Editorial: Design of extended networks for tuning functionality of materials

Artificial intelligence technologies and mathematical modeling integrates into chemistry and materials science with sophisticated tools capable to extract complicated relations "composition-structureproperty". They reduce uncertainties related with experimental synthesis and provide digital background for the design of materials with required properties. Design of crystalline (extended) structures contrasts with organic chemistry by low predictability of the former one. Furthermore, periodic structures have additional stereochemical, topological and symmetrical constraints, which are not yet fully understood. Novel computational approaches involved in the systematization of information and new descriptors derived from structures of extended networks uncover patterns and regularities dictating the structural organization and functionality of materials.In this Research Topic, four researches were devoted to the methods of designing extended networks tailored to tune the functionality of materials: octahedral and icosahedral networks, covalent organic frameworks, zeolites as adsorbents, planar tetracoordinate carbon molecule as catalyst. A summary of main results of these works is presented below.Extended networks such as metal-organic coordination polymers, high-performance polymers, covalent organic frameworks, hydrogen-bonded organic frameworks have high structural complexity that complicates their structural description and search of correlation between structural descriptors and properties. Symmetry and topology indexes decipher the bonding pattern and structural properties of networks. The greatest size of irregularity in a network is still open question. Therefore, irregularity indices are in demand in chemistry. Xiujun Zhang et al. proposed new computational schemes for irregularity indices of octahedral OTn and icosahedral ISn networks. Higher values were found for ISn networks in the all range of varied network complexity. Irregularity indices are useful in estimation of entropy, enthalpy, and phase transitions. The results offer pathways for designing new, more complex, networks.Computation of energetical characteristics of extended structures using quantum chemical methods requires use of powerful supercomputers. Energy characteristics determines mechanical properties, chemical stability, solubility, etc. Empirical mathematical relations can facilitate energy computation in the orders of magnitude. However, they can be determined for series of topologically related structures. Such mathematical models were proposed by Zahid Raza et al. to predict graph energy for Marta covalent organic frameworks (COFs). The COFs are made up of polycyclic aromatic hydrocarbons with contorted hexabenzocoronene (c-HBC) in the core. The c-HBC unit, copolymerized with pyrene-2,7-diboronic acid, forms Marta-COF-1. Similarly, Marta-COF-2 was obtained by copolymerizion of c-HBC with benzene-1,4diboronic acid. The mathematical expressions for topological descriptors were derived from index functions combined with the edge classes: geometric, harmonic, and Zagreb descriptors. Shannon's entropy method used the structural information function to get entropy quantities. Using correlation analysis, the relationship between topological descriptors and graph energy for two series of Marta-COFs were identified. The predicted energy of Marta-COFs based on degree descriptors was predicted with high precision that shows its usability for estimating graph energy values in complex Marta-COFs.Zeolites are microporous minerals of alumosilicate nature widely used as adsorbents and catalysts in gasoline production, medicine, ion exchanger and sensors. Pancras Peter et al. focused on developing generalized expressions of degree-based and degree-sum-based measures of graphs for the AWW zeolite structure. The complexity the AWW zeolite was estimated using these descriptors. Furthermore, mathematical models of relationships between the measured entropies and molecular interaction energies gave insights into the energy and structural characteristics of the zeolite. Eigenvalues of structures provided bases for calculation of the HOMO-LUMO gap, global chemical reactivity descriptors and spectral properties. Thus, the quantitative structure-property relationship approach shows efficacy for the prediction of stability and properties of structurally similar zeolite materials.Planar tetracoordinate carbon (ptC) has found significant theoretical and experimental interest. ptC molecules are experimentally identified by generating clusters in the gas phase under laser irradiation followed by their isolation through time-of-flight mass spectrometry. Knowledge about ptC structures and mechanisms of their interactions with organic molecules in chemical reactions can open new directions in chemical synthesis. Abdul Hamid Malhan and Krishnan Thirumoorthy studied the potential of the ptC molecule CAl3MgH2¯ in catalysis of hydrogenation reactions based on quantum chemical computations for the first time. CAl3MgH2¯ was found effective for conversion of alkyne to alkene and alkenes to alkanes under similar conditions. Significantly, a detailed reaction mechanism has been proposed for the catalytic process of hydrogenation of alkyne and alkene using CAl3MgH2¯ catalyst. The mechanistic insights into the hydrogenation of alkyne and alkene on CAl3MgH2¯ will assist in designing effective main-group metalbased catalysts for hydrogenation reactions.Summarizing, the findings of the authors of collected works within the Research Topic provide mathematical background for the search and design of extended architectures with promising adsorption and catalytic properties. We thank the authors, reviewers, and editors for contribution to this Research Topic.EVA prepared the first draft, AEK and YL revised the manuscript.