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A modular approach to azulene building blocks was developed starting from readily available aryl‐substituted cyclopentadiene and ortho‐haloaryl aldehyde by dehydration condensation followed by palladium‐catalyzed C−H coupling. It facilitates the synthesis of four nonalternant isomers of pentacene and hexacene, namely, dibenzo[e,g]azulene, benzo[1,2‐f : 5,4‐f′]diazulene, benzo[1,2‐f : 4,5‐f′]diazulene, and naphtho[2,3‐f : 6,7‐f′]diazulene, which exhibit narrow band gaps with high stability in addition to protonation‐caused enhanced near‐infrared fluorescence. We discovered that in these isomers, i) constitutional isomerism influences significantly their photoelectric properties and ii) the elongation of the conjugation system does not necessarily lead to a narrowing in the band gap. Due to the easy modifiability of the nonazulene building blocks, this strategy can be extended to modularly prepare numerous multiazulene‐fused aromatics. [ABSTRACT FROM AUTHOR]

The strong metal‐support interaction (SMSI) is widely used in supported metal catalysts and extensive studies have been performed to understand it. Although considerable progress has been achieved, the surface structure of the support, as an important influencing factor, is usually ignored. We report a facet‐dependent SMSI of Pd‐TiO2 in oxygen by using in situ atmospheric pressure TEM. Pd NPs supported on TiO2 (101) and (100) surfaces showed encapsulation. In contrast, no such cover layer was observed in Pd‐TiO2 (001) catalyst under the same conditions. This facet‐dependent SMSI, which originates from the variable surface structure of the support, was demonstrated in a probe reaction of methane combustion catalyzed by Pd‐TiO2. Our discovery of the oxidative facet‐dependent SMSI gives direct evidence of the important role of the support surface structure in SMSI and provides a new way to tune the interaction between metal NPs and the support as well as catalytic activity. [ABSTRACT FROM AUTHOR]

We report here the one‐pot synthesis of benzo[1,2‐a : 3,4‐a′ : 5,6‐a′′]triazulene (BTA), wherein three azulene units are embedded through a tandem reaction comprising two steps, Suzuki coupling and Knoevenagel condensation, between a readily available triborylated truxene precursor and 8‐bromo‐1‐naphthaldehyde. Its nitration leads to a regioselective trinitrated product, namely, BTA‐NO2. Single‐crystal X‐ray crystallography revealed that the superstructure of BTA consists of a dimer stacked by two enantiomeric helicene conformers, while that of BTA‐NO2 consists of an unprecedented π‐tetramer stacked from two enantiomeric dimers, that is, four distinct helicene conformers. Both compounds show excellent stability and fluorescence with large Stokes shifts of up to 5100 cm−1. In addition, BTA‐NO2 exhibits a unique solvatochromic effect in different solvents and hydrogen‐bonding‐induced emission transfer in different ratios of THF/H2O solutions. [ABSTRACT FROM AUTHOR]

A modular approach to azulene building blocks was developed starting from readily available aryl‐substituted cyclopentadiene and ortho‐haloaryl aldehyde by dehydration condensation followed by palladium‐catalyzed C−H coupling. It facilitates the synthesis of four nonalternant isomers of pentacene and hexacene, namely, dibenzo[e,g]azulene, benzo[1,2‐f : 5,4‐f′]diazulene, benzo[1,2‐f : 4,5‐f′]diazulene, and naphtho[2,3‐f : 6,7‐f′]diazulene, which exhibit narrow band gaps with high stability in addition to protonation‐caused enhanced near‐infrared fluorescence. We discovered that in these isomers, i) constitutional isomerism influences significantly their photoelectric properties and (i) the elongation of the conjugation system does not necessarily lead to a narrowing in the band gap. Due to the easy modifiability of the nonazulene building blocks, this strategy can be extended to modularly prepare numerous multiazulene‐fused aromatics. [ABSTRACT FROM AUTHOR]

Efficient radiative recombination is essential for perovskite luminescence, but the intrinsic radiative recombination rate as a basic material property is challenging to tailor. Here we report an interfacial chemistry strategy to dramatically increase the radiative recombination rate of perovskites. By coating aluminum oxide on the lead halide perovskite, lead–oxygen bonds are formed at the perovskite‐oxide interface, producing the perovskite surface states with a large exciton binding energy and a high localized density of electronic state. The oxide‐bonded perovskite exhibits a ≈500 fold enhanced photoluminescence with a ≈10 fold reduced lifetime, indicating an unprecedented ≈5000 fold increase in the radiative recombination rate. The enormously enhanced radiative recombination promises to significantly promote the perovskite optoelectronic performance. [ABSTRACT FROM AUTHOR]

There is a strong desire to design and synthesize catalysts that assemble at the oil-water interface to improve the efficiency of biphasic reactions. Anisotropic dumbbell-shaped bi-component mesoporous carbon-organosilica Janus particles with asymmetric wettability are synthesized through a one-step compartmentalized growth of a mesoporous organosilica sphere attached to a mesoporous resorcinol-formaldehyde (RF) sphere. A library was prepared of tunable Janus particles possessing diverse hollow structures with various functionalities. As a proof of concept, the Janus particle-derived catalyst can assemble at the oil-water interface to stabilize Pickering emulsions. Owing to the increased reaction interface area, the Janus catalyst exhibits a more than three-fold increase in catalytic efficiency compared to the Pt loaded carbon sphere catalyst in aqueous hydrogenation reactions. [ABSTRACT FROM AUTHOR]