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-1κO-di-μ-chlorido-1:2κ(4) Cl:Cl-di-chlorido-1κCl,2κCl-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. C71, 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†à (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.