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The ring-closure reactions of 2,3-dichloro-5,6-dicyanopyrazine with enamines are useful methodologies to extend the π -conjugation system giving new heterocycles. The synthesis and characterization of tetrapyrazinoindoloporphyrazines from 2,3-dichloro-5,6-dicyanopyrazine are described. Alkylpyrazinoindoloporphyrazines have push-pull intramolecular charge-transfer chromophoric systems and have good solubility in most organic solvents. Large spectral changes caused by molecular aggregation of these dyes affected by solvent polarity and temperature were studied.A variety of technological applications of phthalocyanines have been actively investigated for purposes such as optical discs, laser dyes, liquid crystals, electrocatalysis, electrochromism and chemical sensors, etc. 1 Their characterization was influenced by the nature of the peripheral substituents and the central metal ion. In the case of phthalocyanine macrocycles having long alkyl chains, segregation occurs between the rigid aromatic moieties and the flexible alkyl chains, which leads to columnar mesophase. 2 Tetrapyrazinoporphyrazine derivatives 3 and octaalkyl phthalocyanines 4 have also been reported to form liquid crystalline phases. A cholesteric columnar mesophase has been obtained in the case of phthalocyanine with optically active side chains.On the other hand, unsymmetrically substituted phthalocyanines having a donor and/or acceptor groups have been suggested as interesting candidates for second harmonic generation. 5, 6 Some papers recently reported the secondorder hyperpolarizabilities of unsymmetrically substituted push-pull phthalocyanines. 7Organic molecules with nonlinear optical (NLO) properties have been extensively studied because of their potential applications in optical communications, data storage, and electro-optical signal processing.During the past few years we have been interested in nitrile-containing molecules as the mother compound for designing nonlinear optical materials. In particular, our research group has been interested in how nitrile substitution affects the chemical, electronic, and physical properties of pyrazines. We found that some new styryl dyes have large differences in λ max between solution and solid states, resulting from their strong intermolecular π -π interactions. 8 These compounds are rather small in molecular size but have extended π -conjugation systems and strong intramolecular charge-transfer chromophoric systems. Pyrazinoporphyrazine dyes are also very interesting as they produce large third-order NLO susceptibility as well as phthalocyanines. Consequently, push-pull pyrazinoindoloporphyrazine analogs with a large π -conjugation system were synthesized. Strong intermolecular π -π interactions are essential for third-order nonlinear optical materials. 9This paper describes a new synthesis and characterization of tetrapyrazino[2,3-b ]indoloporphyrazines derived from 2,3-dichloro-5,6-dicyanopyrazine. These dyes have a strong intramolecular charge-transfer chromophoric system in which the indole moiet...