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The multiple thermal decomposition channels of glycerol are calculated at the M06-2X-D3/6-311+G(d,p) level. In addition, the CAM-B3LYP and ωB97X-D functionals are used to show the functional influence on the free energy barrier. For the highly competitive primary channels, the DLPNO-CCSD(T)/CBS method is applied for the energy calculations. The results show that the dominant paths are: (1) breakage of the C–C, C–O, and O–H bonds of glycerol successively to form carbonyl and alkene, and then generation of water, formaldehyde, and acetaldehyde; (2) glycerol undergoing an intramolecular dehydration reaction and producing 3-hydroxypropionaldehyde; it has two subsequent reactions: C–C bond fracture occurring to form formaldehyde, acetaldehyde, and water; and intramolecular dehydration forming acrolein and water. The ΔG1 is 65.6 kcal mol−1 while the ΔG2 is 65.5 kcal mol−1 at 101 kPa and 298 K, and fitted rate equations are 1.09 × 1013 exp[65.6 × 103/RT] s−1 and 8.07 × 1012 exp[65.4 × 103/RT] s−1, respectively. Besides, UPLC and TG-GC/MS are applied complementarily to investigate the anaerobic pyrolysis products of glycerol at different temperatures. The experimental results are consistent with theoretical calculations. [ABSTRACT FROM AUTHOR]

Endowing thermally activated delayed fluorescence (TADF) emitters with aggregation-induced emission (AIE) characteristics and a fine film-forming ability is significant for realizing efficient solution-processed non-doped organic light-emitting diodes (OLEDs). Herein, a class of AIE-active TADF emitters adopting phenyl ketone as an acceptor and 9,9-diphenyl-9,10-dihydroacridine (or 9,9-dimethyl-9,10-dihydroacridine and phenoxazine) as a donor are exploited. The suppressed intermolecular packing derived from the highly twisted molecular configuration and multiple transition channels induce improved luminescence efficiency and more efficient reverse intersystem crossing (RISC) simultaneously in the solid state. Solution-processed non-doped and doped devices with the maximum external quantum efficiencies (EQEs) of 12.1% and 17.6%, respectively, are obtained when employing the dendritic luminogens of 3PXZ-BPCTPA as the emitter, which are better than the reference non-dendritic luminogens of PXZ-BPCTPA. This work thus provides an approach for designing dendritic luminogens with TADF and AIE features as promising candidates for high-performance solution-processed OLEDs. [ABSTRACT FROM AUTHOR]

A new series of thermally initiated self-crosslinkable diarylfluorene-based copolymers have been reasonably designed and successfully synthesized, aiming to improve both efficiency and stability of blue light-emitting diodes. The crosslinking groups in side chains endow these copolymers with excellent solvent resistance and anti-oxidation abilities, as verified through Raman and UV-vis absorption as well as variable temperature photoluminescence spectra. The surface roughness of the thermal self-crosslinking copolymer film is almost unchanged with a low value of 0.73 nm, compared to a roughness of 0.68 nm for the original film without crosslinking. The modulation of the energy levels of copolymers with/without a crosslinking reaction is analyzed through computations and experiments. The up-shifted highest occupied molecular orbital (HOMO) energy level of the thermal self-crosslinking copolymer film by about 0.1 eV in comparison with that of the uncrosslinked copolymer film is conducive to the establishment of a better pathway for hole injection from the anode. In the end, a high external quantum efficiency of 4.29% with a maximum brightness of 7491 cd m−2 is achieved for the optimized blue polymer light-emitting diode (PLED) with the use of a thermal crosslinking copolymer emitter, which is the highest efficiency reported so far in the field of self-crosslinking blue fluorescent emitters. This work demonstrates that the introduction of self-crosslinkable side-chain units far from the blue polymer backbone is a very promising strategy for developing highly efficient and stable blue PLEDs. [ABSTRACT FROM AUTHOR]

