Tubelike Uranyl–Phenylenediacetate Assemblies from Screening of Ligand Isomers and Structure-Directing Counterions

Abstract

under solvo-hydrothermal conditions and in the presence of [M(L)n] q+ cations, in which M = transition metal cation, L = 2,2ʹ-bipyridine (bipy) or 1,10-phenanthroline (phen), n = 2 or 3, and q = 1 or 2, gave ten complexes which have been crystallographically characterized. The diacetate ligands are bis-chelating and the uranyl cations are tris-chelated in all cases. [UO2(1,2-PDA)2Zn(phen)2]⋅2H2O (1) and [UO2(1,4-PDA)2Mn(bipy)2]⋅H2O (2) are heterometallic, neutral one-dimensional (1D) coordination polymers in which the carboxylate-coordinated 3d block metal cation is either decorating only (1), or participates in polymer building (2). [Zn(phen)3][(UO2)2(1,3-PDA)3] (3) and [Ni(phen)3][(UO2)2(1,4-PDA)3]⋅H2O (4), with separate counterions, crystallize as anionic twodimensional (2D) networks, as does [Cu(bipy)2][H2NMe2][(UO2)2(1,4-PDA)3] (5), which displays parallel 2D interpenetration. The complex [Zn(phen)3][(UO2)2(1,2-PDA)3]⋅7H2O (6) crystallizes as a ladderlike, slightly inflated ribbon. The same topology is found in [Zn(bipy)3][(UO2)2(1,3-PDA)3] (7), but the larger separation between coordination sites and the coexistence of curved and divergent ligand conformations produce a tubelike assembly. An analogous, but more regular and spacious tubular geometry is found in [M(bipy)3][(UO2)2(1,4-PDA)3] with M = Co (8) or Ni (9), and {Λ-[Ru(bipy)3]}[(UO2)2(1,4-PDA)3] (10). The disordered counterions in 8 and 9 are replaced by well-ordered, enantiomerically pure chiral counterions in 10. The tubular assemblies formed in 7-10 are characterized by an oblong section and the presence of gaps in the walls, which enable the inclusion of two rows of counterions in the cavity.

Structure-Directing Effects of Coordinating Solvents, Ammonium and Phosphonium Counterions in Uranyl Ion Complexes with 1,2-, 1,3-, and 1,4-Phenylenediacetates

“…(3.3%), 7 (7.2%), 14 (7.4%) and particularly 11 (14%). This range of values is similar to those previously found in related complexes, 9,10 larger values in uranyl carboxylate complexes being uncommon. 38,39…”

“…In combination with our previous work, 9,10 consideration that this flexibility could be used to minimise repulsion between like charges leads to the conclusion that the most favoured conformation for all three isomeric ligands would be the trans form, while a cis conformation would be unfavourable. Since the barrier to rotation about a simple C-C single bond is typically ~12 kJ mol -1 , 32 and is an energy spanned by that of hydrogen bonds, which range from ~12 kJ mol -1 for a weak interaction such as CHO, 27 to >100 kJ mol -1 for a strong interaction such as OHO, 33,34 it might be anticipated that any deviation from a trans form might be associated with such interactions.…”

“…Similar (UO2)2(1,4-pda)2 rings have previously been found as subunits in different 1D or 2D assemblies. 9,10 This difference in conformation between the 1,2-pda 2ligand in 7 and 8 and the 1,3-and 1,4-pda 2ligands here is probably due to the reduced repulsion between the ring substituents in the latter. The 1,3-pda 2ligands which connect these dinuclear rings in 9 are in the trans conformation, and the chains are linear as consequence, while the 1,4-pda 2connecting ligands in 10 are also cis, which gives the chain a zigzag shape.…”

“…We have previously reported mono-or diperiodic (denoted 1D or 2D for convenience) coordination polymers based on these ligands, the 1D chains having in some cases a tubelike shape, which incorporate diverse organic or metal-containing counterions, particularly those of the form [M(L)n] q+ , in which M = transition metal cation, L = 2,2ʹ-bipyridine (bipy) or 1,10phenanthroline (phen), n = 2 or 3, and q = 1 or 2, and Ni II or Cu II complexes with azamacrocycles, as well as Pb II cations. 9,10 Overall, all three ligands have a strong tendency to favour the formation of 1D polymers, no higher periodicity having been obtained with 1,2-pda 2-alone (not associated with 1,4-pda 2-) in particular. Both 1,3-and 1,4-pda 2were shown to give some examples of 2D networks with separate [M(L)n] q+ counterions, in which case they display topologies of the hcb type or derived from it, with 2-fold interpenetration in one case.…”

1,3‐Adamantanedicarboxylate and 1,3‐Adamantanediacetate as Uranyl Ion Linkers: Effect of Counterions, Solvents and Differences in Flexibility

“…The solid‐state photoluminescence quantum yields (PLQYs) are low (≤ 1 %) for all compounds but 3 , for which the moderate value of 5 % has been measured. Such values are usual for uranyl carboxylate complexes,, [22b], although in some cases much larger yields were found,[30d], comparable to or larger than that of 24 % for uranyl nitrate hexahydrate.…”