A brightly emissive halomanganates(II) with triphenylphosphonium cation: Synthesis, luminescence, and up-conversion phenomena

Abstract

A series of [HL]2[MnX4] [X = I, Br, Cl] tetrahalomanganates with triphenylphosphonium cation has been designed and investigated in photophysics and EPR terms. At room temperature, the solid complexes exhibit a remarkably bright green phosphorescence (λmax = 525 nm–555 nm) resulted from the Mn(II) d-d transitions (4T1 → 6A1) with high quantum efficiency (>50%) and a short lifetime of the iodomanganate complex (≈41 μs). Under infrared excitation (λEx = 780 nm) the complexes exhibit unusually luminescence in the visible region (λmax ≈ 500 nm). The EPR spectra of complexes are characterized by the deviation of the g-factor from the ge free electron value and by the high value of the zero-field splitting parameters on account of the spin-orbit coupling. The correlations between the luminescence and magnetic properties of the title complexes are discussed.