SPAAC iClick: progress towards a bioorthogonal reaction in-corporating metal ions
Combining strain-promoted azide–alkyne cycloaddition (SPAAC) and inorganic click (iClick) reactivity provides access to metal 1,2,3-triazolates.
Shen, Yu-Hsuan↗
SEARCH · Engineering Papers
Results for “azides”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Efficient Synthesis of High-Performance Anion Exchange Membranes by Applying Clickable Tetrakis(dialkylamino)phosphonium Cations
Tetrakis(dialkylamino)phosphonium (TKDAAP) compounds exhibit extraordinary base resistance, a prerequisite feature for high-performance anion exchange membranes (AEMs). It is, however, challenging to synthesize a TKDAAP compound with reactive functionality that can be used to link the cation to a polymer backbone. In this study, two TKDAAP compounds with alkyne functionality were synthesized and incorporated into an azide-modified SBS triblock copolymer backbone via Cu(I)-catalyzed alkyne–azide cycloaddition (CuAAC) “click” chemistry. The properties of the resulting AEMs were characterized. It was found that (1) the triazole linker between the cation and the polymer backbone was stable under alkaline conditions; (2) varying the substituents of TKDAAP compounds could dramatically alter the stability; and (3) increasing the hydrophilicity of the AEM was an efficient way to enhance its ionic conductivity. Using clickable TKDAAP compounds makes it easy to combine various cations into polymer backbones with adjustable cation content, thus potentially leading to an efficient way to screen a wide variety of polyelectrolyte structures to identify the most promising candidates for high-performance AEMs.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Study of monopropellants for electrothermal thrusters. Evaluation test program task summary report
An electrothermal thruster designed for operation with MIL-grade hydrazine is suitable for operation with propellants having lower freezing points. These propellants are 76% hydrazine - 24% hydrazine azide, Aerozine-50, 50% hydrazine - 50% monomethylydrazine, and a TRW-formulated mixture of 35% hydrazine - 50% monomethylhydrane - 15% ammonia. A steady-state specific impulse of 200 sec was exceeded by all propellants. A pulse-mode value of 175 sec specific impulse was exceeded by the azide blend for pulse widths greater than 50 ms and was met by the carbonaceous propellants for pulse widths greater than 100 ms. Longer residence times were required for the carbonaceous propellants; the original thruster design was modified by increasing the characteristic chamber length and density of screen packing. A substantial amount of thermal energy must be supplied to initiate decomposition of propellants containing unsymmetrical-dimethylhydrazine and monomethylhydrazine. The rate controlling factor appeared to be the endothermic removal of methyl radicals.
Kuenzly, J. D.↗
Study of monopropellants for electrothermal thrusters
A 333 mN electrothermal thruster designed to use MIL-grade hydrazine was demonstrated to be suitable for operation with low freezing point monopropellants containing hydrazine azide, monomethylhydrazine, unsymmetrical-dimethylhydrazine and ammonia. The steady-state specific impulse was greater than 200 sec for all propellants. The pulsed-mode specific impulse for an azide blend exceeded 175 sec for pulse widths greater than 50 msec; propellants containing carbonaceous species delivered 175 sec pulsed-mode specific impulses for pulse widths greater than 100 msec. Longer thrust chamber residence times were required for the carbonaceous propellants; the original thruster design was modified by increasing the characteristic chamber length and screen packing density. Specific recommendations were made for the work required to design and develop flight worthy thrusters, including methods to increase propellant dispersal at injection, thruster geometry changes to reduce holding power levels and methods to initiate the rapid decomposition of the carbonaceous propellants.
