Planar Octagonal Tetranuclear Cobaltacarborane Macrocycle [(η5-C5Me5)Co(2,3-Et2C2B4H3-5-C≡C-7-C≡C)]4 for 2D Nonlinear Optics: Ultra-High-Response and Multistate Controlled Cubic NLO Switch

Abstract

Owing to the potential application in the development of new nonlinear optical (NLO) materials, metallomacrocycles have currently attracted considerable attention. The unusual 24 atoms {C16B8} cobaltacarborane ring 4, [Cp*Co(2,3-Et2C2B4H3-5-C≡C-7-C≡C)]4 (Cp* = η5-C5Me5), featured highly symmetrical, 2D planar, tetratruncated square architectures have been investigated and characterized compared to its 1D rod-like dinuclear building blocks 2a, [Cp*Co(2,3-Et2C2B4H3-7-C≡C)]2, 2b, [Cp*Co(2,3-Et2C2B4H3-5-C≡C)]2, and the 0D sandwich monomer 1, Cp*Co(Et2C2B4H4), by density functional theory. Calculations of geometric and electronic structures, UV–vis absorption spectra, polarizabilities (αave), and second hyperpolarizabilities (γtot) have been performed herein with the aim of rationalizing the structure–property relationship and providing a novel high-performance NLO molecular materials. It is found that the tetranuclear species present long-range bidirectional charge transfer behaviors, leading to an excellent ...