Synthesis, crystal structure and photophysical properties of a dinuclear MnII complex with 6-(di­ethyl­amino)-4-phenyl-2-(pyridin-2-yl)quinoline

The two Mn^II atoms in the complex display a different coordination number, viz. five with a distorted trigonal–bipyramidal Cl₃N₂ and six with a distorted octa­hedral Cl₃N₂O coordination set.

A new quinoline derivative, namely, 6-(di­ethyl­amino)-4-phenyl-2-(pyridin-2-yl)quinoline, C₂₄H₂₃N₃ (QP), and its Mn^II complex aqua-1κO-di-μ-chlorido-1:2κ⁴Cl:Cl-di­chlorido-1κCl,2κCl-bis­[6-(di­ethyl­amino)-4-phenyl-2-(pyridin-2-yl)quinoline]-1κ²N¹,N²;2κ²N¹,N²-dimanganese(II), [Mn₂Cl₄(C₂₄H₂₃N₃)₂(H₂O)] (MnQP), were synthesized. Their compositions have been determined with ESI-MS, IR, and ¹H NMR spectroscopy. The crystal-structure determination of MnQP revealed a dinuclear complex with a central four-membered Mn₂Cl₂ ring. Both Mn^II atoms bind to an additional Cl atom and to two N atoms of the QP ligand. One Mn^II atom expands its coordination sphere with an extra water mol­ecule, resulting in a distorted octa­hedral shape. The second Mn^II atom shows a distorted trigonal–bipyramidal shape. The UV–vis absorption and emission spectra of the examined compounds were studied. Furthermore, when investigating the aggregation-induced emission (AIE) properties, it was found that the fluorescent color changes from blue to green and eventually becomes yellow as the fraction of water in the THF/water mixture increases from 0% to 99%. In particular, these color and intensity changes are most pronounced at a water fraction of 60%. The crystal structure contains disordered solvent mol­ecules, which could not be modeled. The SQUEEZE procedure [Spek (2015#). Acta Cryst. C71, 9–18] was used to obtain information on the type and qu­antity of solvent mol­ecules, which resulted in 44 electrons in a void volume of 274 ų, corresponding to approximately 1.7 mol­ecules of ethanol in the unit cell. These ethanol mol­ecules are not considered in the given chemical formula and other crystal data.