Kuenzly, J. D.↗
Dinitrogen as a Universal Electron Acceptor in Solid-State Chemistry: An Example of Uncommon Metallic Compounds Na 3 (N 2 ) 4 and NaN 2
With the exception of Li, alkali metals do not react with elemental nitrogen neither at ambient conditions nor at elevated temperatures, requiring the search for alternative synthetic routes to their nitrogen-containing compounds. Here using a controlled decomposition of sodium azide NaN3 at high pressure conditions we synthesize two novel compounds Na 3 (N 2 ) 4 and NaN 2 both containing dinitrogen anions. NaN 2 synthesized at 4 GPa might be the common intermediate in high-pressure solid-state metathesis reactions where NaN 3 is used as a source of nitrogen, while Na 3 (N 2 ) 4 opens a new class of compounds, where [N 2 ] units accommodate a non-integer formal charge of -0.75. This finding can dramatically extend the expected compositions in other group 1-2 metal-nitrogen systems. Electronic structure calculations show the metallic character for both compounds.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Lewis Acid Supported Nickel Nitrenoids
Metalation of the polynucleating ligand F,tbs LH 6 (1,3,5-C 6 H 9 (NC 6 H 3 −4-F−2-NSiMe 2 t Bu) 3 ) with two equivalents of Zn(N(SiMe 3 ) 2 ) 2 affords the dinuclear product ( F,tbs LH 2 )Zn 2 (1), which can be further deprotonated to yield ( F,tbs L)Zn 2 Li 2 (OEt 2 ) 4 (2). Transmetalation of 2 with NiCl 2 (py) 2 yields the heterometallic, trinuclear cluster ( F,tbs L)Zn 2 Ni(py) (3). Reduction of 3 with KC 8 affords [KC 222 ][( F,tbs L)Zn 2 Ni] (4) which features a monovalent Ni centre. Addition of 1-adamantyl azide to 4 generates the bridging μ 3 -nitrenoid adduct [K(THF) 3 ][( F,tbs L)Zn 2 Ni(μ 3 -NAd)] (5). EPR spectroscopy reveals that the anionic cluster possesses a doublet ground state (S = 1/2). Cyclic voltammetry of 5 reveals two fully reversible redox events. The dianionic nitrenoid [K 2 (THF) 9 ][( F,tbs L)Zn 2 Ni(μ 3 -NAd)] (6) was isolated and characterized while the neutral redox isomer was observed to undergo both intra- and intermolecular H-atom abstraction processes. Here, Ni K-edge XAS studies suggest a divalent oxidation state for the Ni centres in both the monoanionic and dianionic [Zn 2 Ni] nitrenoid complexes. However, DFT analysis suggests Ni-borne oxidation for 5.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
iClick Synthesis of Metallopolymers and Highly Emissive Materials
This project involves the exploitation of iClick (Inorganic Click) to link two or more metal ions. The novel cycloaddition between a metal-azide and a metal-acetylide developed at UF provides an opportunity to prepare materials that were previously unimaginable. Further developing the synthetic methodology of iClick will open new frontiers for materials synthesis. Three specific goals are outlined in the project: 1) investigate the chemistry of iClick and its application to linking metal ions, 2) develop a method to dynamically tune the emission color of soluble gold-oligomers, and 3) exploit iClick synthesis to develop new conjugated Pt- and Ru-metallopolymers. Metallopolymers are on the cusp of revolutionizing the energy sector, information storage, and materials synthesis. Uniquely, transition metal chemistry marries polymer science in these hybrid materials wherein the metal ion imparts new properties unimaginable for organic polymers alone.
36 MATERIALS SCIENCE↗
Efficient and Robust Dynamic Crosslinking for Compatibilizing Immiscible Mixed Plastics through In Situ Generated Singlet Nitrenes
Abstract Creating a sustainable economy for plastics demands the exploration of new strategies for efficient management of mixed plastic waste. The inherent incompatibility of different plastics poses a major challenge in plastic mechanical recycling, resulting in phase‐separated materials with inferior mechanical properties. Here, this study presents a robust and efficient dynamic crosslinking chemistry that effectively compatibilizes mixed plastics. Composed of aromatic sulfonyl azides, the dynamic crosslinker shows high thermal stability and generates singlet nitrene species in situ during solvent‐free melt‐extrusion, effectively promoting C─H insertion across diverse plastics. This new method demonstrates successful compatibilization of binary polymer blends and model mixed plastics, enhancing mechanical performance and improving phase morphology. It holds promise for managing mixed plastic waste, supporting a more sustainable lifecycle for plastics.
