Physical Phenomena in Porous Frameworks

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Learn More CiteCitationCitation and abstractCitation and referencesMore citation options ShareShare onFacebookX (Twitter)WeChatLinkedInRedditEmailJump toExpandCollapse EditorialFebruary 4, 2025Physical Phenomena in Porous FrameworksClick to copy article linkArticle link copied!Thomas Heine*Thomas HeineFaculty of Chemistry and Food Chemistry, TU Dresden, Bergstrasse 66c, 01069 Dresden, GermanyHelmholtz-Zentrum Dresden-Rossendorf, Centrum for Advanced Systems Understanding, CASUS, Untermarkt 20, 02826 Görlitz, GermanyDepartment of Chemistry, Yonsei University and IBS center for nanomedicine, Seodaemun-gu, Seoul 120-749, Republic of Korea*Email: [email protected]More by Thomas Heinehttps://orcid.org/0000-0003-2379-6251Mircea DincaMircea DincaDepartment of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United StatesMore by Mircea Dincahttps://orcid.org/0000-0002-1262-1264Guangshan ZhouGuangshan ZhouKey Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education, School of Chemistry, Northeast Normal University, Changchun 130024, ChinaMore by Guangshan Zhouhttps://orcid.org/0000-0002-5794-3822Open PDFAccounts of Chemical ResearchCite this: Acc. Chem. Res. 2025, 58, 3, 327–329Click to copy citationCitation copied!https://pubs.acs.org/doi/10.1021/acs.accounts.4c00835https://doi.org/10.1021/acs.accounts.4c00835Published February 4, 2025 Publication History Received 23 December 2024Published online 4 February 2025Published in issue 4 February 2025editorialCopyright © Published 2025 by American Chemical Society. This publication is available under these Terms of Use. Request reuse permissionsThis publication is licensed for personal use by The American Chemical Society. ACS PublicationsCopyright © Published 2025 by American Chemical SocietySubjectswhat are subjectsArticle subjects are automatically applied from the ACS Subject Taxonomy and describe the scientific concepts and themes of the article.Electrical conductivityMaterialsMetal organic frameworksQuantum mechanicsTwo dimensional materialsPorous materials are characterized by a high internal surface area and significant pore volume. Natural examples, such as microporous zeolites, have been known to humanity since ancient times, but their systematic investigation only started in the 1930s and flourished with the discovery of synthetic zeolites and their critical role in modern catalysis, molecular sieving, and ion exchange. The broader family of framework compounds was later enriched with the development of coordination networks (1,2) and metal–organic frameworks (MOFs). (2) The latter are distinguished by their increased stability and permanent porosity. (3,4) MOFs, along with their purely organic relatives, covalent organic frameworks (COFs) (5) and porous aromatic frameworks (PAFs), (6) are obtained by reticular chemistry, "the chemistry of linking molecular building blocks by strong bonds to make crystalline open frameworks". (7) The vast structural complexity of molecular building blocks results in a plethora of crystal nets that describe these framework materials. (8) Because the crystal structure significantly influences the physical properties (e.g., see ref (9) for a tutorial review on two-dimensional systems), targeting particular topologies can be used as a rational design element for new property-tailored materials.Traditional applications of framework materials take advantage of their porosity, for instance, in gas storage, molecular separation, and catalysis. However, reticular framework materials offer possibilities beyond these, which take advantage of the long-range order, the particular topology, crystallographic nets, and dimensionality of the extended structures. Indeed, framework materials can range from zero-dimensional cages to one-dimensional chains or tubular networks, to two- and three-dimensional networks. Likewise, dimensionality can be thought of as structural or electronic, with structurally three-dimensional frameworks exhibiting exotic one- or two-dimensional electronic properties, for instance. (10) Exotic, complex extended structures are often a prerequisite for exotic electronic structures, such as Dirac or Weyl points, van Hove singularities, and flat bands, which excite our fellow physicists. The combination of molecular functionality and crystalline order is beneficial for applications in light harvesting and optoelectronics. Concerted molecular flexibility can result in flexible framework materials that open and close upon external stimuli and which, hence, change the crystal properties dynamically.This special issue focuses on physical