Unprecedented Morphology Research Articles

Pore-Specific Anisotropic Etching of Zeolitic Imidazolate Frameworks by Carboxylic Acid Vapors.

Anisotropic etching is a powerful way to customize metal-organic frameworks with advanced nanostructures, but it is still in its infancy. Herein, we proposed an unprecedented etching strategy that created anisotropic hollow structures in various zeolitic imidazolate framework (ZIF) nano/single crystals via pore-specific carving. The etching occurred through a newly discovered gas-solid reaction where carboxylic acid vapors bind with ligands in ZIFs at room temperature to form ionic liquid (IL). A series of experiments were conducted to decode the origin of anisotropy and the "hollowing out" effect. We found that large pore openings on {111} facets provide access for the entry of carboxylic acid vapors and the outflow of the IL, resulting in pore-dependent anisotropy features. The unique "etching after adsorption" mechanism and the adsorption capacity of the IL enable acid vapors to hollow out nanocrystals and even single crystals. By altering carboxylic acids and ligands in ZIFs, the etching process can be precisely tuned from the inside out or the outside in. This new method demonstrates broad universality and brings unprecedented morphologies and complexities. It may offer great opportunities for achieving purposeful modification of ZIFs and the rational construction of intricate architectures.

(Electrodeposition Division Research Award) Electrodeposition as an Enabling Technology in Future Semiconductors, Energy Storage, and Sustainable Metal Production

Electrodeposition is a truly fascinating process. On the one hand, it is highly complex as it entails a myriad of intricately intertwined physiochemical events (transport, kinetics, nucleation, growth, to name a few). Despite this, to a practitioner, electrodeposition can be remarkably simple, easy to control, and safe to operate. Electrodeposition is also extremely versatile, enabling fabrication of various materials (metals, alloys, semiconductors), fabrication onto conductive or resistive substrates, facilitating intricate pattern formation, and providing selectivity in growth. These advantages make electrodeposition a process of choice in a broad range of technologically-important applications: batteries, semiconductor devices, electrometallurgy, and others.1-3 Morphology control is crucial in the industrial practice of electrodeposition. During metallization of nano-scale interconnects in advanced semiconductor devices, metal deposition with near atomic precision is required.1 Similarly, during operation of lithium metal rechargeable batteries, electrodeposition must be controlled to avoid dendritic growth during battery charging.2 Electrodeposition processes in high temperature molten salts, such as those used for electrowinning rare-earth metals, favor spongy deposits which can manifest in entrapment of impurities – here too, controlling morphology is central to overall electrowinning efficacy.3 In this talk, I will discuss and demonstrate how unprecedented morphology control can be achieved in electrodeposition. Such control leverages fundamental understanding of the electrochemical processes at the electrode-electrolyte interface. Specifically, by regulating the electrolyte properties, applied current or potential waveforms, and by employing ‘additives’, the diffusion-reaction processes can be controlled yielding desirable electrodeposit morphologies. Such design of electrodeposition processes is considerably aided by mathematical modeling. I will provide a few examples of how quantitative modeling enables improved process designs in aforementioned applications.During my odyssey in electrodeposition since 2001, I have been fortunate to have exceptional colleagues, collaborators, sponsors, mentors, students and friends, who have made this journey enjoyable and enriching. I am also very thankful for my affiliation to the Electrochemical Society and its electrodeposition division. In my talk, I will provide a few perspectives and anecdotes on how the ECS community has positively impacted me personally and professionally.

Micrometric drilling of (meta-)studtite square platelets formed by pseudomorphic conversion of UO2 under high-frequency ultrasound

Pseudomorphic transformations are related to chemical conversions of materials while conserving their shape and structural features. Structuring ceramic shapes this way can be used to tailor the physico-chemical properties of materials that can benefit particular applications. In the context of spent nuclear fuel storage interacting with radiolysis products, the sonochemical behavior of powdered UO2 was investigated in dilute aqueous solutions saturated with Ar/(20 %)O2 (20 °C). Optimized parameter settings enabled the complete conversion of UO2 micrometric platelets into uranyl peroxide precipitates, referred to as (meta-)studtite [(UO2(O2)(H2O)2)xH2O] with x = 2 or 4. While the most acidic conditions yielded elongated crystal shapes in agreement with a dissolution/reprecipitation mechanism, softer conditions allowed the pseudomorphic transformation of the platelet shape oxide suggesting a complex formation mechanism. For specific conditions, this unprecedented morphology was accompanied with the formation of a hole in the platelet center. Investigations revealed that the formation of the drilled polymorphs is related to a perfect blend of H+, in-situ generation of H2O2 and high-frequency ultrasound, and is most probably related to the sono-capillary effect. These insights pave the way for new sonochemical approaches dedicated to the preparation of material polymorphs tailoring specific structural properties.

