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8Фталоцианины Phthalocyanines
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Сообщение Communication
Application of Monohydroxyphthalocyanines
for Selective Preparation of Homo- and Heteroligand Macrocyclic Compounds
Alexander Yu. Tolbinab and Larisa G. Tomilovaab@
a M.V. Lomonosov Moscow State University, Moscow,119991, Russia
hInstitute of Physiologically Active Compounds, Russian Academy of Sciences, Chernogolovka, Moscow Region, 142432, Russia
@Corresponding author E-mail: [email protected]
The direct synthesis of functionally substituted monohydroxyphthalocyanines has been developed with application of these compounds as building-blocks for synthesizing homo- and heteroligand bisphthalocyanine complexes.
Keywords: Phthalocyanine, subphthalocyanine, selective synthesis, nucleophilic substitution, heteroligand complex.
Introduction
Unsymmetrically substituted monophthalocyanines represent considerable interest not only from theoretical, but also from the practical point of view. Functional substitution of various nature in such macrocyclic compounds allows to design new supramolecular structures possessing unique physical and chemical properties.[2,3] For this reason development of the direct synthetic methods for these compounds is one of priority field in phthalocyanine chemistry.
Experimental
XH, nB NMR spectra were registered on Brucker AM-300 (300.13 MHz), using Py-d5 and CDCl3 as the solvents. Mass spectra were obtained on Autoflex II (MALDI-TOF) equipment. IR-spectra were recorded on Nicolet Nexus IR-Furje (KBr pills). UV-vis spectra were recorded on ThermoSpectronic Helios-a spectrophotometer in quartz cell (CHCl3, THF). Chromatographyc separation was carried out on Merck Silicagel 60 (40x63 |im) and Biorad BioBeads (SX-1).
Zn(OAc) 2-2H2O salt was kept under 100oC for 4h before synthesis. CH3OLi was freshely prepared and used immediately.
Compounds 1,[1] 2[4] and 6[7] were obtained according to described procedures.
2-Hydroxysubstituted phthalocyanine, 3. CH3OLi (0.32 g, 8.33 mmol) was added to the solution of compounds 1 (0.15 g, 0.64 mmol) and 2 (1.18 g, 6.41 mmol) in n-hexanol (20 ml). The mixture was refluxed for 2 h, and then the solvent was evaporated with following treatment of crude product with conc. H2SO4. The reaction mixture was kept for 5 min and poured onto ice. The phthalocyanine products precipitated were filtered off, repeatedly washed with water to neutral pH, and chromatographed on silica gel (CHCl3) to give compound 3. Yield 0.24 g (50%). IR (KBr) v cm-1: 3200-3300 (OH). MS (m/e) 760 [MH]+. XH NMR (Py-d5) 5H ppm: 1.21-1.38 (group s, 27H, C(CH3)3), 8.75-9.12 (m, 12H, Pc). UV-vis (CHCl3) Xmax nm: 350, 611, 679.
Bis(bromomethyl)benzene, 4. To the solution of o-xylene (1 ml, 8.29 mmol) in CCl4 (5 ml) bromine (0.9 ml, 18.24 mmol) was added dropwise at lighting (300 W halogen lamp) and refluxing for 30 min. After reaction was finished the mixture was cooled and
concentrated followed by filtration of target compound to give 2 g of 4 (82%). CAS 91-13-4, PubChem Substance ID: 24893875
Homonuclear clamshell-type complex, 5. NaH (2 mg, 0.080 mmol) was added to a solution of compound 3a (85 mg, 0.111 mmol) in DMF (2 ml). Once the reaction was completed, reagent 4[4] (17 mg, 0.056 mmol) was added to the reaction mixture with vigorous stirring, and the mixture was kept for 15-20 min at 25-30°C with chromatographic monitoring of the reaction. The reaction mixture was treated with water; the precipitated product was filtered off, washed with water (3*10 ml), then with methanol (2^10 ml), and purified by chromatography on silica gel (Merck, 40*63 p,m, CHCl3-THF=20:1) to give 86 mg (95%) of complex 5. MS (m/e) 1626 [MH]+, 761 [M-C52H49N8OZn]+. XH NMR (Py-d5) 5H ppm: 1.2-1.4 (group s, 54H, C(CH3)3), 58.5 (s, 4H, OCH2), 8.70-9.10 (m, 28H, Ar). UV-vis (CHCl3) Xmax nm: 336, 637, 678.
Heteronuclear clamshell-type complex, 7. Compound 3 (15 mg, 0.02 mmol) was added to a solution of compound 6[5] (18 mg, 0.03 mmol) in toluene (5 ml). The mixture was refluxed for 25 h and then concentrated in vacuo. The target product 7 was isolated by chromatography on BioBeads SX1. The yield of compound 7 was 24 mg (90%). MS (m/e): 1340 [M-H]+, 579 [M-C44H39N8OZn]+. XH NMR (Py-d5) 5H ppm: 1.2-1.4 (group s, 54H), 8.70-9.10 (m, 21H). nB NMR (CDCl3) 5B ppm: -15.20 (s, B). UV-vis (THF) I nm: 348, 573, 614, 681.
max
Results and Discussion
Initially, mixed cyclization of 4-benzyloxy-phthalodinitrile (1) with 4-tert-butylphthalodinitrile (2) in the presence of zinc acetate gave 2-benzyloxy-9,16,23-tri-tert-butylphthalocyanine. However, it was shown by TLC data this product and a side zinc phthalocyanine have close Rf values. That is why, we have treated a mixture by H2SO4 without preliminary isolation of intermediate product. As a result compound 3 was obtained in 50 % yield. Presence of OH-group in compound 3 has allowed us to synthesize of homo- and heteroligand complexes.
