Organic Assemblies Research Articles

Block Copolymers‐Enabled Organic–Organic Assembly for Unique Carbonaceous Micro‐/Nano‐Structures

AbstractOver the past decade, there has been growing research interest in deriving advanced carbonaceous materials with unique architectures, including diverse morphologies and compositions, from polymer‐based precursors with tailored nano/micro‐structures. The organic–organic assembly between organic molecules and block copolymers (BCPs) has emerged as a promising strategy for advancing the preformed polymers with multiple levels of complexity. This review provides a comprehensive overview of the synthesis and potential applications of unique carbonaceous nano/micro‐structures derived from commonly used organic precursors, including phenol/formaldehyde, dopamine, and biomass. It begins with a brief summary of the polymerization mechanism for each type of precursors. Following this, it details the delicate design and preparation strategies for unique polymer architectures, including the formation mechanisms of the first‐level assembly involving BCPs and organic precursors, which form composite micelles as building units, and the principles for manipulation the higher‐level assembly process of the composite micelles, illustrated with some representative examples. The review then highlights the advanced applications of these materials in heterogeneous catalysts, secondary batteries, separation, and intelligent drug delivery systems. Finally, the synthetic challenges and potential development directions of unique carbonaceous nano/micro‐structures are outlined, underscoring a pathway for developing advanced materials.

Rational design of metal–organic cages to increase the number of components via dihedral angle control

The general principles of discrete, large self-assemblies composed of numerous components are not unveiled and the artificial formation of such entities is a challenging topic. In metal–organic cages, design strategies for tuning the coordination directions in multitopic ligands by the bend and twist angles were previously developed to solve this problem. In this study, the importance of remote geometric communications between components is emphasized, realizing several types of metal–organic assemblies based on dihedral angle control in multitopic ligands although they have the same coordination directions. Self-assembly of a tritopic ligand with dihedral angles θ = 36.5° and a cis-protected Pd(II) ion affords M9L6 and M12L8 cages as kinetic and thermodynamic products, respectively, whereas an M12L8 sheet is formed when θ = 90°. Geometric analyses of strains in the subcomponent rings reveals that remote geometric communications among neighboring multitopic ligands through coordination bonds are key for large assemblies.

Engineering modulation of cellulose-induced metal–organic frameworks assembly behavior for advanced adsorption and separation

The exploration of methods to remove harmful pollutants has become inevitable due to the increasing number of industries and the intensification and acceleration of environmental pollution. Therefore, the development of effective adsorption and separation process technologies is essential to ensure environmental remediation. Metal-organic framework (MOF) has attracted great attention in adsorption and separation area due to its large porosity, large specific surface area, tunable pore structure, and high chemical and thermal stability. However, the powder state of MOF results in weak flexibility, manufacturability, and recyclability, severely limiting its application. In this case, the synthesis of MOF composites by in-situ or ex-situ growth with abundant and sustainable cellulose family materials is an effective strategy for stabilizing these MOF species, modulating the assembly behavior of MOF, and expanding the forms of MOF application. Particularly, exciting research activities have emerged ranging from fabrication strategies for cellulose/MOF composites to adsorption and separation applications. In this review, the recent advances in cellulose/MOF composites regarding assembly methods, processing strategies, and adsorption and separation areas are comprehensively summarized. Meanwhile, focusing on the design concept of using cellulose to regulate the assembly behavior of MOF to construct macrostructures, the property characteristics and design principles of cellulose/MOF composites are deeply analyzed with examples. Moreover, the crucial challenges and future perspectives are also meticulously analyzed and discussed. We sincerely hope this review can further promote the research enthusiasm for cellulose/MOF composites in adsorption and separation applications and provide useful references for the design and application strategies of cellulose/MOF.

Circular Dichroism Reflectance Anisotropy of Chiral Atomically Thin Films

Recently, a technical modification of a Reflectance Anisotropy Spectroscopy (RAS) spectrometer has been proposed to investigate the circular dichroism (CD) of samples instead of the normally studied linear dichroism. CD-RAS measures the anisotropy of the optical properties of a sample under right-handed and left-handed circularly polarized light. Here, we present the application of CD-RAS to measure the circular dichroism of a twisted bilayer of graphene, purposely prepared as a possible substrate for the adsorption of thin molecular layers, in air, in liquid or in a vacuum. This result demonstrates the performance of the apparatus and shows interesting perspectives for the investigation of chiral organic assemblies deposited in solid film.

