Cholesterol crystallization is integral to the pathology of diseases such as atherosclerosis and gallstones, yet the relevant mechanisms of crystal growth have remained elusive. Here, we use a variety of in situ techniques to examine cholesterol monohydrate crystallization over multiple length scales. In this study, we first identified a biomimetic solvent to generate triclinic monohydrate crystals, while avoiding the formation of non-physiological solvates and enabling crystallization at rates where the dynamics of surface growth could be captured in real time. Using a binary mixture of water and isopropanol, with the latter serving as a surrogate for lipids in physiological environments, we show that cholesterol monohydrate crystals grow classically by the nucleation and spreading of crystal layers. Time-resolved imaging confirms that layers are generated by dislocations and monomers incorporate into advancing steps after diffusion along the crystal surface and not directly from the solution. In situ atomic force microscopy (AFM) and microfluidics measurements concertedly reveal abundant macrosteps, which engender a self-inhibition mechanism that reduces the rate of crystal growth. This finding stands in contrast to numerous other systems, in which classical mechanisms lead to unhindered growth by spreading of single layers.

The role of an organic structure-directing agent on zeolite crystallization is conventionally interpreted based on the final, bulk crystal structure. However, few studies have examined their effect on the dynamics of zeolite crystal growth and restructuring, particularly with respect to the interzeolite transformations that are increasingly being exploited in zeolite synthesis. Herein, we compare two organic structure-directing agents that both direct the formation of the small-pore zeolite SSZ-39 (AEI). The organics have nearly identical molecular structures but exhibit distinct chemical compositions by virtue of a single heteroatom substitution. Our findings reveal that the organics have a dramatic impact on the crystallization kinetics, physicochemical properties, and catalytic performance of zeolite AEI prepared by the transformation of zeolite FAU parent crystals. The conventional quaternary ammonium structure-directing agent, “Pippy”, produces a distinct intermediate metastable structure with defects and anisotropic crystal shape that transitions into relatively thick zeolite AEI platelets with compromised hydrothermal stability. This transition is accompanied by an unusual morphological evolution from rod-like to platelet crystals that defies common Ostwald ripening processes. We demonstrate that a new quaternary ammonium-ether structure-directing agent, “Morphy”, produces thinner platelets of zeolite AEI and bypasses the defective intermediate observed for the conventional organic. Syntheses with Morphy produce a more hydrothermally stable product, which exhibits superior activity in the NH3 selective catalytic reduction of NOx used as a benchmark reaction for assessing structure-performance relationships.

Transitioning from conventional aluminosilicate zeolites to isostructures with alternative heteroatom compositions is a subject of growing interest because the unique properties of these materials offer advantages for relevant catalytic reactions. Replacing aluminum with different metal sites can alter the physicochemical properties of zeolites in ways that improve their catalytic performance. In this study, we focus on designing titanosilicalite-1 (TS-1) zeolite catalysts with controlled morphology and Ti atom zoning that improve performance for olefin epoxidation reactions. Here we introduce two TS-1 catalysts prepared by leveraging direct TS-1 synthesis with recent developments in the generation of MFI-type zeolites comprising finned and eggshell configurations. These synthetic approaches create silicalite-1@TS-1 materials in which the Ti active sites reside preferentially on highly accessible exterior regions of silicalite-1 crystals. Direct synthesis of nanosized TS-1 (<100 nm) is nontrivial; however, these findings demonstrate that finned materials behave as pseudo-nanoparticles (30–50 nm fins) while eggshell TS-1 materials function as pseudo-nanosheets (10–20 nm thickness). Structure–performance relationships are established by comparing finned and eggshell TS-1 catalysts against commercial and in-house TS-1 analogues using 1-heptene epoxidation as a benchmark reaction. Both finned and eggshell TS-1 reduce reactant and product contact times with Ti sites within zeolite pores, and consequently, these catalysts exhibit greater epoxide selectivities and slower catalyst deactivation. Our study reveals that the silicalite-1@TS-1 materials outperform conventional TS-1 with respect to turnover rates and 1,2-epoxyheptane selectivities. Collectively, these findings highlight alternative routes to tailor the properties of metal-substituted zeolites for improved catalytic performance in commercially relevant classes of reactions, particularly those that form products susceptible to secondary decomposition.

One-dimensional zeolites have distinct pore topologies for shape-selective catalysis, yet their performance in conventional reactions is frequently compromised by severe diffusion limitations. Creating opportunities to employ one-dimensional (1D) zeolites in catalytic applications requires advanced synthesis methods to design materials with ultrasmall diffusion path lengths. In this study, we show that the postsynthesis modification of ZSM-23 (MTT) using a protocol analogous to the generation of finned zeolites dramatically improves its mass transport properties. This is accomplished by a facile secondary growth process that introduces surface roughness on the exterior surfaces of MTT crystals and creates greater access to interior pores through the putative removal of intrinsic defects. High-resolution electron microscopy images show that roughened interfaces are step bunches of unfinished layers with ultrasmall dimensions that present a series of short 1D channels. Comparison of these materials against conventional and nanosized ZSM-23 catalysts using methanol to hydrocarbons as a benchmark reaction reveals dramatic enhancement in cumulative turnovers and a propene/ethene ratio that is much higher than conventional ZSM-5 (MFI) zeolites. The improved mass transport of MTT catalysts after secondary growth also markedly extends their lifetime at much shorter reactant contact times without any observed changes in the mechanism of coking. Collectively, these findings highlight an efficient route to generate high-performance 1D zeolites as potential catalysts for commercial applications.

