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

A new quinoline derivative, namely, 6-(diethylamino)-4-phenyl-2-(pyridin-2-yl)quinoline, C 24 H 23 N 3 ( QP ), and its Mn II complex aqua-1κ O -di-μ-chlorido-1:2κ 4 Cl : Cl -dichlorido-1κ Cl ,2κ Cl -bis[6-(diethylamino)-4-phenyl-2-(pyridin-2-yl)quinoline]-1κ 2 N 1 , N 2 ;2κ 2 N 1 , N 2 -dimanganese(II), [Mn 2 Cl 4 (C 24 H 23 N 3 ) 2 (H 2 O)] ( MnQP ), were synthesized. Their compositions have been determined with ESI-MS, IR, and 1 H NMR spectroscopy. The crystal-structure determination of MnQP revealed a dinuclear complex with a central four-membered Mn 2 Cl 2 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. C 71 , 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 Å 3 , 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.