Practical Synthetic Strategy Research Articles

Multicolor Photoluminescent Carbon Dots à La Carte for Biomedical Applications.

Dual-emission fluorescence probes that provide high sensitivity are key for biomedical diagnostic applications. Nontoxic carbon dots (CDs) are an emerging alternative to traditional fluorescent probes; however, robust and reproducible synthetic strategies are still needed to access materials with controlled emission profiles and improved fluorescence quantum yields (FQYs). Herein, we report a practical and general synthetic strategy to access dual-emission CDs with FQYs as high as 0.67 and green/blue, yellow/blue, or red/blue excitation-dependent emission profiles using common starting materials such as citric acid, cysteine, and co-dopants to bias the synthetic pathway. Structural and physicochemical analysis using nuclear magnetic resonance, absorbance and fluorescence spectroscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy in addition to transmission electron and atomic force microscopy (TEM and AFM) is used to elucidate the material's composition which is responsible for the unique observed photoluminescence properties. Moreover, the utility of the probes is demonstrated in the clinical setting by the synthesis of green/blue emitting antibody-CD conjugates which are used for the immunohistochemical staining of human brain tissues of glioblastoma patients, showing detection under two different emission channels.

Deciphering the Role of the Ser‐Phosphorylation Pattern on the DNA‐Binding Activity of Max Transcription Factor Using Chemical Protein Synthesis

AbstractThe chemical synthesis of site‐specifically modified transcription factors (TFs) is a powerful method to investigate how post‐translational modifications (PTMs) influence TF‐DNA interactions and impact gene expression. Among these TFs, Max plays a pivotal role in controlling the expression of 15 % of the genome. The activity of Max is regulated by PTMs; Ser‐phosphorylation at the N‐terminus is considered one of the key regulatory mechanisms. In this study, we developed a practical synthetic strategy to prepare homogeneous full‐length Max for the first time, to explore the impact of Max phosphorylation. We prepared a focused library of eight Max variants, with distinct modification patterns, including mono‐phosphorylated, and doubly phosphorylated analogues at Ser2/Ser11 as well as fluorescently labeled variants through native chemical ligation. Through comprehensive DNA binding analyses, we discovered that the phosphorylation position plays a crucial role in the DNA‐binding activity of Max. Furthermore, in vitro high‐throughput analysis using DNA microarrays revealed that the N‐terminus phosphorylation pattern does not interfere with the DNA sequence specificity of Max. Our work provides insights into the regulatory role of Max′s phosphorylation on the DNA interactions and sequence specificity, shedding light on how PTMs influence TF function.

Deciphering the Role of the Ser-Phosphorylation Pattern on the DNA-Binding Activity of Max Transcription Factor Using Chemical Protein Synthesis.

The chemical synthesis of site-specifically modified transcription factors (TFs) is a powerful method to investigate how post-translational modifications (PTMs) influence TF-DNA interactions and impact gene expression. Among these TFs, Max plays a pivotal role in controlling the expression of 15% of the genome. The activity of Max is regulated by PTMs; Ser-phosphorylation at the N-terminus is considered one of the key regulatory mechanisms. However, the molecular impact of the phosphorylation pattern on the DNA binding and sequence specificities remains elusive. Here, we developed a practical synthetic strategy to prepare homogeneous full-length Max for the first time, to explore the impact of Max phosphorylation. We prepared a focused library of eight Max variants, with distinct modification patterns, including mono-phosphorylated, and doubly-phosphorylated analogs at Ser2/ Ser11 as well as fluorescently-labeled variants via native chemical ligation. Through comprehensive DNA binding analyses, we discovered that the phosphorylation position plays a crucial role in Max's DNA binding activity. Furthermore, in-vitro high-throughput analysis using DNA microarrays revealed that the N-terminus phosphorylation pattern does not interfere with Max's DNA sequence specificity. Our work provides insights into the regulatory role of Max's phosphorylation on the DNA interactions and sequence specificity, shedding light on how PTMs influence TF function.

