Liquid Metal Encased in Biomimic Polydopamine Armor to Reinforce Photothermal Conversion and Photothermal Stability

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Liquid Metal Encased in Biomimic Polydopamine Armor to Reinforce Photothermal Conversion and Photothermal Stability

Spontaneous coalescence, prone oxidizability, and deterioration in photothermal conversion of liquid metal (LM) impeded the potential application as photothermal agent. Herein, a new surface engineering strategy for LM was developed by implementing self-polymerization of biomimetic polydopamine armor on eutectic gallium-indium-tin ternary alloy, a typical low melting point gallium-based LM alloy.liquid metalsurface engineeringpolydopaminephotothermal conversionphotothermal stability


Abstract

Liquid metal (LM) faces numerous obstacles like spontaneous coalescence, prone oxidizability, and deterioration in photothermal conversion, impeding the potential application as photothermal agent. To tackle these issues, several studies have focused on surface engineering strategy. Developing a feasible and efficient surface engineering strategy is crucial to prevent the aggregation and coalescence of LM, while also ensuring exceptional photothermal conversion and biosecurity. In order to achieve these goals in this work, the biomimetic polydopamine (PDA) armor was chosen to encase a typical LM (eutectic gallium-indium-tin alloy) via self-polymerization. Characterization results showed that the PDA encased LM nanoparticle exhibited enhanced photothermal stability, photothermal conversion, and biosecurity, which could be derived from the following factors: (1) The PDA protective shell acted as an “armor”, isolating LM from dissolved oxygen and water, inhibiting heating-accelerated oxidation and shape morphing. (2) The exceptional near-infrared absorption of PDA was conducive to the photothermal conversion. (3) The biomimetic characteristic of polydopamine (PDA) was advantageous for improving the biosecurity. Hence, this work presented a new surface engineering strategy to reinforce LM for photothermal conversion application.

Multiple Force‐Triggered Downconverted and Upconverted Emission in Polymers Containing Diels‐Alder Adducts

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Multiple Force-Triggered Downconverted and Upconverted Emission in Polymers Containing Diels-Alder Adducts

Downconverted and upconverted emission are mechanochemically activated by ultrasound, compression and freezing, respectively, in polymers incorporated with a Diels-Alder adduct mechanophore that releases 9-styrylantharene chromophores when force is applied.


Abstract

Fluorescent mechanophores can indicate the deformation or damage in polymers. The development of mechanophores with multi-triggered response is of great interest. Herein, Diels-Alder (DA) adducts are incorporated into linear poly(methyl acrylate) PMA-BA and network poly(hexyl methacrylate) (PHMA) as mechanophores to detect the stress caused by ultrasound, freezing, and compression. The DA mechanophores undergo retro-DA reaction to release 9-styrylanthracene chromophore upon applying force, resulting in cyan fluorescence. The dissociation ratio of the DA mechanophore after pulsed ultrasonication of PMA-BA solution for 240 minutes is estimated to be 52 % by absorption spectra and 1H NMR. Additionally, the rate constant of mechanical cleavage is calculated to be 1.2×10−4 min−1⋅kDa−1 with the decrease in molecular weight from 69 to 22 kDa measured by gel permeation chromatography. Freezing of PHMA gels as well as compression of PHMA bulk samples turn-on the DA mechanophores, revealing the microscale fracture. Photon upconversion responses toward various force stimuli are also achieved in both polymer solutions and bulk samples by doping platinum octaethylporphyrin (PtOEP) or palladium meso-tetraphenyltetrabenzoporphyrin (PdTPTBP) sensitizers with multiple excitation wavelengths.

Cu/MgO Reverse Water Gas Shift Catalyst with Unique CO2 Adsorption Behaviors

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Cu/MgO Reverse Water Gas Shift Catalyst with Unique CO2 Adsorption Behaviors

MgO supported Cu catalyst can consistently drive the reverse water gas shift reaction with high activity. The high performance is attributed to the uniquely configured adsorbed CO2 on the Cu/MgO catalyst. The adsorption behaviors of CO2 were identified by in-situ infrared spectroscopy with coupled temperature programmed desorption and explained by theoretical calculation.


