Huayu Qiu

Stereoselective Synthesis, Efficient Light Emission, and High Bipolar Charge Mobility of Chiasmatic Luminogens

Stereoregular tetraphenylethene derivatives (Z)-o-BCaPTPE and (Z)-o-BTPATPE featured with chiasmatic conformations and aggregation-enhanced emission characteristics are synthesized using a McMurry reaction. Both luminogens exhibit high hole and electron mobilities. Organic light-emitting diodes (OLEDs) using (Z)-o-BCaPTPE and (Z)-o-BTPATPE as both the light-emitting and electron-transporting layers show high efficiencies.

Using tetraphenylethene and carbazole to create efficient luminophores with aggregation-induced emission, high thermal stability, and good hole-transporting property

Tetraphenylethene (TPE) is an archetypal luminogen that exhibits a phenomenon of aggregation-induced emission (AIE), while carbazole is a conventional chromophore which shows the opposite effect of aggregation-caused quenching (ACQ) of light emission in the condensed phase. Melding the two units at the molecular level generates a group of new luminescent materials that suffer no ACQ effect but depict high solid-state fluorescence quantum yields up to unity, demonstrative of the uniqueness of the approach to solve the ACQ problem of traditional luminophores. All the TPE–carbazole adducts are thermally and morphologically stable, showing high glass-transition temperatures (up to 179 °C) and thermal-degradation temperatures (up to 554 °C). Multilayer electroluminescence devices with configurations of ITO/NPB/emitter/TPBi/Alq3/LiF/Al are constructed, which exhibit sky blue light in high luminance (up to 13u2006650 cd m−2) and high current and external quantum efficiencies (up to 3.8 cd A−1, and 1.8%, respectively). The devices of the luminogens fabricated in the absence of NPB or hole-transporting layer show even higher efficiencies up to 6.3 cd A−1 and 2.3%, thanks to the good hole-transporting property of the carbazole unit.

A tetraphenylethene-based red luminophor for an efficient non-doped electroluminescence device and cellular imaging

An efficient red luminophor (TTPEBTTD) consisting of a 4,7-di(thiophen-2-yl)benzo-2,1,3-thiadiazole core and tetraphenylethene peripheries is developed. The non-doped electroluminescence device based on TTPEBTTD radiates red light with high efficiency up to 3.7%. The nanoparticles of TTPEBTTD are promising fluorescent visualizers for cellular imaging with low cytotoxicity.

Aggregation‐Induced Emission and Efficient Solid‐State Fluorescence from Tetraphenylethene‐Based N,C‐Chelate Four‐Coordinate Organoborons

In it together: Thermally stable N,C-chelate four-coordinate organoborons were attained by grafting intramolecular B⋅u2009⋅u2009⋅N coordination into tetraphenylethene-pyridine and -quinoline adducts. They exhibit aggregation-induced emission characteristics (see figure), and high fluorescence quantum yields approaching unity in solid films.

A fluorescent supramolecular polymer with aggregation induced emission (AIE) properties formed by crown ether-based host–guest interactions

A fluorescent supramolecular polymer with aggregation induced emission properties formed by crown ether-based host–guest interactions was prepared. It can be used as a fluorescent sensor for Pd2+ ions.

Construction of efficient solid emitters with conventional and AIE luminogens for blue organic light-emitting diodes

9,9-Bis(9-heptyl-3-carbazolyl)fluorenes (BPyBCF, BAnBCF, BTPABCF, and BTPEBCF, where B = Bis, Py = pyrene, C = carbazole, F = fluorene, An = anthracene, TPA = triphenylamine, and TPE = tetraphenylethene) with different chromophoric units at the 2,7-positions are synthesized in moderate to high yields (52–89%) by Suzuki coupling reactions of 9,9-bis(9-heptyl-3-carbazolyl)-2,7-dibromofluorene with the corresponding arylboronic acid and utilized as active layers for the construction of blue organic light-emitting diodes (OLEDs). BPyBCF, BAnBCF and BTPABCF emit intense blue light with high fluorescence quantum yields (ΦF = 75–94%) in solution. However, they exhibit much lower ΦF values (30–61%) in the film state, revealing that aggregate formation has quenched their light emission. On the contrary, BTPEBCF is weakly emissive in solution (ΦF = 0.3%) but becomes a strong emitter (ΦF = 100%) when fabricated into solid film, demonstrating a phenomenon of aggregation-induced emission (AIE). Restriction of intramolecular rotation and suppression of intermolecular interactions due to the propeller-like tetraphenylethene unit are responsible for the AIE phenomenon. All the luminogens are thermally and morphologically stable, showing high glass-transition (Tg = 109–147 °C) and thermal-degradation temperatures (Td = 396–478 °C). Non-doped OLEDs using BPyBCF, BAnBCF, and BTPABCF as light-emitting layers are constructed, which give blue electroluminescence with maximum current (ηC,max) and external quantum (ηext,max) efficiencies of 4.8 cd A−1 and 2.3%. With the same device configuration, BTPEBCF shows higher ηC,max and ηext,max values of 7.9 cd A−1 and 2.9%, respectively, thanks to its AIE feature.