Shape-stabilized 1-hexadecanol/g-C3N4/Cu composite phase change material with high thermal conductivity for efficient photo-thermal conversion

Phase change materials (PCM) have received much attention for thermal energy storage and release in the form of latent heat. 1-hexadecanol (HD), as a representative of organic phase change materials, has the advantages of high thermal storage density, almost constant operating temperature and stable thermochemical properties, which shows outstanding potential in the field of phase change energy storage. Nevertheless, single HD as thermal storage material inevitably faces challenges in terms of liquid phase leakage, low thermal conductivity, and poor photo-thermal conversion. To further improve the practical application of HD, we demonstrate a convenient encapsulation and modification strategy of composite phase change materials (CPCMs) with low liquid leakage and high thermal conductivity. Hence, a novel shape-stabilized Cu-doped HD/ graphitic carbon nitride (g-C3N4) CPCM was developed for efficient photo-thermal storage. By the melt blending method, HD is infiltrated into tightly stacked and aligned nano-porous g-C3N4, and the carbon-based lattice inlay achieves the encapsulation of HD to solve the leakage problem during the solid–liquid phase transition. Then, metallic Cu powder is introduced to further strengthen the thermal conductivity of the materials. With this encapsulation and modification strategy, the obtained 5 wt% Cu-doped HD/g-C3N4 composites (CPCM3) exhibits superior performance in both thermal and optical energy storage. This composite has appropriate phase change temperature and extremely high heat storage density, with melting temperature and latent heat of 48.88 °C and 249.63 J/g. The corresponding solidification temperature and latent heat is 48.52 °C and 242.22 J/g, respectively. Its thermal conductivity is enhanced to 0.5307 W/m·K, which is 59.8% higher than pure HD. The photo-thermal conversion efficiency is up to 81.6% for rapid solar energy harvesting and delivery. In particular, after 100 times thermal cycling tests and thermogravimetric analysis, this special CPCM can maintain good thermal reliability and thermal stability. In conclusion, the composite phase change materials obtained by the synergistic modification strategy of nano-porous g-C3N4 and metallic Cu significantly improved the thermochemical properties of HD. This work provides a practical and efficient synthetic strategy for the preparation of CPCMs, which is expected to present a promising future in the field of solar conversion and storage.

1,2-Amino oxygenation of alkenes with hydrogen evolution reaction

1,2-Amino oxygenation of alkenes has emerged as one of the most straightforward synthetic methods to produce β-amino alcohols, which are important organic building blocks. Thus, a practical synthetic strategy for 1,2-amino oxygenation is highly desirable. Here, we reported an electro-oxidative intermolecular 1,2-amino oxygenation of alkenes with hydrogen evolution, removing the requirement of extra-oxidant. Using commercial oxygen and nitrogen sources as starting materials, this method provides a cheap, scalable, and efficient route to a set of valuable β-amino alcohol derivatives. Moreover, the merit of this protocol has been exhibited by its broad substrate scope and good application in continuous-flow reactors. Furthermore, this method can be extended to other amino-functionalization of alkenes, thereby showing the potential to inspire advances in applications of electro-induced N-centered radicals (NCRs).

The tunable bandgap of phosphorus-arsenic alloys for mid-and long-infrared regime photodetectors

Alloys are an effective and practical synthetic strategy for modulating the bandgap of materials. Here, we construct a series of phosphorus-arsenic alloys, hoping to effectively tune the bandgap width by introducing arsenic elements in the phosphorus monolayer. Among the many isomers, we have chosen the most stable α and β phases to construct the alloys. For the α phase, the introduction of arsenic can effectively narrow the bandgap width (0.92–0.15 eV), while for the β phase, the introduction of arsenic does not drastically change the bandgap width (1.63–0.99 eV) than that of α phase, and this difference in electronic structure largely arises from the anisotropy of the structure itself and its tolerance to strain. The design of this alloy is promising for the application of this material in photodetectors in the mid- and long-infrared wavelengths.

Boron, nitrogen co-doped biomass-derived carbon aerogel embedded nickel-cobalt-iron nanoparticles as a promising electrocatalyst for oxygen evolution reaction

The electrocatalytic performance of oxygen evolution reaction (OER) electrocatalysts is highly reliant on the activity of its catalytic active site, which may be augmented by raising the number of active sites. In this study, nanoscaled nickel–cobalt-iron (NiCoFe) alloy was embedded on conductive boron(B), nitrogen(N) co-doped/biomass-derived carbon aerogel as an OER electrocatalyst. The synthesized electrocatalysts were calcined under different temperatures and with variable dopants. The optimal electrocatalyst (BN/CA-NiCoFe-600) demonstrated a low overpotential of 321 mV (at current density of 10 mA cm−2) and a minute Tafel slope of 42 mV dec-1, which was even smaller than that of IrO2 and RuO2. Its mass activity and specific activity were calculated to be 201.7 A g−1, and 34.1 cm−2ECSA, respectively. Furthermore, the electrocatalyst showed excellent stability and durability. This work provides an easy and practical synthetic strategy for acquiring very active and durable electrocatalysts for OER.

