Unusual method for phenolic hydroxyl bridged lanthanide CPs: Syntheses, characterization, one and two photon luminescence

Abstract

A "basophilic method" for phenolic hydroxyl bridged lanthanide coordination polymers (CPs) was developed. With this method, eleven CPs with the general formula of [Ln(HL1)L1·H(2)O](n) (Ln = Tb (1), Nd (2), Eu (3), Gd (4), La (5), Er (6), Y (7), H(2)L1 = 4-methyl salicylic acid) and [Ln(HL2)L2·2MeOH](n) (Ln = Eu (8), Tb (9), Gd (10), La (11), H(2)L2 = 3-hydroxy-2-naphthoic acid) were synthesized based on two ligands, and five of them (1-4 and 8) were characterised by X-ray single crystal diffraction. The powder X-ray diffraction patterns (PXRD) of complexes showed that 1-7 are isostructural, 8-11 are isostructural. Furthermore, 1 was characterised by Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), elemental analysis (EA), one and two photon luminescence were investigated in detail.

A polymorphic lanthanide complex as selective Co2+ sensor and luminescent timer

“…S2). Bond lengths of Tb O vary in 2.321-2.639Å, are within the range of those usually encountered bond length of Ln O in lanthanide complexes [6]. Two Tb 3+ are pulled together by two carboxyl and two O, which make a short Tb Tb distance of 3.933Å.…”

“…As shown in Fig. 3, under the best excitation of 347 nm, 1 displayed the characteristic emission bands at 488, 544, 587 and 621 nm, which are assigned to the transitions of 5 D 4 -7 F 6 , 5 D 4 -7 F 5 , 5 D 4 -7 F 4 and 5 D 4 -7 F 3 , respectively [6,42]. Luminescence decay curve (Fig.…”

“…1 crystallizes in the same triclinic space group P-1, with the same formula of [Tb 2 (4-Msal) 6 (H 2 O) 4 ]·6H 2 O as 1a. However, the cell parameters and Z value are distinct (Scheme 1).…”

“…However, it is still a great challenge in controlling and predicting the precise structures of coordination complexes, attribute to both the binding flexibility of metal ions and versatile coordination mode of organic ligands, as well as the influence of reaction solvents, reaction temperature, reaction time, ratio of reactants and guestmolecules, etc. [6]. Consequently, as an important research topic of coordination complexes, crystallographic polymorphism is not just an obstacle or challenge, but also a good opportunity for developing novel materials and better understanding of crystal growth [7].…”

“…In this study, as the further and succession of our previous work [6,20], a simple ligand of 4-methyl salicylic acid (4-Msal), which has two coordination groups of carboxyl and phenolic hydroxyl, was selected to synthesize polymorphic lanthanide complex purposely. Fortunately, after 9 months of tentative experiments, a rarely reported polymorphic lanthanide complex was obtained by acac tuning method.…”