FIELD: medicine. SUBSTANCE: invention relates to the field of luminescent europium complex compounds, namely to a europium complex of monosodium salt of 2,2',2'',2'''-(2,2'-((5'-(4-aminophenyl)-2,2'-bipyridine-6-yl)methylazadiyl)bis-(ethane-2,1-diyl))-bis(azatriyl)tetraacetic acid of the formula 1. EFFECT: proposed complex shows improved photophysical properties; it can be used as a luminescent mark for immune analysis and can be used in medicine. 1 cl, 4 dwg, 2 tbl.