Distinct magnetic relaxation behaviors in nitronyl nitroxide-based cocrystalline supramolecular system with DyIII-O-H⋯O-N hydrogen bond

Abstract

The self-assembly of Dy(hfac)3·2H2O, Co(hfac)2·2H2O or Mn(hfac)2·2H2O (hfac = hexafiuoroacetylacetonate) with NITPh-triazole radical (NITPh-triazole = 2-[2-(1H-1,2,4-triazol-1-yl)phenyl]-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide) produces two 2p-3d-4f compounds of formula {[Dy(hfac)3(H2O)2][Co2(hfac)4(NITPh-triazole)2]2.CH2Cl2}n (1) and {[Dy(hfac)3(H2O)2][Mn2(hfac)4(NITPh-triazole)2]2}n (2) featuring extraordinary intermolecular hydrogen bonds between coordinated H2O molecules and uncoordinated NO groups linking into a supramolecular one-dimensional chain. Notably, the LnIII-O-H⋯O-N hydrogen bond bridge has been rarely observed in nitronyl nitroxide-metal system. Magnetic performance and heat capacity of both 2p-3d-4f compounds are detected. Interestingly, 1 and 2 both show apparent double peaks of χ′′ signals with two-step magnetic relaxation processes. Furthermore, the effective barrier of 1 is obviously higher than 2. As far as we know, employing unusual intermolecular LnIII-O-H⋯O-N hydrogen bond, it is the first to obtain supramolecular 2p-3d-4f one-dimensional heterospin materials with apparent slow magnetic relaxation and heat capacity behaviors.