Spectroscopic investigations of acrylodan dye interactions with poly(amidoamine) and poly(propyleneimine) dendrimers

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The novel molecular architecture of dendrimers facilitates use in many applications. Using the solvatochromic probe phenol blue, the first direct examination of the polyamidoamine (PAMAM) and polypropylenimine (PPI) dendrimer core cavities was reported by a previous research group member. This previous work revealed the need to further understand the sequestering abilities and host-guest properties of these materials. Therefore, the association of 6-acryloyl-2-dimethylaminonaphthalene (acrylodan) with amine-terminated PAMAM and PPI dendrimers was investigated. Generations with surface group (SG) numbers 4, 16, 64, and 256 of PAMAM and SG 4, 16, and 64 of PPI were used. Association was driven by the hydrophobicity of the dyes in aqueous dendrimer solutions. The nature of the host-guest association was probed using absorption and steady-state fluorescence emission, and anisotropy techniques with samples in a range of dendrimer-to-dye ratios. Additionally, extraction studies tested the stability of the host-guest relationship and the ability of the dendrimer to shield the dye molecules from the solution environment of the sample. The nature of the acrylodan-dendrimer association is described, and was found to be a in a more polar and less protected area of the dendrimer than that of phenol blue. Experimental results showed significant, but less specific, association of the smaller acrylodan probe with all dendrimer generations.