The Effect of Cyano Substitution on the Fluorescence Behavior of 1,2‐Bis(pyridylphenyl)ethene

Abstract

The effect of cyano substitution on the fluorescence behavior of 1,2-bis(pyridylphenyl)ethene was investigated. While nonsubstituted 1,2-bis(pyridylphenyl)ethene has fluorescence quantum yield of 97 % in CH 2 Cl 2 solution, cyano-substituted ones fluoresces very little. In contrast, both the no-substituted and the cyano-substituted ones fluoresce moderately in the solid state. The aggregate-induced enhanced emission (AIEE) behavior for the cyano-substituted 1,2-bis(pyridylphenyl)ethene was understood as that the severe quenching of the fluorescence in solution was not operating in the solid state. The fluorescent behaviors in solution and in the solid state are discussed in terms of the emission and the nonradiative decay rate constants.

Bridging the Void: Halogen Bonding and Aromatic Interactions to Program Luminescence and Electronic Properties of π-Conjugated Materials in the Solid State

“…While rod-like packing of linearly arranged XB partners in BPPa-2I resulted in fluorescence similar to the twisted, slipped-stacked stilbenes in parent BPPa (Em. λ max = 470 vs 478 nm), 68 the trifunctional XB donor 3I yielded complex zigzag XB topology with planarized backbones. The resulting increased throughspace overlap between stilbene chromophores in crystal BPPa-3I (as well as BPPa-TCNB) produced red-shifted green fluorescence (505 nm) with attenuated intensity (Figure 4b).…”

Origin of aggregation-induced enhanced emission: role of pseudo-degenerate electronic states of excimers formed in aggregation phases

“…1) has been reported to exhibit the AIEE behavior in solid phase. 24 The rate constants of the non-radiative transitions are decreased from > 1.0 × 10 10 s −1 in CH 2 Cl 2 solution to 5.0 × 10 7 s −1 in solid phase. Accordingly, the fluorescence quantum yield is increased from 0.002 to 0.72 by aggregation.…”

“…It should be noted that the Figure 2 (a) shows the crystal structure of the CNPPE solid. 24 We modeled the CNPPE solid as a dimer with a cofacial configuration ( Fig. 2 (b)), Dimer Model 1, where the cofacial dimer was calculated by the QM method and the surrounding 16 molecules were calculated by the MM method based on the ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) approach.…”

Synthesis and Photoluminescent Properties of 2-(3-Carboxymethylindazol-1-yl)anilines

“…A sharp difference is observed for compounds 4а and 4c, for which the excited state lifetime is 653 and 518 ns, respectively. Such a sharp increase in the excited state lifetime may be explained by more dense molecular packing due to the strong intermolecular dipole-dipole interaction [24,25].…”