Distinct vibrational motions promote disparate excited-state decay pathways in cofacial perylenediimide dimers.

A complex interplay of structural, electronic, and vibrational degrees of freedom underpins the fate of molecular excited states. Organic assemblies exhibit a myriad of excited-state decay processes, such as symmetry-breaking charge separation (SB-CS), excimer (EX) formation, singlet fission, and energy transfer. Recent studies of cofacial and slip-stacked perylene-3,4:9,10-bis(dicarboximide) (PDI) multimers demonstrate that slight variations in core substituents and H- or J-type aggregation can determine whether the system follows an SB-CS pathway or an EX one. However, questions regarding the relative importance of structural properties and molecular vibrations in driving the excited-state dynamics remain. Here, we use a combination of two-dimensional electronic spectroscopy, femtosecond stimulated Raman spectroscopy, and quantum chemistry computations to compare the photophysics of two PDI dimers. The dimer with 1,7-bis(pyrrolidin-1'-yl) substituents (5PDI2) undergoes ultrafast SB-CS from a photoexcited mixed state, while the dimer with bis-1,7-(3',5'-di-t-butylphenoxy) substituents (PPDI2) rapidly forms an EX state. Examination of their quantum beating features reveals that SB-CS in 5PDI2 is driven by the collective vibronic coupling of two or more excited-state vibrations. In contrast, we observe signatures of low-frequency vibrational coherence transfer during EX formation by PPDI2, which aligns with several previous studies. We conclude that key electronic and structural differences between 5PDI2 and PPDI2 determine their markedly different photophysics.

The Influence of Light‐Generated Radicals for Highly Efficient Solar‐Thermal Conversion in an Ultra‐Stable 2D Metal‐Organic Assembly

AbstractSolar‐thermal water evaporation is a promising strategy for clean water production, which needs the development of solar‐thermal conversion materials with both high efficiency and high stability. Herein, we reported an ultra‐stable cobalt(II)‐organic assembly NKU‐123 with light‐generated radicals, exhibiting superior photothermal conversion efficiency and high stability. Under the irradiation of 808 nm light, the temperature of NKU‐123 rapidly increases from 25.5 to 215.1 °C in 6 seconds. The solar water evaporator based on NKU‐123 achieves a high solar‐thermal water evaporation rate of 1.442 and 1.299 kg m−2 h−1 under 1‐sun irradiation with a water evaporation efficiency of 97.8 and 87.9 % for pure water and seawater, respectively. A detailed mechanism study revealed that the formation of light‐generated radicals leads to an increase of spin density of NKU‐123 for enhancing the photothermal effect, which provides insights into the design of highly efficient photothermal materials.

The Influence of Light-Generated Radicals for Highly Efficient Solar-Thermal Conversion in an Ultra-Stable 2D Metal-Organic Assembly.

Solar-thermal water evaporation is a promising strategy for clean water production, which needs the development of solar-thermal conversion materials with both high efficiency and high stability. Herein, we reported an ultra-stable cobalt(II)-organic assembly NKU-123 with light-generated radicals, exhibiting superior photothermal conversion efficiency and high stability. Under the irradiation of 808 nm light, the temperature of NKU-123 rapidly increases from 25.5 to 215.1 °C in 6 seconds. The solar water evaporator based on NKU-123 achieves a high solar-thermal water evaporation rate of 1.442 and 1.299 kg m-2 h-1 under 1-sun irradiation with a water evaporation efficiency of 97.8 and 87.9 % for pure water and seawater, respectively. A detailed mechanism study revealed that the formation of light-generated radicals leads to an increase of spin density of NKU-123 for enhancing the photothermal effect, which provides insights into the design of highly efficient photothermal materials.

