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The syntheses of a variety of substituted diaminomaleonitriles, with variable nitrogen substituents, were undertaken. Linstead macrocyclization of the resulting diaminomaleonitriles gave access to a wide range of functionalized porphyrazine-octaamines and hexamines and norphthalocyaninediamines. Conversion of these macrocycles into metallic derivatives and studies of their electronic absorption, solubility and electrochemistry are described. These flexible tetraazaporphyrins show potential in a range of applications including biomedical agents, novel charge–transfer complexes, chemical sensors, novel electronic materials and non-linear optics.

The syntheses of two novel CuI-bis(benzonitrile) complexes of the type [Cu(dCNn)2][PF6] {where dCNn = NCPhO(CH2)nOPhCN, n = 3, 4} are described. Both compounds have been characterized by X-ray crystallography. To our surprise, and although the two complexes were quite similar, two very distinct structures were obtained. For the [Cu(dCN4)2][PF6] complex, a tetrahedral geometry was observed whereas for [Cu(dCN3)2][PF6], a polymeric assembly was formed. A further extension of this work involved the syntheses of two threaded species bearing the M30 macrocycle, Cu metal and a dCNn ligand. The formation of the desired complexes was confirmed by means of mass spectrometry as well as 1-D and 2-D 1H NMR spectroscopy. Finally, the cyclic voltammograms of all 4 new species were recorded giving rise to redox potentials ranging from +0.88 to +1.25 V. These new threaded complexes are of particular interest since they can form the basis of novel rotaxane structures. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

Co-macrocyclizations of 2,3-dipropylmaleonitrile and 2,3-di-(4-(methoxycarbonyl)phenyl)maleonitrile, respectively, with N , N ′-dibenzyl- N , N ′-di-(11-tetrahydropyranyloxy-3,6,9-trioxo-undecyl))maleonitrile and N , N , N ′, N ′-tetramethylmaleonitrile were used to prepare derivatives of the 4,5-diamino-porphyrazine systems including the zinc(II) complexes. Subsequent oxidation of the macrocycles with potassium permanganate gave the corresponding seco -porphyrazines. These were shown to be efficient sensitizers for the production of singlet oxygen ( Φ Δ =0.15–0.57) by the determination of their photophysical properties.

Base-catalyzed cross condensation of dipropylmaleonitrile 1 with bis(dimethylamino)maleonitrile 2 in an equimolar ratio afforded the porphyrazines 3a, 4a, 5a, 6a and 7a. Subsequent demetalation of 5a with TFA followed by remetalation with Zn(OAc)(2) gave ligand 5c in good yield. Compound 5c was, in turn, selectively oxidized and further peripherally functionalized using Pt(PhCN)(2)Cl(2) and PdCl(2) to yield the novel seco solitaire porphyrazines 10a and 10b. The photophysical profiles of the seco solitaire porphyrazines 10a and 10b were evaluated by means of absorption, emission, and transient absorption spectroscopy. The new pigments 10a and 10b were found to be photochemically more stable than the solitaire complexes 3d and 3e and mediated the generation of singlet oxygen with quantum yields of 0.59 and 0.45, respectively.

Unsymmetrical porphyrazines (tetraazaporphyrins) bearing a single bidentate phenanthroline chelating group M[pz(t-butylphenyl)6phen] have been prepared by the base-catalyzed cross condensation of 3,4-bis(4-tert-butylphenyl)pyrroline-2,5-diimine (in excess) with 6,7-dicyanodipyridoquinoxaline. Treatment of these centrally metalated (M=Mg, Zn) ligands with various Ru(II) salts has yielded several bimetallic complexes including the first coordinatively linked porphyrazine trimer. The optical properties of these complexes are shown to be a function of the additional ligands surrounding the asymmetric ruthenium center.

The photophysics of the two novel solitaire porphyrazines 3 and 4 (obtained via coordination of PdCl2 and PtCl2 to the peripheral bis(dimethylamino) entity of the Zn-porphyrazine 1, respectively) have been examined using absorption, emission and transient absorption spectroscopy. While the free ligand 1 exhibits neither fluorescence nor triplet absorption, the peripherally metallated derivatives 3 and 4 display both fluorescence as well as intersystem crossing.

A cyclic pseudo-rotaxane tetramer has been synthesised quantitatively at room temperature by threading two two-coordination site rods through two bis-macrocycles in the presence of copper(I) as a template.