Ensemble of Donor-engineered Pyrene Chromofores Playing a Harmony of Different Emissive States, Light Amplification and Triplet Harvesting

Nandi, Arnab (2022) Ensemble of Donor-engineered Pyrene Chromofores Playing a Harmony of Different Emissive States, Light Amplification and Triplet Harvesting. Masters thesis, Indian Institute of Science Education and Research Kolkata.

Text (MS dissertation of Arnab Nandi (17MS012)) 17MS012_Thesis_file.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

Bright amplified luminescent materials with accessible triplet excitons in solution as well as crystalline states are like “Aladdin’s magic lamp” with fabulous biological and optoelectronic applications. Although in several cases, the Donor-π-Acceptor (D-π-A) architectures successfully covered emission in the entire visible spectrum, modulating three emissive states of pyrene derivatives, namely, monomer, excimer and intramolecular charge transfer (ICT) species is a colossal task. This report presents how simple yet elegant structural modifications at the donor end can have a huge impact on the emissive property of the monomer and the aggregated states (aggregasion-induced emission or AIE). Through host-guest interaction, the fluorescence quantum yields of the as-synthesized fluorophores could be amplified from <5% upto 85% in aqueous medium and solid state. These compounds self-assemble in water forming micelle-assisted hexagonal microcrystals, which show solution phase room temperature phosphorescence (RTP). How do the different packing patterns in the solid state influence triplet state harvesting was also investigated by doping the compounds in a molecular oxygen barrier polymethylmethacrylate (PMMA) film. To our knowledge, this is the first example of heavy element-free AIE pyrene core showing RTP in both the solution and solid phase.

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