b Hebei University of Technology, Tianjin 300401, China;
c Nankai University, Tianjin 300071, China
Molecular materials, together with metals, ceramics, and polymer materials, are among the most important materials. The research efforts on molecular materials are targeting three main aspects, namely the assembly technique, multi-functionality, and their diverse application.In this regard, the main attention from the community is focused on the identification and construction of novel molecular materials with high performance for applications in the fields such as the optoelectronic devices and biological or medicine-related materials.This is a truly multidisciplinary research field driven by the joint efforts of researchers from all different backgrounds including(but not limited to) Organic and Inorganic Chemistry, Supramolecular Chemistry, Semiconductor Molecules and Devices, Materials Science, as well as the Biological Chemistry.This special issue, themed on "Functional Molecular Materials", consists of 5 review articles and 19 original research papers, and covers a broad spectrum of important aspects in the research of functional molecular materials, ranging from the approaches for self-assembly and characterization of functional molecular systems, to their diverse applications in biological systems and optoelectronic materials and devices.
With respect to the approaches to the hierarchical molecular materials, self-assembly with the synergistic covalent and/or noncovalent interactions has been one of the key techniques for constructing well-defined architectures for multiple functionalities.The review article by Zhao et al. (https://doi.org/10.1016/j.cclet.2017.08.042) highlights the concept of a novel supramolecular force, namely the anion-πinteraction, as a valid driving force for the construction of self-assembled molecular systems for recognition and organocatalysis applications.Closely related, Zhang, Bu et al. (https://doi.org/10.1016/j.cclet.2017.08.033) explored in their research the validity of the hydrogen-bonded network for the construction of well-defined inorganic complex for proton conduction; Wang et al. (https://doi.org/10.1016/j.cclet.2017.08.044) investigated the tunability of the architecture of metal-organic motifs(MOFs) for different dye adsorption capabilities.Zhao et al. (https://doi.org/10.1016/j.cclet.2017.08.047)fabricated a hybrid catalyst based on zirconia nanotube-supported H3PW12O40(HPW) for the preparation of fatty acid ethyl esters.In contrast to these inorganic scaffolds, gel is a type of relatively soft supramolecular network with multiple possibilities of functionality.Song, Zhang et al. (https://doi.org/10.1016/j.cclet.2017.06.005) systematically studied the gelation behavior of polyol acetal based gelators in binary solvent mixtures, providing some guidelines for the prediction of gelation in solvent mixtures; Kouwer, Nolte, Rowan et al. (https://doi.org/10.1016/j.cclet.2017.11.002) realized the precise control over the gelation temperature of a biomimetic hydrogel by copolymerization of isocyanide monomers decorated with different ethylene glycol groups.Instead of the dynamic supramolecular self-assembly, Li, Zheng et al. (https://doi.org/10.1016/j.cclet.2017.08.030) took advantages of the extremely strong external pressure(4–10 GPa) as the driving force for the polymerization of the conductive molecular materials.
