Optical properties of composites formed by transition metal macrocyclic complexes intercalated in thiophosphate layered phases

Hybrid materials, formed by strong absorbing macrocyclic complexes [Zn ₂L]·(NO₃)₂·H₂O or [MnL(H₂O)₂]·NO₃·H₂O (LH₂: macrocyclic ligand obtained from the [2 + 2] condensation of 2-hydroxy-5-methyl-1,3-benzenedicarbaldehyde and 1,2-diaminobenzene) intercalated in MnPS₃ and CdPS₃ layered phases, were obtained by the ion exchange method using the potassium precursor, K _0.4M_0.8PS₃(H₂O)_x. As a result of the conventional synthetic method, using stirring at room temperature, the following composites were obtained: [Zn₂L]_0.05K _0.30Mn_0.80PS₃(H₂O)_x (1), [Zn₂L]_0.10K_0.20Mn_0.80PS ₃(H₂O)_x (2), [Zn₂L] _0.05K_0.30Cd_0.80PS₃(H ₂O)_x (4), [MnL]_0.25K_0.15Mn _0.80PS₃(H₂O)_x (6), [MnL] _0.35K_0.05Mn_0.80PS₃(H ₂O)_x (7) and [MnL]_0.25K_0.15Cd _0.80PS₃(H₂O)_x (9). While the microwave assisted method gives: [Zn₂L]_0.05K _0.30Mn_0.80PS₃(H₂O)_x (3), [Zn₂L]_0.05K_0.30Cd_0.80PS ₃(H₂O)_x (5), [MnL]_0.25K _0.15Mn_0.80PS₃(H₂O)_x (8) and [MnL]_0.15K_0.25Cd_0.80PS₃(H ₂O)_x (10). The luminescent properties of the macrocyclic zinc(II) and manganese(III) complexes are not observed in the final composites due to the radiationless decay processes, which are favored by the packing of the macrocyclic species between the layers of the MPS₃ phase. The solid reflectance UV-Vis spectra indicate that the absorption edge of the composites is shifted to lower energies, as compared to the potassium precursor, 2.85 eV for K_0.4Mn_0.8PS₃(H₂O) _x and 3.20 eV for K_0.4Cd_0.8PS ₃(H₂O)_x. The absorption edge varies from 1.85 to 1.70 eV, depending on the stoichiometry of the composite.