Synthesis and Photophysics of Varied Substituted DPNDs for Potential PDT Applications

Understanding how molecular architecture and solvent polarity govern excited-state dynamics is fundamental to developing functional chromophores for photo-energy conversion and manipulation for opto-electronic applications. Here, the photophysical properties of three dipyrrolonaphthyridinedione (DPND) derivatives, tBu-DPND–1 (β-Suzuki), tBu-DPND–1 (β-Sonogashira), and tBu-DPND–3 (α-Sonogashira), were prepared and characterized using advanced photophysical methods to unveil how π-conjugation and topology influence excited-state dynamics. Furthermore, we varied the polarity of the samples to shed light on the contributions of charge transfer (CT) dynamics and their interplay with triplet excited state formation of the three DPND chromophores. Steady-state and time-resolved absorption and emission studies suggest that the three DPND chromophores exhibit longer excited-state lifetimes and stronger triplet signatures in non-polar methylcyclohexane (MCH) solvent. Conversely, in polar 50% (v/v) DCM:EtOH, the excited states were stabilized and underwent equally non-radiative deactivation and ISC to populate the corresponding triplet manifold. Time-resolved Transient absorption spectroscopy (TAS) confirmed the ISC and triplet formation. Moreover, singlet-oxygen generation using these DPNDs as sensitizers yielded quantum yields (ΦΔ) ≈ 0.6. The interplay between conjugation length, positional effect, and solvent polarity dictates the ordering and mixing of excited singlet, CT, and triplet states, thereby controlling ISC efficiency. These findings establish the new π-conjugation DPNDs as polarity-responsive organic chromophores suitable for applications such as triplet sensitization, photodynamic therapy, and singlet-fission processes.

Author dc:creator

• Garvisha Mittal (23292148)

• Photochemistry
• Photo physics
• Organic Chemistry
• Materials Science
• Biochemistry

Statement dc:rights

• In Copyright
• Open Access after 2028-01-01

DOI dc:identifier

https://doi.org/10.25417/uic.31451908.v1

OAI identifier oai:identifier

oai:figshare.com:article/31451908