The engineering of the molecular and supramolecular architectures of the novel molecular materials leads to their broad applications in the fields ranging from the optoelectronics to the biological related systems.π-Conjugated molecular systems provide important skeletons for such functionalities owing to their optoelectronic and supramolecular properties.In their review article, Chen et al.(https://doi.org/10.1016/j.cclet.2017.08.043) summarized the recent progress in organic mechanoluminescent materials.Gao, Grätzel, et al.(https://doi.org/10.1016/j.cclet.2017.09.056) studied in their research the organic dye fused acenes for photovoltaics; while Xiao, Su et al.(https://doi.org/10.1016/j.cclet.2017.10.035) studied the red electroluminescence properties of functionalized tetracene.Li et al.(https://doi.org/10.1016/j.cclet.2017.08.010) realized white-light emission with the lanthanide(Ⅲ)/hectorite based hybrid materials.Organic π-conjugated molecular systems also provide ideal building blocks for light emitting applications in the nonlinear optical(NLO) regime. Rasing, Xu et al.(https://doi.org/10.1016/j.cclet.2017.11.001) studied the structure-property relationship of a fluorenone based NLO molecular system; Sun, Luo et al.(https://doi.org/10.1016/j.cclet.2017.10.016) realized the above-room-temperature phase transition of triethylammonium picrate(TEAP) for efficient switching of the second-order NLO response.As for the electronic molecular materials, Chen, Zhang et al.(https://doi.org/10.1016/j.cclet.2017.09.015) synthesized a series of novel pyrene-phenazine fused monoimide and bisimide derivatives for n-channel organic semiconductors; Wei et al.(https://doi.org/10.1016/j.cclet.2017.08.034) explored the diamine anchored molecular junctions of oligo(phenylene ethynylene) cruciform in the single molecule level.Energy related applications of molecular materials also attracted numerous research efforts in the community.In their research article, Xu, Li et al.(https://doi.org/10.1016/j.cclet.2017.08.016) synthesized novel electron acceptors for nonfullerene organic solar cells based on ethynyl-linked perylene bisimides.In their review paper, Wang et al.(https://doi.org/10.1016/j.cclet.2017.09.005) comprehensively reviewed on the recent progress in the carbonyl polymeric electrode materials for lithium-ion batteries, sodium-ion batteries and magnesiumion batteries.Perovskite type molecular materials have recently emerged as extremely promising photonic materials, particularly the inorganic–organic hybrid perovskite solar cells have achieved great success in photovoltaic performances.Zhao, Li et al.(https://doi.org/10.1016/j.cclet.2017.09.038) discussed in the review paper the latest advances in dopant-free hole transporting materials (HTMs) for perovskite solar cells and outlined the new molecular design strategies towards efficient and stable dopant-free HTMs. Guo et al.(https://doi.org/10.1016/j.cclet.2017.09.013) reviewed on the catalytic performance of nanostructured perovskite oxides as substitutes of noble metals catalyst for combustion of methane.
The development of multifunctional molecular materials also provides unique opportunities for the biological applications.In their research paper, Zhang et al.(https://doi.org/10.1016/j.cclet.2017.10.007) realized the modulation of the subcellular localization of a series thiomorpholine incorporated coumarins with the speciation of sulfur containing functional groups.Leung et al.(https://doi.org/10.1016/j.cclet.2017.09.052) studied the suppression of homogentisic acid γ-lactone for the virulence factors of Pseudomonas aeruginosa by quenching its quorum sensing.In contrast to the molecular materials based on small molecules, the conjugated polymers feature strong light-harvesting ability and fluorescent signal amplification effects.Yuan et al. (https://doi.org/10.1016/j.cclet.2017.09.033) synthesized a cationic poly(p-phenylenevinylene) derivative for lysosome-specific and long-term imaging; while Tang et al.(https://doi.org/10.1016/j.cclet.2017.08.032) reported a new label-free and fluorescence turn-on biosensor based on cationic conjugated poly(9, 9-bis(6'-N, N, N-trimethylammonium)hexyl)fluorine phenylene(PFP) and perylene diimide derivatives(PDI).On the other hand, Xing et al.(https://doi.org/10.1016/j.cclet.2017.09.048) constructed hybrid nanoparticles based on the redox-responsive P[(2-((2((camptothecin)-oxy)ethyl)disulfanyl)ethylmethacrylate)-co-(2-(D-galactose)methylmethacrylate)](P(MACPTS-co-MAGP)) and AgNPs for delivering the anti-cancer drug camptothecin(CPT) and monitoring the drug release by the recovery of the fluorescence of CPT.
Although this special issue covers only the recent progress in some research areas of functional molecular materials, it does highlight the major advances in some emerging key research topics.We hope that this special issue brings readers a timely overview on the latest breakthroughs in the related area.We would like to thank Prof.Xuhong Qian(Editor-in-Chief), Ailian Zheng (Director of Editorial Office) and Dr.Huanfang Guo(Associate Editor-in-Chief) for giving us the opportunity to organize this special issue.Our appreciation extends to the editorial team of Chinese Chemical Letters, especially Editor Junli Wang and Editor Fenglian Jiang, for their professionalism throughout the editing process.We are greatly indebted to all the contributing authors for their efforts and enthusiastic supports.We sincerely wish that this will further stimulate exciting multilateral collaborations among the international scientific communities.