Tuning Photophysical Properties via Positional Isomerization of the Pyridine Ring in Donor-Acceptor-Structured Aggregation-Induced Emission Luminogens Based on Phenylmethylene Pyridineacetonitrile Derivatives.

A series of aggregation-induced emission (AIE)-featured phenylmethylene pyridineacetonitrile derivatives named o-DBCNPy ((Z)-3-(4-(di-p-tolylamino)phenyl)-2-(pyridin-2-yl)acrylonitrile), m-DBCNPy ((Z)-3-(4-(di-p-tolylamino)phenyl)-2-(pyridin-3-yl)acrylonitrile), and p-DBCNPy ((Z)-3-(4-(di-p-tolylamino)phenyl)-2-(pyridin-4-yl)acrylonitrile) have been synthesized by tuning the substitution position of the pyridine ring. The linkage manner of the pyridine ring had influences on the molecular configuration and conjugation, thus leading to different photophysical properties. The absorption and fluorescence emission peak showed a bathochromic shift when the linking position of the pyridine ring changed from the meta to the ortho and para position. Meanwhile, o-DBCNPy exhibited the highest fluorescence quantum yield of 0.81 and the longest fluorescence lifetime of 7.96 ns as a neat film among all three isomers. Moreover, non-doped organic light-emitting diodes (OLEDs) were assembled in which the molecules acted as the light-emitting layer. Due to the relatively prominent emission properties, the electroluminescence (EL) performance of the o-DBCNPy-based OLED was superior to those of the devices based on the other two isomers with an external quantum efficiency (EQE) of 4.31%. The results indicate that delicate molecular modulation of AIE molecules could endow them with improved photophysical properties, making them potential candidates for organic photoelectronic devices.

Design, Synthesis and Antitumor Activity of FAK/PLK1 Dual Inhibitors with Quinazolinone as the Skeleton.

Febrifugine is a kind of quinazolinone compound with high biological activity from a Chinese herb called Chang Shan (Dichroa febrifuga). Febrifugine and its derivatives possess extensive biological activities, some of which exhibited anti-tumor activities as FAK inhibitors. However, they are not very effective at inhibiting tumor metastasis, perhaps because tumors gain energy through compensatory activation of other signaling pathways that promote cell migration and invasion. Therefore, seventeen novel febrifugine derivatives with quinazolinone skeleton were designed, synthesized and acted as potential FAK/PLK1 dual inhibitors. These compounds were determined by 1 H-NMR, 13 C-NMR and MS. Most of the compounds exhibited good inhibitory activity against cancer cell lines by computer-assisted screening, antitumor activity test and FAK/PLK1 inhibitory activity test, wherein compound 3b was screened as a high-efficiency lead compound.

Exploiting singlet excited state conformation for rational design of highly efficient photoinduced electron transfer molecules.

In spite of the pivotal role of excited state electronic structures as regulation of photoinduced electron transfer (PET) process, the effect of excited state conformation on PET remains elusive. Here we exploit distinguishable emission characters of trans and cis singlet excited states of donor-acceptor-donor ensemble MTPAAZO to reveal that its PET efficiency and rate are closely depended on its singlet excited state conformation. The PET process occurs solely in cis conformation of MTPAAZO singlet excited states. Novel molecule (MTPA)2Ab as-designed with similar structure of MTPAAZO cis singlet excited states shows high PET efficacy and rate, leading to long-lived CS states. Our findings enable the rational design of the novel molecules with highly efficient PET process suitable for charge separation applications.

Enhanced Internal Quantum Efficiency in Dye-Sensitized Solar Cells: Effect of Long-Lived Charge-Separated State of Sensitizers.

Effective charge separation is one of the key determinants for the photovoltaic performance of the dye-sensitized solar cells (DSSCs). Herein, two charge-separated (CS) sensitizers, MTPA-Pyc and YD-Pyc, have been synthesized and applied in DSSCs to investigate the effect of the CS states of the sensitizers on the device's efficiency. The CS states with lifetimes of 64 and 177 ns for MTPA-Pyc and YD-Pyc, respectively, are formed via the photoinduced electron transfer (PET) from the 4-styryltriphenylamine (MTPA) or 4-styrylindoline (YD) donor to the pyrimidine cyanoacrylic acid (Pyc) acceptor. DSSCs based on MTPA-Pyc and YD-Pyc exhibit high internal quantum efficiency (IQE) values of over 80% from 400 to 600 nm. In comparison, the IQEs of the charge transfer (CT) sensitizer cells are 10-30% lower in the same wavelength range. The enhanced IQE values in the devices based on the CS sensitizers are ascribed to the higher electron injection efficiencies and slower charge recombination. The results demonstrate that taking advantage of the CS states in the sensitizers can be a promising strategy to improve the IQEs and further enhance the overall efficiencies of the DSSCs.