Synthesis of well-defined star,star-block,and miktoarm star biodegradable polymers based on PLLA and PCL by one-pot azide–alkyne click reaction

Based on the “arm-first” strategy, ring-opening polymerization (ROP) and one-pot azide–alkyne click reaction, well-defined star-shaped polymers with different architectures have been successfully synthesized, including the star homopolymers four-arm star-shaped polycaprolactone (4sPCL) and four-arm star-shaped poly(l-lactic acid) (4sPLLA), star-block copolymer 4sPCL-b-PLLA and miktoarm star-shaped copolymer PCL₂PLLA₂. The star homopolymers 4sPCL and 4sPLLA were synthesized by a click reaction of an azide small molecule initiator and HC C-PCL or HC C-PLLA. The star-block copolymer 4sPCL-b-PLLA was synthesized by a click reaction of an azide small molecule initiator and the block copolymer HC C-PCL-b-PLLA. The miktoarm star polymer PCL₂PLLA₂ was synthesized by a one-pot azide–alkyne click reaction of simultaneous addition of equal proportions of HC C-PCL and HC C-PLLA. The structures of these star-shaped polymers have been confirmed by NMR, FT-IR and GPC. Furthermore, the melting and crystallization behaviors investigated using DSC and WXRD also confirm the formation of star-shaped polymers with different architectures.

Star, star-block, and miktoarm star biodegradable polymers were synthesized by an “arm-first” strategy, ring-opening polymerization and one-pot azide-alkyne click reaction.     

Globally stabilized bent carbon–carbon triple bond by hydrogen-free inorganic–metallic scaffolding Al4F6

For over 100 years, known bent C C compounds have been limited to those with organic (I) and all-carbon (II) scaffoldings. Here, we computationally report a novel type (III) of bent C C compound, i.e., C₂Al₄F₆-01, which is the energetically global minimum isomer and bears an inorganic–metallic scaffolding and unexpected click reactivity.

We report a novel C₂Al₄F₆-01 with metal–inorganic Al₄F₆-scaffolding, which differs from hitherto known bent-C C types, which all involve carbon-based scaffoldings.     

SOMC grafting of vanadium oxytriisopropoxide (VO(OiPr)3) on dehydroxylated silica; analysis of surface complexes and thermal restructuring mechanism

Vanadium oxytriisopropoxide (VO(OⁱPr)₃), 1, was grafted on highly dehydroxylated silica (SiO_2-700: aerosil silica treated at 700 °C under high vacuum) to generate compound 2 following the concepts and methodology of surface organometallic chemistry (SOMC). The resulting compound was analyzed by elemental analysis, FT-IR, ¹H, ¹³C and ⁵¹V solid state (SS) NMR, Raman and EPR spectroscopies. The grafting reaction of 1 to generate 2 was found to lead to the formation of a monopodal surface complex [( Si–O–)V(O)(OⁱPr)₂], 2m, as well as bipodal [( Si–O–)₂V(O)(OⁱPr)], 2b, formed along with ( Si–O–ⁱPr) moieties as an effect of the classical rearrangement of 2m with strained siloxane bridges. Upon controlled thermal treatment at 200 °C under high vacuum, 2m and 2b were found to mainly rearrange to tetrahedral VO₄ moieties [( Si–O–)₃V(O)] (3) with formation of propylene whereas the ( Si–O–ⁱPr) groups were preserved. The mechanism of the thermal rearrangement of the isopropoxide groups was investigated by a DFT approach revealing the occurrence of a concerted γ-H-transfer and olefin elimination mechanism.

VO(OⁱPr)₃ was grafted on highly dehydroxylated silica by a surface organometallic chemistry approach and its thermal evolution was analyzed with support of DFT calculations.     

