CONDUCTIVE TWO-DIMENSIONAL (2D) MOFS AS MULTIFUNCTIONAL MATERIALS

Large л-conjugated conductive 2D MOFs, via the bottom-up approach, emerged as interesting 2D NMs. Du group showed the design and bottom-up fabrication of a noble-metal-free Ni phthalocyanine-based 2D (NiPc-MOF), for highly efficient H,0 oxidation catalysis [71]. The NiPc-MOF was easily grown on various substrates. The TF deposited on F-doped tin oxide (FTO) showed high catalytic O, evolution reaction (OER) activity with a low onset potential (<1.48 V, overpotential < 0.25 V), high mass activity

(883.3 A g^-1) and excellent catalytic durability. Catalyst of 2D MOF TF represented the best OER catalytic activity among molecular catalyst-based NMs. Their work represented the first synthesis of an NiPc-MOF NM and application of ^-conjugated 2D MOF for H,0 oxidation. Livingston group informed polymer nanofilms (NFs) with enhanced microporosity by interfacial polymerization [72]. They suggested an evolutionary algorithm (EA), targeted upon the discovery of optimal structures and properties for molecular materials. Conductive 2D MOFs emerged as an only class of multifunctional NMs, because of compositional and structural diversity accessible via bottom-up self-assembly. Mirica group reviewed progress in the development of conductive 2D MOFs, with emphasis on synthetic modularity, ND integration strategies, and multifunctional properties [73]. They discussed applications spanning sensing, catalysis, electronics, energy conversion, and storage. They addressed challenges and future outlook, in the context of molecular engineering and practical development of conductive 2D MOFs.

CALCULATION RESULTS

Typical 2D NMs were measured with layer-layer separation between layers: graphite, black P (P-black), TMD MoS₂, BN-/;, and an MOF. Separations result lesser than 3.5A « 5 nm. Constancy results in the separation for graphite, P-black, BN-/;, and MOF. Notwithstanding, the separation results the greatest for MoS, owing to its layer-layer arrangement, in which a plane of Mo atoms is inserted in others of S²~. The three strata form an ML of MoS,. The 2D-NMs periodic table of the elements (PTE) was calculated. It shows [B-N, P, S, Mo] with oxidation states (OSs) 6, 3, 5, -3, etc. Again, a steadiness results in separations for B-N atoms (BN-/;, graphite) in period 2. Some quantitative structure-property relationships (QSPRs) were gotten: A linear fit of separations vs. atomic number Z of 2D NMs was carried out. It results that the separation increases with Z:

Notwithstanding, layer-layer separation for S (Z = 16, MoS₂) diverges horn fit owing to three-strata ML of MoS,. Slope decays four-fold if only group-V elements (N, P) are included in the trend line:

Three-parameter power model of layer-layer separations vs. Zwas performed. It betters fit:

Again, layer-layer separation for S (MoS₂) deviates from model owing to three-strata ML of MoS,.

Two-parameter power model of layer-layer separations vs. Z was performed. It betters fit:

One more time, layer-layer separation for S drifts from model owing to three-strata ML of MoS,.

Possible modes of charge transport (CT) were proposed in 2D MOFs: hopping CT, through-space CT, and through-bond CT. Core organic ligand building blocks were obtained for the construction of 2D MOFs. Triphenylene- based organic ligands were achieved with cross-hnking heteroatom (O, S, NH). Table 4.2 lists progress in the field of conductive 2D MOFs with applications (e.g., chemical sensing, FETs, energy conversion, energy storage, catalysis). General methods of integrating conductive 2D MOFs into NDs were found. Applications of traditional and conductive 2D MOFs were gained.

DISCUSSION

Nanoscience is a general term used to specify the level of knowledge, deep to 1 mil = 10“⁹ m. Together with the technology enabling the application of nanoscience, in a variety of fields [e.g., science, technique, health, society, culture (nanotechnology)], they define the Nanoera (new times of unprecedented progress in the human life). Research for materials with applications in technology or healthcare is an important task. The efforts are justified by the need of special properties (e.g., light, and strong, biodegradable, and low-polluting materials and processes).

Interestingly, MOFs are becoming promising materials because of the existence of both inorganic (semiconducting, etc.) and organic (л-л stacking, etc.) properties.

’ HHTP: 2,3,6,7,10.ll-hexahydroxytriphenylene. ^ь ШТР: hexaiminotriphenylene.

^CBHT: benzenehexathiolate. ^d Pc: phthalocyanine. ^s HTTP: hexatliiotriphenylene. ^f LOD: limit of detection.

Source: Ко, Mendecki. and Milica [73].