Photophysical insights behind zinc naphthalocyanine-gold nanoparticle interaction and its effect over supramolecular interaction between zinc napthalocyanine and PyC60 in solution

•Energy transfer from Zn-naphthalocyanine (1) to Au nanoparticle is observed in solution.•Large value of quantum yield of charge-separation is observed for 1-AuNp system.•Binding constant of 1-PyC60 system is reduced considerably in presence of AuNp.•Self-assembled 1-AuNp-PyC60 conjugate can act as efficient photochromic devices

This work envisages an efficient energy transfer phenomenon from zinc naphthalocyanine (1) to dodecanethiol functionalized gold nanoparticles (AuNp) having size of 3-6 nm in toluene. Significant enhancement in singlet energy transfer efficiency is observed for 1-AuNp conjugate. Role of AuNp over the non-covalent interaction between 1 and C60 pyrrolidine tris-acid ethyl ester (PyC60) is studied by various spectroscopic tools; considerable reduction in the magnitude of binding constant for 1-PyC60 supramolecule is observed in presence of AuNp. Dynamic light scattering, atomic force microscope and scanning tunneling microscope measurements give clear evidence in favour of the surface binding of 1 to AuNp.