Birefringence and polarized luminescence of a manganese(ii) chloride–triphenylphosphine oxide compound: application in LEDs and photolithography

Abstract

A new polymorphic modification of the well-known coordination compound [(Ph₃PO)₂MnCl₂] (where Ph₃PO is triphenylphosphine oxide) was designed and investigated in terms of photophysics, electron paramagnetic resonance, and density functional theory. The obtained polymorph emits green luminescence (λ_max ≈ 518 nm) resulting from Mn(II) d–d transitions (⁴T₁ → ⁶A₁) with an excitation wavelength dependence of the quantum yield explained via high-energy transfer from the organic moiety to the manganese(II) ion. The [(Ph₃PO)₂MnCl₂] complex is characterized through high zero-field splitting parameters with high-order terms. Quantum-chemical calculations were carried out to investigate the optical and magnetic properties. It was shown that single crystals and oriented films of [(Ph₃PO)₂MnCl₂] demonstrate birefringence and angular dependence of the polarized-luminescence spectrum, and can be used for projection and proximity printing in lithography.