The electrospray ionization mass spectrometry (ESI-MS) of a series of rhenium (I) bipyridyl complexes [(4,4'-(COOEt)_2-bpy)Re(CO)_3RPF_6], where bpy is 2 2'-bipyridine and R is pyridine, 4-methylpyridine, 4- hydroxypyridine, 4-ammopyridine or 10-(4-picolyl) phenothiazine (py-PTZ ) was studied. The dissociation of the ligands (R) forms the fragment of [(4,4'-(C00Et)2-bpy) Re (CO)_3]~+ at different voltages of in- source collision induced dissociation (CED). The dissociation tendency is in an order: pyiidine> 4-methylpyridine > 4-hydroxypyridine > 4- aminopyridine > py-PTZ. It might be used to deduce the stability of these complexes when they are used as photosensitizers in solar cells.

Key words: ESI-MS;BIPYRIDINE P;CARBOXYLIC ACID ESTER;PYRIDINE P;THIOPHENE P, photosensitive dye