Abstract

Activation of inert CO2 molecules for the reverse water gas shift (RWGS) reaction is tackled by incorporating magnesium oxide as a support material for copper, forming a Cu/MgO supported catalyst. The RWGS performance is greatly improved when compared with pure Cu or carbon supported Cu (Cu/C). Operating under a weight hourly space velocity (WHSV) of 300,000 mL ⋅ g−1 ⋅ h−1, the Cu/MgO catalyst demonstrates high activity, maintaining over 70 % equilibrium conversion and nearly 100 % CO selectivity in a temperature range of 300–600 °C. In contrast, both Cu/C and commercial Cu, even at ten-times lower WHSV, can only achieve up to 40 % of the equilibrium conversion and quickly deactivated due to sintering. Based on the studies of in-situ temperature resolved infrared spectroscopy and temperature programmed desorption, the improved RWGS performance is attributed to the unique adsorption behavior of CO2 on Cu/MgO. Density functional theory studies provides a plausible explanation from a surface reaction perspective and reveals the spill-over property of CO2 from MgO to Cu being critical.

DNA interaction, biological, and structural identification studies of bivalent nano‐sized Nickel, Palladium, and Platinum chelates of 2‐(((Z)‐6‐chloro‐3‐((E)‐([2‐hydroxyphenyl]imino)methyl)‐4H‐chromen‐4‐ylidene)amino)phenol Schiff base ligand

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DNA interaction, biological, and structural identification studies of bivalent nano-sized Nickel, Palladium, and Platinum chelates of 2-(((Z)-6-chloro-3-((E)-([2-hydroxyphenyl]imino)methyl)-4H-chromen-4-ylidene)amino)phenol Schiff base ligand

Three novel nano-sized complexes were synthesized and characterized by spectral, thermal, and DFT were performed to confirm the geometry of nano-sized complexes. The in vitro antimicrobial activity of the complexes was investigated. In addition, the antioxidant study was accomplished to considerate the nature of binding of the synthesized compounds with protein and DNA.


New nano-sized Ni(II), Pd(II), and Pt(II) Schiff base chelates of 2-(((Z)-6-chloro-3-((E)-([2-hydroxyphenyl]imino)methyl)-4H-chromen-4-ylidene)amino)phenol were designed and manufactured. The structural characterization of these isolated compounds was accomplished through spectral measurements, thermal and elemental analyses, and magnetic moment and conductivity determinations. The nano-sized metal(II) complexes molar conductance indicated that they exhibited non-electrolytic behavior. The UV–Vis spectral data and magnetic moment provided evidence for producing octahedral geometries in the nano-sized complexes of Ni(II), Pd(II), and Pt(II). Metal chelates' thermal characteristics and decomposition kinetics were examined through Coats-Redfern technique. The kinetic aspects, including pre-exponential factor (A), the entropy of activation (ΔS), and activation energy (E) were enumerated. The X-ray diffraction (XRD) calculations results of the trivalent metal complexes showed that sharp and intense diffraction peaks signify their crystalline properties with nanoscale particle size, and another proof was obtained from the images of SEM, TEM, EDX, and AFM also homogeneous distribution over the complex surface was confirmed. Molecular modeling techniques were adopted to optimize the metal complexes geometry. The viscosity and UV–Vis absorption determinations were utilized to assess the calf thymus DNA (CT-DNA) interaction with the nano-sized metal(II) chelates. The acquired data revealed that the complexes exhibit a non-intercalative or incomplete binding pattern when interacting with DNA. The calculated DNA-complexes binding constants are 3.93 ± 0.02 × 10,4 1.67 ± 0.3 × 105 and 2.88 ± 0.03 × 105 M−1, for nano-sized Ni(II), Pd(II) and Pt(II) Schiff base chelates, successively. Both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Bacillus subtilis and Streptococcus pneumoniae) micro-organisms were tested against H2L Schiff base ligand and its nano-sized metal(II) complexes. Candida albicans and Aspergillus fumigatus were tested for antifungal activity, revealing that most complexes had activity lower than H2L ligand, while the complex of Ni(II) exhibited no discernible antifungal activities. Furthermore, the manufactured complexes underwent testing for their in-vitro anticancer and antibacterial effectiveness. Furthermore, the complexes antioxidant activity was appraised through DPPH and ABTS inhibition tests, revealing distinct scavenging abilities on DPPH radicals. The complexes were ordered according to their scavenging capacity as follows: Ni(II) complex > Pd(II) complex > Pt(II) complex. Finally, the study of cell cycle arrest by the Ni(II), Pd(II), and Pt(II) complexes on HEPG2 has also been performed through flow cell cytometry.