phenomena in framework materials that have emerged in recent years. A collection of 18 Accounts from experiment and theory cover MOFs, COFs, and PAFs, frameworks ranging from zero to three dimensions, as well as coordination polymer glasses. They feature mechanical flexibility, electrical conductivity, magnetism, and methodological work for their synthesis, assembly, and theoretical description. It contains fine examples where the control of physical properties enables superior performance in chemistry-related applications, such as sensing or photocatalysis.One of the physical core properties of a material is the electrical conductivity. Most framework materials are insulators or semiconductors. Even if the band gap is narrow, conductivity is hindered by largely ionic metal–ligand bonds that act as charge traps or decrease charge mobility. Hopping transport is likewise often hindered by the large distances across the wide pores. Recent advances in the synthesis of electrically conductive framework materials change this picture and open new avenues for applications. For example, a smart synthesis route involving nonplanar linkers to achieve conjugated 2D MOFs with high electric conductivity is described by Liu, Xing, and Chen. (11) Jeong and colleagues discuss strategies to fabricate large-area conductive 2D MOF films. (12) Electrical conductivity by controlled electron hopping can be achieved by manipulating the oxidation state of the metal nodes in MOFs. Li and Ott describe how internal and external factors control conductivity in these redox-conductive frameworks. (13)Enhanced conductivity achieved either by in-plane conjugation in COFs or by suitably embedded metal nodes, coupled with active sensing groups in the framework, enables chemiresistors that enable selective gas sensing, as discussed by Benedetto and Mirica. (14) Electric conductivity is beneficial for photocatalytic energy conservation. Fang et al. control it via the morphology of the framework and also via defects. Moreover, they tune the Fermi level by proper selection of the metal nodes and utilize donor–acceptor building block pairs to facilitate charge separation. (15) Beyond electric conductivity, spin conductivity opens the door for framework materials utilization in spintronics or for quantum materials. To achieve this, Lu, Samori, and Feng highlight the challenges for experimental realization, such as large-scale synthesis, decoupling the in-plane and out-of-plane properties, and the manipulation of spin dynamics. (16) Combination of the chemical sensitivity of MOFs together with the utilization of local spins can result in MOF quantum noses, where qubits in MOFs are used for sensing, allowing for the specific recognition of molecules by particular spin–spin interactions, as discussed by Yamauchi and Yanai. (17)The utilization of lattice morphology to control the properties of framework materials is the subject of three contributions. Chen and Jiang emphasize the impact of structural order to achieve superior charge transfer and separation and highlight the possibility to fine-tune the light-harvesting properties of COF molecular building blocks to facilitate photocatalysis. (18) Creating one-dimensional MOFs and COFs, thus establishing porous organic nanotubes, allows constrained chemistry in 1D. (19) An intriguing property of MOFs is that some of them can suffer lattice changes upon external stimuli. If these MOFs carry lattice-dependent physical properties, then they are also subject to this change. Such responsive flexible MOFs can serve as the basis for multiferroic materials. (20)The processability and large-scale structuring of MOFs, as relatively hard polycrystalline materials, remains challenging. Two interesting approaches are shown here: the transformation of crystalline MOFs and coordination polymer to glasses improves their processability and also their mechanical stability. (21) A parallel approach improves the overall crystallinity by controlling the MOF orientation and morphology during growth using external factors such as electric and magnetic fields. (22)On the theoretical side, Hardiagon et al. summarize recent approaches to predict MOF properties using density-functional theory, machine learning, and data-based approaches for preselection of materials and for hierarchical refinement. (23)Framework materials made of special building ingredients, which in turn give particular properties, are the subject of additional contributions to this issue. They include metal–phosphonate frameworks, their construction, and their wide range of physical and chemical properties. (24) An intriguing approach to capture CO2 is to use this molecule