Non-linear optical properties of β-D-fructopyranose calcium chloride MOFs: an experimental and theoretical approach

The second harmonic generation (SHG) properties of two MOFs, obtained from fructose and calcium chloride, were studied using a Non Linear Optics Multimodal microscope. The first-order hyperpolarizability and the second-order susceptibility were calculated at the DFT level of theory. Moreover, a semi-classical approach to non-linearities in the optical behaviour was used in order to determine the features responsible for the SHG. The MOFs were synthesized both in ethanol and by solid-solid interaction, with a simple, rapid, and low-cost methodology with no environmental impact, and were characterized with IR and RAMAN spectroscopy and both single-crystal and powder X-ray diffraction. Both the metal-carbohydrate based MOFs show an interesting SHG intensity: in particular, compound 1 shows an average SH intensity more than twice that of sucrose, in agreement with the theoretical results. A favorable combination of optical properties, transparency, thermal and chemical stability makes compound 1 a potential candidate for applications in electro-optics devices.