An energy decomposition analysis method is implemented for the analysis of both covalent bonds and intermolecular interactions on the basis of single-determinant Hartree-Fock ͑HF͒ ͑restricted closed shell HF, restricted open shell HF, and unrestricted open shell HF͒ wavefunctions and their density functional theory analogs. For HF methods, the total interaction energy from a supermolecule calculation is decomposed into electrostatic, exchange, repulsion, and polarization terms. Dispersion energy is obtained from second-order Møller-Plesset perturbation theory and coupled-cluster methods such as CCSD and CCSD͑T͒. Similar to the HF methods, Kohn-Sham density functional interaction energy is decomposed into electrostatic, exchange, repulsion, polarization, and dispersion terms. Tests on various systems show that this algorithm is simple and robust. Insights are provided by the energy decomposition analysis into H 2 , methane C-H, and ethane C-C covalent bond formation, CH 3 CH 3 internal rotation barrier, water, ammonia, ammonium, and hydrogen fluoride hydrogen bonding, van der Waals interaction, DNA base pair formation, BH 3 NH 3 and BH 3 CO coordinate bond formation, Cu-ligand interactions, as well as LiF, LiCl, NaF, and NaCl ionic interactions.

The development of crystalline porous materials (CPMs) with high chemical stability is of paramount importance for their practical uses. Here we report the synthesis of novel polyarylether covalent organic frameworks (PAE-COFs) with high crystallinity, porosity and exceptional chemical stability due to the inert nature of polyarylether building blocks. We demonstrate that these materials can be stable against harsh chemical environments involving boiling water, strong acids/bases, oxidation and reduction conditions, which exceed all known CPMs, including zeolites, metal-organic frameworks (MOFs) and COFs. Furthermore, we explore their advantages as an efficient platform for structural design and functional evolution. The functionalized PAE-COFs combine porosity, high stability, and recyclability, and deliver outstanding performance in the removal of antibiotics from water over a wide pH range.

Potassium channels are responsible for the selective permeation of K+ ions across cell membranes. K+ ions permeate in single file through the selectivity filter, a narrow pore lined by backbone carbonyls that compose 4 K+ binding sites. Here, we report 2D IR spectra of a semisynthetic KcsA channel with site-specific 13C18O isotope labels in the selectivity filter. The ultrafast time-resolution of 2D IR spectroscopy provides an instantaneous snapshot of the multi-ion configurations and structural distributions that occur spontaneously in the filter. Two elongated features are resolved, revealing the statistical weighting of two structural conformations. The spectra are reproduced by MD simulations of structures with water separating two K+ ions in the binding sites, ruling out configurations with ions occupying adjacent sites.

Carboxylatopillar[5]arene (CP[5]A), a new water-soluble macrocyclic synthetic receptor, has been employed as a stabilizing ligand for in situ preparation of gold nanoparticles (AuNPs) to gain new insights into supramolecular host-AuNP interactions. CP[5]A-modified AuNPs with good dispersion and narrow size distributions (3.1 ± 0.5 nm) were successfully produced in aqueous solution, suggesting a green synthetic pathway for the application of AuNPs in biological systems. Supramolecular self-assembly of CP[5]A-modified AuNPs mediated by suitable guest molecules was also investigated, indicating that the new hybrid material is useful for sensing and detection of the herbicide paraquat.

The development of three-dimensional covalent organic frameworks (COFs) with large pores and high surface areas is of great importance for various applications. However, it remains a major challenge due to the unavoidable structural interpenetration and pore collapse after the removal of guest species sitiated in the pores. Herein, we report for the first time a series of 3D mesoporous COFs through a general strategy of enhanced steric hindrance. By using methoxy-modified monomer and increasing methyl groups of linkers, these 3D COFs can be obtained successfully as exclusively non-interpenetrated diamondoid structures, permanent mesopores (up to 26.5 Å), and high surface areas (> 3000 m 2 g -1 ), which are far superior to those of reported conventional COFs with the same topology. This work thus opens a way to create 3D large-porous COFs for potential applications in adsorption and separation of large inorganic, organic, and biological species.

Covalent organic frameworks (COFs) have been at the forefront of porous-material research in recent years. With predictable structural compositions and controllable functionalities, the structures and properties of COFs could be controlled to achieve targeted materials. On the other hand, the predesigned structure of COFs allows fruitful postsynthetic modifications to introduce new properties and functions. In this review, the postsynthetic functionalizations of COFs are discussed and their impacts towards structural qualities and performances are comparatively elaborated on. The functionalization involves the formation of specific interactions (covalent or coordination/ionic bonds) and chemical reactions (oxidation/reduction reaction) with pendant groups, skeleton and reactive linkages of COFs. The chemical stability and performance of COFs including catalytic activity, storage, sorption and opto-electronic properties might be enhanced by specific postsynthetic functionalization. The generality of these strategies in terms of chemical reactions and the range of suitable COFs places them as a pivotal role for the development of COF-based smart materials.

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The origin of the intermolecular interaction, especially the many-body interaction, in eight low-lying water hexamer structures (prism, cage, book-1, book-2, cyclic-chair, bag, cyclic-boat-1, and cyclic-boat-2) is unraveled using the localized molecular orbital energy decomposition analysis (LMO-EDA) method at the second-order Møller-Plesset perturbation (MP2) level of theory with a large basis set. It is found that the relative stabilities of these hexamer structures are determined by delicate balances between different types of interaction. According to LMO-EDA, electrostatic and exchange interactions are strictly pairwise additive. Dispersion interaction in these water hexamer structures is almost pairwise additive, with many-body effects varying from -0.13 to +0.05 kcal/mol. Repulsion interaction is roughly pairwise additive, with many-body effects varying from -0.84 to -0.62 kcal/mol. Polarization interaction is not pairwise additive, with many-body effects varying from -13.10 to -8.85 kcal/mol.