Publications by authors named "Alex D Johnson"

1,8-Naphthalimides with an organometallic moiety with anticancer and luminescence or photoactive properties are reviewed. Primarily highlighted are 1,8-naphthalimide complexes with iron, platinum, and ruthenium, while honourable mentions are given to iridium, rhenium and rhodium complexes. The cytotoxicity, mechanism of action and cell selectivity of the compounds are discussed alongside their photophysical properties for monitoring interactions with biomolecules, most notably DNA, by absorption, fluorescence and dichroism spectroscopy.

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Polyacrylamide hydrogels formed by free radical polymerisation were formed by entrapping anthracene and 4-amino-1,8-naphthalimide fluorescent logic gates based on photoinduced electron transfer (PET) and/or internal charge transfer (ICT). The non-covalent immobilisation of the molecules in the hydrogels resulted in semi-solid YES, NOT, and AND logic gates. Two molecular AND gates, examples of Pourbaix sensors, were tested in acidic aqueous methanol with ammonium persulfate, a strong oxidant, and displayed greater fluorescence quantum yields than previously reported.

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Herein we present eight ferrocenyl 4-amino-1,8-naphthalimides. Designed as fluorescent logic gates for acidity and oxidisability, the molecules have been repurposed as anti-proliferation and cellular imaging agents. The compounds were studied against MCF-7 and K562 cancer cell lines by the MTT method.

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Novel water-soluble 4-aminonaphthalimides were synthesised and their cellular fluorescent imaging, cytotoxicity and ability to induced apoptosis evaluated. The lead compound 1 was designed from the cross-fertilisation of the basic hydrophilic amino pharmacophore of mitoxantrone, and an aminonaphthalimide scaffold of the drug candidate, amonafide. The compounds are also fluorescent pH probes based on photoinduced electron transfer (PET) and internal charge transfer (ICT).

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Quantum dots (QDs) are steadily being implemented as down-conversion phosphors in market-ready display products to enhance color rendering, brightness, and energy efficiency. However, for adequate longevity, QDs must be encased in a protective barrier that separates them from ambient oxygen and humidity, and device architectures are designed to avoid significant heating of the QDs as well as direct contact between the QDs and the excitation source. In order to increase the utility of QDs in display technologies and to extend their usefulness to more demanding applications as, for example, alternative phosphors for solid-state lighting (SSL), QDs must retain their photoluminescence emission properties over extended periods of time under conditions of high temperature and high light flux.

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We have investigated how the photoluminescence (PL) of WSe is modified when coupled to Ag plasmonic structures at low temperature. Chemical vapor deposition (CVD) grown monolayer WSe flakes were transferred onto a Ag film and a Ag nanotriangle array that had a 1.5 nm AlO capping layer.

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Pyrazoline-ferrocene conjugates with an "electron-donor-spacer-fluorophore-receptor" format are demonstrated as redox-fluorescent two-input INHIBIT logic gates.

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This mini-review highlights the photophysical properties of fluorescent molecular logic gates responsive to acids and oxidants, particularly those developed in our laboratory the past few years. The review pays tribute to earlier developments that lay the foundation for this emerging class of molecules. The logic gates incorporate design concepts based on photoinduced electron transfer from the cross-fertilization of the fluorophore-spacer-receptor and fluorophore-spacer-electron-donor formats.

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