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1. Tautomerism unveils a self-inhibition mechanism of crystallization

   https://doi.org/10.1038/s41467-023-35924-3  

   Tang, Weiwei; Yang, Taimin; Morales-Rivera, Cristian A.; Geng, Xi; Srirambhatla, Vijay K.; Kang, Xiang; Chauhan, Vraj P.; Hong, Sungil; Tu, Qing; Florence, Alastair J.; et al (December 2023, Nature Communications)

   Abstract Modifiers are commonly used in natural, biological, and synthetic crystallization to tailor the growth of diverse materials. Here, we identify tautomers as a new class of modifiers where the dynamic interconversion between solute and its corresponding tautomer(s) produces native crystal growth inhibitors. The macroscopic and microscopic effects imposed by inhibitor-crystal interactions reveal dual mechanisms of inhibition where tautomer occlusion within crystals that leads to natural bending, tunes elastic modulus, and selectively alters the rate of crystal dissolution. Our study focuses on ammonium urate crystallization and shows that the keto-enol form of urate, which exists as a minor tautomer, is a potent inhibitor that nearly suppresses crystal growth at select solution alkalinity and supersaturation. The generalizability of this phenomenon is demonstrated for two additional tautomers with relevance to biological systems and pharmaceuticals. These findings offer potential routes in crystal engineering to strategically control the mechanical or physicochemical properties of tautomeric materials. 

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2. Self-assembly of photonic crystals by controlling the nucleation and growth of DNA-coated colloids

   https://doi.org/10.1073/pnas.2114050118  

   Hensley, Alexander; Jacobs, William M.; Rogers, W. Benjamin (January 2022, Proceedings of the National Academy of Sciences)

   DNA-coated colloids can self-assemble into an incredible diversity of crystal structures, but their applications have been limited by poor understanding and control over the crystallization dynamics. To address this challenge, we use microfluidics to quantify the kinetics of DNA-programmed self-assembly along the entire crystallization pathway, from thermally activated nucleation through reaction-limited and diffusion-limited phases of crystal growth. Our detailed measurements of the temperature and concentration dependence of the kinetics at all stages of crystallization provide a stringent test of classical theories of nucleation and growth. After accounting for the finite rolling and sliding rates of micrometer-sized DNA-coated colloids, we show that modified versions of these classical theories predict the absolute nucleation and growth rates with quantitative accuracy. We conclude by applying our model to design and demonstrate protocols for assembling large single crystals with pronounced structural coloration, an essential step in creating next-generation optical metamaterials from colloids. 

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3. Physical–chemical approach to identify local structural determinants of molecular mechanisms: Case study of antimalarial drug pyronaridine and crystal-growth inhibition

   https://doi.org/10.1063/5.0308064  

   Medvedeva, Angela; Kolomeisky, Ksenia; Kolomeisky, Anatoly B (January 2026, The Journal of Chemical Physics)

   Understanding how specific molecular substructures control chemical behavior is central to rational molecular design and the development of new materials. However, most current predictive models offer limited mechanistic resolution at the fragmental level. We present a conceptually novel use of fragment-based structure–activity reasoning, based on systematically perturbing a parent molecule, to quantify fragment-level contributions to both a specific mechanistic action and a broader functional outcome. As a case study, we investigated local structural contributions to pyronaridine (PY), a clinically used antimalarial drug with a mechanistically distinctive mode of inhibition of hematin crystal growth via step-bunching. Chemically plausible PY molecular analogs have been computationally generated by selectively removing or substituting functional groups hypothesized to influence either step-bunching mechanisms or whole-parasite blood-stage activity. For each analog, we predicted the probability of four different crystal-growth inhibition mechanisms using a centroid-based similarity model based on a small dataset of experimentally verified crystal-growth inhibitors. The blood-stage antimalarial activity has also been estimated using the MAIP platform. A systematic comparison of molecular analogs revealed that step-bunching mechanisms depend primarily on two protonated pyrrolidines, with chlorobenzene as a strong secondary contributor. In contrast, antimalarial activity is more distributed, relying on coordinated interactions between aromatic–heteroatom scaffolds and an amine linker. The obtained results demonstrate that our approach can disentangle position-specific and cooperative fragmental effects, offering mechanistically interpretable guidance for the design of mechanism-optimized inhibitors. The framework might be broadly applicable across chemical and materials domains where linking local structure to specific mechanisms is essential. 

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4. Preferred orientations of garnet porphyroblasts reveal previously cryptic templating during nucleation

   https://doi.org/10.1038/s41598-021-85525-7  

   Nagurney, Alexandra B.; Caddick, Mark J.; Pattison, David R.; Michel, F. Marc (December 2021, Scientific Reports)

   null (Ed.)

   Abstract Electron back scattered diffraction data of garnet crystals from the Nelson Aureole, British Columbia and the Mosher’s Island formation, Nova Scotia, reveals that 22 garnet crystals are all oriented with one of three crystal directions parallel to the trace of the foliation plane in thin section. Structural models suggest that these relationships are due to preferential garnet nucleation onto muscovite, with the alignment of repeating rows of Al octahedra and Si tetrahedra in each leading to inheritance of garnet orientation from the muscovite. These results highlight that epitaxial nucleation may be a prevalent process by which porphyroblast minerals nucleate during metamorphism and carry implications for the role that non-classic nucleation pathways play in the crystallization of metamorphic minerals, the distribution of porphyroblasts in metamorphic rocks, and, in cases in which nucleation is the rate limiting step for crystallization, the energetics of metamorphic reactions. 

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5. Crystallization in Zirconia Film Nano-Layered with Silica

   https://doi.org/10.3390/nano11123444  

   Larsen, Brecken; Ausbeck, Christopher; Bennet, Timothy F.; DeSalvo, Gilberto; DeSalvo, Riccardo; LeBohec, Tugdual; Linker, Seth; Mondin, Marina; Neilson, Joshua (December 2021, Nanomaterials)

   Gravitational waves are detected using resonant optical cavity interferometers. The mirror coatings’ inherent thermal noise and photon scattering limit sensitivity. Crystals within the reflective coating may be responsible for either or both noise sources. In this study, we explored crystallization reduction in zirconia through nano-layering with silica. We used X-ray diffraction (XRD) to monitor crystal growth between successive annealing cycles. We observed crystal formation at higher temperatures in thinner zirconia layers, indicating that silica is a successful inhibitor of crystal growth. However, the thinnest barriers break down at high temperatures, thus allowing crystal growth beyond each nano-layer. In addition, in samples with thicker zirconia layers, we observe that crystallization saturates with a significant portion of amorphous material remaining. 

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