A critical overview on impact of different nano-catalytic assemblies for photodegradation of tetracycline

Abstract Recently, the removal of tetracycline, a toxic material, from aquatic medium has been a trending subject of research. Several different technologies including adsorption, biological removal method, solvent extraction, coagulation, chemical reduction, photocatalysis and ion exchange method for removal of tetracyclines from wastewater have been reported. However, photocatalysis of tetracyclines (TC) has gained huge interest because of more efficient mineralization of TC into CO2 and water. Several different nanomaterial based photocatalytic assemblies for the removal of tetracyclines have been widely reported for the removal of tetracyclines which have not been critically reviewed in the literature. This study provides an overview of recent progress of classification, synthesis, characterizations, mechanism of inorganic and metal organic framework nanocatalytic assemblies on photocatalysis of tetracyclines in aquatic medium. Additionally, kinetics and factors affecting the photocatalysis of tetracyclines have been discussed briefly. Future perspectives have also been presented for further advancement in this area.

On Analytical Modeling of Hopping Transport of Charge Carriers and Excitations in Materials with Correlated Disorder.

Spatial-energy correlations strongly influence charge and exciton transport in weakly ordered media such as organic semiconductors and nanoparticle assemblies. Focusing on cases with shorter-range interparticle interactions, we develop a unified analytic approach that allows us to calculate the temperature and field dependence of charge carrier mobility in organic quadrupole glasses and the temperature dependence of the diffusion coefficient of excitons in quantum dot solids. We obtain analytic expressions for the energy distribution of hopping centers, the characteristic escape time of charge/exciton from the energy well stemming from energy correlations around deep states, and the size of the well. The derived formulas are tested with Monte Carlo simulation results, showing good agreement and providing simple analytic expressions for analysis of charge and exciton mobility in a broad range of partially ordered media.

Macronutrient and PFOS bioavailability manipulated by aeration-driven rhizospheric organic nanocapsular assembly

Ubiquitous presence of the extremely persistent pollutants, per- and polyfluoroalkyl substances, is drawing ever-increasing concerns for their high eco-environmental risks which, however, are insufficiently considered based on the assembly characteristics of those amphiphilic molecules in environment. This study investigated the re-organization and self-assembly of perfluorooctane sulfonate (PFOS) and macronutrient molecules from rhizospheric organic (RhO) matter induced with a common operation of aeration. Atomic force microscopy (AFM) with infrared spectroscopy (IR)-mapping clearly showed that, after aeration and stabilization, RhO nanocapsules (∼ 1000 nm or smaller) with a core of PFOS-protein complexes coated by “lipid-carbohydrate” layers were observed whereas the capsule structure with a lipid core surrounded by “protein-carbohydrate-protein” multilayers was obtained in the absence of PFOS. It is aeration that exerted the disassociation of pristine RhO components, after which the environmental concentration PFOS restructured the self-assembly structure in a conspicuous “disorder-to-order” transition. AFM IR-mapping analysis of faeces combined with quantification of component uptake denoted the decreased ingestion and utilization of both PFOS and proteins compared with lipids and carbohydrates when Daphnia magna were fed with RhO nanocapsules. RhO nanocapsules acted as double-edged swords via simultaneously impeding the bioaccessibility of hazardous PFOS molecules and macronutrient proteins; and the latter might be more significant, which caused a malnutrition status within merely 48 h. Elucidating the assembly structure of natural organic matter and environmental concentration PFOS, the finding of this work could be a crucial supplementation to the high-dose-dependent eco-effect investigations on PFOS.

In silico investigation of the interaction between α-synuclein aggregates and organic supramolecular assemblies

An α-synuclein aggregate with the PreNAC and NACore areas, responsible for the aggregation, highlighted.

Photobiocatalytic CO2 reduction into CO by organic nanorod-carbon monoxide dehydrogenase assemblies: surfactant matters

Organic nanorods have been prepared to be assembled with carbon monoxide dehydrogenase for photobiocatalytic CO2 reduction. The surfactants used to synthesize organic nanorods have shown significant effect on the performance of biohybrid assemblies.

Biodielectrics: old wine in a new bottle?

