Internal acylation-induced AIE/AIEE switch of pyrimido[2,1-b][1,3]benzothiazoles (PBTs): Restriction of access to dark state caused by distortion of 4H-pyrimidine ring

Photoluminescent Properties and Mechanism of Novel Cyanine‐Borondifluoride Curcuminoid Hybrids as Red‐to‐Near Infrared and Endoplasmic Reticulum‐Targeting Dyes

“…[33] The negative t Chemistry-A European Journal index (separation degree of holes and electrons) values of NCR-1-3 (À 2.34 to À 1.84) confirmed their locally excited (LE) type of excitation for highly efficient emissions. The less negative t index of NCR-4 indicated that its excitation features a combined LE and CT character, [34] which is consistent with its red-shifted emissions and lowered Φ F s. In contrast, both of the parent dyes, Cy5-S and CM-BF 2 , have small d CT values due to their symmetrical structures. However, the less negative t index values indicated that they have significant CT component in their excitation, thereby lowering their Φ F values (Figure 4c).…”

Mechanistic insights into diversified photoluminescence behaviours of BF2 complexes of N-benzoyl 2-aminobenzothiazoles

“…5). 35,36 The theoretical calculation results showed that the C–C single bonds ( φ 1 ) between the phenyl and BF 2 complex ring in all these molecules were not freely rotatable to induce access to a dark state in the S 1 state due to the high energy barriers (Δ E = +0.50 to +0.77 eV). Therefore, it is obvious that these exocyclic phenyl groups are not effective rotors.…”

“…6b) dramatically changes from 0° to 57.3°. 36,37 In addition, the B–N bond is elongated from 1.573 to 1.768 Å in the MECI geometry. This result is consistent with the deformation-induced MECIs of similar BF 2 complex-based AIEgens.…”