Intercalation of a manganese(II)-thiacalixarene luminescent complex in layered double hydroxides: synthesis and photophysical characterization

Utilizing the osmotic swelling of Layered Double Hydroxides (LDHs, [Mg1-xAlx(OH)(2)](x+)(NO3-)(x)) in formamide, the anionic luminescent complex [(ThiaSO(2))(2)(Mn-II)(4)F](-) (ThiaSO(2) = p-tert-butylsulfonylcalixarene) is introduced between the positive layers, leading to doping of LDH. In the recovered LDH layers, the hexagonal prism morphology of the precursor is well retained. The formula of the resulting compound (Mg0.71Al0.29(OH)(2)(NO3)(0.288)((ThiaSO(2))(2)(Mn)(4)F)(0.002)(H2O)(0.5)) (1) was determined by elemental and thermogravimetric analysis. The low doping rate is attributed to the low negative charge density (e angstrom(-2)) of the complex. The basal spacing of 12.02 angstrom indicates that [(ThiaSO(2))(2)(Mn-II)(4)F](-) is sandwiched across the width by positive LDH layers. The photophysical properties of compound 1 were studied in the solid state. 1 presents luminescence properties upon UV excitation, with the emission maximum centered at 630 nm and 650 nm in the presence and the absence of atmospheric O-2, respectively. Photophysical studies have been carried out under different atmospheres and using various excitation wavelengths. The relationship of the extinction of emission with the presence of molecular oxygen is reported, and demonstrates the very high sensitivity of this compound to oxygen. Finally, incorporation of the luminescent complex within the LDH host allows the O-2-sensitivity to remain similar to that observed in solution whilst avoiding photo-degradation, thereby opening perspectives for use in oxygen sensing or singlet oxygen generation.

Automated summary

The anionic luminescent complex [(ThiaSO(2))(2)(Mn-II)(4)F](-) is introduced between the positive layers of Layered Double Hydroxides in formamide, resulting in the doping of LDH. The photophysical properties of the resulting compound show luminescent properties with high sensitivity to oxygen under different atmospheres and excitation wavelengths. Incorporating the luminescent complex within the LDH host allows for high sensitivity to oxygen without photo-degradation, making it potential for oxygen sensing or singlet oxygen generation applications.