Biodielectrics is a subset of biological and/or bioinspired materials that has brought a huge transformation in the advancement of medical science, such as localized drug delivery in cancer therapeutics, health monitoring, bone and nerve repair, tissue engineering and use in other nanoelectromechanical systems (NEMS). While biodielectrics has long been used in the field of electrical insulation for over a century, polar dielectric properties of biological building blocks have not been well understood at the fundamental building block level. In this review article, we provide a brief overview of dielectric properties of biological building blocks and its hierarchical organisations to include polar dielectric properties such as piezo, pyro, and ferroelectricity. This review article also discusses recent trends, scope, and potential applications of these dielectrics in science and technology. We highlight electromechanical properties embedded in rationally designed organic assemblies, and the challenges and opportunities inherent in mapping from molecular amino acid building blocks to macroscopic analogs of biological fibers and tissues, in pursuit of sustainable materials for next-generation technologies.

Streamlining the automated discovery of porous organic cages.

Self-assembly through dynamic covalent chemistry (DCC) can yield a range of multi-component organic assemblies. The reversibility and dynamic nature of DCC has made prediction of reaction outcome particularly difficult and thus slows the discovery rate of new organic materials. In addition, traditional experimental processes are time-consuming and often rely on serendipity. Here, we present a streamlined hybrid workflow that combines automated high-throughput experimentation, automated data analysis, and computational modelling, to accelerate the discovery process of one particular subclass of molecular organic materials, porous organic cages. We demonstrate how the design and implementation of this workflow aids in the identification of organic cages with desirable properties. The curation of a precursor library of 55 tri- and di-topic aldehyde and amine precursors enabled the experimental screening of 366 imine condensation reactions experimentally, and 1464 hypothetical organic cage outcomes to be computationally modelled. From the screen, 225 cages were identified experimentally using mass spectrometry, 54 of which were cleanly formed as a single topology as determined by both turbidity measurements and 1H NMR spectroscopy. Integration of these characterisation methods into a fully automated Python pipeline, named cagey, led to over a 350-fold decrease in the time required for data analysis. This work highlights the advantages of combining automated synthesis, characterisation, and analysis, for large-scale data curation towards an accessible data-driven materials discovery approach.

Phosphorescence resonance energy transfer from purely organic supramolecular assembly.

Phosphorescence energy transfer systems have been applied in encryption, biomedical imaging and chemical sensing. These systems exhibit ultra-large Stokes shifts, high quantum yields and are colour-tuneable with long-wavelength afterglow fluorescence (particularly in the near-infrared) under ambient conditions. This review discusses triplet-to-singlet PRET or triplet-to-singlet-to-singlet cascaded PRET systems based on macrocyclic or assembly-confined purely organic phosphorescence introducing the critical toles of supramolecular noncovalent interactions in the process. These interactions promote intersystem crossing, restricting the motion of phosphors, minimizing non-radiative decay and organizing donor-acceptor pairs in close proximity. We discuss the applications of these systems and focus on the challenges ahead in facilitating their further development.

Insights into the Rearrangement of the Molecular Assembly Structure of 6-Aminonicotinic Acid in Its Hydrated Environment.

Water, as a ubiquitous and essential component of life, is known to have a significant impact on the structure and function of organic molecules. In this study, we investigate the role of water in the phase transition of organic molecular assembly structures by scanning tunneling microscopy at room temperature. The results show that the -O-H···O hydrogen induced by water molecules can lead to a significant structural transition in the molecular assembly, specifically through selective weakening of -C-H···O between 6-aminonicotinic acid and the formation of new -O-H···O bonds between 6-aminonicotinic acid and water molecules. Subsequent thermal treatment of these molecular assembly structures reveals that the formation of -N-H···O hydrogen bonds induced by water molecules has created a different pathway for the phase transition of the molecular assembly structure. This knowledge has important implications for the design of organic molecules with specific nanostructures that can be controlled through hydration.