Robust Chemical Strategy for Stably Labeling Polyester-Based Nanoparticles with BODIPY Fluorophores.

Aliphatic polyesters are among materials most extensively used for producing biodegradable polymeric nanoparticles currently in development as delivery carriers and imaging agents for a range of biomedical applications. Their clinical translation requires robust particle labeling methodologies that allow reliably monitoring the fate of these formulations in complex biological environments. In the present study, a practical and versatile synthetic strategy providing conjugates of poly(D,L-lactide) representative of this class of polymers with BODIPY fluorophores varying in functional groups and excitation/emission maxima was investigated as a tool for making traceable nanoparticles. Polymer-probe conjugation was accomplished by carbodiimide-induced and 4-(dimethylamino)pyridinium 4-toluenesulfonate-catalyzed esterification of the polymer's terminal hydroxyl group, either directly with a carboxy-functionalized fluorophore or with amine-protected amino acids (Boc-glycine or Boc-6-aminohexanoic acid). In the latter case, the amino acid-derivatized polymeric precursors were reacted with amine-reactive BODIPY dyes after the removal of the protective group. Unlike nanoparticles encapsulating a strongly hydrophobic BODIPY505/515 (logPo/w = 4.3), nanoparticles labeled covalently with its carboxy-functionalized analogue (BODIPY FL) demonstrated stable particle-tracer association under perfect sink conditions. Furthermore, in contrast to the encapsulated dye rapidly partitioning from particles onto cell membranes but not stably retained by cultured cells, the internalization of the covalently attached probe was an irreversible process requiring the presence of serum, consistent with active nanoparticle uptake by endocytosis. In conclusion, the conjugation of particle-forming polymers with BODIPY fluorophores offers an effective and accessible labeling strategy for making traceable polyester-based biodegradable nanoparticles and is expected to facilitate their development and optimization as therapeutic carriers and diagnostic agents.

Facile synthesis of 4-amino-3,5-dinitropyrazolated energetic derivatives via 4-bromopyrazole and their performances

The development of practical synthetic strategies towards novel energetic materials fulfilling various civilian and military purposes is a desirable but challenging task. 4-Amino-3,5-dinitropyrazole, an insensitive energetic material, has great potential as an effective building block for the construction of promising primary and secondary explosives. Herein, a facile strategy for the synthesis of 4-amino-3,5-dinitropyrazolate-based energetic derivatives is achieved using 4-bromopyrazole as starting material. The resulted energetic compounds 1–9 were well characterized through IR spectroscopy, multinuclear NMR spectroscopy, and differential scanning calorimetry. The results show that the extension of the three-dimensional caged packing structure related to the hydrogen bonding interactions and self-assembling of potassium ions with 3,5-dinitro-4-aminopyrazolate ligands, could reinforce its thermal stability with a decomposition temperature of 307.0 °C. Thermal stability, sensitivities, as well as detonation performances were studied by the experimental tests and calculated methods. Overall, this work offers a significant improvement and can lead to the broad practical use of 4-amino-3,5-dinitropyrazole as a building block for promising energetic materials.

Synthesis of Structurally Stable and Highly Active PtCo3 Ordered Nanoparticles through an Easily Operated Strategy for Enhanced Oxygen Reduction Reaction