as building unit to form stable porous networks. As pointed out by Kadota and Horike, such MOFs may serve as CO2 reservoirs and potentially even as materials for CO2 upgrading. (25) Wang, Su, and Zuo use tetrathiafulvalene (TTF) and its analogues to form stable framework materials with remarkable conductivity and spin conductivity. They focus on applications of TTF-MOFs and TTF-COFs, ranging from fuel cells, batteries, and photo- and electrocatalysts to sensors and spin crossover devices, among others. (26) PAFs, with networks made entirely from strong covalent bonds and aromatic building blocks, have been developed to carry spin centers, either by introducing them via the building blocks or during the coupling reactions. Another novelty in PAF research is enhanced charge transport facilitated by donor–acceptor PAF variants made of two different building units. (27) Finally, two-dimensional frameworks built from triangulenes have been explored by means of predictive theory. Functionalization of diamagnetic building blocks results in tunable electronic properties including effective charge carrier masses, band gap, and band positions. They can be exploited to create photocatalysts operating without overpotentials. If spin-carrying building blocks are used instead, surprisingly the spin remains in the two-dimensional organic crystal, and in some cases strong magnetic couplings, resulting in Stoner ferromagnetism, have been predicted. (28)The Accounts compiled in this special issue suggest that physical phenomena in framework materials are intriguing and will result both in enhanced chemical properties and in potential applications in nanotechnology and quantum technology. These opportunities may give a twist in the research in framework materials, motivating many more groups to consider applications that stem from their unique and tunable physical properties.Author InformationClick to copy section linkSection link copied!Corresponding AuthorThomas Heine, Faculty of Chemistry and Food Chemistry, TU Dresden, Bergstrasse 66c, 01069 Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf, Centrum for Advanced Systems Understanding, CASUS, Untermarkt 20, 02826 Görlitz, Germany; Department of Chemistry, Yonsei University and IBS center for nanomedicine, Seodaemun-gu, Seoul 120-749, Republic of Korea, https://orcid.org/0000-0003-2379-6251, Email: [email protected]AuthorsMircea Dinca, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States, https://orcid.org/0000-0002-1262-1264Guangshan Zhou, Key Laboratory of Polyoxometalate and Reticular Material Chemistry of Ministry of Education, School of Chemistry, Northeast Normal University, Changchun 130024, China, https://orcid.org/0000-0002-5794-3822NotesViews expressed in this editorial are those of the authors and not necessarily the views of the ACS.ReferencesClick to copy section linkSection link copied! This article references 28 other publications. 1Hoskins, B. F.; Robson, R. Design and construction of a new class of scaffolding-like materials comprising infinite polymeric frameworks of 3D-linked molecular rods. A reappraisal of the zinc cyanide and cadmium cyanide structures and the synthesis and structure of the diamond-related frameworks [N(CH3)4][CuIZnII(CN)4] and CuI[4,4′,4″,4″″-tetracyanotetraphenylmethane]BF4.xC6H5NO2. J. Am. Chem. Soc. 1990, 112 (4), 1546– 1554, DOI: 10.1021/ja00160a038 Google Scholar1Design and construction of a new class of scaffolding-like materials comprising infinite polymeric frameworks of 3D-linked molecular rods. A reappraisal of the zinc cyanide and cadmium cyanide structures and the synthesis and structure of the diamond-related frameworks [N(CH3)4][CuIZnII(CN)4] and CuI[4,4',4'',4'''-tetracyanotetraphenylmethane]BF4.xC6H5NO2Hoskins, B. F.; Robson, RichardJournal of the American Chemical Society (1990), 112 (4), 1546-54CODEN: JACSAT; ISSN:0002-7863. It is proposed that a new and potentially extensive class of scaffolding-like materials may be afforded by linking together centers with either a tetrahedral or an octahedral array of valences by rodlike connecting units. Some simple general principles concerning the design and construction of these frameworks are presented together with reasons for expecting them to show unusual and useful properties. Two of the simplest conceivable systems of this type are isomorphous Zn(CN)2 and Cd(CN)2 whose structures were reexamd. by single-crystal x-ray diffraction, confirming the earlier description based on powder diffraction data of 2 interpenetrating diamond-related frameworks: cubic, space group P‾43m, Z = 2; with a 5.9002(9) Å (Zn(CN)2) and 6.301(1) Å (Cd(CN)2); 2 unique metal centers, 1 surrounded