Bis(indolyl)methane derivatives as highly selective colourimetric and ratiometric fluorescent molecular chemosensors for Cu2+ cations

New probes based on bis(indolyl)methane derivatives only sense Cu2+ among other heavy and transition metal (HTM) ions through two different channels: the colourless to orange or purple colour change, that is visible to the naked eye, and a remarkable enhancement of the fluorescence along with a large red-shift in emission, in a water containing medium (CH3CN/H2O).