Self-assembly of novel fluorescent silole derivatives into different supramolecular aggregates: fibre, liquid crystal and monolayer

Two novel organogelators based on 2,3,4,5-tetraphenylsilole functionalized with long-chain alkoxydiacylamido platforms (1a and 1b) were synthesized. The silole derivatives induced gelation of only hydrocarbon solvents and showed aggregation-induced emission (AIE) in the gel state, in contrast to very weak emission in solution. The polarized optical microscopic (POM) and field emission scanning electron microscopy (FE-SEM) studies exhibited that the xerogels formed fibrous structures. Hydrogen bonding and π-stacking interactions were the main driving forces for the formation of organogels, based on the FT-IR and absorption investigations. Differential scanning calorimetry (DSC) and POM studies indicated that both compounds 1a and 1b exhibited stable liquid crystalline (LC) phases over a wide temperature range. It is interesting that uniform and well-ordered monolayers were also obtained for both compounds on the HOPG surface. The new silole derivatives are quite unique because they can self-assemble into one-dimensional (fibres), three-dimensional (liquid crystal) and even two-dimensional (molecular monolayer) aggregates.

A Multiple‐Responsive Self‐Healing Supramolecular Polymer Gel Network Based on Multiple Orthogonal Interactions

Supramolecular polymer networks have attracted considerable attention not only due to their topological importance but also because they can show some fantastic properties such as stimuli-responsiveness and self-healing. Although various supramolecular networks are constructed by supramolecular chemists based on different non-covalent interactions, supramolecular polymer networks based on multiple orthogonal interactions are still rare. Here, a supramolecular polymer network is presented on the basis of the host-guest interactions between dibenzo-24-crown-8 (DB24C8) and dibenzylammonium salts (DBAS), the metal-ligand coordination interactions between terpyridine and Zn(OTf)2 , and between 1,2,3-triazole and PdCl2 (PhCN)2 . The topology of the networks can be easily tuned from monomer to main-chain supramolecular polymer and then to the supramolecular networks. This process is well studied by various characterization methods such as (1) H NMR, UV-vis, DOSY, viscosity, and rheological measurements. More importantly, a supramolecular gel is obtained at high concentrations of the supramolecular networks, which demonstrates both stimuli-responsiveness and self-healing properties.

Conjugation versus rotation: good conjugation weakens the aggregation-induced emission effect of siloles

Incorporation of polycyclic aromatic hydrocarbons into siloles enhances their light emission in solutions but lowers emission efficiency in the aggregated state. The competitive interaction between conjugation and rotation is thus studied.

2,3,4,5-Tetraphenylsilole-based conjugated polymers: synthesis, optical properties, and as sensors for explosive compounds.

A series of linear 2,5-tetraphenylsilole-vinylene-type polymers were successfully synthesized for the first time. The tetraphenylsilole moieties were linked at their 2,5-positions through a vinylene bridge with p-dialkoxybenzenes to obtain polymer PSVB and with 3,6-carbazole to obtain polymer PSVC. For comparison, 2,5-tetraphenylsilole-ethyne-type polymer PSEB was also synthesized, in which the vinylene bridge of PSVB was replaced with an ethyne bridge. Very interestingly, the bridging group (vinylene or ethyne) had a significant effect on the photophysical properties of the corresponding polymers. The fluorescence peak of PSEB at 504u2005nm in solution originated from the emission of its silole moieties, whereas PSVB and PSVC emitted yellow light and no blueish-green emission from the silole moieties was observed, thus demonstrating that the emissions of PSVB and PSVC were due to their polymer backbones. More importantly, the 2,5-tetraphenylsilole-ethyne polymer exhibited a pronounced aggregation-enhanced emission (AEE) effect but the 2,5-tetraphenylsilole-vinylene polymer was AEE-inactive. Moreover, both AEE-active 2,5-tetraphenylsilole-ethyne polymer and AEE-inactive 2,5-tetraphenylsilole-vinylene polymers were successfully applied as fluorescent chemosensors for the detection of explosive compounds.