Bizarre dermal armour suggests the first African ankylosaur.

Ankylosauria is a diverse clade of armoured dinosaurs whose members were important constituents of many Cretaceous faunas. Phylogenetic analyses imply that the clade diverged from its sister taxon, Stegosauria, during the late Early Jurassic, but the fossil records of both clades are sparse until the Late Jurassic (~150 million years ago). Moreover, Ankylosauria is almost entirely restricted to former Laurasian continents, with only a single valid Gondwanan taxon. Spicomellus afer gen. et sp. nov. appears to represent the earliest-known ankylosaur and the first to be named from Africa, from the Middle Jurassic (Bathonian-Callovian) of Morocco, filling an important gap in dinosaur evolution. The specimen consists of a rib with spiked dermal armour fused to its dorsal surface, an unprecedented morphology among extinct and extant vertebrates. The specimen reveals an unrealized morphological diversity of armoured dinosaurs during their early evolution, and implies the presence of an important but undiscovered Gondwanan fossil record.

Au Nanorings with Intertwined Triple Rings.

We designed complex Au nanorings with intertwined triple rings (ANITs) in a single entity to amplify the efficacy of near-field focusing. Such a complex and unprecedented morphology at the nanoscale was realized through on-demand multistepwise reactions. Triangular nanoprisms were first sculpted into circular nanorings, followed by a series of chemical etching and deposition reactions eventually leading to ANITs wherein thin metal bridges hold the structure together without any linker molecules. In the multistepwise reaction, the well-faceted growth pattern of Au, which induces the growth of two distinctive flat facets in a lateral direction, is important to evolve the morphology from single to multiple nanorings. Although our synthesis proceeds through multiple steps in one batch without purification steps, it shows a remarkably high yield (>∼90%) at the final stage. The obtained high degree of homogeneity (in both shape and size) of the resulting ANITs allowed us to systematically investigate the corresponding localized surface plasmon resonance (LSPR) coupling with varying nanoring arrangements and observe their single-particle surface enhanced Raman scattering (SERS). Surprisingly, individual ANITs exhibited an enormously large enhancement factor (∼109), which confirms their superior near-field focusing relative to other reported nanoparticles.

Dynamic metallization of spherical DNA via conformational transition into gold nanostructures with controlled sizes and shapes

Despite the reversible condensation properties of DNA, DNA metallization during controlled conformational transitions has been rarely investigated. We perform dynamic metallization of spherically condensed DNA nanoparticles (DNA NPs) via a globule-to-coil transition. A positively charged new Au3+ reagent is prepared via ligand-exchange of conventional complex Au3+ ions, which was used to synthesize spherically condensed DNA NPs simply based on the fundamental electrostatic and coordinative interactions between DNA and Au3+ions. Interestingly, the size of the Au3+-condensed DNA NPs (Au3+-DNA NPs) and the type of reducing agents lead to the formation of different Au nanostructures with unprecedented morphologies (cracked NPs, bowl-shaped NPs, and small NPs), owing to the controlled conformational changes in the Au3+-DNA NPs during metallization. The condensed DNA NPs play significant roles for Au nanostructures as (1) the dynamic template for the synthesis, (2) the reservoir and supply of Au3+ for the growth, and (3) the surface stabilizer. The synthesized Au nanostructures are remarkably stable against high ionic strength and exhibit catalytic activities and excellent SERS properties. This is the first study on the morphological control and concomitant dynamic metallization of spherically condensed DNA, proposing new synthetic routes for bioinorganic nanomaterials.

