Indian Journal of Chemistry Vol. 40B, December 2001 , pp. 1 236- 1 238

Note

Synthesis of phthalocyanines crosswise­substituted with two alkylsulfanyl and two

crown-ether

M Salih Aglrta�l , Mehmet Sonmez*2, Mehmet Kandaz3 & Ozer Bekaroglu4

I .Department of Chemistry, Faculty of Arts and Sciences, Kafkas University, 36000 Kars-Turkey

2Department of Chemistry, Faculty of Arts and Sciences,Ylizlincli Y.I University, 65080 Van- Turkey

3·Department of Chemistry, Faculty of Arts and Sciences, Sakarya University, 54 1 00 Sakarya-Turkey

4 Department of Chemistry, Technical University of Istanbul, 80626 Maslak Istanbul-Turkey

Received 30 March 2000; accepted (revised) J 2 December 2000

Crosswise-substutited phthalocyanines with two nitro and two dodecylsulfanyl groups are synthesized by a 1 : 1 condensation of I ,3-dihydro- 1 ,3-diimino-6-(n-dodecylsulfanyl) isoimino indo­lenine with 6-nitro- l ,3,3-trichloroisoindolenine in the presence of sodium methoxide, hydroquinone and triethylamine. Nitro sub­stituents are reduced to amines by sodium sulfide and condensa­tion of the amino groups with benzo- 1 5-crown-5-aldehyde results in a new Pc with two benzo- 1 5-crown-5-imino substituents. The compounds have been characterized by elemental analyses, UVIVis and IR spectroscopy.

Phthalocyanines, in particular their readily soluble peripherally substituted derivatives, possess a wide range of chemical and physical properties that make them interesting building blocks for a number of ap­plications and new materials I . In contrast to the ther­mal stability of phthalocyanines (Pc), their solubility in common solvents causes difficulties for many ap­plications. Peripheral substitution of Pcs with long alkyl chains or bulky groups enable one to overcome these diffuculties2• The consequence of cyclotet­ramerization of substituted phthalonitrile derivatives is normally Pcs with some substituents on all four benzenoid groups I . Various strategies have been promulgated in efforts to achieve products with dif­ferent substituents on each of the benzo units. The use of a mixture of phthalonitrile derivatives in the syn­thesis can be considered as a first approximation, but then the result is a statistical mixture of Pc derivative, which cannot be isolated in any practical way, not even sometimes by chromatographic methods. Pub­lished routes specifically designed include reaction of

a phthalonitrile derivative bound to an insoluble polymer with a large excess of another phthalonitrile derivative3 . Although the cross condensation of a 1 ,3-diiminoisoindolenine derivative with 1 ,3,3-tricholoroisoindolenine has been reported as an inter­esting method to obtain Pcs subtituted with two dif­ferent groups4, only a few further application of this new method has been encountered. In the present work, soluble phthalocyanines peripherally substi­tuted with two amino and two alkylsulfanyl groups located crosswise have been synthesized and their reactivity has been exemplified through the formation of a Schiffs base with benzo- 15-crown-5 aldehyde.

Results and Discussion The synthesis of the crosswise-disubstituted Pcs 6-

7,9 is shown in the Scheme I. The starting point for both of the precursors is 4-nitrophthalimide. It is con­verted into 4-nitrophthalonitrile4 and subsequent nu­cleophilic displacement of the nitro group with Il-dodecylmercaptan gives 4-dodecylsulfanylphthalo­nitriles,6 3, which is reacted with ammonia in the pres­ence of sodium methoxide to obtain the isoiminoin­doline derivative6 5 as the first precursor. The second precursor, namely 6-nitro- l ,3,3-trichloroisoindolenine 4, is prepared by chlorination of 4-nitrophthalirnide with PCIs in o-dichlorobenzene4,6. Cyclotetrameriza­tion of these two reactants in a 1 : 1 rati.o is accom­plished in THF in the presence of triethylamine and sodium methoxide as the base and hydroquinone as the reductant6. An interesting point to be noted about the above sequence concerns the reductive coupling of the chloro 4 with the isoiminoindolenine derivative 5. Reproducible yields of the Pcs could not be ob­tained unless the above acid acceptor and hydrogen donor are present. After purification, the yields of these compounds are found to be rather higher than literature.

Peripheral nitro substituents on the Pc core offer a number of possibilities to obtain reactive binding sites, such as reduction to an amine. For this purpose, sodium sulfide is preferred as the reductant as in the case of tetranitro-substituted Pcs? In order to demon­strate the reactivity of amino groups in diarnino­didodecyl-sulfanyl Pc 7, its condensation with benzo-15-crown-5 aldehyde6•8 was carried out to obtain a

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NOTES 1237

9 Scheme I-Synthesis of the phthalocyanines

new Pc with two benzo- I S-crown-S-imino substitu­ents together with two dodecylsulfanyl units.

Elemental analysis results and the spectral data (IR and UV /Vis) for this new product were consistent with the assigned formulation. The IR spectrum of 8 exhibits characteristic frequencies at 3267 (NH), 3020 (CH arom) , 29 1 3-2823 (CH2), 1 6 1 0 (C=N) and 1 262 (C-O) cm" . UV/Vis absorption spectra of the phthalo­cyanine complexes exhibits characteristic Q and B band. UV /Vis spectra of Pc 8 in toluene, show the intense Q-band absorption of 1t-t1t* transitions at 7 1 1 , 690 nm, respectively. B band of all the phthalo­cyanines arising from the depeer 1t levels -tLUMO transitions are observed in UV region at about 34 1 -42S.

Materials and Methods 4-Nitrophthalamide 1 and 4-nitrophthalonitrile4

2, 4-(n-dodecyl-sulfanyl)-phthalonitrile 3, 6-nitro- l ,3,3-trichloroisoindolenine4

4, 1 ,3-dihydro- l ,3-diimino-6-(Il-dodecylsulfanyl)-isoimino indolenine6 5, . 2/3, \ 6/ 17 -di-(n-dodecylsulfanyl)-9/1 0, 23/24-dinitroph­thalocyanine6 6, di-(n-dodecylsulfanyl)-diaminorh­thalocyanine6 7 and benzo- I S-crown-S aldehyde 8 were prepared according to literature procedures. All other reagents and solvents were of reagent grade

quality, were obtained from commercial suppliers and were dried as described in Perrin and Armaiego be­fore uselO.

Bis (n-dodecylsulfanyl)-bis(benzo-15-crown-5-imino) phthalocyanine 9. 7 (O.OS g, O.OS mmole) was dis­solved in dry toluene. 0,OS9 g (0,2 mmole) of benzo­I S-crown-:5 aldehyde and a catalytic amount of p­toluene sulfonic acid were added to this solution. The mixture was refluxed for 3 hr. After cooling to room temperature the precipitate was filtered off and the solvent was evaporated to dryness. The residue was treated with acetone several times to remove the unre­acted materials; the product was filtered and washed first with methanol, then with acetone and dried. yield 0.03 g, (37%). Anal. Calc. for C86H , 04N 1 00 I OS2: C, 68.87; H, 6.97 ; N, 9.30. Found : C, 68.60 ; H, 6.8 1 , N , 8.93%. lR (KBr) : 3267 (NH), 3020, 29 1 3-2828 (CH2), 1 6 1 O(C=N), 1262 (C-O) cm" . UV-Vis spec­trum (in toluene): 7 1 1 , 690, 42S, 34 1 .

Acknowledgement We thank the Research Fund of the Yiiziincii YII

University for financial support.

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1238 INDIAN J CHEM. SEC B, DECEMBER 2001

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