Heteroligand and heteronuclear clamshell-type phthalocyanines: selective preparation, spectral properties, and synthetic application

Article abstract of DOI:10.1016/j.tetlet.2009.06.048

A direct synthetic method to produce heteronuclear and heteroligand clamshell-type binuclear phthalocyanines via a nucleophilic coupling reaction between A₃B-type monophthalocyanines is developed with the target compounds demonstrating the poss

Full text of DOI:10.1016/j.tetlet.2009.06.048

Tetrahedron Letters 50 (2009) 4848–4850
Contents lists available at ScienceDirect
Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Heteroligand and heteronuclear clamshell-type phthalocyanines: selective
preparation, spectral properties, and synthetic application
Alexander Yu. Tolbin a,b,*, , Victor E. Pushkarev b, , Gennadiy F. Nikitin a, Larisa G. Tomilova a,
*
a Moscow State University, Chemistry Department, Moscow, Russia
b Institute of Physiologically Active Compounds RAS, Chernogolovka, Moscow region, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
A direct synthetic method to produce heteronuclear and heteroligand clamshell-type binuclear phthalo-
cyanines via a nucleophilic coupling reaction between A3B-type monophthalocyanines is developed with
the target compounds demonstrating the possibility to form sandwich-type heterocomplexes for the first
time.
Received 2 March 2009
Revised 19 May 2009
Accepted 5 June 2009
Available online 13 June 2009
Ó 2009 Elsevier Ltd. All rights reserved.
OH
Binuclear phthalocyanines have become the subject of intensive
research owing to their unique spectral and electrochemical
properties resulting from a multicircuit-conjugated
p-electronic
system.1–3 Significant attention has been paid to binuclear phthal-
ocyanines bridged through rigid spacers (clamshell-type). Such
bridges provide a specific geometry resulting in the macrocycles
having a cofacial conformation in solution.4 Clamshell-type metall-
ophthalocyanines are both unique catalysts of biochemical
processes1,5 and components of ion-selective electrodes6 for recog-
nition of bifunctional organic molecules. Varying the nature of the
complexing metals, as well as of the peripheral substituents,
allows the selectivity of such recognition to be increased and wid-
ens appreciably the range of molecules under investigation. In this
connection, the development of direct approaches to heteroligand
and heteronuclear clamshell-type phthalocyanines is an important
task.
O
CN
CN
1
i, ii, iii
R2
R1
R1
R2
N
N
N
N
N
N
M
N
Recently, we developed a selective method for preparing homo-
nuclear clamshell-type phthalocyanines.7 We now describe a new
approach to heteroligand and heteronuclear clamshell-type phthal-
ocyanines based on nucleophilic coupling of functionalized unsym-
metrically substituted monophthalocyanines.
N
R1
R2
O
TMS-protection of phthalogen 18 followed by cyclization of the
isolated TMS-derivative with 4-tert-butylphthalonitrile (2)9,10 in
the presence of CH3OLi in n-hexanol gave unsymmetrically substi-
tuted monophthalocyanine 3a11 after removal of the TMS-group
using AcOH. Analogues have been described earlier, for example,
zinc complex 3b,12 but the yields were poor. Reaction of phthalo-
cyanines 3a, b with TsCl gave the corresponding tosylates 4a, b13
(Scheme 1).
OX
3a,b
1
t
2 t
a: R =H ( Bu), R = Bu (H), M=2H, X=H (52%)
1
2
n
iv
b: R =R =OPr , M=Zn, X=H
4a,b
1
t
2 t
a:R =H ( Bu), R = Bu (H), M=2H, X=Ts (88%)
1
2
n
b:R =R =OPr , M=Zn, X=Ts (79%)
* Corresponding authors. Tel.: +7 495 9391243; fax: +7 495 9390290.
E-mail address: tolbin@newmail.ru (A.Yu. Tolbin).
