Purely Heterometallic Lanthanide(lll) Macrocycles through Controlled Assembly of Disulfide Bonds for Dual Color Emission.

Lanthanide complexes based on bis(amides) of diethylenetriaminepentaacetic acid with thiol functionalities are modified with 2,2'-dipyridyl disulilde to give activated complexes that can selectively react with thiol-functionalized complexes to form heterometallic lanthanide macrocycles. The preparation and full characterization of the polyaminocarboxylate ligands N,N"-bis- [p-thiophenyl(aminocarbonyl)]diethylenetriamine-N,N',N"-triacetic acid (H3L") and the activated N,N"-bis[p-(pyridyldithio)- [phenyl(aminocarbonyl)] ]diethylenetriamine-N,N',N1'-triacetic acid (H3!]') and the complexes LaL", NdLX, SInLx, EULx, GdLX, Dy!]', ThLX, ErLX, and YbLX are reported. The luminescence properties of the LnL" complexes emitting in the visible (where Ln = Dy3+, .p3+ Eu3±, and Sm3+) are examined by steady-state and time-resolved photoluminescence, and the triplet state energy level of GdLX was estimated to be 24100 cm' from the 0-0 band of the 77K phosphorescence spectrum. Near-infrared emission was detected for the NdLX, YbLX and Er!]' complexes, demonstrating the versatility of the thiophenol chromophore. The assembly of purely heterometallic EuThLx2 macrocycles by reaction of Eu!] with ThL was followed by UV-vis absorption spectroscopy, monitoring the characteristic absorption peak of pyridyl-2-thione at 353 nm. Analysis of the solution by mass spectrometry reveals the formation of purely heterometallic macrocycle EuThLx2. This is in contrast with the results obtained by dynamic self-assembly under oxidative conditions, where we observe a statistical mixture of macrocyclic complexes of Eu2!]'2, Th2Lx2, and EuThLx2. The EuThLx2 macrocycle displays dual color emission, incorporating the characteristicf-f transitions of Eu3+ and Th3+. Investigation into the time-resolved photophysical properties of EuThLx2 reveals energy transfer from Tb3+ to Eu3+, facilitated by the different conformations of the macrocycle in solution. [ABSTRACT FROM AUTHOR]