Photophysicochemical behaviour of anionic indium phthalocyanine when grafted onto AgxAuy and porous silica nanoparticles

This work reports on the synthesis of glutathione functionalised Ag3Au1 (Ag rich alloy, denoted as AgAu) and Ag1Au3 (Au rich alloy - denoted as AuAg) nano alloys as well as aminopropyl triethoxylsilane capped Ag1Au3 doped silica nanoparticles (NPs). The NPs were covalently linked to indium(III) chloride 2,9(10),16(17),23(24)-tetra-(3-carboxyphenoxy)phthalocyanine (1) via amide bond to form 1-AgAuNPs-GSH and 1-AuAgNPs-GSH. The AgAuNPs were also doped into aminopropyl triethoxylsilane (APTES) silica NPs (SiNPs-APTES) followed by linkage to complex 1 to form 1-AgAu-SiNPs-APTES. The photophysicochemical behaviour of complex 1 and its nanoconjugates were investigated. Decrease in the fluorescence quantum yields and lifetimes was observed in the conjugates in comparison to 1 alone. The singlet oxygen quantum yield for 1-AgAuNPs-GSH and 1-AuAgNPs-GSH decreased probably due to the screening effect caused by the NPs, while that of 1-AgAu-SiNPs-APTES increased in dimethylsulfoxide probably due to the permeability of the porous silica matrix to molecular oxygen.