Synthesis Of Phthalocyanines

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INTRODUCTION
Background
The macrocyclic organic molecules Phthalocyanines (1) which are comparable to the naturally occurring porphyrin (2) ring systems shown in (Figure 1). The porphyrin molecule consists up of four pyrrole subunits which are associated in n-conjugation by methine carbons. 1 2
Figure 1: structures of phthalocyanine and porphyrins molcule

The compound Phthalocyanine molecule consist of four isoindole subunits which are connected together by aza nitrogens and an aromatic 18π electron inner core which is further delocalized or shared into the four peripheral benzo units. The manifestation of the four aza nitrogens
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Most recently, Pcs have found high-tech applications in electrophotography and ink-jet printing and as photoconducting agents in photocopying devices. In addition, their novelty is rapidly growing in other fields where they are used as sensing elements in chemical sensors, electrocatalysts, liquid crystals, electrochromic display devices, information storage systems, semiconductors, functional polymers and molecular metals, among others. They have also found use in photodynamic therapy (PDT). [15-17]
Synthesis of Phthalocyanines
A number of different methods are available for the synthesis of phthalocyanines. Phthalonitriles are commonly used as starting materials for their preparation. One of the earliest methods involves the condensation of phthalonitrile (4) with lithium 1 -pentanolate in refluxing 1 -pentanol, giving dilithium phthalocyanine which, when treated with concentrated sulfuric acid, is converted to the metal-free phthalocyanine (1) (Scheme 2) [18]. ln another method, a solution of 4 in sodium methoxide in methanol at room temperature can be converted to 1 ,3-diiminoisoindoline (5) with gaseous ammonia; this product is readily converted to 1 by refluxing in 2-N,N,-dimethylaminoethanol (DMAE) (Scheme 2) [19]. Scheme 2: methode for the synthesis of Phthalocyanine

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