Tel./fax: +7 496 5249508.
Scheme 1. The synthesis of starting tosyl derivatives 4a, b. Reagents: (i)
[(CH3)3Si]2NH/THF, (CH3)3SiCl, 30 min; (ii) 4-tert-butylphthalonitrile (2), CH3OLi/
n-C6H13OH, 4 h; (iii), AcOH/H2O; (iv) NaH/DMF, TsCl, 8 h.
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.06.048

A. Yu. Tolbin et al. / Tetrahedron Letters 50 (2009) 4848–4850
4849
R2
R2
R1
R1
R1
R1
R2
R2
4a,b
N
Zn
N
N
N
N
N
N
N
N
N
Zn
N
N
N
+
N
N
R2
R1
R1
N
R2
R1
R1
N
R2
R2
O
O
i
ii
N
N
M
N
N
tBu
tBu
N
N
O
O
N
N
N
R1
N
N
N
NH
N
R2
HO
N
N
M
N
N
5a-c
N
HN
N
a: R1=tBu (H), R2=H (Bu), M=2H
b: R1=tBu (H), R2=H (tBu), M=Zn
c: R1=R2=nBu, M=Zn
t
N
N
t Bu
tBu
tBu
tBu
6a-c
7a-d
a: R1=tBu (H), R2=H (tBu) (51%)
b: R1=R2=nBu (64%)
a: R1=tBu (H), R2= H ( Bu), M=Cu (99%)
R = Bu (H), R = H ( Bu), M=Ni (95%)
t
1
t
2
t
b:
c: R1=R2=OPrn (68%)
c: R1=R2=nBu, M=Zn (98%)
d: R1=R2=OPrn, M=Zn (99%)
Scheme 2. The nucleophilic coupling reaction and synthesis of heteronuclear and heteroligand binuclear clamshell-type phthalocyanines 6a–c and 7a–d. Reagents: (i) K2CO3/
DMF (20–48 h, 25–80 °C) or NaH/DMF (15–20 min, 60–80 °C); (ii) M(OAc)nÁmH2O, DBU/1,2,4-trichlorobenzene, 15 min.
Tosyl derivatives 4a, b as well as 2-hydroxyphthalo-cyanines
5a–c14 were used to prepare the clamshell-type binuclear phthalo-
cyanines 6–8.
We found that the nucleophilic coupling reaction was sensitive
to the nature of the base and the temperature (Scheme 2). Sodium
hydride was found to be a good base for producing target com-
pounds 6a–c15 in yields of 51–68% in comparison with milder
K2CO3. As a result the reaction time was reduced. However,
increasing the amount of strong base led to decomposition of the
phthalocyanine compounds which was more pronounced upon
increasing the reaction temperature. Complexes 7a–d16 were
obtained by metal insertion reactions of 6a–c with Zn, Cu, and Ni
acetates.
tBu
tBu
Furthermore, we have found phthalocyanines 6 to be suitable
building-blocks for producing more complicated structures. Start-
ing from 6a, we obtained polynuclear phthalocyanine 8 consisting
of two zinc(II) monophthalocyanine and one lutetium(III) bispht-
halocyanine subunits (Scheme 3). This novel complex represents
a sandwich-clamshell-type phthalocyanine.17
N
N
N
N
N
N
Zn
N
N
tBu
tBu
O
O
The structures of new mono- (3a, 4a, b) and binuclear (6, 7)
phthalocyanines as well as of tetraphthalocyanine 8 were con-
firmed by mass spectrometry and 1H NMR-spectroscopy data.
