Ratiometric Singlet Oxygen Detection in Water Using Acene-Doped Conjugated Polymer Nanoparticles.

Although fluorescent probes for the detection of singlet oxygen (O) have been an active area of research, most such probes rely upon change in intensity of a single band. Herein, we report a FRET-based, O-sensitive aqueous suspension of conjugated polymer nanoparticles (CPNs) comprising the energy-donating host polymer poly[{9,9-dioctyl-2,7-divinylene-fluorenylene}-alt-co-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] doped with an energy acceptor, the O-sensitive thienoacene 5,12-bis(4-methoxyphenyl)-2-butyltetraceno[2,3-b]thiophene. Using a phthalocyanine-based sensitizer, IRDye 700DX, our probe shows a rapid, ratiometric response to photosensitized O in water in both cuvettes and 96-well plates that compares favorably to the commercial O-sensitive dye, singlet oxygen sensor green.

Substituent Effects That Control Conjugated Oligomer Conformation through Non-covalent Interactions.

Although understanding the conformations and arrangements of conjugated materials as solids is key to their prospective applications, predictive power over these structural factors remains elusive. In this work, substituent effects tune non-covalent interactions between side-chain fluorinated benzyl esters and main-chain terminal arenes, in turn controlling the conformations and interchromophore aggregation of three-ring phenylene-ethynylenes (PEs). Cofacial fluoroarene-arene (ArF-ArH) interactions cause twisting in the PE backbone, interrupting intramolecular conjugation as well as blocking chromophore aggregation, both of which prevent the typically observed bathochromic shift observed upon transitioning PEs from solution to solid.