Regioselective synthesis of (Z)‐5‐methylene‐containing morpholin‐2‐ones

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Regioselective synthesis of (Z)-5-methylene-containing morpholin-2-ones

A one-pot, protecting-group-free and regioselective synthesis of enantiomerically pure (Z)-5-methylene-containing morpholin-2-ones, using α-amino acids and 5-bromoenones is presented.


Abstract

An efficient, one-pot, protecting-group-free, and regioselective protocol to obtain enantiomerically pure (Z)-5-methylene-containing morpholin-2-ones, using α-amino acids and 5-bromo-4-methoxy enones as selective starting materials, is reported. The reaction was fully selective in providing the (Z)-regioisomer in all cases, regardless of the α-amino acid used; however, when a secondary amino group was used, only the (E)-isomer was observed. The synthesized compounds were obtained at yields of up to 92%, and their structure was unambiguously assigned by x-ray and 2D-NMR experiments.

Strategic Insertion of Heavy Atom to Tailor TADF OLED Material for the Development of Type I Photosensitizing Catalytic Red Emissive Assemblies

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The work presented in the manuscript describes a simple strategy for transforming thermally activated delayed fluorescent organic light-emitting diodes (TADF OLEDs) compound 10-(dibenzo[a,c]phenazin-11-yl)-10H-phenoxazine (DPZ-PXZ) into type I photosensitizer 10-(dibenzo[a,c]phenazin-11-yl)-10H-phenothiazine   (DPZ-PHZ) by strategically introducing sulfur atom in the photosensitizing core.  The synthesized compound DPZ-PHZ exhibits aggregation-induced enhancement (AIE) and through-space charge transfer (TSCT) characteristics and generates red emissive assemblies in mixed aqueous media.  The original compound DPZ-PXZ exhibits well-separated HOMO and LUMO levels and is reported to have highly efficient reverse intersystem crossing (RISC). In comparison, the incorporation of sulfur atom in the phenothiazine donor regulates the electronic communication between donor and acceptor units and promotes the intersystem crossing (ISC) in DPZ-PHZ molecules. Interestingly, compound DPZ-PHZ exhibits rapid activation of aerial oxygen for instant generation of superoxide radical anion. Backed by excellent type I photosensitizing activity, DPZ-PHZ assemblies have high catalytic potential for the synthesis of benzimidazoles, benzothiazoles and quinazolines derivatives under mild reaction conditions. The work presented in the manuscript provides an insight into the combination of heavy atom approach and TSCT for achieving adequate electronic communication between donor and acceptor units, balanced RISC/ISC, and stabilized-charge separated state for the development of efficient type I photosensitizing assemblies.

Synthesis, characterization, and photocatalytic activity for water remediation and hydrogen evolution of Zn(II) and Ni(II) bis(thiosemicarbazone) complexes

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Synthesis, characterization, and photocatalytic activity for water remediation and hydrogen evolution of Zn(II) and Ni(II) bis(thiosemicarbazone) complexes

Three new dissymmetric bis(thiosemicarbazone) ligands and their nickel(II) and zinc(II) complexes are reported. The potential of the complexes to photocatalyze the degradation of methyl orange is evaluated, and the results show that they can satisfactorily degrade it. Photocatalytic hydrogen evolution by water splitting promoted by nickel complexes is also tested.


The extensive industrial use of organic dyes causes large amounts of these substances to arrive at water sources, so nowadays, organic compound removal from fresh water is a major concern. The use of photocatalysts is an interesting approach to solving this problem, with coordination compounds playing an outstanding role. We report the selective synthesis and characterization of three new dissymmetric bis(thiosemicarbazone) ligands and their nickel(II) and zinc(II) complexes, which have been fully characterized by several techniques. The photocatalytic activity of the six complexes for methyl orange degradation was also evaluated. All the complexes can degrade this organic dye, although the photoefficiency of the nickel compounds is, in general, higher than for the zinc ones, as the degradation is faster and they do not reach a plateau. Density functional theory calculations show a clear dependence of the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap, as well as with the relative energies of these orbitals. On the other hand, the need for green fuels that do not produce the greenhouse effect is one of the major goals of modern life, and molecular hydrogen is one of the most promising ones. Considering the proven potential of bis(thiosemicarbazone) complexes to electrocatalyze H2 evolution recently reported in the literature, we also made some preliminary tests to investigate the potential of the nickel complexes to act as photocatalysts for water splitting. The results indicate that two of the complexes produce H2 in the conditions tested, so they could be used in the development of efficient photocatalytic systems for hydrogen evolution.