Synthesis of poly(ethylene oxide)s with 1,2,4-triazol-4-yl end groups - Macroligands for bistable metal-polymer complexes

Abstract

Poly(ethylene oxide) methyl ether 4H-1,2,4-triazol-4-yl (1) has been synthesized as a novel macroligand. ESI-MS (electrospray ionisation mass spectrometry), MALDI-TOF (matrix-assisted laser desorption ionisation time-of-flight) MS as well as NMR spectroscopy were used for the accurate determination of number-average molecular weights (M̄n), the crucial parameter for subsequent synthesis of metal-polymer complexes of four different samples 1a-d. Reaction of polymer 1a with [Fe(H2O) 6](nps)2 (nps = 3-nitrophenylsulfonate) gave [Fe(1a) 3](nps)2, a bistable metalpolymer complex that exhibited low-spin (LS) to high-spin (HS) transitions around T1/2 = 257 K, accompanied by a change in colour from violet (LS) to slightly yellow (HS).