Lead halide perovskites are promising materials for a range of applications owing to their unique crystal structure and optoelectronic properties. Understanding the relationship between the atomic/mesostructures and the associated properties of perovskite materials is crucial to their application performances. Herein, the detailed pressure processing of CsPbBr perovskite nanocube superlattices (NC-SLs) is reported for the first time. By using in situ synchrotron-based small/wide angle X-ray scattering and photoluminescence (PL) probes, the NC-SL structural transformations are correlated at both atomic and mesoscale levels with the band-gap evolution through a pressure cycle of 0 ↔ 17.5 GPa. After the pressurization, the individual CsPbBr NCs fuse into 2D nanoplatelets (NPLs) with a uniform thickness. The pressure-synthesized perovskite NPLs exhibit a single cubic crystal structure, a 1.6-fold enhanced photoluminescence quantum yield, and a longer emission lifetime than the starting NCs. This study demonstrates that pressure processing can serve as a novel approach for the rapid conversion of lead halide perovskites into structures with enhanced properties.

The assembly of uniform nanocrystal building blocks into well ordered superstructures is a fundamental strategy for the generation of meso- and macroscale metamaterials with emergent nanoscopic functionalities. The packing of spherical nanocrystals, which frequently adopt dense, face-centred-cubic or hexagonal-close-packed arrangements at thermodynamic equilibrium, has been much more widely studied than that of non-spherical, polyhedral nanocrystals, despite the fact that the latter have intriguing anisotropic properties resulting from the shapes of the building blocks. Here we report the packing of truncated tetrahedral quantum dot nanocrystals into three distinct superstructures-one-dimensional chiral tetrahelices, two-dimensional quasicrystal-approximant superlattices and three-dimensional cluster-based body-centred-cubic single supercrystals-by controlling the assembly conditions. Using techniques in real and reciprocal spaces, we successfully characterized the superstructures from their nanocrystal translational orderings down to the atomic-orientation alignments of individual quantum dots. Our packing models showed that formation of the nanocrystal superstructures is dominated by the selective facet-to-facet contact induced by the anisotropic patchiness of the tetrahedra. This study provides information about the packing of non-spherical nanocrystals into complex superstructures, and may enhance the potential of self-assembled nanocrystal metamaterials in practical applications.

This article describes the use of gel permeation chromatography (GPC) as a means to separate natively capped colloidal CdSe and CdSe/Cd x Zn 1−x S quantum dots (QDs) from small-molecule impurities in hydrophobic solvents. A range of analysis techniques, including 1 H NMR, diffusion-ordered NMR analysis (DOSY), and thermogravimetric analysis (TGA) have been used to compare the nature and quantities of ligands adsorbed on the QDs after GPC and after alternative purification methods. We show that the GPC purified samples display lower ligand-to-QD ratio (135 oleate substituents per nanocrystal for CdSe QDs with lowest-energy absorption peak at 534 nm) than what we can achieve by the multiple precipitation/redissolution method, and the GPC purified samples are stable at both room temperature and high temperature (180−200 °C for CdSe QDs). The achievement of an efficient and highly reproducible method for the preparation of clean QD samples allowed us to test whether impurities that reside in samples prepared by standard purification methods have a significant effect on further surface modification reactions. We found that the reactivity of CdSe QDs toward precursors for CdS shell growth was profoundly affected by the presence of excess ligands in impure QD samples prepared by multiple precipitations and that the removal of excess ligands and impurities significantly improved the speed and reliability by which water-soluble CdSe/Cd x Zn 1−x S QDs could be prepared by ligand exchange with cysteine. GPC purification provides a preparative-scale, consistent, size-based purification of QDs without perturbing the solvent environment and as such could serve as the basis for advanced syntheses and enable detailed measurements of QD surface chemical properties.

Background: A systemic pro-inflammatory state has been hypothesized to mediate the association between comorbidities and abnormal cardiac structure/function in heart failure with preserved ejection fraction (HFpEF). We conducted a proteomic analysis to investigate this paradigm. Methods: In 228 HFpEF patients from the multicenter PROMIS-HFpEF study, 248 unique circulating proteins were quantified by a multiplex immunoassay (Olink) and used to recapitulate systemic inflammation. In a deductive approach, we performed principal component (PC) analysis to summarize 47 proteins known a priori to be involved in inflammation. In an inductive approach, we performed unbiased weighted co-expression network analyses of all 248 proteins to identify clusters of proteins that overrepresented inflammatory pathways. We defined comorbidity burden as the sum of 8 common HFpEF comorbidities. We used multivariable linear regression and statistical mediation analyses to determine whether and to what extent inflammation mediates the association of comorbidity burden with abnormal cardiac structure/function in HFpEF. We also externally validated our findings in an independent cohort of 117 HFpEF cases and 30 comorbidity controls without HF. Results: Comorbidity burden was associated with abnormal cardiac structure/function and with PCs/clusters of inflammation proteins. Systemic inflammation was also associated with increased mitral E velocity, E/e' ratio, and tricuspid regurgitation (TR) velocity; and worse right ventricular function (tricuspid annular plane systolic excursion [TAPSE] and right ventricular. [RV] free wall strain). Inflammation mediated the association between comorbidity burden and mitral E velocity (proportion mediated 19-35%), E/e' ratio (18-29%), TR velocity (27-41%), and tricuspid annular plane systolic excursion (13%) (P<0.05 for all) but not RV free wall strain. TNF-R1, UPAR, IGFBP-7 and GDF-15 were the top individual proteins that mediated the relationship between comorbidity burden and echocardiographic parameters. In the validation cohort, inflammation was upregulated in HFpEF cases versus controls, and the most prominent inflammation protein cluster identified in PROMIS-HFpEF was also present in HFpEF cases (but not controls) in the validation cohort. Conclusions: Proteins involved in inflammation form a conserved network in HFpEF across 2 independent cohorts and may mediate the association between comorbidity burden and echocardiographic indicators of worse hemodynamics and RV dysfunction. These findings support the comorbidity-inflammation paradigm in HFpEF.

