Fluorescent sensors that illuminate specific molecules and chemical events allow the selectivea nd sensitive study of the cellular environment. At the centre of this technology lies the fluorescent reporter molecule, and it is therefore crucial to provide ab readth of fluorophores with varying photophysical and biological behaviour.4 -Amino-1,8naphthalimides are commonly employed in fluorescent sensors, but the narrow range of structurald erivativesl imits versatility of application.H ere we report the synthesis and investigation of as et of twelve 4-amino-1,8-naphthalimides bearinga na dditional substituent on the aromatic core. Pho-tophysical characterisation and time-dependent density functional theory studies provided insights into the structure-photophysical property relationships of these derivatives, which show an expanded range of emissionw avelengths and other photophysical properties. These compounds coulda ll be visualised within cells by confocal microscopy,s howingc ytoplasmic or lipid droplet localisation. Our studies have demonstratedt hat simple structural modification of 4-amino-1,8-naphthalimides provides derivatives with considerable breadtho fb ehaviour that lend valuable versatility to the design of fluorescents ensors.

Dyads consisting of a photochromic switch covalently linked to a fluorescent dye allow the emission from the dye to be controlled by reversible photoisomerization of the switch; one form of...

Sensing hypoxia in tissues and cell models can provide insights into its role in disease states and cell development. Fluorescence imaging is a minimally-invasive method of visualising hypoxia in many biological systems. Here we present a series of improved bioreductive fluorescent sensors based on a nitro-naphthalimide structure, in which selectivity, photophysical properties, toxicity and cellular uptake are tuned through structural modifications. This new range of compounds provides improved probes for imaging and monitoring hypoxia, customised for a range of different applications. Studies in monolayers show the different reducing capabilities of hypoxia-resistant and non-resistant cell lines, and studies in tumour models show successful staining of the hypoxic region.

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