Constructing robust and cost-effective Pt-based electrocatalysts with an easily operated strategy remains a crucial obstacle to fuel cell applications. Conventional Pt-based catalysts suffer from high Pt content and an arduous synthetic process. Herein, through the spray dehydration method and annealing treatment, facile producible synthesis of a small-sized (5.2 nm) low-Pt (10.5 wt %) ordered PtCo3/C catalyst (O-PtCo3/C) for oxygen reduction reaction is reported. The fast spray evaporation rate contributes to small size and uniform nucleation of nanoparticles (NPs) on carbon support. O-PtCo3/C-600 exhibits efficient electrocatalytic performance with mass activity (MA) 6.0-fold and specific activity 3.9-fold higher than commercial Pt/C. The ordered chemical structure generates superior stability with merely 3.5% decay in MA after 10,000 potential cycles. Density functional theory calculations reveal that the enhanced catalytic performance originates from rational modification of d-band through strain and ordering effect and accompanying weaker adsorption of intermediate OH. This work highlights the potentials of low-Pt PtM3-type ordered NPs for prospective fuel cell cathodic catalysis. The proposed facile and practical synthetic strategy also shows promising prospects for preparing effective Pt-based electrocatalysts.

Dinuclear Rhombic Copper(I) Iodide Complexes with Rigid Bidentate Arsenic Ligands

Abstract We have recently developed a series of arsenic ligands based on practical synthetic strategies. Herein, three kinds of bidentate arsenic ligands with rigid linkers were selected to construct dinuclear rhombic copper(I) iodide (CuI) complexes, whose structures were analyzed by X-ray crystallography. They had sufficient solubility in organic solvents, and it was confirmed that their coordination forms were kept in the solutions. Intense solid-state emissions were observed even at room temperature, and the emission colors were varied from yellow to red by the ligands.

Catalyst‐ and Additive‐Free Decarboxylative C‐4 Phosphorylation of Coumarin‐3‐Carboxylic Acids at Ambient Conditions

AbstractA catalyst‐ and additive‐free practical and green synthetic strategy for decarboxylative C‐4 phosphorylation of coumarin‐3‐carboxylic acids, for the first time, has been accomplished to access a series of substituted 4‐(diarylphosphoryl)chroman‐2‐ones at ambient conditions. The developed protocol is successfully applied to large‐scale synthesis.magnified image

Nanoribbon Superstructures of Graphene Nanocages for Efficient Electrocatalytic Hydrogen Evolution

Two-dimensional carbon architectures are attracting tremendous interests for various promising applications due to their outstanding electronic and mechanical properties, although it is a great challenge to rationally devise facile and operative methodologies to engineer their structural traits owing to complex synthetic processes. Herein, for the first time, we fabricate two-dimensional carbon nanoribbons via direct thermal exfoliation of one-dimensional Ni-based metal-organic framework (MOF) nanorods, in which interconnected graphitic carbon nanocages are self-assembled into a belt-like superstructure with carbon-encapsulated Ni nanoparticles immobilized on the surface. Due to the unparalleled structural superiority, the MOF-derived carbon nanobelts exhibit excellent catalytic performances in electrocatalytic hydrogen evolution. Importantly, the practical synthetic strategy may trigger the rapid development of carbon-based superstructures in many frontier fields.

Sequential one-pot synthesis of (1→6) amide-linked oligosaccharide mimetics under mild conditions

An efficient and practical synthetic strategy, suitable for one-pot synthesis, for novel amide-linked oligosaccharide mimetics from sugar amino acid precursors is described. Twenty substrates, including twelve amide-linked disaccharide mimetics, four amide-linked trisaccharide mimetics and four amide-linked tetrasaccharide mimetics, were synthesized based on this strategy and its optimal conditions. This potentially general method is featured by high yields, gram-scale synthesis, wide substrate scope, and mild reaction conditions.

Nife2o4@Sio2pra/PC-Ni(II) as a highly efficient catalyst for microwave promoted one pot synthesis of tetra substituted imidazoles

A simple and practical microwave irradiation synthetic strategy for preparation of catalyst nanostructured NiFe2O4@SiO2PrA/PC-Ni(II) was developed. The preparation of imidazole derivatives by using this catalyst in the reaction medium is much easier, faster, higher yields, simple separation of products and pure products. The structure of NiFe2O4@SiO2PrA/PC-Ni(II) was characterized by various analyses such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), magnetic properties by vibrating sample magnetometer (VSM) and thermogravimetric analysis (TGA). The pure products were identified and characterized by physical and spectroscopic data such as melting point, IR and 1H NMR techniques.

"Double-Acceptor-Type" Random Conjugated Terpolymer Donors for Additive-Free Non-Fullerene Organic Solar Cells.

