Effects of coumarin substituents on the photophysical properties of newly synthesised phthalocyanine derivatives

Abstract

In this study, synthesis of new ligands, 8-hydroxy-3-[p-(3′,4′-dicyanophenoxy)-phenyl]coumarin and 8-hexyloxy-3-[p-(3′,4′-dicyanophenoxy)-phenyl]coumarin, and their phthalocyanines, 2,9,16,23-tetrakis[8-hexyloxy-3-(4-oxyphenyl)coumarin]-metal-free and metallophthalocyanines {M[Pc(OBzCou)₄] (M = 2H, Zn(II), Co(II); Bz: benzene; Cou: coumarin)} were synthesised. The novel chromogenic compounds were characterised by elemental analysis: ¹H NMR, ¹³C NMR, MALDI-TOF, IR and UV–vis spectral data. The effect of coumarin substituents on the photophysical properties of metal-free (H₂Pc) and zinc phthalocyanines (ZnPc) derivatives has been examined. Spectrophotometric measurements revealed that coumarin-substituted ZnPc derivatives were in the unaggregated form, whereas those of H₂Pc species were in aggregated form. It means that substitution of coumarin derivative prevents the cluster formation in the presence of zinc ion in the centre of Pc.

Keywords:

• phthalocyanines
• fluorescence
• coumarin derivatives
• aggregation
• cobalt
• zinc

Acknowledgements

We are thankful to the Scientific and Research Council of Turkey (TUBITAK) [(107T347) and (108T094)], The Research Foundation of Marmara University (Commission of Scientific Research Project under grant FEN-BGS-1207070149, 2007) and DPT-2004 (project no. 2003K120970).