Synthesis and crystal structures of PrIII and NdIII complexes with the macrocyclic cavitand cucurbit[6]uril

Abstract

24 O 12 )][Nd(NO 3 ) 6 ] complexes were prepared by heating a mixture of lanthanide nitrates, cucurbit[6]uril, and water in a sealed tube. X ray diffraction study demonstrated that the metal atoms in the former complex are linked to the macrocycle through tridentate coordination of the portal oxygen atoms of cucurbit[6]uril to the praseodymium(III) cation. The neodymium(III) complex is the first example of lanthanide compounds with cucurbit[6]uril belonging to coordination polymers.

Direct coordination of metal ions to cucurbit[n]urils

“…The alkaline earth metal ions include calcium, strontium, and barium dications ( Figure 5). Figure 5(a) shows that the structures of the tubular polymers of TMeQ [6] with Ca 2+ and Sr 2+ dications are similar, and Figure 5 [45]. Liu et al, in a recent publication, were the first to demonstrate a tubular polymer of Q [6] with a transition metal ion, Cu 2+ dication, which resulted in a honeycomblike framework [43].…”

“…Cucurbit[n]urils (Q[n]) readily include different organic molecules to form various hostguest inclusion complexes, pseudorotaxanes, catenanes, and molecular knots [25][26][27][28][29][30][31][32][33][34]. In addition, they also readily coordinate to metal ions, such as alkali and alkaline earth metal ions [35][36][37][38][39][40], transition metal ions [41][42][43], lanthanide metal ions, uranyl ions and their complexes [44][45][46][47][48][49][50][51] or clusters [52][53][54][55][56][57][58][59][60][61]. These interactions result in the formation of various exclusion complexes, one-dimensional (1D) or poly-dimensional architectures and frameworks.…”

Advances in the lanthanide metallosupramolecular chemistry of the cucurbit[n]urils

“…Its structure shows pseudo hexagonal packing of polymeric chains that consist of Q [6] molecules linked via pairs of neodymium cations bound to portal carbonyl groups (see Fig. 11f) [89]. In this arrangement, each Q [6] molecule is thus coordinated to four Nd 3+ ions, with each Nd 3+ bound to two Q [6] molecules (by one carbonyl group from one Q [6] molecule and two carbonyl groups from the adjacent Q[6] molecule).…”

“…In this arrangement, each Q [6] molecule is thus coordinated to four Nd 3+ ions, with each Nd 3+ bound to two Q [6] molecules (by one carbonyl group from one Q [6] molecule and two carbonyl groups from the adjacent Q[6] molecule). Each Nd 3+ site also binds to four water molecules and a bidentate nitrate anion so that each metal centre is again 9-coordinate [89]. Use of a lanthanide bromide salt rather than a nitrate salt results in changes in both the composition and the structure of the corresponding Ln 3+ -Q [6] complexes -once again emphasising the difficulties in predicting the nature of the product from a given synthetic procedure [87].…”

Simple Coordination Complexes of Cucurbit[n]urils with Metal Ions

“…A guest water molecule resides in the cavity of the Q6 and is disordered between two positions (Fig. 2.17d) [47]. An X-ray diffraction study (Fig.…”