Integration of Ag/AgCl and Au nanoparticles into isostructural porous coordination polymers of Ni(ii), Co(ii) and Mn(ii): magnetic studies

Abstract

A systematic investigation of silver/silver chloride (Ag/AgCl) and gold (Au) nanoparticle (NP) formation within non-activated isostructural porous coordination polymers (PCPs) namely Ni-PCP, Co-PCP and Mn-PCP at room temperature is reported without the use of any reducing agent and deterioration of host frameworks. A supercharged environment due to the presence of free anions make these PCPs suitable templates for the growth of nanoparticles (NPs) in high yields. High resolution transmission electron microscopy (HRTEM) images provided insight into the size, shape and distribution of the NPs within the frameworks. Different shapes and sizes of the NPs are attributed to the differences in the levels of supramolecular interactions within these isostructural series and the ionic radii which is related to the charge density of metal nodes. From an electron paramagnetic resonance (EPR) study it is evidenced that synthesis of Au NPs in Ni-PCP is completely through redox reaction via strong charge transfer between coordinated metal and the metal precursor, and the others are via acid formation through anions present in the cavities of PCPs. Au NPs integrated frameworks display different soft ferromagnetic properties when placed in a magnetic field at room temperature.