Facile, Mild-Temperature Synthesis of Metal-Free Phthalocyanines

Abstract

It is important for the synthesis and research of phthalocyanine compounds for these compounds to be easily obtained at low temperature. We observed that metal-free phthalocyanine was sometimes found in a simple system used to synthesize phthalocyanine precursors at room temperature, and further studies showed that the key to the effective formation of phthalocyanines at low temperature lay in the presence of equal volumes of alcohol and amine, in addition to substrate phthalonitriles and solvents, in the reaction system. A synthetic mechanism was proposed and facile syntheses have been realized, such as the synthesis of tetra-α(β)-nitrophthalocyanines and tetra-α(β)-(4-tert-butylphenoxy)phthalocyanines from the corresponding substituted phthalonitriles at mild temperature (37 °C). The results are significant for the design and synthesis of new phthalocyanine derivatives, and the method is convenient and easy to adopt for general use in standard laboratories.

A Greener Route to Blue: Solid‐State Synthesis of Phthalocyanines

“…Therefore, they are multifunctional molecular materials with applications in optoelectronics, [17, 23–25] catalysis, [26–28] sensors, [29] and nanomedicine [30–35] . Traditional Pc synthesis in solution is carried out by cyclotetramerization of the phthalic anhydride, phthaloimide, 1,3‐diiminoisoindoles, or phthalonitrile of interest in solvents such as dimethylaminoethanol (DMAE), or alkoxides like lithium 1‐pentanolate [36–40] . Catalytic amounts of non‐nucleophilic bases such as 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) are commonly used as catalyst.…”

“…[ 30 , 31 , 32 , 33 , 34 , 35 ] Traditional Pc synthesis in solution is carried out by cyclotetramerization of the phthalic anhydride, phthaloimide, 1,3‐diiminoisoindoles, or phthalonitrile of interest in solvents such as dimethylaminoethanol (DMAE), or alkoxides like lithium 1‐pentanolate. [ 36 , 37 , 38 , 39 , 40 ] Catalytic amounts of non‐nucleophilic bases such as 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) are commonly used as catalyst. Pcs have been reported to show crystallographic polymorphism under ball‐milling processing, [41] and have been employed in solid‐state preparation of composite materials for traditional applications such as catalysis,[ 42 , 43 , 44 ] energy conversion [45] and storage,[ 46 , 47 ] and others.…”

A Greener Route to Blue: Solid‐State Synthesis of Phthalocyanines

“…Therefore, they are multifunctional molecular materials with applications in optoelectronics, [17, 23–25] catalysis, [26–28] sensors, [29] and nanomedicine [30–35] . Traditional Pc synthesis in solution is carried out by cyclotetramerization of the phthalic anhydride, phthaloimide, 1,3‐diiminoisoindoles, or phthalonitrile of interest in solvents such as dimethylaminoethanol (DMAE), or alkoxides like lithium 1‐pentanolate [36–40] . Catalytic amounts of non‐nucleophilic bases such as 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) are commonly used as catalyst.…”

“…[30][31][32][33][34][35] Traditional Pc synthesis in solution is carried out by cyclotetramerization of the phthalic anhydride, phthaloimide, 1,3-diiminoisoindoles, or phthalonitrile of interest in solvents such as dimethylaminoethanol (DMAE), or alkoxides like lithium 1pentanolate. [36][37][38][39][40] Catalytic amounts of non-nucleophilic bases such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) are commonly used as catalyst. Pcs have been reported to show crystallographic polymorphism under ball-milling processing, [41] and have been employed in solid-state preparation of composite materials for traditional applications such as catalysis, [42][43][44] energy conversion [45] and storage, [46,47] and others.…”

Controlling the reactivity of phthalonitriles for the efficient synthesis of chiral phthalocyanines with self-assembly abilities

“…Self-condensation of phthalonitriles is by far the most widely used method for the synthesis of Pcs, 6–10 which in many cases is initiated by a nucleophilic attack of a lithium alkoxide (or another strong nucleophile) on the electrophilic carbon of the nitrile, which generates nucleophilic nitrogen that proceeds with the self-condensation process. Not less important is the template method, which utilizes a transition metal salt to coordinate to the nitrogen of the nitrile functions, causing the necessary polarization that induces self-condensation.…”