Hybrid Molecular-Based Magnets Containing Organic NLO Chromophores: A Search toward an Interplay between Magnetic and NLO Behavior

Abstract

A new hybrid molecular-based ferromagnet of formula [(dmaph)PPh3][MnCr(ox)3], where [(dmaph)PPh3]+ stands for the (4-dimethylaminophenyl)triphenylphosphonium cation (ox2- being the oxalate anion), has been synthesized. It crystallizes in the monoclinic P21 space group, with lattice parameters a = 13.954(2) Å, b = 16.297(2) Å, c = 14.323(2) Å, and β = 99.27(1)°. Refinement based on Fo2 yields R = 0.072 and wR2 = 0.156. The compound exhibits a ferromagnetic interaction between Cr3+ and Mn2+, with a long-range magnetic ordering at TC = 4.5 K. The hyperpolarizability (β) of the cation is calculated within the framework of the INDO/SOS-based method, which indicates a β value comparable to that of p-nitroaniline for an absorption maximum at 306 nm (εmax = 28 500 M-1 cm-1). This result is consistent with the observation of a SHG efficiency 4 times that of urea for the parent [(dmaph)PPh3]Br salt, at 1.907 μm. The non-centrosymmetric [(dmaph)PPh3][MnIICrIII(ox)3] derivative is used as a model compound for an investigation of the potential effect of a ferromagnetic ordering on the bulk NLO response of hybrid materials made of NLO cations inserted between magnetic anionic layers.