Crown ether-phthalocyanines

Scheme 60 Crown ether phthalocyanines 114 with different substituents in the central core...

Crown ether-phthalocyanines 118 (n = 0, 1,2) (Scheme 65) were used as gas sensors for N02. They were found to be superior to the previously used materials... 

Scheme 63 Liquid crystalline crown ether phthalocyanine 116 without peripheral alkyl chains...

Scheme 64 Crown ether phthalocyanine 117 with redox-active tetrathiafulvalene groups...

Scheme 65 Crown ether phthalocyanines 118 as sensor materials for NQ2...

The first 6w-calixarenes bridged by a tetrathiafulvalene superstructure have been synthesized via (EtO)3P-mediated dechalcogenation-dimeiization of l,3-dithiol-2-(thi)ones <05JOC6254>. A tetra(thiafulvalene-crown ether) phthalocyanine, prepared in five-steps from 4,5-dibromo-catechol, was synthesized and shown to self-assemble into hehcal tapes <05CC1255>. Diverse... 

Phthalocyanines have been developed as new sensor materials [53]. Like the crown ethers, phthalocyanines have been discovered as by-products of a synthesis, namely the reaction of o-cyanobenzamide with phthalodinitrile [54], They consist of four indole units, and most of them have square-planar structure a metal ion can be co-ordinated in the center of the square. According to this structure, molecular interaction with an analyte is not an effect of a cavity. 

Nolte. R.J.M. Rabe, J.P. Self-assembly and manipulation of crown ether phthalocyanines at the gel-graphite interface. Angew. Chem., Int. Ed. 2001. 40. 2348-2350. 34. 

The synthesis is performed by bromination of benzo-15-crown-5, and the product, dibromobenzo-15-crown-5 (yield 70%), is reacted with CuCN in DMF (Scheme 13). Subsequently, dicyano-benzo-15-crown-5 (yield 31-70%) is converted to 15-crown-5-phthalocyanine by heating in JV,iV-dimethylaminoethanol (yield 26-41 %). The crown ether phthalocyanines CEPcM (M = Hj, Zn, Cu, Co, Ni, Fe) are well-soluble in CHCI3 and CH2CI2, but less soluble in acetone, DMF, DMSO, toluene, or benzene, almost insoluble in hexane, dioxane, ethylacetate, and insoluble in water [173, 174]. 

Fig. 22. Synthesis of sheet polymers consisting of crown ether phthalocyanine units (Permission for printing)...

For solid phases of CEPcHj and CEPcCu orthorombic structures were found by X-ray determinations at small angles. In these forms two-dimensional rectangular arrays of the substituted phthalocyanines lead to corrugated planes whereby the Pc macrocycles form an angle with the crown ether moieties. The substituents are arranged in an eclipsed conformation and the crown ether macrocycles form channels. Metastable mesophases of the crown ether phthalocyanines are constituted of two-dimensional square lattices superposed in a staggered conformation. The behavior of these mesophases bas been compared to that of liquid crystalline phthalocyanines [179]. 

Figure 37 Pc-Ceo ensemble 57 formed by a zinc crown-ether phthalocyanine supramolecular dimer similar to 54 (Figure 35a) coordinated to a pyridyl-functionalized Cgo component bearing an alkylammonium cation that is able to further interact with one of the crown ether.

Figure 38 Phthalocyanine-Ceo supramolecular dimer held by hydrogen-bonding interactions between crown-ether phthalocyanine 58 and dialalkylammonium-functionalized C 59.

Unsymmetrically substituted crown ether phthalocyanines H2L642 have been assembled from o-dicyanobenzo-15-crown-5 and L641 in the presence of Zn" and a strong organic base, or from the corresponding diirainoisoindoline derivatives on Pt as template in hexan-l-ol or pentan-l-ol and isolated as [M(L642)] (Eqs 2.250 and 2.251) [508]. Hexyl or pentyl ester derivatives are formed by the transesterification reaction that accompanies the process of template synthesis. The products have been purified by preparative TLC and identified by FAB mass spectrometry. Hydrolysis of metal(II) monoester phthalocyaninate leads to the acid derivative, which can be converted into its methyl ester by reaction with methanol. 

The electrical properties of liquid crystalline phthalocyanines have been determined for example by complex impedance spectroscopy measurements [10a,72]. Thus it was possible to observe that liquid crystalline phthalocyanines show a slight increase in conductivity when going from the solid to the mesophase. The conductivities of these compounds are low ca.5 x 10 ° S/cm) [75]. Higher conductivities are obtained if crown ether phthalocyanines (CEPcM) are aggregated by adding metal pricate salts (M = K +, Rb +, Cs+ (Trt 10 ° to lO " S/cm)... 

Dipotassium phthalocyanine (PcK2) can be prepared analogously to the dilithium compound by refluxing phthalonitrile and potassium pentoxide in pentan-l-ol.58 With additional oxygen-donor ligands (e.g., crown ethers) it forms crystals with the potassium bulging outside of the phthalocyanine ring.133134... 

Some cyclic substituents, like crown ethers, are bound at two positions of the isoindolinediimine. The products are 2 3,9 10,16 17,23 24-tetrabridged phthalocyanines. 

Calcium-binding proteins, 6, 564, 572, 596 intestinal, 6, 576 structure, 6, 573 Calcium carbonate calcium deposition as, 6, 597 Calcium complexes acetylacetone, 2, 372 amides, 2,164 amino acids, 3, 33 arsine oxides, 3, 9 biology, 6, 549 bipyridyl, 3, 13 crown ethers, 3, 39 dimethylphthalate, 3, 16 enzyme stabilization, 6, 549 hydrates, 3, 7 ionophores, 3, 66 malonic acid, 2, 444 peptides, 3, 33 phosphines, 3, 9 phthalocyanines, 2,863 porphyrins, 2, 820 proteins, 2, 770 pyridine oxide, 3,9 Schiff bases, 3, 29 urea, 3, 9... 

Phthalocyanines provided with crown ethers and chiral alkyl side chains (64) have also been reported to self-assemble in nonpolar solvents.77 These molecules form helical columns as could be deduced from the presence of a Cotton effect upon aggregation. To investigate the expression of chirality at the mesoscopic level, sergeants-and-soldiers experiments75 were performed. Chiral phthalocyanine molecules 64 were used as the sergeants and achiral... 

Figure 6.8 Phthalocyanine 63 self-assembles in chloroform to give bundles of micrometer length fibers. Single fibers have diameter of 50 A (highlighted between arrows) and can be envisaged as nanowires (top left). Chiral derivative 64 forms left-handed super helices (top right) due to chirality within side chains. This chiral expression can be turned-off by addition of K+ ions, which bind within the crown-ether part of the molecule, forcing the phthalocyanines to be stacked directly on top of each other, resulting in straight wires (bottom left).

These complexes, unlike the crown ether complexes but similar to the aza-crown and phthalocyanine complexes, are fairly stable in water. Their dissociation kinetics have been studied and not surprisingly they showed marked acid catalysis.504 Association constant values for lanthanide cryptates have been determined.505,506 A study in dimethyl sulfoxide solution by visible spectroscopy using murexide as a lanthanide indicator showed that there was little lanthanide specificity (but surprisingly the K values for Yb are higher than those of the other lanthanides). The values are set out in Table 9.507... 

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