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Two type lanthanide complexes obtained by salen-type ligand N,N'-ethylenebis(salicylideneimine) (HL) and N,N'-ethylene-bis(3-methoxysalicylideneimine) (HL) have been isolated. They are 2D coordination polymer [Yb(HL)(NO)] ( 1), mononuclear Ln(HL)(NO) [Ln = Sm ( 2), Ho ( 3)]. The structures of 1- 3 were determined by single crystal X-ray crystallographic studies and their photophysical properties were investigated. [ABSTRACT FROM AUTHOR]

A series of novel lanthanide coordination polymers havebeen successfullysynthesized under hydrothermal or solvothermal conditions, namely,[Eu2(2,4′-bpdc)2(OH)(NO3)(H2O)3]n(1), [Ln(2,4′-bpdc)(1,4-bdc)0.5(DMF)-(H2O)·H2O]n[Ln = Eu (2); Ln = Pr (3); Ln = Nd (4)], [Ln(2,4′-bpdc)(DMF)2NO3]n[Ln = Eu (5); Ln = Nd (6); Ln = Gd (7)], and[Eu(2,4′-bpdc)(2,4′-Hbpdc)(H2O)]n(8), (2,4′-H2bpdc= 2,4′-biphenyldicarboxylic acid, 1,4-H2bdc = 1,4-benzenedicarboxylicacid, and DMF = N,N′-dimethylformamide).X-ray crystallographic studies reveal that 1featuresa three-dimensional (3D) framework with 45topology. 2–4, which are isostructural and synthesizedby using a mixture of 2,4′-H2bpdc and 1,4-H2bdc, exhibit two-dimensional (2D) (3,4)-connected net structures. 5–7show 2D layered structures containingdouble helix chains (Δ and Λ) with 44topology. 8possesses a 2D layered structure containing (4,6)-connectednetworks, which are connected by means of infinite zigzag chains linkedby 2,4′-bpdc2–and 2,4′-Hbpdc–anions. Furthermore, steady-state and time-resolvedspectroscopic measurements reveal that the four Eu(III) complexes, 1, 2, 5, and 8, exhibitremarkable red luminescence emissions with lifetimes at the millisecondscale. Complexes 4and 6display characteristicluminescent properties for Nd(III) in the near-infrared region. Thesinglet state and the lowest triplet level of ligand 2,4′-H2bpdc were calculated on the basis of the UV–vis absorbanceedges of ligand and the phosphorescence spectrum of Gd(III) complex 7. The energy transfer mechanisms in the lanthanide polymersare described and discussed. [ABSTRACT FROM AUTHOR]