Regular Article – Optical Phenomena and Photonics
Chloridocobaltate(II) metal–organic cocrystal delivering intermolecular-charge transfer-enhanced passive optical limiting: A comprehensive study on structure–property relation
Division of Physics, School of Advanced Sciences, Vellore Institute of Technology, 600 127, Chennai, India
Accepted: 10 July 2021
Published online: 26 July 2021
The structure–property relation of a novel metal–organic cocrystal piperazine-1,4-diium tetrachloridocobaltate(II) monohydrate (abbreviated as PCo) for third-order nonlinear optical applications is reported. The acid hydrolysis during pH optimization yielded anionic and cationic which together formed a stable chemical structure. The bulk single crystals were grown by slow solvent evaporation method with optimized solution pH of 3.5. Its response to the single-crystal X-ray diffraction confirmed PCo belongs to the monoclinic () crystal system. Investigated thermal, mechanical, linear absorption and emission properties show the suitability of PCo for optoelectronic device applications. The calculated molecular interaction energy at B3LYP/6-31G(p,d) level reveals the possibility of noncovalent intermolecular charge transfer via, and types of interactions. Rich availability of polarizable electronegative interactions between radicals upon laser stimuli enhanced nonlinear optical property in PCo cocrystal. The magnitude of third-order nonlinear optical susceptibility (), nonlinear refractive index () and nonlinear absorption coefficient () of PCo cocrystal under continuous-wave laser excitation were found to be esu, and , respectively. The excited state-assisted sequential two-photon absorption responsible for optical limiting is demonstrated by measuring the at different intensities of nanosecond pulsed laser excitations. Superior physicochemical properties with a low optical limiting threshold for both nanosecond pulsed and CW laser irradiance ( and , respectively) promote the PCo cocrystal as a promising candidate for optical limiting application.
© The Author(s), under exclusive licence to EDP Sciences, SIF and Springer-Verlag GmbH Germany, part of Springer Nature 2021