Further insights into platinum carbonyl Chini clusters

The oxidation of [Ph3P(CH2)12PPh3][Pt15(CO)30] with CF3COOH in THF afforded [Ph3P(CH2)12PPh3][Pt18(CO)36] as a precipitate which was re-crystallized from dmf/isopropanol. This salt self-assembles in the solid state adopting an unprecedented morphology which consists of infinite chains of [Pt9(CO)18]− units. The solid state structure of [Ph3P(CH2)12PPh3][Pt18(CO)36] may be viewed as a snapshot in which [Pt9(CO)18]− units are approaching and ready to exchange outer Pt3(CO)6 fragments. The reactions of Chini clusters with isonitriles proceed via redox-fragmentation, at difference with those involving phosphines that may occur both via non-redox substitution and redox fragmentation, depending on the experimental conditions. Thus, the reaction of [Pt6(CO)12]2− with CNXyl afforded Pt5(CNXyl)10, whereas Pt9(CNXyl)13(CO) was obtained from the reaction of [Pt15(CO)30]2− with CNXyl. These two new neutral clusters have been structurally characterized as their Pt5(CNXyl)10·2toluene and Pt9(CNXyl)13(CO)·solv solvates. DFT studies on the CO exchange of [Pt6(CO)12]2− suggest an associative interchange mechanism, which may be extended also to larger Chini clusters and the initial steps of their reactions with other soft nucleophiles.

Unprecedented morphology control of gas phase cocrystal growth using multi zone heating and tailor made additives.

Herein, it is shown for the first time that cocrystals can be grown by cosublimation with unprecedented morphology control using tailor made additives. Multicrystalline sea-urchin motifs and solids that look like candy-floss are transformed into block-like and needle-like single crystals using additives.

Carbazole-Bearing Porous Organic Polymers with a Mulberry-Like Morphology for Efficient Iodine Capture.

Three kinds of carbazole-based porous organic polymers were successfully prepared via simple Friedel-Crafts alkylation of 1,3,5-tri(9-carbazolyl)-benzene. External cross-linking agents named 1,4-bis(chloromethyl)-benzene, cyanuric chloride, and 1,4-dimethoxybenzene were selected, and the derived polymers (denoted as CSU-CPOPs-1, CSU-CPOPs-2, and CSU-CPOPs-3) gave high surface areas (up to 1032 m2/g) and good stability. Interestingly, varying the nature of "knitting" agents led to an unprecedented morphology evolution, and it is worth noting that a mulberry-like morphology was observed for the case of 1,4-bis(chloromethyl)-benzene. Taking advantage of the unique mulberry-like morphology as well as abundant porosity, CSU-CPOPs-1 showed ultrahigh iodine vapor adsorption performance with a capacity of 494 wt % at 348 K and 1 bar, which is the highest value reported to date for amorphous polymers. This study presented a feasible way to develop efficient iodine sorbents with tunable morphologies for addressing environmental issues.

Engineering pore surface and morphology of microporous organic polymers for improved affinity towards CO2

The increasing carbon dioxide (CO2) emissions from coal-fired power plants exacerbates the need for polymeric sorbents that can preferentially capture CO2 over nitrogen (N2). Herein we report two amine-functionalized microporous organic polymers (PTPNHs) through one-step facile modification of carboxyl-rich microporous organic polymers (PTPMA) that was prepared from a classic Friedel–Crafts coupling of commercially available monomers. The amidation chemistry enables an unprecedented morphology evolution of the microporous organic polymer from nanospheres to uniform nanorods and the choice of amidation agents allows a good control on the diameter and length of the as-made nanorods. More interestingly, the amine-appended PTPNHs show enhanced CO2 adsorption per unit surface area (0.281 mg/m2, at 273 K/1.0 bar) and exceptionally high ideal selectivity (CO2: N2 = 123) with high affinity towards CO2, despite of their decreased Brunauer–Emmett–Teller (BET) surface areas (554 m2 g−1). The CO2 adsorption per unit surface area of the nanorods is about 1.6 folds of that of pristine PTPMA. This study constitutes a step on regulating channel surface polarity and morphology control, and offers the prospect for low-cost direct CO2 capture technologies.

The Solvent Induced Inter-Dimensional Phase Transformations of Cobalt Zeolitic-Imidazolate Frameworks.

Studying inter-dimensional phase transitions of zeolitic-imidazolate frameworks (ZIFs) is essential for developing strategies in controlling morphology and properties. Herein, the inter-dimensional topotactic phase transformations of 3D ZIF-67 to 2D ZIF-L are investigated in detail by employing a simple and efficient solvent-induced growth method. In addition to ZIF-67 and ZIF-L, a series of novel core-shell composites of ZIF-67@ZIF-L, with unprecedented morphologies, are also obtained and well-defined. The different behaviors of the amine hydrogen of 2-MIM in the solvents play a pivotal role for inter-dimensional phase transformations, and in combination with the concentration of 2-MIM, the 2D to 3D phase transformations are also revealed. The findings are very beneficial for morphological design of the ZIFs, along with exploration of the corresponding properties. Impressively, Co-ZIFs exhibit interesting tunable CO2 adsorption behaviors with the phase evolution, which might bring broader understanding for designing CO2 detection and adsorption devices.