Chemistry↗
Surface Functionalization of Black Phosphorus with Nitrenes: Identification of P=N Bonds by Using Isotopic Labeling
Abstract Surface functionalization of two‐dimensional crystals is a key path to tuning their intrinsic physical and chemical properties. However, synthetic protocols and experimental strategies to directly probe chemical bonding in modified surfaces are scarce. Introduced herein is a mild, surface‐specific protocol for the surface functionalization of few‐layer black phosphorus nanosheets using a family of photolytically generated nitrenes (RN) from the corresponding azides. By embedding spectroscopic tags in the organic backbone, a multitude of characterization techniques are employed to investigate in detail the chemical structure of the modified nanosheets, including vibrational, X‐ray photoelectron, solid state 31 P NMR, and UV‐vis spectroscopy. To directly probe the functional groups introduced on the surface, R fragments were selected such that in conjunction with vibrational spectroscopy, 15 N‐labeling experiments, and DFT methods, diagnostic P=N vibrational modes indicative of iminophosphorane units on the nanosheet surface could be conclusively identified.
Walz Mitra, Kendahl L.↗
Lewis Acid Supported Nickel Nitrenoids
Abstract Metalation of the polynucleating ligand F,tbs LH 6 (1,3,5‐C 6 H 9 (NC 6 H 3 −4‐F−2‐NSiMe 2 t Bu) 3 ) with two equivalents of Zn(N(SiMe 3 ) 2 ) 2 affords the dinuclear product ( F,tbs LH 2 )Zn 2 ( 1 ), which can be further deprotonated to yield ( F,tbs L)Zn 2 Li 2 (OEt 2 ) 4 ( 2 ). Transmetalation of 2 with NiCl 2 (py) 2 yields the heterometallic, trinuclear cluster ( F,tbs L)Zn 2 Ni(py) ( 3 ). Reduction of 3 with KC 8 affords [KC 222 ][( F,tbs L)Zn 2 Ni] ( 4 ) which features a monovalent Ni centre. Addition of 1‐adamantyl azide to 4 generates the bridging μ 3 ‐nitrenoid adduct [K(THF) 3 ][( F,tbs L)Zn 2 Ni(μ 3 ‐NAd)] ( 5 ). EPR spectroscopy reveals that the anionic cluster possesses a doublet ground state ( S = ). Cyclic voltammetry of 5 reveals two fully reversible redox events. The dianionic nitrenoid [K 2 (THF) 9 ][( F,tbs L)Zn 2 Ni(μ 3 ‐NAd)] ( 6 ) was isolated and characterized while the neutral redox isomer was observed to undergo both intra‐ and intermolecular H‐atom abstraction processes. Ni K‐edge XAS studies suggest a divalent oxidation state for the Ni centres in both the monoanionic and dianionic [Zn 2 Ni] nitrenoid complexes. However, DFT analysis suggests Ni‐borne oxidation for 5 .
