Phthalocyanines, conductivity crystal structures

The macrocyclic phthalocyanine ligand will form a complex Pt(phthalocyanine). The crystal structure shows two polymorphs present because of molecular packing.The platinum is in a square planar coordination geometry with a mean Pt—distance of 1.98 A. The complex can be partially oxidized with iodine to give conducting mixed valence solids. Eighteen fundamental and overtone combination bands are observed in the resonance Raman spectrum of platinum phthalocyanine, and from this data the symmetry of the excited singlets are found to be D-ai, Qv or... 

These results illustrate that electrochemical techniques can be employed to synthesize a vast range of [Si(Pc)0]n-based molecular metals/conductive polymers with wide tunability in optical, magnetic, and electrical properties. Moreover, the structurally well-defined and well-ordered character of the polymer crystal structure offers the opportunity to explore structure/electro-chemical/collective properties and relationships to a depth not possible for most other conductive polymer systems. On a practical note, the present study helps to define those parameters crucial to the fabrication, from cheap, robust phthalocyanines, of efficient energy storage devices. 

Abstract In this chapter, recent progress in the synthesis, crystal structures and physical properties of monomeric phthalocyanines (Pcs) is summarized and analysed. The strategies for synthesis and modification of Pcs include axial coordination of central metal ions, peripheral substitution of Pc rings and the ionization of Pcs. The crystal structures of various typical Pcs, especially the effects of different synthetic and modification strategies on the supramolecular assemblies of Pcs via %—% interactions between Pc rings, are discussed in detail. Finally, the UV-vis spectroscopic, conducting, magnetic and catalytic properties of some Pcs with crystal structures are presented briefly, and the correlations between various properties and the molecular structure discussed. 

Single crystals of a number of other iodinated phthalocyanines, tetrabenzoporphyrins, and triazatetrabenzoporphyrins have also been prepared127,131,133, as have crystals of Co(pc)Br127,131. Typically, these compounds have the stoichiometry M(L)Ilo, and it is likely that the structures are the same as for Ni(pc)I and Ni(tbp)I. All these compounds conduct well, but with a variety of temperature responses. 

It has long been known that the electrical conductivity of phthalocyanines is very sensitive to the presence of certain gases. The increased conductivity is confined to the surface of the crystal, therefore phthalocyanines have been studied as gas sensors in the form of vacuum-sublimed films [244, 245]. Unfortunately, because phthalocyanines exhibit polymorphism (see however Ref 189d), the exact structure of such films can be complicated, making interpretation of results and subsequent device optimisation difficult. 

Except for the macrocyclic modification of phthalocyaninatolead(II) (8) in its monoclinic arrangement, the stacked arrangement has never been observed. Metallophthalocyanines in general crystallize in the a- or B-modifica-tion which is not favourable for x-orbital overlap and thus for the formation of a conduction band. However, if certain transition metal phthalocyanines, e.g. phthalocyaninatonickel(II) are doped with iodine, stacked structures are obtained which exhibit high conductivities (9). 

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