Impressive second harmonic generation response in a novel phase-matchable NLO-active MOF derived from achiral precursors

Abstract

It is highly desirable but challenging to design and synthesize novel non-centrosymmetric (NCS) metal–organic frameworks (MOFs) with excellent nonlinear optical (NLO) properties. And the origin of their NLO responses remains vague. Herein, a novel 1D Zn-based MOF with unique zigzag helical chains, [Zn(bct)(H₂O)₂] (MOF-FJ1), has been prepared from achiral precursors. It crystallizes in an NCS space group P2₁2₁2₁ (no. 19) and is found to be a remarkable NLO material with a strong second-harmonic-generation (SHG) response (3.5 × commercial KH₂PO₄ (KDP)) and high laser-induced damage threshold (1.6 × commercial KDP). Moreover, theoretical calculations based on the length-gauge formalism are discussed to unveil a deepened cognition of the structure–property relationship, providing theoretical insight into the origin of the NLO response.