Co-existence of heterometallic Zn2Er and ZnEr arrayed chromophores for the sensitization of near-infrared (NIR) luminescence

With the Zn-Schiff-base [ZnL(Py)] from the simple Salen-type Schiff-base ligand H2L (H2L = N,N′-bis(salicylidene)ethylene-1,2-diamine) as the precursor, two co-crystallized heterometallic (Zn2Ln and ZnLn array) complexes [Zn2Ln(L)2(Py)2(NO3)2]·[ZnLn(L)(Py)(NO3)3(H2O)]·NO3·mMeOH·nS (Ln = Er(1), S = CH3CN, m = 2, n = 1 or Gd(2), S = H2O, m = 1, n = 3) were obtained by the further reaction with Ln(NO3)3·6H2O, respectively. The result of their photophysical properties shows the intramolecular effective energy transfer has been demonstrated in the Zn2Er and ZnEr arrayed complex 1, and the co-existence of different chromophores should be a potentially new way to the fine-tuning properties of NIR luminescence from Er3+ ions.