The synthesis, using microwave irradiation and characterization of novel, metal-free and metallophthalocyanines

Phthalocyanines Synthesis: A State-of-The-Art Review of Sustainable Approaches Through Green Chemistry Metrics

Driven by escalating environmental concerns, synthetic chemistry faces an urgent need for a green revolution. Green chemistry, with its focus on low environmental impacting chemicals and minimized waste production, emerges as a powerful tool in addressing this challenge. Metrics such as the E-factor guide the design of environmentally friendly strategies for chemical processes by quantifying the waste generated in obtaining target products, thus enabling interventions to minimize it. Phthalocyanines (Pcs), versatile molecules with exceptional physical and chemical properties, hold immense potential for technological applications. This review aims to bridge the gap between green chemistry and phthalocyanine synthesis by collecting the main examples of environmentally sustainable syntheses documented in the literature. The calculation of the E-factor of a selection of them provides insights on how crucial it is to evaluate a synthetic process in its entirety. This approach allows for a better evaluation of the actual sustainability of the phthalocyanine synthetic process and indicates possible strategies to improve it.

Novel Nonmetalated Hydrophobic and Metalated Phthalocyanines Bearing Pyridine-2-Thiol and 2,4,6-Trimethylphenylamine Substituents: Synthesis, Spectroscopic, Aggregation and Thermal Properties

Novel metal–free and metallo-phthalocyanines, with different substituents at peripheral positions, have been synthesised by cyclotetramerisation of 4-(2,4,6-trimethylphenylamino)phthalonitrile and 4-(pyridine-2-ylsulfanyl)phthalonitrile in the presence of the corresponding divalent metal salts [Zn(II), Cu(II), Co(II) and Ni(II)]. Quaternisation of the metallophthalocyanine functionality produced quaternised cationic Zn, Cu, Ni and Co phthalocyanines, which are soluble in DMF, H2O and DMSO. The aggregation behaviour of these compounds was investigated in different concentrations of DMSO. Their thermal stability and electronic stability are reported.