Juda, Cristin E.↗
Surface Design for Immobilization of an Antimicrobial Peptide Mimic for Efficient Anti-Biofouling
Microbial surface attachment negatively impacts a wide range of devices from water purification membranes to biomedical implants. Mimics of antimicrobial peptides (AMPs) constituted from poly(N-substituted glycine) „peptoids“ are of great interest as they resist proteolysis and can inhibit a wide spectrum of microbes. We investigate how terminal modification of a peptoid AMPmimic and its surface immobilization affect antimicrobial activity. We also demonstrate a convenient surface modification strategy for enabling alkyne–azide „click“ coupling on amino-functionalized surfaces. Our results verified that the N- and C-terminal peptoid structures are not required for antimicrobial activity. Moreover, our peptoid immobilization density and choice of PEG tether resulted in a „volumetric“ spatial separation between AMPs that, compared to past studies, enabled the highest AMP surface activity relative to bacterial attachment. Our analysis suggests the importance of spatial flexibility for membrane activity and that AMP separation may be a controlling parameter for optimizing surface anti-biofouling.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Synthesis of a new 1,2,4-triazine derived Azidoxime
A 1,2,4-triazine based azidoxime was formed via the substitution of a chloroxime (3) with sodium azide in ethanol. This compound was characterized via single-crystal X-ray diffraction. This material has a calculated density of 1.746 g•cm –1 and is less sensitive to impact, spark, and friction, as compared to PETN and RDX. The dehydrated material has a calculated density of 1.823 g•cm –1 and the detonation pressure and velocity of 4 are calculated to be 29.1 GPa and 8.67 km•s –1 , respectively.
1,2,4-Triazine↗
Tailoring a 3D Covalent Organic Framework Toward Facile Functionalization
Three-dimensional covalent organic frameworks (3D COFs) are notably crystalline and stable, but their architectures and monomer structures make them difficult to functionalize. Here, a new strategy is presented to render COF-300 and other imine-linked frameworks amenable to facile functionalization in the last step of synthesis. By reducing the imine linkages to secondary amines and appending them with acetyl halide groups, the linkages are converted to electrophiles that can be readily reacted with nucleophilic guests. This route yields eight new COF-300 derivatives, bearing chloroacetyl, bromoacetyl, azide, cyano, amino, hydroxyl, methoxy, or thiomethyl groups appended to the inter-monomer linkages. The new materials are characterized through solid-state NMR, infrared spectroscopy, and powder X-ray diffraction, among other techniques, finding that the reported linkage transformations proceed to complete conversion while retaining the crystallinity of the materials. Microcrystal electron diffraction (microED) data are used to solve the evacuated structure of the amine-linked framework COF-300-AR for the first time, providing conclusive evidence of this framework's guest-induced phase change, along with the structure of the new framework COF-300-NH 2 . Finally, COF-300-NH 2 is shown to have significantly improved adsorption capacity for CO 2 and perfluoroalkyl substances (PFAS), highlighting the benefits of this synthetic strategy for the generation of customized adsorbents.
COF-300↗
Pincers with diverse donors and their interconversion: application to Ni(II)
Abstract A pincer ligand composed of a pyridine with ortho positions substituted by a bulky phosphine arm and a pyrazole arm (PNNH) is installed on nickel(II) to yield the diamagnetic planar complex [(PNNH)NiCl]Cl. The chloride anion can be replaced by BPh 4 − by a metathesis. The acidic pyrazole proton can be removed with LiN(SiMe 3 ) 2 to yield the square planar neutral molecule (PNN − )NiCl. The coordinated chloride can be metathetically replaced by azide to yield diamagnetic (PNN − )Ni(N 3 ). To evaluate changing the phosphine donor for a phosphine sulfide, the corresponding pincer ligand SPNNH was synthesized and installed on NiBr 2 . The reduced steric bulk from the more distant phosphorous keeps both halides coordinated in the paramagnetic molecular species (SPNNH)NiBr 2 . Several attempts to dehydrobrominate this species result in synthesis and characterization of two unexpected products. One effort revealed that the electrophilic character of P(V) leaves the phosphorus atom in (SPNNH)NiBr 2 vulnerable to nucleophilic attack, resulting in a P/C cleavage product which was characterized.