tetrahedrally by 4C and the other by 4N donors; MCNM rods linear; Zn-C 1.923(6), Zn-N 2.037(5), Cd-C 2.099(5), Cd-N 2.196(4), C-N 1.150(5) Å in Zn(CN)2, and 1.162(5) Å in Cd(CN)2. The interpenetration of sep. frameworks demonstrated in these archetypal structures is likely to be a major concern in future studies of more complex scaffolding materials. [N(CH3)4][CuZn(CN)4] was deliberately designed to demonstrate one conceivable way of preventing interpenetration; it is cubic, space group F‾43m, with A 11.609(3) Å; Z = 4. The structure contains a single diamond-related framework with alternating tetrahedral Cu(I) and Zn(II) centers and linear rods that are very likely of the type CuCNZn with bond distances Cu-C 1.877(8) and Zn-N 2.069(15) Å, Z(CH3)4+ ions occupy half the adamantane cavities generated by the framework, the remaining cavities being vacant. CuI[4,4',4'',4'''-tetracyanotetraphenylmethane]BF4·xC6H5NO2 (x ≥ 7.7) represents the first attempt to generate an infinite 3-dimensional framework with rods of some complexity. It is tetragonal, space group I‾4m2, with a 13.620(2) and c 22.642(2) Å; Z = 2. The structure contains a diamond-related cationic framework with C·C6H4·CN·Cu rods of length 8.856(2) Å. The framework is tetragonally elongated along the c axis apparently as a result of nonbonded interactions between the 8 ortho-H atoms around the methane C centers. There is no interpenetration. The framework generates very large adamantane-like cavities occupied by disordered C6H5NO2 (at least 7.7 mols. per Cu) together with BF4- ions. The crystals undergo ready anion exchange. The material is unusual in that approx. two thirds by vol. of what is undoubtedly a crystal is effectively liq. The results provide confidence that a wide range of scaffolding-like solids should prove accessible. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK3cXovVOjtw%253D%253D&md5=2a9efabcd93072e8668a50199c51320c2Yaghi, O. M.; Sun, Z.; Richardson, D. A.; Groy, T. L. Directed Transformation of Molecules to Solids: Synthesis of a Microporous Sulfide from Molecular Germanium Sulfide Cages. J. Am. Chem. Soc. 1994, 116 (2), 807– 808, DOI: 10.1021/ja00081a067 Google Scholar2Directed Transformation of Molecules to Solids: Synthesis of a Microporous Sulfide from Molecular Germanium Sulfide CagesYaghi, O. M.; Sun, Z.; Richardson, D. A.; Groy, T. L.Journal of the American Chemical Society (1994), 116 (2), 807-8CODEN: JACSAT; ISSN:0002-7863. The use of Ge4S104- anion cages as mol. building blocks in the synthesis of an extended microporous sulfide network, MnGe4S10·2(CH3)4N, was demonstrated at room temp. X-ray structural anal. of single crystals of the starting material Ge4S10[(CH3)4N]4 [cubic, a 19.554(2), P43n, Z=8] revealed the presence of discrete adamantane-like cages of Ge4S104- anions, each contg. four tetrahedral germanium centers. The Ge atoms are each linked to three doubly-bridging sulfides and one terminal sulfide. Addn. copolymn. of this anion in the presence of Mn(II) results in the formation of an extended solid, MnGe4S10·2(CH3)4N, which was obtained in cryst. form. X-ray single crystal structural anal. performed on this solid [tetragonal, a 9.513(1), c 14.281(2) Å, I‾4, Z=2] showed that the four terminal sulfides present in the cage building block have been linked by manganese to form a three-dimensional channel system, where the channels are occupied by tetramethylammonium cations. Pro. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2cXhsFaisr0%253D&md5=ae60ea31c8068de18751d7f78ac1bfda3Yaghi, O. M.; Li, G.; Li, H. Selective binding and removal of guests in a microporous metal–organic framework. Nature 1995, 378 (6558), 703– 706, DOI: 10.1038/378703a0 Google Scholar3Selective binding and removal of guests in a microporous metal-organic frameworkYaghi, O. M.; Li, Guangming; Li, HailianNature (London) (1995), 378 (6558), 703-6CODEN: NATUAS; ISSN:0028-0836. (Macmillan Magazines) Microporous inorg. materials such as zeolites find widespread application in heterogeneous catalysis, adsorption and ion-exchange processes. The rigidity and stability of such frameworks allow for shape- and size-selective inclusion of org. mols. and ions. Analogous microporous structures based on org. building blocks have the potential for more precise rational design, through control of the shape, size and functionalization of the pores. Here we report the synthesis of a metal-org. framework designed to bind arom. guest mols. selectively. The basic building block is a sym. org. mol., which binds metal ions to form layers of the metal-org. compd. alternating with layers whose compn. is detd. by the functionalization of the starting mols. The layers create channels in which guest arom. mols. may be selectively bound. We show that the crystal lattice thus formed is thermally stable up to 350°C, even after removal of included guest mols., and that the inclusions can be selectively readsorbed. