18-Crown-6 Coordinated Metal Halides with Bright Luminescence and Nonlinear Optical Effects

The crown-ether coordination compounds ZnX2(18-crown-6), EuX2(18-crown-6) (X: Cl, Br, I), MnI2(18-crown-6), Mn3Cl6(18-crown-6)2, Mn3I6(18-crown-6)2, and Mn2I4(18-crown-6) are obtained by ionic-liquid-based synthesis. Whereas MX2(18-crown-6) (M: Zn, Eu) show conventional structural motives, exhibit unusual single MnX4 tetrahedra coordinated to the complex. Surprisingly, some outstanding photoluminescence. Thus, rare Zn2+-based luminescence is observed unexpectedly efficient for ZnI2(18-crown-6) with a quantum yield of 54%. Unprecedented yields also EuBr2(18-crown-6), EuI2(18-crown-6) values 98, 72, 82%, respectively, which can be rationalized based on specific features. Most remarkable, however, Mn2I4(18-crown-6). Its features finite sensitizer–activator couples result in an extremely strong emission 100%. Consistent its features, moreover, anisotropic angle-dependent under polarized light nonlinear optical (NLO) effects occur, including second-harmonic generation (SHG). title their properties characterized single-crystal structure analysis, X-ray powder diffraction, chemical density functional theory (DFT) calculations, advanced spectroscopic methods.