Real-time monitoring of the cytochrome P450 1A1 (CYP1A1) activity in complex biological systems via a practical tool is highly sought after because of its significant role in the metabolism and bioactivation of various xenobiotics. Herein, according to slight differences in the 3D structure and substrate preference between CYP1A1 and its homologous CYP1A2, a series of novel ratiometric fluorescent probes were designed and synthesized using 1,8-naphthalimide because of its trait of naked-eye visualization and ratiometric fluorescence to achieve the detection of CYP1A1 in biological samples. Among these probes, NEiPN showed good water solubility, highly isoform selectivity and great sensitivity (LOD = 0.04874 nM) for CYP1A1 under simulated physiological conditions, which makes it favorable for monitoring CYP1A1 in vivo. Remarkably, NEiPN exhibited excellent reproducibility when it was used to detect the CYP1A1 content in human liver microsomes, which indicated that it has a great potential for quantifying the CYP1A1 content in real biological samples. Furthermore, NEiPN showed relatively low cytotoxicity and has been successfully applied in biological imaging in living cells and zebrafish. These findings indicate that NEiPN is capable of real-time monitoring of the activity of endogenous CYP1A1, which could provide support for CYP1A1-associated pathological processes. [ABSTRACT FROM AUTHOR]

The development of luminescent materials simultaneously possessing thermally activated delayed fluorescence (TADF), aggregation-induced emission (AIE), and high luminescence efficiency in the solid state is urgent for fabricating efficient non-doped organic light-emitting diodes (OLEDs). Herein, two novel emitters bearing triphenylamine as the donor moiety and phenyl ketone as the acceptor unit, named as DTPA-DTM and DTPA-DDTM, were designed and synthesized. Combined charge transfer pathways in a single molecule could be achieved via linking the donor and acceptor units in the ortho-position, which was favorable for reducing singlet–triplet energy splitting (ΔEst) and increased the luminescence efficiency. The TADF characteristics, AIE properties, solvatochromism, theoretical calculations, and crystallography of the designed emitters were systematically investigated to determine the structure–property relationship. By virtue of the inhibited concentration quenching in the solid state, the non-doped OLEDs employing DTPA-DDTM as the emitter realized high current efficiency (LE) and external quantum efficiency (EQE) of 25.6 cd A−1 and 8.2%, respectively. The obtained results clearly demonstrate that combining the charge transfer pathways in a single molecule is a promising strategy to construct highly efficient TADF emitters that can be used for fabricating non-doped organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

The fabrication of electroluminescent devices that combine high device performance with simple device configuration remains an attractive challenge due to their low cost and simple fabrication processes. In this paper, a new series of electrophosphorescent small molecule iridium(iii) complexes with diphenylamine-based dendrons of good solubility have been designed. The relationships between their dendritic structures and their photophysical, electrochemical, and electrophosphorescent performances have been systematically investigated. With second-generation dendrons, the photoluminescence quantum yields of the neat film of the dendrimers are almost seven times higher than that of their prototype G0 (Ir(LG0)3, LG0 = 1-methyl-2-phenyl-1H-benzimidazole), and three times that of the first-generation dendron G1 (Ir(LG1)3, LG1 = 4-(1-methyl-1H-benzimidazol-2-yl)-N,N-diphenylbenzenamine). High-quality films of the dendrimers G2 (Ir(LG2)3, LG2 = 1-methyl-2-[4-bis[4-(diphenylamino)phenyl]-aminophenyl]-1H-benzimidazole) and G2Cz (Ir(LG2Cz)3, LG2Cz = 1-methyl-2-[4-bis[4-(9-carbazolyl)phenyl]-aminophenyl]-1H-benzimidazole) have been fabricated by spin-coating, producing highly efficient, non-doped phosphorescent organic light-emitting diodes (PhOLEDs). With a device structure of indium tin oxide/poly(3,4-ethylene-dioxythiophene):poly(styrene sulfonic acid)/neat dendrimer/Cs2CO3/Al, maximum luminous efficiencies of 14.02 cd A−1 and 18.35 cd A−1 have been realized, exhibiting ultrahigh luminous efficiency for single-layer self-host green PhOLEDs. The excellent performances are due to the flower bouquet-shaped iridium dendrimers, which may improve the electron injection and result in greater balance between electron and hole fluxes by the exposure of electron-deficient moieties. The molecular design reported here provides a simple and effective approach to balance charge injection/transporting capacities and develops highly efficient non-doped phosphors suitable for low-cost single-layer device technologies. [ABSTRACT FROM AUTHOR]