World of Conductive Two-Dimensional Metal-Organic Frameworks

ABSTRACT

A way of transfonning matter is manufacturing nanomaterials (NMs)/ devices or composites/layers. More is different. Layered metal-organic (MO) frameworks are modular solids with a width of a few atomic coatings. What are they used for? They exhibit properties distinct from the bulk. Layered materials are obtained and characterized as thin-layered nanostructures. Layered MO frameworks are interesting for materials and applications, owing to theh atomically thin-layered structure, large surface chemical reactivity, high surface/volume quotient, and large chemical-adsorption ability. Their structural, electronic, optical, and magnetic properties are utilized for learning. The interlayer distance is the greatest for MoS, because of its layered structure, in which a plane of Mo atoms is inserted" in other planes of S^2_. The three strata form a monolayer of MoS_v The table of periodic properties of the elements for some layered materials is analyzed: A steadiness results in interlayer distances for B-N in period 2. Model principles and structure-property relationships are derived: A series of linear models of the interatomic distance between coatings, vs. atomic number of layered materials, results in that the distance raises with atomic number. Non-linear equations improve correlations. Interlayer distance for S diverges from fits because of the three-stratum monolayer of MoS _v

INTRODUCTION

Here is an example of MO framework (MOF, cf. Figure 4.1). Layered- nanomaterials (NMs) questions follow [1]:

Ql. (Feynman). What could we do with layered structures with just the right layers?

Q2. (Feynman). What would the properties of materials be if we could really arrange the atoms the way we want them?

What can be done in the regard of classification for MOFs?

FIGURE 4.1 Conductive MOF with hexagonal pore apertures formed with triphenylene (HXTP) ligands. Source: Mirica [73].

The MOFs combine the properties of their inorganic and organic parts (cf. Table 4.1). In condensed matter physics (CMP), more is different [2]. Geim group reported bulk-graphite exfoliation into graphene (GR) [3], which paved the way to other two-dimensional (2D) crystals [4]. In this laboratory, Coronado group published superconductivity (SC)-magnetism co-existence by chemical design [5]. They imagined the magnetic reversal of isolated and organized molecular-based nanoparticles (NPs), via magnetic force microscopy (MFM) [6]. They switched magnetic vortex core in an only NP [7]. To induce quantum confinement effects drives current interest in one-monolayer (ML)-thick 2D NMs [8].

In earlier publications, it was informed the effects of type, size, and elliptical deformation on molecular polarizabilities of model single-wall carbon nanotubes (SWNTs) from atomic increments [9-12], SWNTs periodic properties and table based on the chiral vector [13,14], calculations on SWNTs solvents, co-solvents, cyclo pyranoses [15-18] and organic-solvent dispersions [19, 20], packing effect on cluster nature of SWNTs solvation features [21], information entropy analysis [22], cluster origin of SWNTs transfer phenomena [23], asymptotic analysis of coagulation-fragmentation equations of SWNT clusters [24], properties of follerite and symmetric С-forms, similarity laws [25], fullerite crystal thermodynamic characteristics, law of corresponding states [26], cluster nature of nanohoms (SWNHs) solvent features [27], SWNTs (co-)solvent selection, best solvents, acids, superacids, host-guest inclusion complexes [28], C/BC₂N/BN fullerenes/ SWNTs/nanocones (SWNCs)/SWNHs/buds (SWNBs)/GRs cluster solvation models in organic solvents [29-35], elementary polarizability of Sc/ fullerene!GR aggregates, di/GR-cation interactions [36] and conductive layered MOFs [37-40]. Conductive 2D MOFs were examined via instances from the Mirica group as examples.

TABLE 4.1 Metal-Organic Frameworks Combine the Properties of Their Inorganic and Organic Parts

UNIQUE CHARACTERISTICS AND CHALLENGES OF ULTRA-THIN 2D NMS

The NMs present a high surface-to-volume ratio and are more active than their micro and macro counterparts. Why 2D NMs? Their properties follow: (1) atomically thick, (2) control over the thickness, and (3) free of defects (pinhole-free device). Atomic sheets of 2D are atomically thin, layered crystalline solids with the defining characteristics of intralayer covalent bonding and interlayer van der Waals (VDW) bonding. An MOF is an ordered nanoporous three-dimensional (3D) coordination polymer composed of an inorganic part, an ion, or cluster, co-ordinated by organic linkers. It is a co-ordination net with organic ligands containing potential voids, or a co-ordination net being co-ordination compounds extending in at least one dimension via repeating co-ordination entities. The MOFs are net materials comprised of organic ligands connected by metal ion clusters into multidimensional structures, which usually present permanent porosity.

The unique characteristics of ultra-thin 2D NMs follow: (1) the electron confinement in 2D of ultra-thin 2D NMs without interlayer interactions, especially single-layer nanosheets, enables greatly compelling electronic properties compared to other NMs, rendering them appealing candidates for fundamental CMP study, electronic, optical, and magnetic nanodevice (ND) applications, (2) the atomic thickness offers them maximum mechanical flexibility and optical transparency, making them promising for the fabrication of highly flexible and transparent electronic/optical- electronic (optoelectronic) NDs, (3) the large lateral size and ultra-thin thickness endow them with ultra-high specific surface area, making them highly favorable for surface-active applications (chemical reactivity, adsorption, catalysis, etc.), (4) magnetic MOFs, (5) biological MOFs (bio- MOFs), (6) supramolecularly organized MOFs (SOFs), etc.

The MOFs present numerous fascinating applications associated with their important porosity and chemical versatility, e.g., gases separation, sensors, catalysts, biomedicine use, etc. Beyond the direct applications, MOFs serve for molecular sponges, which allow incorporating inside different molecules in an orderly way, facilitating the structural determination of the molecules that, otherwise, would be impossible. However, MOFs are considered to be inert for the fabrication of electronic NDs, owing to their poor electrical conductivity and difficult film-forming ability. The construction of conductive or semiconductive 2D MOFs is one of the promising possible solutions for MOFs integration into electronic NDs.