Synthesis, crystal structure and photophysical properties of a dinuclear Mn II complex with 6-(di-ethyl-amino)-4-phenyl-2-(pyridin-2-yl)quinoline.

A new quinoline derivative, namely, 6-(di-ethyl-amino)-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 -di-chlorido-1κ Cl ,2κ Cl -bis-[6-(di-ethyl-amino)-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 mol-ecule, resulting in a distorted octa-hedral 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 mol-ecules, 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 qu-antity of solvent mol-ecules, which resulted in 44 electrons in a void volume of 274 Å 3 , corresponding to approximately 1.7 mol-ecules of ethanol in the unit cell. These ethanol mol-ecules are not considered in the given chemical formula and other crystal data.