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK2MXhtVSnt7rP&md5=b0f48a6fa756cb3acc150b91b847516e4Li, H.; Eddaoudi, M.; O'Keeffe, M.; Yaghi, O. M. Design and synthesis of an exceptionally stable and highly porous metal-organic framework. Nature 1999, 402 (6759), 276– 279, DOI: 10.1038/46248 Google Scholar4Design and synthesis of an exceptionally stable and highly porous metal-organic frameworkLi, Hailian; Eddaoudi, Mohamed; O'Keeffe, M.; Yaghi, M.Nature (London) (1999), 402 (6759), 276-279CODEN: NATUAS; ISSN:0028-0836. (Macmillan Magazines) Open metal-org. frameworks are widely regarded as promising materials for applications in catalysis, sepn., gas storage and mol. recognition. Compared to conventionally used microporous inorg. materials such as zeolites, these org. structures have the potential for more flexible rational design, through control of the architecture and functionalization of the pores. So far, the inability of these open frameworks to support permanent porosity and to avoid collapsing in the absence of guest mols., such as solvents, has hindered further progress in the field. The authors report the synthesis of a metal-org. framework, Zn4O(BDC)3.(DMF)8.(PhCl) (named MOF-5, where BDC = 1,4-benzenedicarboxylate), which remains cryst., as evidenced by x-ray single-crystal analyses, and stable when fully desolvated and when heated up to 300°. This synthesis is achieved by borrowing ideas from metal carboxylate cluster chem., where an org. dicarboxylate linker was used in a reaction that gives supertetrahedron clusters when capped with monocarboxylates. The rigid and divergent character of the added linker allows the articulation of the clusters into a three-dimensional framework resulting in a structure with higher apparent surface area and pore vol. than most porous cryst. zeolites. This simple and potentially universal design strategy is currently being pursued in the synthesis of new phases and composites, and for gas-storage applications. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1MXnvFSiuro%253D&md5=68f27e20a7e4e15ea2c2f49a2a61e98a5Côté, A. P.; Benin, A. I.; Ockwig, N. W.; O'Keeffe, M.; Matzger, A. J.; Yaghi, O. M. Porous, crystalline, covalent organic frameworks. Science (New York, N.Y.) 2005, 310 (5751), 1166– 1170, DOI: 10.1126/science.1120411 Google ScholarThere is no corresponding record for this reference.6Ben, T.; Ren, H.; Ma, S.; Cao, D.; Lan, J.; Jing, X.; Wang, W.; Xu, J.; Deng, F.; Simmons, J. M.; Qiu, S.; Zhu, G. Targeted synthesis of a porous aromatic framework with high stability and exceptionally high surface area. Angewandte Chemie (International ed. in English) 2009, 48 (50), 9457– 9460, DOI: 10.1002/anie.200904637 Google ScholarThere is no corresponding record for this reference.7Yaghi, O. M. Reticular Chemistry-Construction, Properties, and Precision Reactions of Frameworks. J. Am. Chem. Soc. 2016, 138 (48), 15507– 15509, DOI: 10.1021/jacs.6b11821 Google Scholar7Reticular Chemistry-Construction, Properties, and Precision Reactions of FrameworksYaghi, Omar M.Journal of the American Chemical Society (2016), 138 (48), 15507-15509CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society) There is no expanded citation for this reference. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhvFOgtbnJ&md5=aeeb3573f65a2cb69bb61ed7bcf623038O'Keeffe, M.; Peskov, M. A.; Ramsden, S. J.; Yaghi, O. M. The Reticular Chemistry Structure Resource (RCSR) database of, and symbols for, crystal nets. Accounts of chemical research 2008, 41 (12), 1782– 1789, DOI: 10.1021/ar800124u Google Scholar8The Reticular Chemistry Structure Resource (RCSR) database of, and symbols for, crystal netsO'Keeffe, Michael; Peskov, Maxim A.; Ramsden, Stuart J.; Yaghi, Omar M.Accounts of Chemical Research (2008), 41 (12), 1782-1789CODEN: ACHRE4; ISSN:0001-4842. (American Chemical Society) During the past decade, interest has grown tremendously in the design and synthesis of cryst. materials constructed from mol. clusters linked by extended groups of atoms. Most notable are metal-org. frameworks (MOFs), in which polyat. inorg. metal-contg. clusters are joined by polytopic linkers. (Although these materials are sometimes referred to as coordination polymers, we prefer to differentiate them, because MOFs are based on strong linkages that yield robust frameworks.) The realization that MOFs could be designed and synthesized in a rational way from mol. building blocks led