The mass spectra (MALDI-TOF, matrix—DCTBà) revealed molecular
ion peaks [M]+, [M+nH]+ or [MÀnH]+ (n = 1–3) as well as signals
characteristic of phthalocyanine fragment ions, in particular, phen-
oxide- or benzyl-type. It is important to note that changing the ma-
trix to DHB§ intensifies the fragmentation process and only fragment
ion peaks were detected. All the ion peaks observed in the mass
spectra have the characteristic isotope pattern corresponding to nat-
ural isotope distribution. The 1H NMR spectra showed all the typical
signals, but in the case of tert-butyl-substituted phthalocyanines, the
asymmetry results in a higher amount of regioisomers and broaden-
ing of the aromatic signals. Variation of the solvent as well as the
concentration and temperature did not affect the resolution of the
spectra.
Unsymmetrical binuclear phthalocyanines 6–7 as well as
tetraphthalocyanine 8 were also characterized from their UV–vis
spectra. These spectra differed strongly from the spectra of the cor-
responding monophthalocyanines. Taking into account previous
physico-chemical investigations of related compounds4 we envis-
age that the binuclear phthalocyanines synthesized in the present
investigation have ‘partially-opened’ conformations in solution.
N
N
N
N
N
N
N
N
tBu
tBu
i
Lu
6a
tBu
tBu
N
N
N
N
N
N
N
N
O
O
tBu
t Bu
N
N
N
N
N
Zn
N
N
N
t Bu
tBu
8
à
DCTB—2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]-malonitrile.
DHB—2,5-dihydroxybenzoic acid.
Scheme 3. Synthesis of sandwich-clamshell tetraphthalocyanine 8. Reagents: (i)
Lu(acac)3Á3H2O, MeOLi/n-hexadecanol.
§

4850
A. Yu. Tolbin et al. / Tetrahedron Letters 50 (2009) 4848–4850
were treated with a 10% solution of AcOH. After filtration of the phthalocyanine
The UV–vis spectrum of 8 exhibits a split Soret band in the
region 320–350 nm and a weaker absorption at 466 nm both
typical of -radical bisphthalocyanine species. The Q-band at
675 nm, showing superimposition of the mono- and bisphthalocy-
anine absorptions is widened and has a poorly resolved vibrational
satellite as evidence of particular interactions between macrocy-
cles, which is a subject for more detailed research.
products and following washing with CH3OH (2 Â 50 ml) and H2O (50 ml) the
mixture was chromatographically separated (eluent–CHCl3:THF 10:1) to give
t
compound 3a (642 mg, 52%). MS– (m/z): 818 [MÀH]+ (11), 720 [MÀ Bu-2CH3]+
p
(13), 697 [MÀC8H9O]+ (97). 1H NMR (300 MHz, THF-d8, 25 °C): d 1.66 (s, 27H,
Me), 4.90 (s, 2H, CH2), 5.69 (s, 2H, CH2), 7.31–8.38 (m, 4H, Ar), 9.15–9.59 (m, 12H,
Ar) ppm. UV–vis (CHCl3), kmax/nm: 345, 604, 644, 664, 699.
12. Tolbin, A. Yu.; Tomilova, L. G.; Zefirov, N. S. Russ. Chem. Bull. 2005, 54, 2099–
2103.
13. Typical procedure: To a solution of phthalocyanine 3a or 3b (0.6 mmol) in DMF
(10 ml), NaH (0.65 mmol) was added. Next, TsCl (0.9 mmol) was added
followed by stirring for 8 h at room temperature (TLC). After the reaction
was complete the product was precipitated by adding water. The solid residue
was filtered and washed with CH3OH (2Â20 ml) to give compounds 4a, b.Data
for 4a: Yield 88%. MS (m/z): 836 [MÀC7H7O2S+H2O]+ (38), 697 [MÀC15H15O3S]+
(89). UV–vis (CHCl3), kmax/nm: 347, 604, 647, 665, 671.Data for 4b: Yield 79%.
MS (m/z): 1061 [MÀC7H7O3S]+ (8), 1045 [MÀC7H7O3S]+ (24), 939
[MÀC15H15O3S]+ (92). UV–vis (CHCl3), kmax/nm: 356, 612, 680.