Aromatic alkyne insertion into six-membered cyclometalated pyridine complexes of iridium: different insertion modes and structurally novel products

Reactions of 2-benzoylpyridine or 2-benzylpyridine with [Cp*MCl₂]₂ (M = Ir, Rh) have been carried out in the presence of NaOAc in refluxing methanol, which form the corresponding six-membered cyclometalated products (1–3) except for the reaction of 2-benzylpyridine with [Cp*RhCl₂]₂. Insertion reactions of two six-membered cyclometalated pyridine iridium complexes (1 and 2) with terminal or internal aromatic alkynes were studied. Terminal alkynes p-XC₆H₄C CH (X = H, MeO, and F) with 1 give the corresponding five- and seven-membered doubly cycloiridated complexes 4a–c, internal alkynes p-XC₆H₄C CC₆H₄X-p (X = H, MeO, and Br) form the similar five- and seven-membered doubly cycloiridated complexes (5a,b) and/or di-insertion products (6a,c), whereas the acyl alkyne PhC CCOPh affords the novel spiro-metalated complex 7. For complex 2, internal alkynes p-XC₆H₄C CC₆H₄X-p (X = H, MeO, and Br) form similar five- and seven-membered doubly cycloiridated complexes (8a–c). However, in the case of PhC CCOPh, the reaction gives the novel four-membered cyclometalated complex 9. These results suggest that the products formed by alkyne insertion reactions of the six-membered cycloiridated pyridine complexes are very diverse. Plausible pathways for the formation of these novel insertion products were proposed. Molecular structures of seven cyclometalated complexes were determined by X-ray diffraction.

Insertion reactions of aromatic alkynes into the Ir–C bond of six-membered cycloiridated complexes formed various novel products via different insertion modes.     

The relationship between basic group resonance and quantum yield of high efficiency red light fluorescent solutions

Compared with rare earth elements and heavy metal elements, rare-earth-element-free fluorescent films can greatly reduce environmental hazards. In this study, we use a solution method to produce the fluorescent films. The film thickness is 10 μm, which can maintain fluorescent light intensity in an environment with an average humidity of 55.1 (RH%) after encapsulation. We also find that the type of solvent affects the resonance position of the C N functional group in DCJTB at a wavenumber of 2196 (cm⁻¹), measured with Fourier transform infrared spectroscopy. The functional group is affected by the polar effect with its displacement decreasing with the quantum yield. Finally, we successfully made a fluorescent solution with a resonance displacement of only 12.8 (cm⁻¹) for the C N functional group with the quantum yield being as high as 81.3% and a fluorescent film with a quantum yield as high as 84.8%.

The fluorescent solution with a resonance displacement of only 12.8 (cm⁻¹) for the C N functional group gives this film a quantum yield as high as 84.8%.     

Formation of bicyclic polycyclic aromatic hydrocarbons (PAHs) from the reaction of a phenyl radical with cis-3-penten-1-yne

The formation of polycyclic aromatic hydrocarbons (PAHs) on the C₁₁H₁₁ potential energy surface involved in the reactions of a phenyl radical (C₆H₅) with cis-3-penten-1-yne (cis-C¹H C²–C³H C⁴H–C⁵H₃, referred to as C₅H₆) and its three radicals (CH C–Ċ CH–CH₃, CH C–CH Ċ–CH₃, and cis-CH C–CH CH–ĊH₂, referred to as the C³-, C⁴-, and C⁵-radicals with the same chemical components, C₅H₅) assisted by H atoms is investigated by performing combined density functional theory (DFT) and ab initio calculations. Five potential pathways for the formation of PAHs have been explored in detail: Pathways I–II correspond to the reaction of C₆H₅ with C₅H₆ at the C¹ and C² position, and Pathways III–V involve the reaction of C₆H₅ with the C³-, C⁴-, and C⁵-radicals with the assistance of H atoms. The initial association of C₆H₅ with C₅H₆ or C₅H₅ is found to be highly exothermic with only minor barriers (1.4–7.1 kcal mol⁻¹), which provides a large driving force for the formation of PAHs. The hydrogen atom is beneficial for the ring enlargement and ring formation processes. The present calculations predict 9 potential PAHs, six (CS6, CS10, CS13, CS26, CS28 and CS29) of which are indicated to be energetically more favorable along Pathways I, III, IV and V at low temperature. The calculated barriers for the formation of these PAHs are around 19.2–38.0 kcal mol⁻¹. All PAHs products could be formed at flame temperature, for the medium barriers are easily overcome in various flame conditions. The theoretical results supplement the PAH formation pathway and provide help to understand PAH growth mechanism.

The formation of PAHs within 4-, 5-, 6- and 7-membered rings on the C₆H₅ + C₅H₆ potential energy surface.     

