Tetraazaporphyrins phthalocyanines

Organometallic complexes are known which contain a wide variety of macrocycles closely related to porphyrins corroles, porphycenes, tetraazaporphyrins. phthalocyanines, tetraazaannulenes, and porphyrinogens are the best known examples. Examples containing the first four of these macrocycles are included where there is a useful comparison or contrast with the relevant porphyrin chemistry, but the discussion will not be comprehensive. The four macrocycles are shown in Fig. 2. 

The general structures of iron porphyrins are shown in Figure 1, together with the stractures of closely related ring systems, including iron chlorins and isobacteriochlorins, thiaporphyrins, tetraazaporphyrins, phthalocyanines, corroles, and texaphyrin. Examples of substituents present on commonly investigated natural and synthetic iron porphyrins are also included. 

Synthesis and characterization of other related macrocycles, including chlorins, " isobacteriochlorins, bacteriochlorins, mono- and dioxoporphyrins, " other more highly saturated hydroporphyrins, N-alkyl- or A-arylporphyrins, some of which are chiral, porphodimethenes, thiaporphyrins, " oxaporphyrins, N-confused " and carbapor-phyrins, porphycenes " and corrphycenes, " tetraazaporphyrins, phthalocyanines, the ring-expanded sapphyrins, texaphyrins and others, and the ring-contracted corroles " and corrolazines have also been synthesized and are discussed in the indicated references. 

Macrocycles such as porphyrins, tetraazaporphyrins, phthalocyanines, and their derivatives are compounds with diverse, applicable properties [47,48]. 

A -alkyl- or A -arylporphyrins, thiaporphyrins, tetraazaporphyrins, phthalocyanines, and corroles have also been investigated and, where appropriate, will be mentioned briefly. 

Let us conclude shortly with tetraazaporphyrins, the most popular members of which are constituted by phthalocyanines and porphyrazines, Scheme 12. 

L. Lee, N. H. Sabelli, and P. R. LeBreton, Theoretical characterization of phthalocyanine, tetraazaporphyrin, tetrabenzoporphyrin, and porphyrin electronic spectra, J. Phys. Chem, 86, 3926-3931 (1982). 

The photochemistry of true organomagnesium compounds remains almost completely unexplored. A literature search in preparation of this work found only a few scattered examples of photochemical studies, mostly in relation to Grignard reactions and 1,3-diketonate chelates Similar to the situation with organozinc compounds magnesium tetrapyrrole chelates, i.e. magnesium porphyrins 1, 5,10,15,20-tetraazaporphyrins (por-phyrazines) 2 and phthalocyanines 3 have found more interest. This is primarily related... 

Schnurpfeil G, Sobbi AK, Spiller W, Kliesch H, Wohrle D. Photooxidative stability and its correlation with semi-empirical MO calculations of various tetraazaporphyrin derivatives in solution. J Porphyrins Phthalocyanines 1997 1 159-167. 

Nyokong T, Isago H (2004) The renaissance in optical spectroscopy of phthalocyanines and other tetraazaporphyrins. J Porphyrins Phthalocyanines 8(9) 1083-1090... 

All of the dithienylethene-based tetraazaporphyrin and phthalocyanine hybrids exhibited obvious photochromism by alternate irradiation with UV and visible light. Their photochromism in solution depended on the solvents to some degree. Scheme 11 gives a representation of the most typical photochromic reaction of these... 

Tetraazaporphyrin and phthalocyaninate ligand complexes Tetraanionic tetradentate ligand complexes... 

Metal-phthalocyanine Metal-triazolehemiporphyrazine Metal-tetraazaporphyrin... 

Fig. 1. Structure of the metal-free macrocycles tetraazaporphyrin (H2TAP), phthalocyanine (H2PC), 2,3-naphthalocyanine (2,3-H2Nc), 1,2-naphthalocyanine (l,2-H2Nc), and 9,10-phenanthrenocyanine (H2Phc).

Here we review our work aimed at correlating the reactivity of a series of M(II) N4-ligands, see Figure 12.1, (M = Co, Fe, Mn and N4 = porphyrin (P), phthalocyanine (Pc), teraphenylporphyrin (TPP), tetrabenzoporphyrin (TBP) and tetraazaporphyrin (TAP)) towards the electrocatalytic oxidation of 2-mercaptoethanol. Different effects will be analysed, namely the role of the metal atoms, the role of the N4 functionalisation, solvent and the impact of the adsorption on the electrode on the electrochemical activity. The whole machinery of DFT and the notions of hardness, chemical potential, intramolecular hardness and elec-trophilicity are used to better quantify these effects and discriminate between the examined molecular complexes. 

Up to now, we have shown how the reactivity towards the oxidation of 2-mercaptoethanol changes within the different members of a Co(II)-N4 complex family (porphyrin, phthalocyanine, tetraphenylporphyrin, tetrabenzoporphyrin and tetraazaporphyrin) and due to solvation (gas phase vs. solution). In other words we have investigated how the nearest chemical environment (nature of the N4 cycle) and the far chemical environment (bulk solvent) can influence their... 

Eichhorn, H. (2000). Mesomeric phthalocyanines, tetraazaporphyrins, porphyrins and triphenylenes as charge-transporting materials. J. Porphyrins Phthalocyanines 4(1), 88-102. 

Because of space limitations, we will only briefly discuss the most basic application in the area of porphyrin optical spectra. Much work has already been done in this area, both with TDDFT and related methods. The TDDFT applications include free base porphin and its ss-octahalogenated derivatives, the porphyrinato-porphyrazinato-zirconiumhV) complex, NiP, NiPz, NiTBP, and NiPc, zinc phthalocyanine, chlorophyll a, zinc complexes of porphyrin, tetraazaporphyrin, tetrabenzoporphyrin, phthalocyanine, phenylene-linked free-base and zinc porphyrin dimers, metal bis(porphyrin) complexes a series of porphyrin-type molecules, and many more. We refer to ref. 75 for an extensive discussion of TDDFT calculations on the spectra of porphyrins and porphyrazines, as well as their interpretation. For further theoretical work on porphyrines, we mention ref. 76 and other papers in that special issue. 

Phthalocyanine (PCH2) is structurally similar to porphyrin (PHj) (see Fig. 1). The four isoindoline units are linked together in the 1,3-position by aza bridges to form a cyclic system. Formally, phthalocyanines are tetrabenzo-tetraazaporphyrins. 

Bridged macrocyclic complexes are mainly derivatives of tetraazaporphyrin or phthalocyanine ... 

T. Fukuda and N. Kobayashi, Hydrogenated Tetraazaporphyrins-Old but New Core-Modified Phthalocyanine Analogues , Dalton Trans., 2008, 4685. 

---