N-oxide-4,4′-bipyridine, a forgotten ligand in coordination chemistry: structure–photoluminescence property relationships in 2D and 1D lead-coordination polymers

Abstract

In the strong orange luminescent material of [Pb(bp4mo)Cl 2 ], two different types of octahedra, namely PbCl 4 N 2 and PbCl 4 O 2 , are bridged by the N-oxide-4,49-bipyridine (bp4mo) ligand, while its protonated form, Hbp4mo + , coordinates to Pb 2+ center only with the N-oxide group in [Pb(Hbp4mo) 2 Cl 2 ](NO 3 ) 2 . Important relationships between structures and luminescence properties are revealed.

Lead(II) 4,4′‐Bipyridine N‐Oxide Coordination Polymers – Highly Phosphorescent Materials with Mechanochromic Luminescence Properties

“…All compounds 1 – 4 were obtained as nice crystals from a slow liquid–gas diffusion synthesis. The crystal structure of 2 is isomorphous to that of 1 , which was already described . It consists of 2D coordination polymers (CPs) built from the coordination of metal ions by bp4mo molecules along one direction and by edge sharing of lead octahedra in the perpendicular direction (Figure ).…”

“…Synthesis and Characterization: The bp4mo ligand has been synthesized as (bp4mo) · 2H 2 O according to the literature (details in the Supporting Information). As for the known [PbCl 2 (bp4mo)] compound ( 1 ), all the three compounds [PbX 2 (bp4mo)], X = Br ( 2 ), X = I ( 3 ) and X = NO 3 ( 4 ) were obtained at room temperature by a slow liquid–gas diffusion method from a mixture of PbX 2 and (bp4mo) · 2H 2 O, which were solubilized in a minimum of DMSO [ 2 : 20 mg = 5.4 × 10 –5 mol PbBr 2 and 22 mg = 1.1 × 10 –4 mol (bp4mo) · 2H 2 O; 3 : 64.5 mg = 1.4 × 10 –4 mol PbI 2 and 26.5 mg = 1.4 × 10 –4 mol (bp4mo) · 2H 2 O] or water [ 4 : 42.2 mg = 1.3 × 10 –4 mol Pb(NO 3 ) 2 and 26.5 mg = 1.4 × 10 –4 mol (bp4mo) · 2H 2 O] with ethyl acetate ( 2 , 3 ) or acetone ( 4 ) as the counter solvent. After a few days, pale yellow crystals of 2 , yellow crystals of 3 and pale yellow crystals of 4 were obtained.…”

“…These ligands, which are not commercially available, have been rarely used in the field of coordination chemistry, in contrast with the well‐known symmetrical 4,4′‐bipyridine or 4,4′‐bipyridine N , N′ ‐dioxide . Up to now, only a series of four metal complexes based on 4,4′‐bipyridine N ‐oxide were reported by Loeb et al and, in 2012, we described the first coordination polymer based on bp4mo ligands [PbCl 2 (bp4mo)], which is characterized by a bright emission in the orange‐red region . Focusing on Bi 3+ metal ions, luminescent complexes based on bipyridinium derivatives ligands including a pyridyl N ‐oxide group ( N ‐alkyl‐4,4′‐bipyridinium N′ ‐oxide) were first obtained, but the most interesting and promising results were obtained in the Bi 3+ /bp2mo and Bi 3+ /bp4mo systems where three polymorphic complexes, [BiBr 3 (bp2mo)], and two highly luminescent compounds (TBA)[BiBr 4 (bp4mo)] and [BiBr 3 (bp4mo) 2 ], were characterized (TBA = tetrabutylammonium).…”

Photoluminescent lead(II) coordination polymers stabilised by bifunctional organoarsonate ligands

“…Hybrid coordination compounds containing Pb(II) ions may have interesting photochemical and photophysical properties [61–67, 86]. However, in comparison to many transition metal or lanthanide systems, the photoluminescence properties of lead(II)-organic frameworks are less explored.…”

Sonochemical synthesis of a novel nanoscale 1D lead(II) [Pb2(L)2(I)4]n coordination Polymer, survey of temperature, reaction time parameters

“…During the past two decades, the rational design, construction, and characterization of metalorganic coordination polymers (CPs) have received significant attention in the fields of materials chemistry and crystal engineering, owing to intriguing structures and potential applications in a variety of fields such as luminescence [1,2], magnetism [3][4][5], gas absorption and separation, chemical sensors [6][7][8], heterogeneous catalysis [9][10][11] and drug delivery [12,13]. Although a great number of coordination polymers with diverse structures and interesting properties have been constructed, the precise prediction and controllable preparation of such materials are still a great challenge for chemists, since a lot of factors may largely affect the overall structural formation.…”