Synthesis and Characterization of New Lithium and Boron Based Metal Organic Frameworks with NLO Properties for Application in Neutron Capture Therapy

Abstract

In this work, we synthetized and characterized new crystalline materials with theranostic properties, i.e., they can be used both as bio-sensors and for “drug delivery”. The two solid crystalline compounds studied are Metal Organic Frameworks and have formulas Li[(C6H12O6)2B]·2H2O and Li[(C4H2O6)2B]·5.5H2O. They can be synthetized both with natural isotopes of Li and B or with 6Li and 10B isotopes, that can be explored for Neutron Capture Therapy (NCT) for anti-cancer treatment. The presence of chiral organic molecules, such as mannitol and tartaric acid, provides the NLO property to the crystals and thus their capability to generate the Second Harmonic, which is useful for applications as bio-sensors. The two compounds were characterized with X-ray Diffraction and the Second Harmonic Generation (SHG) responses were estimated by theoretical calculations, and the results were compared with experimental measurements of powdered samples. In order to test the behavior of such compounds under thermal neutron irradiation, we preliminary exposed one of the two compounds in the e_LiBANS facility at the Torino Physics Department. Preliminary results are reported.

[C(NH2)3][B(C2O2H4)2]: An Organic–Inorganic Hybrid Borate Containing Nonlinear-Optical Active Unit [B(C2O2H4)2]− with Solar-Blind-Region Optical Nonlinearity

“…Additionally, absorption peaks from 1077 to 926 cm –1 and from 756 to 548 cm –1 are attributed to the stretching and bending vibrations of the B–O bonds, respectively. The aforementioned absorption peaks additionally validate the existence of each group within the crystal structure, thereby aligning with that previously reported. − …”

“…This modification disrupts the symmetry of the (BO 4 ) 5− groups, leading to enhanced hyperpolarizability and polarizability anisotropy. Additionally, this method yields numerous high-performance fluorooxoborate crystals that find applications in the UV and deep-UV region, such as MB 5 O 7 F 3 (M = Mg 2+ , Ca 2+ , and Sr 2+ ), 11−14 23 and so on. However, as the carbon (C) chain grows, the excess dangling C−O bonds (or nonbonding orbitals) of the organic molecules may result in a decrease of the band gap.…”

“…Lots of organic–inorganic hybrid borates that exhibit exceptional properties have merged under this process, i.e. ASr­[C 4 H 2 O 6 ·B­(OH) 2 ]·4H 2 O (A = NH 4 + , K + , and Rb + ), , K 2 Cd 4 [(C 4 H 2 O 6 ) 2 B] 2 (H 2 O) 2 , NaB­(DL-C 4 H 4 O 5 ) 2 , Li­[(C 6 H 12 O 6 ) 2 B]·2H 2 O, and so on. However, as the carbon (C) chain grows, the excess dangling C–O bonds (or nonbonding orbitals) of the organic molecules may result in a decrease of the band gap.…”

Chiral metal–organic frameworks for photonics

“…While these molecules have been used directly as ligands, the resulting frameworks typically do not yield high SHG efficiencies, most likely due to their lack of conjugated systems (excepting some amino acid side chains). 131,[139][140][141]144 A more common strategy is to instead couple these enantiopure precursors to an aromatic moiety to derive chiral ligands with greater hyperpolarisability (Fig. 8).…”