Random conjugated terpolymers (RCTs) not only promote great comprehension and realization for the state-of-the-art highly effective non-fullerene organic solar cells (OSCs) but also offer a simple and practical synthetic strategy. However, the photovoltaic properties of RCTs yet lagged behind that of the donor-acceptor (D-A) alternating copolymer, especially in additive-free devices. Hence, we developed two feasible "double-acceptor-type" random conjugated terpolymers, PBDB-TAZ20 and PBDB-TAZ40. The additive-free OSCs based on PBDB-TAZ20:ITIC and PBDB-TAZ40:ITIC exhibit decent efficiencies of 12.34 and 11.27%, respectively, which both surpass the PBDB-T:ITIC-based device. For RCTs, the reasonably weakened crystallinity and the reduced phase separation degree are demonstrated to help in improving charge transport, reducing bimolecular recombination, and thus enhancing the photovoltaic performance of additive-free OSCs. The results imply that adding a third moiety into the D-A polymer donors provides a simple but efficient synthetic approach for high-performance OSCs.

Intermolecular Radical C(sp3 )-H Amination under Iodine Catalysis.

The direct amination of aliphatic C-H bonds has remained one of the most tantalizing transformations in organic chemistry. Herein, we report on a unique catalyst system, which enables the elusive intermolecular C(sp3 )-H amination. This practical synthetic strategy provides access to aminated building blocks and fosters innovative multiple C-H amination within a new approach to aminated heterocycles. The synthetic utility is demonstrated by the synthesis of four relevant pharmaceuticals.

Production of acetophenone C-glucosides using an engineered C-glycosyltransferase in Escherichia coli

Eight novel acetophenone mono- and bis-C-glucosides were obtained by whole cells harboring an engineered C-glycosyltransferase. Optimization of the fed-bath process improved the yield of 4a to 0.97 mg/mL with 95% conversion rate, which is 2.9-fold higher than that of the single-bath. Four mono-C-glucosides (1a–4a) exhibited potent SGLT2 inhibitory activities with IC50 values at 10−6 M. These findings provide a cost-effective and practical synthetic strategy to produce structurally diverse and novel bioactive C-glucosides for drug discovery.

Biocatalytic C-Glucosylation of Coumarins Using an Engineered C-Glycosyltransferase.

The enzymatic synthesis of coumarin C-glucosides by an engineered C-glycosyltransferase, MiCGTb-GAGM, was explored in vitro and in vivo. MiCGTb-GAGM exhibited a robust C-glucosylation capability toward structurally diverse coumarin derivatives. The whole-cell bioconversion of MiCGTb-GAGM was exploited for large-scale production of coumarin C-glucosides. Two C-glucosides exhibited potent SGLT2 inhibitory activities with IC50 values at 10-6 M. These findings provide cost-effective and practical synthetic strategies to generate structurally diverse and novel bioactive coumarin C-glycosides for drug discovery.

Innovative lithium storage enhancement in cation-deficient anatase via layered oxide hydrothermal transformation.

The soft-chemistry synthetic routes of anatase phases for energy conversion and storage usually employ expensive and air-sensitive amorphous alkoxides, which hardly access the electrochemically active cationic vacancy defects in the cationic donor-substituted anatase compositions. Here we demonstrate an innovative way of using layered K3Ti5NbO14 as a cost-effectively crystalline precursor to synthesize cation-deficient Nb-doped TiO2 (NTO, formulated as Ti0.8Nb0.16□0.04O2) anatase by a one-pot hydrothermal route. When used as an anode in lithium ion batteries, the NTO electrode displayed initial discharge and charge capacities of 618 and 384.6 mA h g-1 at a current density of 0.2C respectively, with a remarkable discharge capacity of ~246.8 mA h g-1 retained after 100 cycles, representing the highest value among those reported for Nb-doped TiO2 anatases at low current density. A discharge capacity of 137.1 mA h g-1 was obtained even at a high current density of 2C. A full cell, fabricated using the NTO electrode as the anode and a commercial LiCoO2 cathode, is shown to deliver a discharge capacity of 220.2 mA h g-1 after 57 cycles, which exceeds those of most previously reported full cells based on the TiO2 anode and makes this NTO material a promising anode candidate for LIBs. These results present a practical synthetic strategy for tuning cationic vacancies through aliovalent cationic substitution to improve the electrochemical performance of actual LIBs and possibly to develop further relevant devices.