to the emergence of a discipline that we call reticular chem.MOFs can be represented as a special kind of graph called a periodic net. Such descriptions date back to the earliest crystallog. studies but have become much more common recently because thousands of new structures and hundreds of underlying nets have been reported. In the simplest cases (e.g., the structure of diamond), the atoms in the crystal become the vertices of the net, and bonds are the links (edges) that connect them. In the case of MOFs, polyat. groups act as the vertices and edges of the net.Because of the explosive growth in this area, a need has arisen for a universal system of nomenclature, classification, identification, and retrieval of these topol. structures. We have developed a system of symbols for the identification of three periodic nets of interest, and this system is now in wide use. In this Account, we explain the underlying methodol. of assigning symbols and describe the Reticular Chem. Structure Resource (RCSR), in which about 1600 such nets are collected and illustrated in a database that can be searched by symbol, name, keywords, and attributes. The resource also contains searchable data for polyhedra and layers.The database entries come from systematic enumerations or from known chem. compds. or both. In the latter case, refs. to occurrences are provided. We describe some crystallog., topol., and other attributes of nets and explain how they are reported in the database. We also describe how the database can be used as a tool for the design and structural anal. of new materials. Assocd. with each net is a natural tiling, which is a natural partition of space into space-filling tiles. The database allows export of data that can be used to analyze and illustrate such tilings. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXht1SgsrjF&md5=392c624f403dd8457460a7649aa496f39Springer, M. A.; Liu, T.-J.; Kuc, A.; Heine, T. Topological two-dimensional polymers. Chem. Soc. Rev. 2020, 49 (7), 2007– 2019, DOI: 10.1039/C9CS00893D Google Scholar9Topological two-dimensional polymersSpringer, Maximilian A.; Liu, Tsai-Jung; Kuc, Agnieszka; Heine, ThomasChemical Society Reviews (2020), 49 (7), 2007-2019CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry) A review. There are more than 200 two-dimensional (2D) networks with different topologies. The structural topol. of a 2D network defines its electronic structure. Including the electronic topol. properties, it gives rise to Dirac cones, topol. flat bands and topol. insulators. In this Tutorial Review, we show how electronic properties of 2D networks can be calcd. by means of a tight-binding approach, and how these properties change when 2nd-neighbor interactions and spin-orbit coupling are included. We explain how to det. whether or not the resulting electronic features have topol. signatures by calcn. of Chern nos., Z2 invariants, and by the nanoribbon approach. This tutorial gives suggestions how such topol. properties could be realized in explicit atomistic chem. 2D systems made of mol. frameworks, in particular in 2D polymers, where the edges and vertices of a given 2D net are substituted by properly selected mol. building blocks and stitched together in such a way that long-range π-conjugation is retained. >> More from SciFinder ®https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXlsVegtrY%253D&md5=bc4bd69f131da50fc781af3e8f97580b10Skorupskii, G.; Le, K. N.; Cordova, D. L. M.; Yang, L.; Chen, T.; Hendon, C. H.; Arguilla, M. Q.; Dincă, M. Porous lanthanide metal-organic frameworks with metallic conductivity. Proc. Natl. Acad. Sci. U.S.A. 2022, 119 (34), e2205127119 DOI: 10.1073/pnas.2205127119 Google ScholarThere is no corresponding record for this reference.11Liu, J.; Xing, G.; Chen, L. 2D Conjugated Metal-Organic Frameworks: Defined Synthesis and Tailor-Made Functions. Acc. Chem. Res. 2024, 57 (7), 1032– 1045, DOI: 10.1021/acs.accounts.3c00788 Google ScholarThere is no corresponding record for this reference.12Jeong, H.; Park, G.; Jeon, J.; Park, S. S. Fabricating Large-Area Thin Films of 2D Conductive Metal-Organic Frameworks. Acc. Chem. Res. 2024, 57 (16), 2336– 2346, DOI: 10.1021/acs.accounts.4c00292 Google ScholarThere is no corresponding record for this reference.13Li, J.; Ott, S. The Molecular Nature of Redox-Conductive Metal-Organic Frameworks. Acc. Chem. Res. 2024, 57 (19), 2836– 2846, DOI: 10.1021/acs.accounts.4c00430 Google ScholarThere is no corresponding record for this reference.14Benedetto, G.; Mirica, K. A. Conductive Framework Materials for Chemiresistive Detection and Differentiation of Toxic Gases. Acc. Chem. Res. 2024, 57 (19), 2775– 2789, DOI: 10.1021/a