Metal–organic frameworks as competitive materials for non-linear optics

Abstract

The last five years have witnessed a huge breakthrough in the creation and the study of the properties of a new class of compounds - metamaterials. The next stage of this technological revolution will be the development of active, controllable, and non-linear metamaterials, surpassing natural media as platforms for optical data processing and quantum information applications. However, scientists are constantly faced with the need to find new methods that can ensure the formation of quantum and non-linear metamaterials with higher resolution. One such method of producing metamaterials in the future, which will provide scalability and availability, is chemical synthesis. Meanwhile, the chemical synthesis of organized 3D structures with a period of a few nanometers and a size of up to a few millimeters is not an easy task and is yet to be resolved. The most promising avenue seems to be the use of highly porous structures based on metal-organic frameworks that have demonstrated their unique properties in the field of non-linear optics (NLO) over the past three years. Thus, the aim of this review is to examine current progress and the possibilities of using metal-organic frameworks in the field of non-linear optics as chemically obtained metamaterials of the future. The review begins by presenting the theoretical principles of physical phenomena represented by mathematical descriptions for clarity. Major attention is paid to the second harmonic generation (SHG) effect. In this section we compare inorganic single crystals, which are most commonly used to study the effect in question, to organic materials, which also possess the required properties. Based on these data, we present a rationale for the possibility of studying the non-linear optical properties of metal-organic structures as well as describing the use of synthetic approaches and the difficulties associated with them. The second part of the review explicitly acquaints the reader with a new class of materials which successfully combines the positive properties of organic and inorganic materials. Using recently synthesized metal-organic frameworks and coordination polymers in the field of non-linear optics as an example, we consider synthetic approaches used for obtaining materials with desired properties and the factors to be considered in this case. Finally, probable trends towards improving the quality of the synthesized materials with regards to their further use in the field of non-linear optical effects are described.

Enantiopure Chiral Coordination Polymers Based on Polynuclear Paddlewheel Helices and Arsenyl Tartrate

“…No significant decrease of the dichroic signals was found when compared with those of the freshly prepared solutions ( Figure 5). The robustness of these polynuclear helices in solution was also demonstrated by a decrease of only 15% in the intensity of the dichroism spectrum of ∆-2 after heating to 80 • C (the highest attainable temperature for our experimental setup) for 3 h. This is similar to what was observed for enantiomerically resolved [Co 3 (dpa) 4 6 ] 2 complexes, which showed conformational stability in MeCN solution, even in the absence of chiral anions [29]. DMF was chosen for the present experiments, as it was one of the few solvents in which the compounds were sufficiently soluble.…”

“…Specifically, chiral Coordination Polymers (CPs) offer a great potential in the context of numerous fields such as enantioselective catalysis [1][2][3][4], nonlinear optics [5,6], ferroelectricity [7], and magnetochiral dichroism [8]. Such enantiopure complexes can be obtained fortuitously by spontaneous resolution during crystallization [9,10] or by design, using chiral ligands, metalloligands [11][12][13], or chiral inductors, such as solvents, templates, or counteranions [14][15][16].…”

A Recyclable Metal–Organic Framework as a Dual Detector and Adsorbent for Ammonia

“…[12] MOFs are characterized by high porosity, with some of them possessing the highest volume and surface area, and lowest crystal density among all materials known to date. [13] The immense choice of metal ions or clusters and ligands offers vast opportunities to rationally design and synthesize MOFs with specific functionalities for targeted applications in areas of gas storage and separation, [14] catalysis, [15] sensing, [16] non-linear optics, [17] ferroelectricity, [18] magnetism, [19] and conductivity. [20] Recently, there is an increasing interest in developing porous and robust MOFs for the selective detection, capture and destruction of harmful molecules including toxic industrial chemicals (SO2 and NH3), and chemical warfare agents (sarin, sulfur mustard, and dimethyl methylphosphonate).…”

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

“…The strengthened π–π interaction consequently caused increased oscillator strength of 2 , which is proportional to the square of transition dipole moment. Under the external electric field, the electrons are delocalized and can easily move, which ultimately lead to an increase in total dipole moment and the asymmetry of the system . The results show that increased interpenetration induces larger transition dipole moment of 2 .…”

“…Second‐order nonlinear optical (NLO) properties present in the non‐centrosymmetric solids have widespread applications in the emerging field of photonics for optical signal transmission and processing . Non‐centrosymmetric MOFs can be rationally designed and constructed from carefully chosen rigid bridging ligands with the desired metal coordination geometries.…”