Cabelof, Alyssa C.↗
Cyclotron production of a 204 Bi/ 204m Pb generator by 24 MeV proton irradiation of natural Pb foil targets
This work focuses on the formation of a generator of 204 Bi/ 204m Pb for future applications in perturbed angular correlation spectroscopy and biological radiotracing with lead and bismuth isotopes. Generators were formed from the irradiation of natural Pb targets with 24 MeV protons producing 203,204,205,206,207 Bi that were rapidly dissolved in 3 M HNO 3 and 30 % H 2 O 2 and exchanged into a 0.1 M HCl matrix. Use of 100 mg anion exchange resin (AG 1-x8) allowed 203,204m Pb to be eluted in 600 μL of 0.1 M HCl. Furthermore, the longer-lived 205,206 Bi were eluted in 5 mL or 3 mL of either 0.25 M sodium acetate buffer pH 4.4 or 1.0 M H 2 SO 4 . Initial radiolabeling was conducted with eluted 206 Bi using DTPA and DOTA and 203 Pb using TCMC-Azide.
07 ISOTOPE AND RADIATION SOURCES↗
In-situ polarization modulation IRRAS investigation of ammonia electrooxidation on Pt-Ir and Pt-Ru nanoparticles prepared on engineered catalyst supports
The catalytic activity and surface reactivity of monometallic Pt and bimetallic Pt-Ir and Pt-Ru nanoparticles, supported on two distinct Engineered Catalyst Supports (ECSs), were investigated for the Ammonia Electrooxidation Reaction (AmER) in alkaline media. XRD measurements confirmed alloy formation between Pt-Ir and Pt-Ru nanoparticles, as indicated by the shift of the (111) reflection to higher 2θ values. Cyclic voltammetry, linear sweep voltammetry, and chronoamperometry experiments were conducted to assess the catalytic activity of the Pt, Pt-Ir, and Pt-Ru electrocatalysts. All bimetallic catalysts exhibited lower onset potentials compared to Pt. The differing Tafel slopes between Pt (74 mV dec⁻¹), Pt-Ir (152 mV dec⁻¹), and Pt-Ru (118–197 mV dec⁻¹) suggest that alloying Pt with Ir or Ru alters the reaction mechanisms. Furthermore, the bimetallic Pt-Ir and Pt-Ru catalysts demonstrated greater tolerance for concentrated ammonia solutions relative to Pt. In-situ Polarization Modulation Infrared Reflection Absorption Spectroscopy (PM-IRRAS) provided insights into the formation of N-H species, azide anions (N₃⁻), and N-O compounds. For the Pt-Ru catalyst, an additional peak around ~3600 cm⁻¹ was observed, corresponding to OH⁻ species. The PM-IRRAS results align with the Gerischer–Mauerer mechanism, indicating that partially dehydrogenated ammonia adsorbates act as active intermediates in the oxidation of ammonia over Pt-Ir and Pt-Ru catalysts.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
N-heterocyclic carbene platinum-butadiyne Click/iClick complexes. Towards blue-violet phosphorescence
By employing two different methods, namely, Click and iClick, a series of four trans-NHC-Pt(II) triazole-acetylide complexes containing benzyl (3a), methylnaphthalene (3b), methylanthracene (3c), and phenyl (3d) substituents at the terminal triazole ring were synthesized and characterized. The traditional click approach involves first synthesizing a triazole-acetylene and then attaching to the Pt ion. In the iClick approach, the triazole is formed via cycloaddition by combining a trans-platinum butadiyne with the corresponding organic azide. The complexes were interrogated to determine the effects of conjugation and ligand substituent on their photophysical properties. Complex 3a exhibits a photoluminescence lifetime of 4.3 μs at 77 K. Ascribed to emission from conformers differing due to the torsion of the aryl acetylide ligands, employing different excitation wavelengths results in different emission spectra. Complex 3a emits in the violet region with CIE coordinates of (0.159, 0.021) under 290 nm excitation and shifts to CIE coordinates of (0.161, 0.019) under 320 nm excitation. Finally, complex 3d, having a photoluminescence lifetime of 13.1 μs at room temperature, emits in the sky-blue region with CIE coordinates of (0.237, 0.355).
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Cyclophane-based two-dimensional polymer formed by an interfacial click reaction
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Roy, Indranil↗