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By introducing two cholesteric liquid crystal monomers with different chain lengths (M1 and M2) and brominated naphthalimide fluorescent monomer (M3) into polymethyl hydrosiloxane, a series of fluorescent cholesteric liquid crystal polymers (FL-LCP) was prepared, which not only have excellent performance of liquid crystal and fluorescence but also own performance of selective reflection. Their chemical structures were confirmed to be in accord with molecular design by FT-IR and 1 H NMR spectroscopy, and found them with excellent thermal stability, mesomorphic behaviour and thermal performance by TGA, POM, DSC and XRD, and confirmed all the polymers belonged to the cholesteric phase. The FL-CLCPs emitted different intensity fluorescence under UV light, and conclusions about the relationship between fluorescence and temperature had been drawn. A comparative study was conducted on the fluorescence properties of powders and films of monomers and polymers. [ABSTRACT FROM AUTHOR]

In this study, we have synthesised fluorescent liquid crystal polymers with good fluorescence and optical properties through effective molecular design. Firstly, two series of cholesteric liquid crystal polymers (PN and PS series) were prepared by graft copolymerisation of cholesteric monomer(N1), monomer containing cyanobiphenyls with different length of carbon-chain (N2 and N3) and monomer containing bromine (6-Br) with polymethylhydrosiloxane chain as the polymer backbone. Secondly, we obtained fluorescent polymers RPN and RPS series by etherification reaction of PN and PS series with fluorescent monomer (F). The molecular structures and mesomorphic behaviour of monomers and polymers were characterised by usual ways. All the polymers are confirmed to consist with molecular design. The fluorescence of the polymers was investigated by fluorescence spectroscopy and fluorescent images. The fluorescence intensity of polymers is highly dependent on temperature. Fluorescent cholesteric liquid crystal polymers emitted different intensity fluorescence under ultraviolet irradiation and some regularities were summarised. RPN series with short carbon-chain meets our expectations for performance with dual effects of fluorescence and selective reflection, which were well verified. The effect of monomers with different chain lengths on the properties of fluorescent polymers has been described. Fluorescent cholesteric liquid crystal polymers were synthesised with polymethylhydrogensiloxane as the main chain by hydrosilylation and etherification reaction, which seems a viable strategy for preparing such multifunction polymers. The polymers of RPN series we synthesised are equipped with both selective reflection and fluorescence properties. The selective reflection and fluorescence both have a characteristic of depending on temperature. The fluorescent cholesteric liquid crystal polymers we synthesised presented lower glass transition temperature and higher isotropic transition temperature. In other words, it has a wide range of application. [ABSTRACT FROM AUTHOR]

Tyrosyl‐DNA phosphodiesterase 2 (TDP2) is a recently discovered DNA repair enzyme that can repair topoisomerase 2‐mediated DNA damage, resulting in cancer cell resistance. In this study, two compounds, robustadial A and B, were isolated from a fraction of the ethyl acetate extract of Eucalyptus globulus Labill. fruits based on TDP2 inhibition screening. The biological experiments indicated that robustadial A and B have TDP2 inhibitory activity with EC50 values of 17 and 42 μM, respectively, but no tyrosyl‐DNA phosphodiesterase 1 inhibition at 100 μM. Robustadial A showed significant synergistic effects with the anticancer drug etoposide in four human cancer cell lines, non‐small cell lung cancer cell line (A549), prostate cancer cell line (DU145), breast cancer cell line (MCF‐7), colorectal adenocarcinoma cell line (HCT‐116), and chicken lymphoma cell line (DT40), and chicken lymphoma cell line complementation with human TDP2 (DT40 hTDP2) with combination index values ranging from 0.21 to 0.74. This work will facilitate future efforts for the development of robustadial A‐based TDP2 selective inhibitors. [ABSTRACT FROM AUTHOR]

Cholesteric liquid crystals with selective reflection have important applications in the field of light control and optical thin films. In this study, a series of side-chain cholesteric liquid-crystal polymers (named as PPL series) was synthesised by a one-step hydrosilylation reaction among monomer LA containing cholesterol group, monomer LB containing D(+)-camphoric acid group and monomer LG containing cyano group. The chemical structures and the mesogenic properties of the monomers and polymers were determined by usual test methods. Testing results showed that PPL series polymers had excellent thermal stability and wide range of mesophases. As the content of monomer LB increased, PPL1-PPL6 could be observed colourful Grandjean textures and good selective reflection. The optical rotation experiment indicated that the rotation direction of the PPL series was consistent with that of the monomer LB, and the specific rotation was linearly related to the content of the monomer LB. [ABSTRACT FROM AUTHOR]

In this study, we synthesised two series of cholesteric liquid crystal polymers CPQ and CPZ series. First, we prepared four different monomers ML1 containing a cholesteryl group, ML2 containing a cyano group, ML3 containing a phenolic hydroxyl group and ML4 containing isosorbide with azo groups. With the polymethylsiloxanes as the main chain, CPQ series were then synthesised by copolymerisation among the monomers ML1, ML2 and ML3 and CPZ series were synthesised by esterification between the CPQ series and the monomer ML4. 1HNMR and FT-IR spectra confirmed the chemical structures of all the monomers and polymers. The mesomorphic behaviours and thermal properties were investigated by TGA, DSC, POM and XRD. Both the CPQ and CPZ series exhibited excellent thermal stability and reversible phase transitions, as well as interesting Grandjean textures under POM. CPZ series showed higher optical activity than CPQ series due to the introduction of the isosorbide group and the azo group, which could tune the pitch to make Bragg selective reflection appear more easily. UV–Vis spectra investigated the photoresponse behaviours of CPZ series thoroughly. [ABSTRACT FROM AUTHOR]

We synthesized two series of cholesteric liquid-crystal elastomers by hydrosilylation among monomers MA containing a cholesteryl group, MB (MC) containing a phenolic hydroxyl group and MD as the crosslinker. The chemical structures of all the monomers and LCEs were confirmed by 1H NMR and FT-IR. We explored the mesomorphic properties and phase behaviours by TGA, DSC, POM, and XRD. All the LCEs presented elasticity, reversible phase transition, and high thermal stability. For two series of LCEs, the glass transition temperature increased slowly, and the isotropic transition temperature increased obviously. PA-I-PA-V and PB-I-PB-IV displayed selective reflection and colourful Grandjean texture, but PA-VI, PB-V, and PB-VI needed external pressure to show them. [ABSTRACT FROM AUTHOR]

The cholesteric polysiloxanes (PLQ series) were obtained by reacting cholesteric monomer and phenolic hydroxyl monomer in different ratios with polysiloxanes. The chiral azo-containing polysiloxanes liquid-crystalline elastomers (LCEs) were synthesised by esterifying PLQ series with acyl acid of azo diacid catalysed by 4-dimethylaminopyridine (DMAP). The chemical structures and mesomorphic properties of monomers and polymers were confirmed by conventional spectroscopic methods. The elastomers displayed elastic properties, reversible phase transition and high thermal stability. The Tg values changed irregularly and Ti values decreased at the beginning and then increased afterwards. The chiral azo-LCEs showed colourful textures and a Grandjean texture could be observed, which exhibited a red shift with increasing content of azo moiety. PLQ2-PLQ6 exhibited selective reflection in the visible light region, but PLZ1-PLZ4 can only observe selective reflection when appropriate mechanical pressure was imposed on the polymers. The PLZ series was carefully investigated by ultra violet-visible spectroscopy. [ABSTRACT FROM AUTHOR]