Publication: Excited-State Dynamics of Fully Fused Tetrapyrazinoporphyrazine-Based Three-Dimensional Polymers

Excited-State Dynamics of Fully Fused Tetrapyrazinoporphyrazine-Based Three-Dimensional Polymers

Teruki Toya, Kosuke Watanabe, Yuto Toyota, Yuki Nagai, Yasutomo Segawa, Yoichi Kobayashi

ChemPhotoChem 2026, 10, e70271. DOI: 10.1002/cptc.70271

Fused aromatic network (FAN) polymers are promising π-conjugated materials, yet the photophysics of three-dimensional (3D) architectures remains largely unexplored. Here, we investigate the excited-state dynamics of a fully fused tetrapyrazinoporphyrazine (TPyzPz)-based 3D FAN by femtosecond-to-microsecond transient absorption spectroscopy, in comparison with its 2D analog and the TPyzPz. Both FAN polymers exhibit enhanced Soret-band absorption and ultrafast singlet excited-state decay (11.6 ps for 3D FAN and 6.5 ps for 2D FAN), resulting in drastically reduced triplet quantum yields. The efficiency of triplet-state formation, determined from singlet oxygen measurements, correlates well with the singlet-state lifetimes, indicating that accelerated internal conversion predominates over intersystem crossing. These findings demonstrate how dimensional π-expansion governs excited-state relaxation in conjugated network polymers and provide insight into the design of advanced photofunctional materials based on 3D network architectures.