So, reaction of 3 with bis(bromomethyl)benzene (4) gave binuclear phthalocyanine 5 of clamshell-type.
Due to the high reactivity of dibromide 4, the reagent ratio should be taken into account in this synthesis. The
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^CN + UCN
A.Yu. Tolbin and L.G. Tomilova
... CH3OLi/n-hexanol ' Zn(0Ac)22H20
H2S04 (conc.) ' H20 (ice)
co
4 (0-5 eg.) NaH/DMF, 25°C
^uSubPcBCKe)
toluene, 110 °C, 25 h
èr ,
Scheme 1. Synthesis of monohydroxyphthalocyanine 3, homo- (5) and heteronuclear (7) complexes.
reaction was carried out in DMF in the presence of NaH. Initially, the treatment of compound 3 with NaH (25oC) in the reaction mixture gave phenol-type alkoxy anions required for nucleophilic coupling. After addition of 4 in 0.5 equivalent quantity we managed to obtain the binuclear complex 5 with high selectivity and 95% yield. However, it is important to note that the yield of the target binuclear phthalocyanine 5 drastically decreased upon a considerable increase of the reaction temperature due to the destruction of phthalocyanine macrocycles in the highly basic medium. This reaction gives a single product, namely, homonuclear phthalocyanine complex 5 with quantitative conversion of starting compound 3. It is important to note that the total yield of phthalocyanine 5 at two-stage synthesis was 47% that almost in 4 times more than yields of the similar compounds obtained by Leznoff.[6]
We have previously found that nonsymmetrically-substituted monophthalocyanines containing a benzyl-type
OH group in the peripheral substituent are able to react with subphthalocyanines to give heteronuclear complexes.[7] In the case of 3 we have also demonstrated the possibility of phenol-type OH-group to give related compounds. The reaction of compound 3 with ^-chloro-[boron-2,9,16-tri-tert-butylsubphthalocyanine] (6) resulted in a heteronuclear complex 7. It was found that the decrease in the distance between the macrocycles in compound 7 create certain steric hindrance that primarily results in a considerable increase in the reaction time in comparison with the related heterodimer that we obtained previously.[7]
Structures of compounds 3, 5, 7 were proved by MS-spectrometry, 1H NMR and IR-spectroscopy. So, massspectrum MALDI-TOF (2- [(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylidene]malonitrile as a matrix) of 3 contains only peak with m/z 760 ([M+H]+). The mass-spectra of complexes 5 and 7 contain, in addition to molecular ion peak (m/z 1626 and 1341), also signals of fragment ions
Figure 1. Mass-spectrum (MALDI-TOF) of binuclear phthalocyanine 5.
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Preparation of Homo- and Heteroligand Macrocyclic Compounds
(m/z 760 and 581) formed upon cleavage of CH2-OPc and ether bonds correspondingly. Mass-spectrum of compound 5 is presented in Figure 1.
Peaks of all ions in mass-spectra have the charac-teristic isotope splitting peculiar to natural distribution of isotopes.
In 1H NMR spectra of target phthalocyanines 3, 5 and 7 signals of all proton types are presented. Mainly, signals of aromatic protons are found widened owing to aggregation of macrocycles and presence of statistical isomers. Signals of tert-butyl groups are detected in the form of imposed singlets (group of signals) in a range of 1.2-1.4 ppm. Singlet of benzyle-type protons of compound 5 (4H) is observed at 5.5 ppm. The 11B NMR spectrum of compound 7 was found to contain a singlet at -15.20 ppm that is somewhat shifted upfield in comparison with compound 6.[7]
Conclusions
Unsymmetrically substituted complex 3 was synthesized and used as a precursor for obtaining homo-(5) and heteronuclear (7) complexes in the practically quantitative yields.
Acknowledgements. This work was supported by the Russian Foundation for Basic Research (Grant no. 08-0333202) and by the Programme for fundamental studies of Presidium of the Russian Academy of Sciences "Development of synthetic methods for chemical compounds and creation of novel materials".
References
1. Tolbin A.Yu., Tomilova L.G. Mendeleev Commun. 2008, 18, 286-288.
2. Tolbin A.Yu., Tomilova L.G., Zefirov N.S. Russ. Chem. Rev. 2007, 76, 681-692.
3. Sukeguchi D., Yoshiyama H., Shibata N., Nakamura S., Toru T., Hayashi Y., Soga T. J. Fluor. Chem. 2009, 130, 361-364.
4. Kikuchi D., Sakaguchi S., Ishii J. J. Org. Chem. 1998, 63, 6023-6026.
5. Claessens C.G., Gonzalez-Rodriguez D., Torres T. Chem. Rev. 2002, 102, 835-853.
6. Marcuccio S.M., Svirskaya P.I., Greenberg S., Lever A.B.P., Leznoff C.C. Can. J. Chem. 1985, 63, 3057-3069.
7. Tolbin A.Yu., Breusova M.O., Pushkarev V.E., Tomilova L.G. Russ. Chem. Bull. 2005, 54, 2083-2087.
Received 29.04.2009 Accepted 22.05.2009
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