Doping and ion substitution in colloidal metal halide perovskite nanocrystals and their implication on compositions, properties, and applications.

Macromolecular self-assembly (MSA) has been an active and fruitful research field since the 1980s, especially in this new century, which is promoted by the remarkable developments in controlled radical polymerization in polymer chemistry, etc. and driven by the demands in bio-related investigations and applications. In this review, we try to summarize the trends and recent progress in MSA in relation to biomimetic chemistry and bio-inspired materials. Our paper covers representative achievements in the fabrication of artificial building blocks for life, cell-inspired biomimetic materials, and macromolecular assemblies mimicking the functions of natural materials and their applications. It is true that the current status of the deliberately designed and obtained nano-objects based on MSA including a variety of micelles, multicompartment vesicles, and some hybrid and complex nano-objects is at their very first stage to mimic nature, but significant and encouraging progress has been made in achieving a certain similarity in morphologies or properties to that of natural ones. Such achievements also demonstrate that MSA has played an important and irreplaceable role in the grand and long-standing research of biomimetic and bio-inspired materials, the future success of which depends on mutual and persistent efforts in polymer science, material science, supramolecular chemistry, and biology.

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Protein crystalline frameworks are attractive for biomimetic and nanotechnological studies because they could augment the useful functionalities of numerous proteins through dense packing and uniform orientation. However, their formation and precise structural control is challenging. Here we present novel protein crystalline frameworks with controllable interpenetration. The homotetrameric lectin concanavalin A is crosslinked by predetermined inducing ligands containing monosaccharide and rhodamine groups connected by an oligo(ethylene oxide) spacer. Two non-covalent interactions, that is, sugar-lectin binding and the dimerization of RhB, are responsible for the framework formation. The three-dimensional structure of the framework is fully characterized by X-ray crystallographic methods. For the first time, either interpenetrating or non-interpenetrating frameworks are obtained, and they are controlled by the spacer length of the inducing ligand. Further kinetics and mechanistic investigations reveal that, in the self-assembly process, the carbohydrate-protein binding occurs first, followed by RhB dimerization. This sequence favours rapid crystallization with a high yield when an excess amount of inducing ligand is used. In short, by using wellcontrolled dual non-covalent interactions, fast and versatile preparation of protein crystalline framework was achieved with high crystallization ratio of the proteins, which may shed light on protein crystallization in near future.

Two novel porphyrin-polythiophene star-shaped polymer (P-bs1 and P-bs2) containing triphenylamine terminated poly(3 0 -hexyl-2,2 0 -bithiophene) and poly(3 0 -hexyl-2,2 0 -bithiophene) as four arms in the peripheral of porphyrin core were synthesized by Stille reaction. The thermal, photophysical, electrochemical and photovoltaic properties of the porphyrin-polythiophene derivatives were investigated. The porphyrin-polythiophene derivatives showed broad absorption in the region of 350 $ 650 nm. In particular, the absorption intensity at 450 $ 650 nm was greatly enhanced for the meso-substituted polythiophene derivatives, P-bs2. The photoluminescence spectra indicated that the emission peaks of porphyrin units were suppressed by the intensive emission of thiophene units. The electrochemical properties indicated that the porphyrin-polythiophene derivatives are potential electron-donor materials for bulk heterojunction solar cells and dye-sensitized solar cells (DSSCs). Polymer bulk heterojunction solar cells based on P-bs2 : PCBM (1 : 1, w/w) showed power conversion efficiencies (PCE) up to 0.61% under the illumination of AM 1.5, 100 mW cm À2 , which increased by 69% compared to that of P-bs1 (0.36%). Meanwhile, higher PCE of 2.17% and 3.91% based on P-bs1 and P-bs2 polymer-sensitized solar cells were attained. The better photovoltaic properties benefited from longer arms of polythiophene derivatives.

The selectivity for sulfur removal from oils is an important topic. In this work, the selectivity for different sulfur removal methods has been studied by conceptual density functional theory (CDFT) at the B3LYP/6-31111G(3df,2p) level of theory. In principle, the selectivity is directly related to the mechanisms of sulfur removal. It cannot be precisely elucidated until the mechanisms are totally known. However, current work shows that relationships can be constructed between CDFT and the selectivity. That is, for hydrodesulfurization, good descriptors will be ionization energy, hardness, and bond lengths of SAC; for adsorptive desulfurization, the hardness is a good descriptor; for oxidative desulfurization, good descriptors are electron density and Fukui function. And for extractive desulfurization (nonmetal-based ionic liquids), electron affinity and electrophilicity may be good descriptors. In addition, structures and frontier orbitals of various sulfides have also been discussed. It is hoped that these relationships between CDFT and selectivity can give useful information to develop highly efficient sulfur removal methods for specific sulfides, like 4,6-dimethyldibenzothiophene, and 4-methyldibenzothiophene.

The key to exploiting perovskite nanocrystals (NCs) for long-term practical use in optoelectronic materials and devices lies in the ability to access stable NCs. Herein, we report the crafting of hairy perovskite NCs with a set of markedly improved stabilities by capitalizing on rationally designed star-like molecular bottlebrush trilobes as nanoreactors. An intriguing star-like molecular bottlebrush trilobe, poly­(2-hydroxyethyl methacrylate)-graft-(poly­(acrylic acid)-block-partially cross-linked polystyrene (denoted PHEMA-g-(PAA-b-cPS)) is synthesized. Subsequently, it is employed as a polymeric nanoreactor to direct the growth of green-emitting all-inorganic perovskite CsPbBr3 NCs intimately and stably tethered by partially cross-linked PS “hairs” (i.e., cPS-capped CsPbBr3 NCs). The resulting CsPbBr3 NCs exhibit an array of impressive stabilities against UV irradiation, moisture, heat, and water, due to permanently ligated hydrophobic cPS “hairs” on the surface of CsPbBr3 NCs as a result of the original covalent bonding between PAA and cPS blocks. More importantly, cPS-capped CsPbBr3 NCs manifest outstanding stability in various polar organic solvents. Such greatly improved stability can be attributed to the reduced surface defects enabled by the favorable interaction (i.e., coordination interaction and hydrogen bonding) between CsPbBr3 NCs and polar solvents, which dominates over their dissolution by polar solvents. Such exceptional stabilities impart the use of cPS-capped CsPbBr3 NCs as a selective probe for tracing the presence of Cl–/I– in polar organic solvents. The amphiphilic nonlinear block copolymer nanoreactor strategy can afford easy access to stable perovskite NCs of interest with controlled compositions and surface chemistry. They may find applications in solar cells, LEDs, photodetectors, lasers, bioimaging, biosensors, etc.

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