Mechanism for Topology Selection of Isomeric Two-Dimensional Covalent Organic Frameworks
Xiang-Kun Yu1, Huan-Yu Zhao1, Jun-Peng Li2
1State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130023, China.
Abstract:
The mechanism of growth of one of the competitive topologies for covalent organic frameworks with constitutional isomers is poorly understood. Herein, we employ molecular dynamics to study the isoenergetic assembly of the rhombic square (sql) and Kagome lattice (kgm). The concentration, solvent conditions, and the reversibility of chemical reactions are considered by means of an Arrhenius two-state model to describe the reactions. High concentrations and poor solvent both result in sql, agreeing well with recent experiments. Moreover, the high reversibility of reactions gives rise to sql, while the low reversibility leads to kgm, suggesting a new way of regulating the topology. Our analyses support that the nucleation of isomers influenced by experimental conditions is responsible for the selection of topologies, which improves understanding of the control of topology. We also propose a strategy in which a two-step growth can be exploited to greatly improve the crystallinity of kgm.
Related Concept Videos
02:40MO Theory and Covalent Bonding
02:34Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
02:02Chair Conformation of Cyclohexane
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this...
02:42Valence Bond Theory
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:11Conformations of Cyclohexane
The chair form is the most stable and derives its name from its resemblance to the “easy chair.” In the chair conformation, two carbon atoms are arranged out-of-plane — one above and one below, minimizing the torsional strain. In the chair form, the bond angle is very close to the ideal...