Thus, we have developed a direct synthetic method to produce
heteroligand and heteronuclear clamshell-type phthalocyanines for
scientific investigations.
A new tetraphthalocyanine di-Zn-Lu
heteronuclear complex has been synthesized for the first time.
Acknowledgments
14. Tolbin, A. Yu.; Tomilova, L. G. Mendeleev Commun. 2008, 18, 286–288.
15. Typical procedure. To a solution of 5a–c (0.07 mmol) in DMF (2 ml), NaH
(0.08 mmol) and 4a or 4b (0.05 mmol) were added. The mixture was heated to
60–80 °C for 15–20 min. After the reaction was complete (TLC) the products
were precipitated by adding water followed by filtration and washing with
CH3OH (3 Â 20 ml). After chromatographic separation (eluent–CHCl3:THF
50:1) the target binuclear compounds 6a–c were obtained.Data for 6a: Yield:
51%. MS (m/z): 1561 [MÀ2H]+ (5), 759 [MÀC52H49N8O]+ (49), 697
[MÀC52H47N8OZn]+ (96). 1H NMR (300 MHz, THF-d8, 25 °C): d 1.77 (s, 54H,
Me), 4.81 (s, 2H, CH2), 5.32 (s, 2H, CH2), 5.38 (s, 2H, CH2), 7.82–9.44 (m, 28H,
Ar) ppm. UV–vis (CHCl3), kmax/nm: 341, 680.Data for 6b: Yield: 64%. MS (m/z):
1731 [M]+ (99). UV–vis (CHCl3), kmax/nm: 338, 648, 671.Data for 6c: Yield: 68%.
MS (m/z): 1743 [M]+ (84), 1395 2Â[MÀC58H59N8O7Zn+H]+ (41), 1043
[MÀC44H41N8O]+ (77), 940 [MÀC52H49N8O]+ (62). UV–vis (CHCl3), kmax/nm:
347, 679.
This study was supported by the Russian Foundation for Basic
Research (Grant no. 05-08-33202) and the program of fundamental
studies of the Presidium of the Russian Academy of Sciences
‘Development of methods for synthesizing chemical compounds
and creating new materials’.
Supplementary data
Supplementary data (mass spectra and UV–vis spectra of binu-
clear phthalocyanines 6, 7, and tetraphthalocyanine 8) associated
with this article can be found, in the online version, at
doi:10.1016/j.tetlet.2009.06.048.
16. Typical procedure. To a solution of 6a–c (0.015 mmol) in DMF (2 ml), DBU
(0.02 ml) and a stoichiometric amount of Zn(OAc)2Á2H2O, Cu(OAc)2ÁH2O or
Ni(OAc)2Á4H2O were added. The reaction mixture was refluxed for 20–30 min
(TLC, UV–vis). After the reactions were complete the solvent was evaporated
followed by addition of CH3OH (15 ml) and water to precipitate target
compounds 7a–d.Data for 7a: Yield: 99%. MS (m/z): 1624 [M]+ (22), 911
[MÀC52H47N8OZn+DBU]+ (86), 759 [MÀC52H47N8OZn]+ (81). UV–vis (CHCl3),
kmax/nm: 344, 680.Data for 7b: Yield: 95%. MS (m/z): 1619 [M]+ (24), 753
[MÀC52H47N8OZn]+ (89). UV–vis (CHCl3), kmax/nm: 338, 641, 673.Data for 7c:
Yield: 98%. MS (m/z): 1795 [M]+ (58), 929 [MÀC52H47N8OZn]+ (82), 761
[MÀC64H71N8OZn]+ (16). UV–vis (CHCl3), kmax/nm: 344, 638, 681.Data for 7d:
Yield: 99%. MS (m/z): 1807 [M+H]+ (11), 941 [MÀC52H47N8OZn]+ (96), 761
[MÀC58H59N8O7Zn]+ (9). UV–vis (CHCl3), kmax/nm: 342, 634, 676.
