Photophysical insights on effect of gold nanoparticles over fullerene–porphyrin interaction in solution

Abstract

The present article reports the role of gold nanoparticles, i.e., AuNp (having diameter ∼2–4nm), in non-covalent interaction between fullerenes (C60 and C70) and a monoporphyrin (1) in toluene. Both UV–vis and fluorescence measurements reveal considerable reduction in the average value of binding constant (Kav) for the C70–1 system (KC70–1(av)=19,300dm3mol−1) in presence of AuNp, i.e., KC70–1–AuNp(av)=13,515dm3mol−1 although no such phenomenon is observed in case of C60–1 system, viz., KC60–1(av)=1445dm3mol−1 and KC60–1–AuNp(av)=1210dm3mol−1. DLS study reveals sizeable amount of increase in the particle size of C70–1–AuNp nanocomposite, i.e., ∼105nm, compared to C60–1–AgNp system, e.g., ∼5.5nm which gives very good support in favor of decrease in the value of Kav for the former system. SEM study reveals that nanoparticles are dispersed in larger extent in case of C70–1–AuNp system. Time-resolved fluorescence study envisages that deactivation of the excited singlet state of 1 by C70 takes place at a faster rate in comparison to C60 in presence of gold nanoparticles.