In a quest for the still elusive dual-state emission (DSE), i.e., intense emissions both in solution and in the solid state, the luminescence properties of novel boron difluoride complexes with flavonolates bearing substituent(s) at the B ring (R: 4-Ph (2b); 4-OPh (2c); 4-NPh₂ (2d); 2,6-Me₂ (2e)) have been investigated. The emission intensity and maximum wavelength are strongly influenced by the electronic and steric factors of the substituents, which are responsible for the character of the π-conjugated system over the ligand. Complexes 2b and 2c with a rigid flat π-skeleton exhibited DSE (emission quantum yield (Φ) ≥ 0.34). Complex 2d bearing a rotatable diphenylamino group showed an aggregation-induced enhanced emission (AIEE), that is strong (Φ = 0.38) in the solid state but weak (Φ = 0.13) in CH₂Cl₂. Thus, 2b–2d exhibited intense solid-state emissions, although the corresponding ligands presented quenched solid-state emissions. Conversely, complex 2e, in which the B ring adopted a twisted position from the fused AC ring, that is, a twisted π-system, exhibited an aggregation-caused quenching (ACQ) resulting in an intense (Φ = 0.50) and a weak (Φ = 0.02) emission in CH₂Cl₂ and the solid state, respectively. This work provides important insights into the role of the π-system in the changeover of emission features in dual-state.

为了寻求仍然难以捉摸的双态发射（DSE），即在溶液和固态下均产生强发射，新型二氟化硼与黄酮酸酯在B环上带有取代基的新型二氟化硼配合物的发光特性（R：已经研究了4-Ph（2b）; 4-OPh（2c）; 4-NPh ₂（2d）; 2,6-Me ₂（2e））。发射强度和最大波长受取代基的电子和空间因素的强烈影响，这些因素决定了配体上π共轭体系的特性。具有刚性平面π骨架的配合物2b和2c表现出DSE（发射量子产率（Φ）≥0.34）。带有可旋转的二苯氨基的复合物2d表现出聚集诱导的增强发射（AIEE）， 固态时强（Φ = 0.38），而 CH ₂ Cl _2中弱（Φ = 0.13）。因此，2b - 2d表现出强烈的固态发射，尽管相应的配体表现出淬灭的固态发射。相反，复合物2e的B环相对于稠合的AC环呈扭曲位置，即π扭曲，表现出聚集引起的猝灭（ACQ），导致强（Φ  = 0.50）和弱 CH _2中的（Φ = 0.02）发射Cl ₂和固态。这项工作为π系统在双态发射特性转换中的作用提供了重要的见识。