Giant Enhancement of Second Harmonic Generation Accompanied by the Structural Transformation of 7‐Fold to 8‐Fold Interpenetrated Metal–Organic Frameworks (MOFs)

Abstract

Interpenetration in metal–organic frameworks (MOFs) is an intriguing phenomenon with significant impacts on their properties, and functional applications. Herein, we show that a 7‐fold interpenetrated MOF (1) is transformed into an 8‐fold interpenetrated MOF by the loss of DMF in a single‐crystal‐to‐single‐crystal manner. This is accompanied by a giant enhancement of the second harmonic generation (SHG ca. 125 times) and two‐photon photoluminescence (ca. 14 times). The strengthened π–π interaction between the individual diamondoid networks and intensified oscillator strength of the molecules aid the augment of dipole moments and boost the nonlinear optical conversion efficiency. Large positive and negative thermal expansions of 1 occur at 30–150 °C before the loss of DMF. These results offer an avenue to manipulate the NLO properties of MOFs using interpenetration and provide access to tunable single‐crystal NLO devices.

Engineering entangled photon pairs with metal–organic frameworks

“…Recent experimental reports of competitive second-order [28][29][30] and third-order optical nonlinearities [31] with polycrystalline MOF crystals, have stimulated the need to develop a computational methodology that is capable of screening the available MOF databases, and generate a list of leading candidate structures with a suitable combination of features in their linear and nonlinear optical responses that make them competitive materials for applications in quantum optics. Large-scale computational MOF screening methods for applications in gas storage and gas separation have been developed [32,33], but extensions of these techniques are needed to discover novel applications of MOF materials in quantum technology.…”

Crystalline Porous Materials for Nonlinear Optics

“…[110] Copyright 2013, Royal Society of Chemistry. [115] In the crystal of [Zn(pvb) 2 ]•DMF, each Zn 2+ center has a distorted five coordinate geometry which extends in three dimensions to form a diamondoid network with a sevenfold interpenetration (Figure 2a,b). In contrast, [Zn(pvb) 2 ] forms four coordinated and eightfold interpenetrated networks, by the loss of DMF molecules from the crystal channels of [Zn(pvb) 2 ]•DMF (Figure 2c,d).…”

Millimeter-Sized Metal-Organic Framework Single Crystals without Inversion Symmetry: Controlled Growth and Self-Assembly Mechanism

“…Metal-organic frameworks (MOFs) are an established class of porous materials with demonstrated use in a wide range of applications that benefit from their record-high surface areas, including gas storage, 1 gas separation, 1,2 water purification, 3 fuel cells, 4 drug delivery, 5,6 catalysis, 7 and chemical sensing. 8,9 MOFs are also considered promising materials for applications in nonlinear optics, [10][11][12][13][14] given the variety of non-centrosymmetric structures with large optical nonlinearities that can be formed, 12,15 in comparison with the limited number of inorganic standards available in industry. Contrary to MOF applications that rely on crystal pore engineering, MOF crystals with small porosities are most favorable in nonlinear optics.…”