Multifunctional pyrenoimidazole substituted tetraphenylethylene derivatives: Mechanochromism and aggregation-induced emission

Mechanoluminescence and Aggregation-Induced Emission in Bipolar Phenanthroimidazoles: Role of Positional Isomerization-Induced Switching Effect

“…The hydrogen-bonding interaction of CN with the hydrogen atoms in PyCNPPI-CCz and PyCNPPI-NCz increases the molecular packing, which results in a high thermal stability . From the electrochemical behavior, E HOMO [−( E onset + 4.8) eV]/ E LUMO [ E HOMO – 1239/λ onset eV] was found to be 5.15/2.12 eV (PyNPPI-CCz), 5.28/2.75 eV (PyCNPPI-CCz), 5.23/2.22 eV (PyNPPI-NCz), and 5.32/2.36 eV (PyCNPPI-NCz) . The shallow E LUMO of PyNPPI-CCz, PyCNPPI-CCz, PyNPPI-NCz, and PyCNPPI-NCz promotes the electron injection and shows excellent optical properties.…”

“… − The red-shifted absorption may be due to the effective conjugation of C6/C9-pyrene with phenanthroimidazole, and the pyrene-substituted materials show intensified vibronic broad absorption attributed to CT interactions . The high extinction coefficient (ε max ) [PyNPPI-CCz281 nm: ε max 35,587 cm –1 M –1 , 314 nm: ε max 31,847 cm –1 M –1 ; PyCNPPI-CCz275 nm: ε max 36,363 cm –1 M –1 , 305 nm: ε max 32,786 cm –1 M –1 ; PyNPPI-NCz299 nm: ε max 33,444 cm –1 M –1 , 321 nm: ε max 31,152 cm –1 M –1 ; and PyCNPPI-NCz286 nm: ε max 34,965 cm –1 M –1 , 319 nm: ε max 31,348 cm –1 M –1 ] confirmed strong conjugation and CT transition. , The red-shifted absorption of PyNPPI-CCz (301, 365 nm), PyCNPPI-CCz (311, 372 nm), PyNPPI-NCz (316, 380 nm), and PyCNPPI-NCz (318, 378 nm) in solid state may confirm the weak intermolecular stacking . The energy gap of 3.03 eV (PyNPPI-CCz), 2.53 eV (PyCNPPI-CCz), 3.01 eV (PyNPPI-NCz), and 2.96 eV (PyCNPPI-NCz) deduced from the absorption onset (λ onset ) was comparable with that of 1-(4- t -butylphenyl)-2-(4-(pyrenyl)­phenyl)­phenanthroimidazole.…”

“… The formation of single HLCT emissive state can be confirmed by LE and CT excitation energies. The wider band gap between T 1 and T 2 of PyNPPI-CCz (1.62 eV), PyCNPPI-CCz (1.84 eV), PyNPPI-NCz (1.36 eV), and PyCNPPI-NCz (1.51 eV) , and small Δ E ST ≈ 0 assisted the fast RISC due to the HLCT character (Figures and S8).…”

Adsorption of Dye Molecules and Its Potential for the Development of Photoactive Hybrid Materials Based on Layered Silicates

“…Other fields, where intensive progress has been seen lately, include, for instance, the usage of AIE materials to achieve aggregation-induced mechanochromism, , or aggregation-induced delayed fluorescence (AIDF), , or circularly polarized luminescence …”

“…The preparation of this system was based on the entrapment of a water-soluble AIE labeled polymer within the silicate layers. 57 Other fields, where intensive progress has been seen lately, include, for instance, the usage of AIE materials to achieve aggregation-induced mechanochromism, 58,59 or aggregationinduced delayed fluorescence (AIDF), 60,61 or circularly polarized luminescence. 62 We believe that the present paper highlighted that the controlled adsorption of the above-mentioned novel luminophores on different types of surfaces has great yet unexplored potential.…”