The series of homoleptic tetranuclear [Ln(4)(L)(2)(HL)(2)(NO3)(2)(OH)(2)]center dot 2(NO3) (Ln = Nd, 1; Ln = Yb, 2; Ln = Er, 3; Ln = Gd, 4) have been self-assembled from the reaction of the Salen-type Schiff-base ligand H2L with Ln(NO3)(3)center dot 6H(2)O (Ln = Nd, Yb, Er or Gd), respectively (H2L: N, N'-bis(salicylidene) cyclohexane-1,2-diamine). The result of their photophysical properties shows that the strong and characteristic NIR luminescence for complexes 1 and 2 with emissive lifetimes in microsecond ranges are observed and the sensitization arises from the excited state (both (LC)-L-1 and (LC)-L-3) of the Salen-type Schiff-base ligand with the flexible linker.National Natural Science Foundation 21173165, 20871098Ministry of Education of China NCET-10-0936Higher Education of China 20116101110003State Key Laboratory of Structure Chemistry 20100014Education Committee Foundation of Shaanxi Province 11JK0588Hong Kong Research Grants Council, P. R. of China HKBU 202407, FRG/06-07/II-16)Hong Kong Research Grants Council, Robert A. Welch Foundation F-816Texas Higher Education Coordinating Board ARP 003658-0010-2006Petroleum Research Fund 47014-AC5Chemistr