Mix-and-Match Assembly of Block Copolymer Blends in Solution

The chemical structure of a block copolymer (BCP) dictates the size, shape, and function of its self-assembled structure in solution. This direct correspondence demands precision synthesis of a specific BCP with optimized structural parameters to obtain the desired nanostructures with structural and functional complexity by solution self-assembly. Here we show that the binary blends of BCPs self-assemble into the desired nanostructure in solution by adjusting the composition of the blend. By modifying the structural parameters of a binary BCP blend through control of the composition, two BCPs sharing the repeating units in both polymer blocks coassemble into the desired structures, which range from spherical micelles to inverse cubic and hexagonal mesophases. These BCP blends not only allow the direct creation of complex periodic mesoporous structures of the desired periodicity and pore size but also provide nanostructures of unprecedented morphology by simple solution self-assembly without relying on the synthesis of correspondingly designed BCPs.

Post-Synthetic Anisotropic Wet-Chemical Etching of Colloidal Sodalite ZIF Crystals.

Controlling the shape of metal-organic framework (MOF) crystals is important for understanding their crystallization and useful for myriad applications. However, despite the many advances in shaping of inorganic nanoparticles, post-synthetic shape control of MOFs and, in general, molecular crystals remains embryonic. Herein, we report using a simple wet-chemistry process at room temperature to control the anisotropic etching of colloidal ZIF-8 and ZIF-67 crystals. Our work enables uniform reshaping of these porous materials into unprecedented morphologies, including cubic and tetrahedral crystals, and even hollow boxes, by an acid-base reaction and subsequent sequestration of leached metal ions. Etching tests on these ZIFs reveal that etching occurs preferentially in the crystallographic directions richer in metal-ligand bonds; that, along these directions, the etching rate tends to be faster on the crystal surfaces of higher dimensionality; and that the etching can be modulated by adjusting the pH of the etchant solution.

Synthesis, Structures, and Properties of 3D Lanthanide (III) Coordination Polymers Based on 5-Nitroisophthalic Acid

A three lanthanide-based coordination compounds of [Sm4(NIPH)5(ox)(H2O)5](H2O)4 (1), [Eu4(NIPH)5(oba)(H2O)5](H2O) (2) and [Eu2(NIPH)3(H2O)14](H2NIPH)(H2O)6 (3) (H2NIPH = 5-nitroisophthalic acid, ox = oxalic acid, H2oba = 4,4′-oxydibenzoic acid) were synthesized by hydrothermal reaction and characterized by single-crystal X-ray diffraction. These compounds contain an -Ln-O-C-O-Ln- zigzag chain, which connect to each other through the oxygen atoms of the H2NIPH ligands to form a wave-like layer. These layers are bridged by oxalate or H2NIPH ligands to generate three-dimensional coordination framework. Within these compounds, porous structure with one-dimensional channels which were filled with isolated organic ligands or lattice water molecules are also observed. Fascinatingly, these lattice water molecules display unprecedented water morphology and play important roles in the stabilizing the whole network. In addition, these compounds show strong photoluminescence at room temperature, respectively, and may be good candidates for potential luminescence materials.

One-pot synthesis of a TiO2–CdS nano-heterostructure assembly with enhanced photocatalytic activity

An unprecedented morphology of a titanium dioxide (TiO2) and cadmium sulfide (CdS) self-assembly obtained using a ‘truly’ one-pot and highly cost effective method with a multi-gram scale yield is reported here.

Morphology of latex and nanocomposite adsorbents prepared by freeze-casting

Freeze-cast monoliths prepared from a common amorphous latex in aqueous media presented unprecedented morphologies that contribute to dye sorption capacity.

Metschnikowia drakensbergensis sp. nov. and Metschnikowia caudata sp. nov., endemic yeasts associated with Protea flowers in South Africa.