In this paper, a photochromic diarylethene-based derivative that is coordinatively immobilized within an extended porphyrin framework is shown to maintain its photoswitchable behavior and to direct the photophysical properties of the host. In particular, emission of a framework composed of bis(5-pyridyl-2-methyl-3-thienyl)cyclopentene (BPMTC) and tetrakis(4-carboxyphenyl)porphyrin (H4TCPP) ligands anchored by Zn(2+) ions can be altered as a function of incident light. We attribute the observed cyclic fluorescence behavior of the synthesized porphyrin-BPMTC array to activation of energy transfer (ET) pathways through BPMTC photoisomerization. Time-resolved photoluminescence measurements show a decrease in average porphyrin emission lifetime upon BPMTC insertion, consistent with an ET-based mechanism. These studies portend the possible utilization of photochromic ligands to direct chromophore behavior in large light-harvesting ensembles.

This work describes the first rigorous example of a single-component block copolymer system forming unconventional spherical phases. A library of discrete block polymers with uniform chain length and diverse architectures were modularly prepared through a combination of a step-growth approach and highly efficient coupling reactions. The precise chemical structure eliminates all the molecular defects associated with molar weight, dispersity, and compositional ratio. Complex spherical phases, including the Frank–Kasper phase (A15 and σ) and quasicrystalline phase, were experimentally captured by meticulously tuning the composition and architectures. A phase portrait with unprecedented accuracy was mapped out (up to one monomer resolution), unraveling intriguing details of phase behaviors that have long been compromised by inherent molecular weight distribution. This study serves as a delicate model system to bridge the existing gaps between experimental observations and theoretical assessments and to provide insights into the formation and evolution of the unconventional spherical phases in soft matter systems.

Heterostructural core–shell quantum dots (hetero-QDs) have garnered a copious amount of research effort for not only scientific advances but also a range of technological applications. Particularly, controlling the heteroshell deposition, which in turn determines the particle morphology, is vital in regulating the photophysical properties and the application potential of the hetero-QDs. In this work, we present the first report on a synthesis of pyramidal shaped (i.e., hexagonal pyramid, HP, and hexagonal bipyramid, HBP) CdSe-CdS hetero-QDs with high morphological uniformity and epitaxial crystallinity through a two-step shell growth method. The stabilization of the exposed (0002) and {101̅1} facets by octadecylphosphonic acid and oleic acid ligands, respectively, is the key for the formation of pyramidal particle shapes. High photoluminescence quantum yield (94%, HP-QDs and 73%, HBP-QDs), minimal inhomogeneous PL line width broadening, and significantly suppressed single-QD blinking are observed. Specifically, the “giant” HBP-QDs showed an average “On” time fraction of 96% with more than 50% of measured particles completely nonblinking. Additionally, high multiexciton emission, prolonged ensemble and single-QD PL lifetimes as compared to their spherical counterparts are also reported. Finally, the HBP-QDs have been successfully transferred into an aqueous solution without aggregation. High cellular uptakes associated with low cytotoxicity render these water-soluble HBP-QDs an excellent candidate for intracellular imaging and labeling.

Chromophores with a benzylidene imidazolidinone core define the emission profile of commonly used biomarkers such as the green fluorescent protein (GFP) and its analogues. In this communication, artificially engineered porous scaffolds have been shown to mimic the protein β-barrel structure, maintaining green fluorescence response and conformational rigidity of GFP-like chromophores. In particular, we demonstrated that the emission maximum in our artificial scaffolds is similar to those observed in the spectra of the natural GFP-based systems. To correlate the fluorescence response with a structure and perform a comprehensive analysis of the prepared photoluminescent scaffolds, (13)C cross-polarization magic angle spinning solid-state (CP-MAS) NMR spectroscopy, powder and single-crystal X-ray diffraction, and time-resolved fluorescence spectroscopy were employed. Quadrupolar spin-echo solid-state (2)H NMR spectroscopy, in combination with theoretical calculations, was implemented to probe low-frequency vibrational dynamics of the confined chromophores, demonstrating conformational restrictions imposed on the coordinatively trapped chromophores. Because of possible tunability of the introduced scaffolds, these studies could foreshadow utilization of the presented approach toward directing a fluorescence response in artificial GFP mimics, modulating a protein microenvironment, and controlling nonradiative pathways through chromophore dynamics.