Covalent organic frameworks (COFs), an emerging class of porous crystalline materials, have potential applications ranging from separation to catalysis. However, the harsh conditions required by the classical amorphous transformation route limit the scalability of COF synthesis, especially for three-dimensional covalent organic frameworks (3D COFs). Here, we propose a novel crystalline intermediate (CIM) transformation method that circumvents the stage of amorphous phase generation, enabling the facile and scalable synthesis of imine-linked 3D COFs. In contrast with the classical route of 3D COF synthesis, the CIM transformation process requires no deoxygenation or high-temperature treatment and offers gram-scalable production with efficient and controllable structure interpenetration. The transformation mechanism from a CIM to a 3D COF was investigated in detail, showing a direct crystal-to-crystal pathway. The structure of a CIM nanocrystal, determined by scanning three-dimensional electron diffraction (3DED), reveals a tightly packed diamond-like structure. Furthermore, this strategy was also successfully applied to the synthesis of other three imine-linked 3D COFs that leads to the discovery of two new COFs, demonstrating its broad applicability.

The DIALS package provides a set of tools for crystallographic data processing. The open-source nature of the project, and a flexible inter­face in which individual command-line pro­grams each have a dedicated job, have enabled the adaptation of DIALS to a wide range of experiment types, including electron diffraction. Here we present detailed instructions for the use of DIALS to process chemical crystallography diffraction data from con­tin­u­ous rotation electron diffraction experiments. We demonstrate processing and structure solution from three different samples from three different instruments, including two commercial instruments dedicated to electron diffraction. Each instrument has a pixel array detector, allowing low-noise data to be obtained, resulting in high quality structures. Various new features were added to DIALS to simplify the workflow for these use cases. These are described in detail, along with useful pro­gram options for electron diffraction work.

We present the successful synthesis and characterization of a one-dimensional high-entropy oxide (1D-HEO) exhibiting nanoribbon morphology. These 1D-HEO nanoribbons exhibit high structural stability at elevated temperatures (to 1000°C), elevated pressures (to 12 gigapascals), and long exposure to harsh acid or base chemical environments. Moreover, they exhibit notable mechanical properties, with an excellent modulus of resilience reaching 40 megajoules per cubic meter. High-pressure experiments reveal an intriguing transformation of the 1D-HEO nanoribbons from orthorhombic to cubic structures at 15 gigapascals followed by the formation of fully amorphous HEOs above 30 gigapascals, which are recoverable to ambient conditions. These transformations introduce additional entropy (structural disorder) besides configurational entropy. This finding offers a way to create low-dimensional, resilient, and high-entropy materials.

High Entropy Alloys (HEAs) have garnered attention due to their remarkable tribological attributes. Predominantly, failure mechanisms in HEAs emanate from stress-induced dislocations, culminating in crack propagation and film delamination. In this study, we report on the synthesis of 2D HEA of (MoWNbTaV)0.2S2 which facilitates shear-induced energy dissipation at sliding interfaces. The ball-on-disk tribological investigations demonstrate unprecedentedly low average coefficients of friction (0.076) and wear rates (10−9 mm3 (N∙m)−1) under high contact pressures (0.936 GPa) within ambient conditions. Employing multi-scale characterizations alongside molecular dynamic simulations, we elucidate that the presence of the HEA triggers tribocatalytic activity under high contact pressures emerging as a pivotal factor in extending lubricant lifespan during tribological tests. The resilient lubriciousness coupled with the facile spray coating methodology of (MoWNbTaV)0.2S2 in ambient environments paves the way for the development of a new class of solid lubricants based on 2D HEA.

We present serial electron diffraction with tilt (t-SerialED), a method for fast autonomous phase and structural analysis of beam-sensitive, nano-sized polycrystalline materials. Unlike traditional workflows collecting datasets crystal by crystal, t-SerialED acquires datasets using a batch-by-batch approach, which speeds up the data acquisition. t-SerialED combines robust indexing from 3D reciprocal space with still-shot integration and merging methods from serial crystallography. t-SerialED enables high-throughput analysis of beam-sensitive, multi-phase mixtures across a wide range of materials, from nanoporous frameworks to pharmaceutical compounds. By resolving key challenges in serial crystallography such as indexing and preferred orientation, this method enables precise structure determination, including the visualization of guest molecules and non-covalent interactions like hydrogen bonding and proton charge transfer. Demonstrated on a range of samples from nanoporous materials to pharmaceuticals, t-SerialED expands the capabilities of serial chemical crystallography from single-phase to complex multi-phase systems. It can become a complementary method to traditional crystallography methods, offering a robust solution for routine quantitative phase analysis and structure determination.

Understanding and exploiting material flexibility through phenomena such as the bending and twisting of molecular crystals has been a subject of increased interest owing to the number of applications that benefit from these properties, such as optoelectronics, mechanophotonics, soft robotics, and smart sensors. Here, we report the growth of spontaneously bent and twisted ammonium urate crystals induced by the keto–enol tautomerism of the urate molecule. The major tautomer is native to biogenic crystals, whereas the minor tautomer functions as an effective crystal growth modifier to induce naturally bent and twisted ammonium urate crystals. We show that the degree of curvature can be tailored based on the judicious selection of growth conditions. A combination of state-of-the-art microscopy and spectroscopy techniques are used to characterize the origin of bending. Spatially resolved nano-electron diffraction and high-resolution electron microscopy of naturally bent crystals show nearly single crystallinity with local lattice deformations generated by a combination of screw and edge dislocations. These observations are consistent with photoinduced force microscopy and contact resonance atomic force microscopy, which confirmed spatially resolved changes in the intermolecular interactions and the mechanical properties throughout the cross-sectional and axial regions of bent crystals. A mechanism of bending involving the generation of regionally specific dislocations is proposed as an alternative to more commonly reported models. These findings highlight a unique characteristic of tautomeric crystals that may have broader implications for other biogenic materials.