In a taxonomic study of yeasts recovered from nectar of flowers and associated insects in South Africa, 11 strains were found to represent two novel species. Morphological and physiological characteristics and sequence analyses of the large-subunit rRNA gene D1/D2 region, as well as the actin, RNA polymerase II and elongation factor 2 genes, showed that the two novel species belonged to the genus Metschnikowia. Metschnikowia drakensbergensis sp. nov. (type strain EBD-CdVSA09-2(T) =CBS 13649(T) =NRRL Y-63721(T); MycoBank no. MB809688; allotype EBD-CdVSA10-2(A) =CBS13650(A) =NRRL Y-63720(A)) was recovered from nectar of Protea roupelliae and the beetle Heterochelus sp. This species belongs to the large-spored Metschnikowia clade and is closely related to Metschnikowia proteae, with which mating reactions and single-spored asci were observed. Metschnikowia caudata sp. nov. (type strain EBD-CdVSA08-1(T) =CBS 13651(T) =NRRL Y-63722(T); MycoBank no. MB809689; allotype EBD-CdVSA57-2(A) =CBS 13729(A) =NRRL Y-63723(A)) was isolated from nectar of Protea dracomontana, P. roupelliae and P. subvestita and a honeybee, and is a sister species to Candida hainanensis and Metschnikowia lopburiensis. Analyses of the four sequences demonstrated the existence of three separate phylotypes. Intraspecies matings led to the production of mature asci of unprecedented morphology, with a long, flexuous tail. A single ascospore was produced in all compatible crosses, regardless of sequence phylotype. The two species appear to be endemic to South Africa. The ecology and habitat specificity of these novel species are discussed in terms of host plant and insect host species.

Universal Sulfide-Assisted Synthesis of M–Ag Heterodimers (M = Pd, Au, Pt) as Efficient Platforms for Fabricating Metal–Semiconductor Heteronanostructures

We report a universal sulfide-assisted synthesis strategy to prepare dumbbell-like M-Ag heterodimers (M = Pd, Au, Pt). Sulfide ions can give fine control over the reaction kinetics of Ag precursors, resulting in the anisotropic overgrowth of Ag to realize the dumbbell-like heterodimers irrespective of the surface facets or components of the M domain. The M-Ag heterodimers were facilely transformed to M-Ag2S heterodimers via a simple sulfidation reaction. This study provides a versatile approach to realizing not only metal-metal heterodimers but also semiconductor-metal heterodimers and will pave the way for designing heteronanostructures with unprecedented morphologies and functions.

Fabrication of Structured Porous Films by Breath Figures and Phase Separation Processes: Tuning the Chemistry and Morphology Inside the Pores Using Click Chemistry

Herein, a facile water-assisted templating technique, the so-called breath figures method, in combination with phase separation process, was employed to prepare multifunctional micropatterned films. Tetrahydrofuran solutions of incompatible ternary blends consisting of high-molecular-weight polystyrene, an amphiphilic block copolymer, polystyrene-b-poly[poly(ethylene glycol) methyl ether methacrylate] (PS40-b-P(PEGMA300)48), and a fluorinated homopolymer, poly(2,3,4,5,6-pentafluorostyrene) (P5FS21) were casted under humid atmosphere varying the proportion of the components. Two simultaneously occurring processes, i.e., the breath figures mechanism and the phase separation process, lead to unprecedented morphologies that could be tuned by simply varying the relative humidity or the composition of the blend. Confocal micro-Raman spectroscopy served to provide information about the location and distribution of the different functionalities in the films. As a result, both the amphiphilic block copolymer and the fluorinated polymer were mainly located in the cavities. Above a certain percentage of relative humidity, honeycomb structured films were obtained in which the block copolymer is distributed on the edge of the pore as a result of the affinity by the condensing water droplet and the coffee stain effect. The homopolymer is also preferentially situated at the pore edge, but forming spherical domains with narrow polydisperse sizes. Moreover, thiolated glucose molecules were specifically attached to the P5FS21 domains via thiol-para fluorine "click" reaction. Subsequently, the specific lectin (Concanavalin A, Canavalia ensiformis) was attached to the surface by conjugation with the glucose moieties. The successful binding of the Con A was demonstrated by the fluorescence, observed exclusively at the areas where P5FS21 domains are located. This nonlithographic method opens a new route to fabricate a huge variety of microstructured polymer films in terms of morphology not only for protein patterning, as illustrated in this manuscript, but also to produce a diversity of functional group arrangements.

Templated deposition of porous fullerene-C60in the interior of siliceous sponge spicules as a biogenic microvessel

Abstract