References and notes
1. Nevin, W. A.; Liu, W.; Lever, A. B. P. Can. J. Chem. 1987, 65, 855–858.
2. Ceyhan, T.; Altindal, A.; Ozkaya, A. R.; Celikbicak, O.; Salih, B.; Erbil, M. K.;
Bekaroglu, O. Polyhedron 2007, 26, 4239–4249.
3. Nemykin, V. N.; Koposov, A. Y.; Subbotin, R. I.; Sharma, S. Tetrahedron Lett.
2007, 48, 5425–5428.
4. Dodsworth, E. S.; Lever, A. B. P.; Seymour, P.; Leznoff, C. C. J. Phys. Chem. 1985,
89, 5698–5705.
5. Liu, W.; Hempstead, M. R.; Nevin, W. A.; Melnik, M.; Lever, A. B. P.; Leznoff, C. C.
J. Chem. Soc., Dalton Trans. 1987, 2511–2518.
17.
A mixture of Zn-free-base phthalocyanine 6a (50 mg, 0.032 mmol) and
Lu(acac)3Á3H2O (8.5 mg, 0.016 mmol) was heated in n-hexadecanol (800 mg)
under argon in the presence of MeOLi (0.6 mg, 0.016 mmol) for 30 min until
the starting phthalocyanine had completely disappeared. The reaction was
monitored by TLC (SiO2, C6H6 as eluent) and UV–vis spectroscopy. The
resulting solution was diluted with C6H6 (5 mL), rinsed through a glass filter,
and the solvent was removed under reduced pressure. The residue was washed
with boiling 80% aqueous MeOH (3 Â 50 mL), filtered, and dried in a vacuum
desiccator. The resulting powder was dissolved in C6H6 and chromatographed
on a column (2.5 Â 40 cm, Bio-Beads S-X1, C6H6 as eluent), to afford 8 as a
green-colored fraction in 45% yield. MS (m/z): 3297 [M+3H]+ (14), 2553
[MÀC44H39N8Zn] (15), 2432 [MÀC52H47N8OZn] (10), 1670 [MÀC44H39N8OZn-
6. Blikova, Yu. N.; Ivanov, A. V.; Tomilova, L. G.; Shvedene, N. V. Russ. Chem. Bull.
2003, 52, 150–153.
7. Tolbin, A. Yu.; Pushkarev, V. E.; Tomilova, L. G.; Zefirov, N. S. Mendeleev
Commun. 2009, 19, 78–80.
8. Tolbin, A. Yu.; Ivanov, A. V.; Tomilova, L. G.; Zefirov, N. S. J. Porphyrins
Phthalocyanines 2003, 7, 162–166.
9. Hanack, M.; Metz, J.; Pawlowski, G. Chem. Ber. 1982, 34, 2836–2853.
10. Larner, B. W.; Peters, A. T. J. Chem. Soc. 1952, 680–686.
11. To a solution of 1 (400 mg, 1.51 mmol) in THF (10 ml) hexamethyldisilazane
(0.48 ml, 2.25 mmol) and several drops of trimethylchlorosilane were added.
The mixture was heated at reflux for 30 min followed by evaporation of the
solvent to give the crude TMS-derivative. This compound along with
C52H47N8OZn]
(98),
1566
[MÀ2ÂC52H47N8OZn]
(44),
760
[MÀC148H133LuN24O3Zn] (82). UV–vis (CHCl3), kmax/nm: 329, 347, 466, 615
phthalonitrile
2 (2.8 g, 151 mmol) and CH3OLi (860 mg, 22.6 mmol) was
sh, 675.
dissolved in n-hexanol (5 ml). The reaction mixture was heated at reflux for
3.5 h. After completion, the solvent was evaporated and the crude products
–
All of the mass spectra were recorded on an Autoflex II MALDI-TOF mass
spectrometer.