Changes in soil stoichiometry, soil organic carbon mineralization and bacterial community assembly processes across soil profiles

Soil organic carbon (SOC) mineralization is essential to biogeochemical recycling in terrestrial ecosystem. However, the microbial mechanisms underlying the nutrient-induced SOC mineralization remain uncertain. Here, we investigated how SOC mineralization was linked to microbial assembly processes as well as soil nutrient availability and stoichiometric ratio in a paddy rice ecosystem at four soil profile levels. Our results showed a sharp decrease in SOC mineralization from topsoil (112.61–146.34 mg CO2 kg−1 day−1) to subsoil (33.51–61.41 mg CO2 kg−1 day−1). High-throughput sequencing showed that both abundance and diversity of specialist microorganisms (Chao1: 1244.30–1341.35) significantly increased along the soil profile, while the generalist microorganisms (Chao1: 427.67–616.15; Shannon: 7.46–7.97) showed the opposite trend. Correspondingly, the proportion of deterministic processes that regulate specialist (9.64–21.59 %) and generalist microorganisms (21.17–53.53 %) increased and decreased from topsoil to subsoil, respectively. Linear regression modeling and partial least squares path modeling indicated that SOC mineralization was primarily controlled by the assembly processes of specialist microorganisms, which was significantly mediated by available soil C:N:P stoichiometry. This study highlighted the importance of soil stoichiometry-mediated bacterial community assembly processes in regulating SOC mineralization. Our results have an important implication for the integration of bacterial community assembly processes into the prediction of SOC dynamics.

C≡N Stretching Frequency as a Convenient Reporter of Charge Separation in Molecular Systems.

Previously, several studies have shown that, for a set of structurally related nitrile compounds, there could be a linear relationship between the total charge on the nitrile group (qCN) and its stretching frequency (νCN). However, it is unclear whether the corresponding frequency and charge properties of structurally different nitrile compounds can be described by a single linear νCN-qCN relationship. Herein, we compute the qCN magnitudes of a large number of nitrile-containing molecules whose νCN values cover a spectral range of ca. 200 cm-1 and are measured under different experimental conditions. Our results reveal that νCN indeed exhibits a linear dependence on qCN, with a slope of 637 ± 30 cm-1/charge. Because the nitrile moiety is a commonly used building block in electronic donor-acceptor (D-A) molecular systems, we believe that this linear relationship will find utility in a wide range of applications where such D-A constructs are used, such as in organic photovoltaic assemblies. In addition, we apply this linear relationship to characterize the degree of charge transfer upon photoexcitation of two indole derivatives, 5-cyanoindole and 6-cyanoindole, and are able to show that in both cases, the fluorescence emission arises from a charge-transfer or La state.

Design of Metal–Organic Assemblies via Shape Complementarity and Conformational Constraints in Dual Curvature Ligands

Design of Metal–Organic Assemblies via Shape Complementarity and Conformational Constraints in Dual Curvature Ligands

A superior strategy for CO2 methanation under atmospheric pressure: Organic acid-assisted Co nanoparticles assembly on diatomite

There is an urgent need to find a cost-effective and energy-efficient catalysts to promote industrial CO2 methanation, and organic acid-assisted Co/diatomite catalysts stands out as a promising alternative strategy. Herein, nine different kinds of organic acid were introduced to assist the assembly of Co nanoparticles on surface of the diatomite (Dt). Among these catalysts, the superior catalytic performance on citric acid (CA)–Co/Dt was attributed to the fact that CA has more hydroxyl and carboxyl groups. The amount of citric acid addition was adjusted to reach the optimal CA/Co molar ratio and consequently the best catalytic performance. 0.5CA-Co/Dt catalyst showed excellent catalytic activity for CO2 methanation with 73% CO2 conversion and 96% CH4 selectivity at 400 °C (GHSV = 20000 mL gcat−1 h−1, P = 1 atm), and exhibited good stability in long-term reaction. The addition of citric acid changed the surface properties, such as the morphology of Co3O4, cobalt oxidation state, basic sites and defect sites, which affected the catalytic performance. The mechanism analysis showed that the improved catalytic performance was attributed to the refinement and increased dispersion of Co nanoparticles, which increased the active catalytic sites on the catalyst surface, enhanced metal-support interaction, and improved the anti-sintering properties. The outstanding features of CA-assisted Co/Dt provide another promising strategy for the design of high-performance CO2 methanation catalysts.