Fig. 2: Characterization and performance study of complexes 1-4.

a Molecular structure of complexes 1-4. b Plots of normalized PL intensity of complexes 1-4 in the aggregate states. c Photoluminescence (PL) spectra of complex 3 (2.0 × 10⁻⁵M) in DMF water mixtures, λ_ex = 480 nm. Insert: photos of DMF solution and DMF/water mixture (f_w = 90%). d Relationship diagram between the relative maximum emission peak intensity (α_AIE) and f_w of the DMF water mixture of complexes 1-4 (where α_AIE = I/I₀; I = emission intensity; I₀ = emission intensity in DMF solution). e DFT calculated the molecular orbitals of HOMO and LUMO, while TD-DFT calculated the energy levels (B3LYP/Def2-TZVP), major orbital configurations, and ISC channels of complexes 1-4. The lowest singlet excited state (S₁), the lowest triplet excited state (T₁), and high-level triplet excited states (T_n) are denoted as different electronic states. Possible intersystem crossing (ISC) channels from the singlet state (S₁) to its higher- or lower-lying triplet states (T_n) are indicated by red and blue dashed arrows, respectively. The symbols H and L represent HOMO and LUMO orbitals, respectively. ΔE_ST represents the energy gap between the S₁ state and the T₁ state.