*2.2. Methods*

1H NMR spectra were recorded on an ARX 300 MHz Bruker Spectrometer (Bruker Daltonics, Billerica, MA, USA). Chemical shifts are reported as δ values (ppm) with corresponding deuterated

solvent peak as an internal standard. Mass spectrometric analysis was performed in the positive ion mode using a quadrupole mass spectrometer (Micromass, Platform II spectrometer). Fluorescence spectra were recorded in Perkin Elmer LS-55 spectrometer (Perkin Elmer Inc., Waltham, MA, USA).
