me). MS (MALDI-TOF), m/z:
2030 (M+).
For more details, see Online Supplementary Materials.
Received: 24th December 2012; Com. 12/4039
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