Inhibition in binding between fullerene and bisporphyrin in presence of silver nanoparticles: a new physicochemical insight into fullerene-bisporphyrin complexation in solution.

The present paper reports non-covalent interaction between fullerenes (C(60) and C(70)) and a designed bisporphyrin (1) in p-xylene in absence and presence of silver nanoparticles (AgNp) having diameter ∼5-15 nm. Both UV-vis and fluorescence experiments reveal reduction in the average binding constant (K(av)) value for C(60)-1 (K(C60-)(1)=27,980 dm(3)mol(-1)) and C(70)-1 systems (K(C70-)(1)=115,020 dm(3)mol(-1)) in presence of AgNp, i.e., K(C60-)(1)(-AgNp)=22,465 dm(3)mol(-1) and K(C70-)(1)(-AgNp)=30,830 dm(3)mol(-1). Dynamic light scattering experiment gives clear indication regarding formation of larger aggregates as a result of electrostatic attraction between porphyrin-based supramolecule and AgNp in solution. Scanning electron microscope measurement reveals formation of molecular cluster comprising C(70)-1-AgNp composite.