Monoterpene-based metallophthalocyanines: Sustainable synthetic approaches and photophysical studies

Author(s)

Gonzalez, Andreia C. S. ^[1] ; Damas, Liliana ^[1] ; Aroso, Rafael T. ^[1] ; Tome, Vanessa A. ^[1] ; Dias, Lucas D. ^{[2, 1]} ; Pina, Joao ^[1] ; Carrilho, Rui M. B. ^[1] ; Pereira, Marlette M. ^[1]

Affiliation

^[1] Univ Coimbra, Coimbra Chem Ctr, Dept Quim, Rua Larga, P-3004535 Coimbra - Portugal

^[2] Univ Sao Paulo, Sao Carlos Inst Phys, BR-13566590 Sao Carlos, SP - Brazil

• Document type: Journal article
• Source: JOURNAL OF PORPHYRINS AND PHTHALOCYANINES; v. 24, n. 5-7, p. 947-958, MAY-JUL 2020.
• Web of Science Citations: 0

Abstract

Tetra-substituted zinc(II) and copper(II) phthalocyanines bearing peripheral alkoxy-monoterpene groups were prepared by conventional vs. non-conventional synthetic approaches (ultrasound and microwave irradiation). The synthesis of (1R)-(-)-myrtenol (a) and (1R,2S,5R)-(-)-menthol (b) derived phthalonitrile precursors was performed through ipso-nitro aromatic substitution reactions, with optimal conditions being obtained using ultrasound irradiation, which allowed us to achieve full conversions in 4.5 h, with isolated yields up to 74%. The subsequent cyclotetramerization of monoterpene-based phthalonitriles was carried out using Zn(II) or Cu(II) salts as metal templates, and also using conventional and non-conventional heating methods. Microwave-assisted synthesis was shown to be the most efficient approach, providing complete conversions in l h, yielding the target monoterpene-based metallophthalocyanines in up to 70% isolated yields. Furthermore, photophysical and photochemical studies revealed that Zn(II) phthalocyanines possess fluorescence quantum yields in the range of Phi(F) = 0.27-0.29, while Cu(II) phthalocyanines exhibited room temperature phosphorescence. In addition, the monoterpene-based Zn(II) phthalocyanines led to high singlet oxygen quantum yields (Phi(Delta) = 0.55-0.69). (AU)

• FAPESP's process: 19/13569-8 - Study of the Mechanisms of Action in Photodynamic Therapy: From Photosensitizer to Practical Application
• Grantee: Lucas Danilo Dias
• Support Opportunities: Scholarships in Brazil - Post-Doctoral