Single-crystal structure of two-dimensional organic framework based on donor-acceptor interactions with charge-transfer effect

An Appraisal for Providing Charge Transfer (CT) Through Synthetic Porous Frameworks for their Semiconductor Applications

In recent years, there has been considerable focus on the development of charge transfer (CT) complex formation as a means to modify the band gaps of organic materials. In particular, CT complexes alternate layers of aromatic molecules with donor (D) and acceptor (A) properties to provide inherent electrical conductivity. In particular, the synthetic porous frameworks as attractive D-A components have been extensively studied in recent years in comparison to existing D-A materials. Therefore, in this work, the synthetic porous frameworks are classified into conjugated microporous polymers (CMPs), covalent organic frameworks (COFs), and metal-organic frameworks (MOFs) and compare high-quality materials for CT in semiconductors. This work updates the overview of the above porous frameworks for CT, starting with their early history regarding their semiconductor applications, and lists CT concepts and selected key developments in their CT complexes and CT composites. In addition, the network formation methods and their functionalization are discussed to provide access to a variety of potential applications. Furthermore, several theoretical investigations, efficiency improvement techniques, and a discussion of the electrical conductivity of the porous frameworks are also highlighted. Finally, a perspective of synthetic porous framework studies on CT performance is provided along with some comparisons.

Rigid-Flexible Hybrid Porous Molecular Crystals with Guest-Induced Reversible Crystallinity

A weak CH/O hydrogen-bonded organic framework (HOF) with both rigidity and flexibility that could easily and reversibly switch from a non-crystalline to a crystalline phase was constructed. The specific solvent molecule acts as a "key" to control the crystallinity, while the highly rigid triangle macrocycle as the building block is the "lock". The introduction and removal of the "key" could influence the local flexibility of the whole framework and lead to switchable crystallinity. Furthermore, the obtained HOF exhibits excellent separation efficiency for benzene and cyclohexane (94.4 %).

Constructing Supramolecular Frameworks Based Imidazolate-Edge-Bridged Metallacalix[3]arenes via Hierarchical Self-Assemblies

Hierarchical self-assembly of novel supramolecular structures has obtained increasing attention. Herein we design and synthesize the palladium(II)-based molecular basket-like structures, as structural analog of metallacalix[3]arene [M3L3]3+ (M = (dmbpy)Pd, (phen)Pd; dmbpy = 4,4’-dimethyl-bipyridine; phen = 1,10-phenanthroline), by coordination-driven self-assembly from imidazolate-containing ligand [4,5-bis(2,5-dimethylthiophen-3-yl)-1H-imidazole (HL) with palladium(II) nitrate precursors (dmbpy)Pd(NO3)2 and (phen)Pd(NO3)2. The difference of the palladium(II) nitrate precursors with π-surface in complex produces variations of the two-dimensional (2-D) and three-dimensional (3-D) high-ordered supramolecular architectures, constructed by π···π packing and hydrogen bonding interactions, with metallacalixarenes as building blocks. These results provide perceptions of further exploring the hierarchical assembly of supramolecular structures based on π···π packing and multiple hydrogen bonding.