Protonated N-oxide-4,4′-bipyridine: from luminescent BiIII complexes to hybrids based on H-bonded dimers or H-bonded open 2D square supramolecular networks
作者:Oksana Toma、Nicolas Mercier、Magali Allain、Chiara Botta
DOI:10.1039/c3ce41579a
日期:——
The N-oxide-4,4â²-bipyridine (bp4mo) ligand has been rarely used in coordination or supramolecular chemistry. Depending on experimental conditions in the bp4mo/BiX3 (X = Cl, Br) system, several compounds, in which the degree of protonation of bp4mo (Ï = H/bp4mo) varies, have been stabilized. In acidic conditions, either a complete N-protonation and a partial O-protonation (Ï = 1.5) or a complete N-protonation (Ï = 1.0) can occur, leading to either a hybrid salt based on H-bonded dimers [H(Hbp4mo)2]3+, or to O(Hbp4mo)âBi photoluminescent complexes. In neutral conditions, a partial N-protonation (Ï = 0.5) occurs in [H(bp4mo)2][BiCl4]. Although the N-oxide parts are free to bind Bi3+ cations, the organic entities prefer self-organizing through H-bonding (NHâ¯N and CHâ¯O) to give an impressive 2D supramolecular square network which accommodates the 1D BiCl4â polymeric anion.
N-氧化-4,4'-联吡啶(bp4mo)配体在配位或超分子化学中很少被使用。根据bp4mo/BiX3(X = Cl,Br)体系的实验条件,已稳定了几种不同程度质子化的bp4mo(τ = H/bp4mo)化合物。在酸性条件下,可以发生完全的N-质子化和部分的O-质子化(τ = 1.5),或完全的N-质子化(τ = 1.0),分别导致基于氢键二聚体的混合盐[H(Hbp4mo)2]3+或O(Hbp4mo)–Bi光致发光复合物。在中性条件下,在[H(bp4mo)2][BiCl4]中发生部分N-质子化(τ = 0.5)。尽管N-氧化部分可以与Bi3+阳离子结合,但有机成分更倾向于通过氢键(NH⋯N和CH⋯O)自组装,形成令人印象深刻的2D超分子方形网络,以容纳1D BiCl4−聚合阴离子。