Structure and assembly mechanism of a centipede-shaped high-nuclear Dy14Cu12 heterometallic nanocluster

The assembly studies of high-nuclear clusters have received much interest in recent years due to their targeted synthesis for some special usages. A Schiff base ligand 2-[N-(2-hydroxynaphthylidene)amino]-2-(hydroxymethyl)propane-1,3-diol (H4L) was thus prepared in this work and was allowed to react with [Cu-2(OAc)(4)(H2O)(2)] and Dy(NO)(3)center dot 6H(2)O, giving a high-nuclear 3d-4f heterometallic Cu12Dy14 nanocluster (1) with the formula [(C2H5)(3)NH](4)[Cu12Dy14O(OH)(16)(H2L)(8)(HL)(4)(HL')(4)(OAc)(10)](NO3)(4)(OAc)(2)center dot 6CH(3)CN center dot 5EtOH center dot 1.5H(2)O (H3L'= 1,1,1-tris-(hydroxymethyl)methanamine). It features a centipede-shaped structure constructed from eight Dy3Cu cubanes sharing the Dy(iii) vertices. Its assembly mechanism was explored through time-dependent high-resolution electrospray ionization mass spectrometry (HRESI-MS). This revealed that the hierarchical assembly of 1 undergoes two possible routes: H4L -> DyCuL -> Dy2CuL -> Dy3Cu2L2 -> Dy4Cu2L2 -> Dy4Cu3L3 -> Dy5Cu4L4 -> Dy14Cu12L12L'(4) and H4L -> DyCuL -> DyCu2L -> Dy2Cu2L2 -> Dy2Cu3L4 -> Dy3Cu4L4 -> Dy5Cu4L4 -> Dy14Cu12L12L'(4). These results not only provide solid evidence for understanding the assembly mechanism of high-nuclear 3d-4f clusters, but also help to give some hints for designing and preparing new high-nuclear clusters.