Tuning macrocycles to design 'turn-on' fluorescence probes for manganese(ii) sensing in live cellsElectronic supplementary information (ESI) available: Synthetic procedures, characterization, spectra, and cell study details. See DOI: 10.1039/c4cc09542a

We tune the coordination environment of macrocyclic ligands to design two novel fluorescence sensors for Mn 2+ . The BODIPY-based Mn 2+ sensor M1 affords an excellent, 52 fold, fluorescence 'turn-on' response despite the paramagnetic nature of Mn 2+ . The lipophilic probe is cell-permeable and confocal imaging demonstrates that the sensor distinctly detects Mn 2+ within live cells. We report novel 'turn-on' fluorescence probes for imaging Mn 2+ in live cells.