Tetraphenylfuran: aggregation-induced emission or aggregation-caused quenching?

Abstract

Tetraphenylfuran, structurally similar to AIE-active siloles, exhibits the traditional aggregation-caused quenching, which is co-caused by the restriction of intramolecular rotation and the conjugation effect.

From Tetraphenylfurans to Ring‐Opened (Z)‐1,4‐Enediones: ACQ Fluorophores versus AIEgens with Distinct Responses to Mechanical Force and Light

“…Additionally, in TPF‐1 , the distance between two adjacent oxygen atoms is 4.495 Å, whereas it is 6.128 and 6.210 Å in TPF‐2 (Figure ). Similar to that of the tetraphenylfuran reported by Tang and co‐workers, these values are in accordance with distinctive intermolecular n–π* interactions in TPF aggregates, prompting the nonradiative channel and efficiently quenching the emission in their aggregate state . Compared with tetraphenylfuran, the introduction of the triphenylamine and thiophene groups extends the distance between two adjacent oxygen atoms, and thus the relatively weakened n–π* interactions lead to a weakened ACQ effect of the two TPFs in comparison with tetraphenylfuran.…”

“…When the fraction of water reached 95 %, the corresponding fluorescence quantum yields of TPBD‐1 and TPBD‐2 increased to 11.16 and 8.9 %, respectively, which is more than 11 and 9 times higher than the values in dilute solution. Additionally, TPBD‐1 shows a larger Stokes shift than TPBD‐2 in solution (see Figure S6), which indicates the greater rigidity of TPBD‐1 compared with TPBD‐2 . The emission spectra of the TPBDs in the film state are almost identical to those in THF/H 2 O (5:95, v/v), but in the crystalline state, the emission bands of TPBD‐1 and TPBD‐2 are remarkably blueshifted (see Figure S5 c,d), which can be ascribed to more orderly molecular packing in the crystal state.…”

“…To shed more light on the structure–property relationship of the four molecules at a molecular level, we obtained their optimized structures and orbital distributions of their HOMOs and LUMOs through density functional theory (DFT) calculations at the B3LYP/6‐31G* level of theory. As revealed in Figure , the π electrons of the HOMOs of TPF‐1 and TPF‐2 are mainly localized on the central heterocyclic rings with energy levels of −4.90 and −5.19 eV, respectively, which indicates that TPF‐1 shows better conjugation than TPF‐2 . The LUMO of TPF‐1 is mainly localized on the furan ring and the four peripheral phenyl rings with a LUMO energy level of −1.17 eV, whereas it is distributed evenly over the whole molecule with a LUMO energy level of −1.31 eV for TPF‐2 .…”

A Strategy of “Self‐Isolated Enhanced Emission” to Achieve Highly Emissive Dual‐State Emission for Organic Luminescent Materials

“…Interestingly, DBBT-C4 with the shortest alkyl chains in the molecular backbonea lso exhibited am uch red-shifted profile compared with DBBT-C8 and DBBT-C12, whichi sp robably caused by its efficient intermolecular interactions. [34][35][36] In contrast to DBBT-C0, decreased k nr values were observed for DBBT-C4 and DBBT-C8, leadingt o their superior emission efficiency in the solid state. Similar to their emission intensity in PL spectra, although inferior F values of 41.93 and 44.15 %w ereo bserved for DBBT-C0 and DBBT-C12, significantly improved emission efficiency with F values of up to 71.39 and 77.46 %w ere finally achieved for DBBT-C4 and DBBT-C8 in their aggregateds olid states, respectively.T ime-resolved PL spectra were then measured and their corresponding decay curves were displayed in Figure 4d.A so utlined in Ta ble 1, lifetimes (t)o f5 .79, 9.09, 14.69, and1 3.92 ns for DBBT-C0, DBBT-C4, DBBT-C8, and DBBT-C12 in solid states were obtained, respectively.U sually,alongerl ifetimef or OLMs means slowerc harge recombination.…”

Poly(cyclotriphosphazene‐co‐tris(4‐hydroxyphenyl)ethane) Microspheres with Intrinsic Excitation Wavelength Tunable Multicolor Photoluminescence

“…The functional dependence of emission colors on the excitation wavelength provide justification that incorporation of THE, a non‐conjugated organic side group on cyclotriphosphazene might be able to produce the microspheres with wavelength tunable photoluminescence. Additionally, lone pair of nitrogen and π‐bond between the PN in a trimer HCCP and intramolecular n–π* conjugation through space, restriction in rotation, and intramolecular π–π conjugation could generate π–π* excimers that be selectively excited . From these experimental results, we can infer that PCZ‐co‐THE microspheres have energetically different sates that can be selectively excited with no transfer of energy among them.…”