Phthalocyanine-modified silica gels and their application in the purification of unsymmetrical phthalocyanines

Abstract

Five species of phthalocyanine-modified silica gels were prepared. The loadings of phthalocyanine on these silica gels were determined by acidic hydrolysis. The concept of using the aggregation phenomenon to advantage to aid chromatographic separation of unsymmetrical phthalocyanines was investigated by employing these modified silica gels as chromatographic media to purify unsymmetrical phthalocyanines. Four groups of phthalocyanine mixtures were prepared by mixed condensation. One of the desired unsymmetrical phthalocyanines was successfully purified by conventional column chromatography while others were separated by the new method described herein. CLIFFORD C. LEZNOFF, COLIN R. MCARTHUR et YONGNIAN QIN. Can. J. Chem. 71, 13 19 (1993).On a prepare cinq espitces de gels de silice modifiCs par des phtalocyanines. On a determine la quantitC de phtalocyanine presente sur ces gels de silice en faisant appel B une hydrolyse acide. On a CtudiC le concept de l'utilisation du phenomkne d'agregation pour faciliter la sCparation chromatographique de phtalocyanines non symktriques en utilisant ces gels de silice modifies comme milieux chromatographiques pour la purification de phtalocyanines non symktriques. On a prCparC quatre groupes de mClanges de phtalocyanines par condensations mixtes. On a rCussi a purifier une des phtalocyanines non symCtriques dCsirCes par chromatographie conventionnelle sur colonne alors que les autres ont CtC sCparCes par la mCthode dCcrite ici.[Traduit par la rCdaction]Unsymmetrical phthalocyanines present challenges in the development of new methods of synthesis and separation. The potential use of phthalocyanines for photodynamic therapy (PDT) of cancer has sparked considerable interest in the photobiology of these compounds (1-9). To find a suitable phthalocyanine as photosensitizer, it is necessary to tune the position of its absorption band. Such fine tuning can be achieved by the stepwise introduction of peripheral substituent groups or by the stepwise adjustment of the size of the T-conjugated macrocyclic systems (10-13). Thus, unsymmetrical phthalocyanines are important goals in synthesis. Although symmetrical tetra-and octasubstituted phthalocyanines are well known, the synthesis of simple mono-and disubstituted and other unsymmetrical phthalocyanines remains a difficult problem (10-21). For instance, all tetrasubstituted phthalocyanines so far synthesized contain one substituent in each of the benzene rings, and no phthalocyanines such as 1,2,3,4-or 1,2,3,8-tetrasubstituted phthalocyanines have been reported.Successful methods for the synthesis of unsymmetrical phthalocyanines can be divided into three groups according to strategy: (1) the polymer support route (14,16,19,20); (2) the homogeneous mixed condensation route ( 12-14, 2 1); and (3) the subphthalocyanine route (1 1). There are difficulties with all three routes for large-scale preparation of unsymmetrical alkoxy-substituted phthalocyanines.Route 1 is not suitable for large-scale preparation of unsymmetrical phthalocyanines....

Tetrathia Macrocycle-bridged Dimeric with Hexakis (alkylthio) Substituents and Network Polymer Phthalocyanines

“…Although at first glance it appears possible to obtain unsymmetrically substituted phthalocyanines by cyclotetramerization of a mixture of two or more phthalonitrile derivatives with different substituents, isolation of each isomer is hardly possible, and the yield of the desired product could be very low [1,10,11]. At the beginning of this decade a new method, the ring enlargement reaction of subphthalocyanines, was described as a very promising route for the preparation of unsymmetrically substituted phthalocyanines [12][13][14][15][16].…”

Synthesis, Separation and Characterization of Naphthobenzo-condensed Porphyrazinato Nickel(II) Complexes

“…For the preparation of unsymmetrical phthalocyanines several strategies can be applied: the polymer support route [9], via subphthalocyanines [10], or a statistical condensation [2] including the separation of the statistical mixture of the different constitutional isomers or products which are normally formed in the synthesis of Pcs starting from either unsymmetrically substituted phthalodinitriles [11] or phthalodinitriles of different structure [1,12]. Using the first two methods, only one product, formed by three identical and one other isoindole unit, should Scheme 1.…”

Synthesis of a Monofunctional Phthalocyanine on Silica

“…For this purpose it is a prospective approach to bind a phthalocyanine bearing only one reactive substituent without crosslinking at suitable carriers like organic polymers, inorganic high molecular weight compounds or monoclonal antibodies. Monofunctional phthalocyanines are prepared by statistical synthesis employing two different dicarbonitriles [6][7][8][9], ring opening of a so-called subphthalocyanine in the presence of a differently substituted dicarbonitrile [10][11][12][13] or reaction of a polymer-bonded dicarbonitrile with differently substituted dicarbonitriles in solution followed by cleavage of the formed phthalocyanine [14][15][16]. Every method exhibits advantages and disadvantages which will not be discussed here.…”

“…Work is in progress to investigate the photosensitizing properties with these materials. Until this study, phthalocyanines on inorganic carriers like silica or titanium dioxide were only obtained by the direct binding of tetrasubstituted derivatives at these carriers [3,4,7,17]. An interesting method uses the binding of phthalocyanine aluminium (III) complexes via the third valence of the aluminium on silica [7].…”