A triflate and alkynyl protected Ag43 nanocluster with a passivated surface

A trifluoromethanesulfonate (OTf) and tert-butylacetylene (^tBuC C⁻) co-protected silver nanocluster (NC), Ag₄₃(^tBuC C)₂₄(CF₃SO₃)₈ (Ag₄₃), was synthesized and characterized. Single crystal X-ray diffraction analysis revealed its total structure. 43 Ag atoms are arranged into a three-concentric-shell Ag@Ag₁₂@Ag₃₀ structure. Both OTf and ^tBuC C⁻ ligands bonded with Ag atoms in a μ₃ mode. The application of Ag₄₃ as a catalyst for the reaction of silane with alcohol or H₂O indicated that the surface ligands had a profound passivation effect, which significantly influenced the reactivity and selectivity.

A trifluoromethanesulfonate (OTf) and tert-butylacetylene (^tBuC≡C⁻) co-protected silver nanocluster (NC), Ag₄₃(^tBuC≡C)₂₄(CF₃SO₃)₈ (Ag₄₃) was synthesized and characterized. Its surface ligands have shown strong passivation effect in the reaction catalyzed by Ag₄₃.     

Synthesis and characterization of sulfur-containing hybrid materials based on sodium silicate

An original method for the one-stage synthesis of sulfur-containing silica of SBA-15 type is developed and described. Instead of tetraethylorthosilicate (TEOS) typically used as a source of silica, the inexpensive sodium metasilicate has been applied in our method. The mesoporous silica material was first functionalized with thiol groups then oxidized by concentrated nitric acid to produce sulfonic groups. The samples obtained possess developed specific surface area (S_sp = 320–675 m² g⁻¹) and porous structure with an effective pore diameter of 3.5–5.7 nm. The orderliness of the structure and presence of surface sulfur-containing acidic groups of various natures in the synthesized materials were determined using XRD, TEM, N₂ adsorption, conductivity and potentiometric titration methods. Based on the results of the measurements of the zeta potential vs. pH and electrolyte concentration, conclusions about the electro-surface properties and aggregation stability of sample dispersion have been drawn. The obtained samples are environmentally-friendly and could be used in green chemistry.

Hybrid Si(CH₂)₃SH–SBA-15 and Si(CH₂)₃SO₃H–SBA-15 silicas were obtained with developed specific surface area and an effective pore diameter of 3.5–5.7 nm.     

Microstructure and characterization of aluminum-incorporated calcium silicate hydrates (C–S–H) under hydrothermal conditions

The phase assembly and microstructure of the aluminum-incorporated CaO–SiO₂–H₂O system, which is technologically important in autoclaved building materials, catalysis and waste management, were investigated using XRD, SEM, FTIR and NMR depending on aluminum addition, reaction temperature and curing time. The content of each phase was obtained using the MAUD program based on the Rietveld refinement. The results revealed that the formation of the tobermorite phase was promoted at Al/(Al + Si) ≤ 0.03, and subsequently retarded by higher aluminum addition, which was corroborated by the presence of more low polymerized and cross-linked (alumino)silicate chains. The phase purity decreased with increasing aluminum addition. Aluminum changed the morphology of tobermorite from plate-like to lath-like and fibrous. About a quarter of the (alumino)silicate chains in the C–S–H structure were linked though a Si–O–Al configuration, and this proportion was almost independent of aluminum addition. Furthermore, only Al[4] substituted for silicon in the aluminum incorporated C–S–H, while Al[6] just exited in the hydrogarnet phase. This work is beneficial for understanding the implication on micro-properties of by-products or admixtures containing aluminum in concrete.

The phase assembly and microstructure of the aluminum-incorporated CaO–SiO₂–H₂O system were investigated using XRD, SEM, FTIR and NMR depending on aluminum addition, reaction temperature and curing time.     

tBuOK-triggered bond formation reactions

Recently, inexpensive and readily available tBuOK has seen widespread use in transition-metal-free reactions. Herein, we report the use of tBuOK for S–S, S–Se, N N and C N bond formations, which significantly extends the scope of tBuOK in chemical synthesis. Compared with traditional methods, we have realized mild and general methods for disulfide, azobenzenes imine etc. synthesis.

Inexpensive and readily available ^tBuOK can trigger a series of bond formation reactions, including S–S, S–Se, Se–Se, and N N and C N bonds.     

Reactions of triosmium and triruthenium clusters with 2-ethynylpyridine: new modes for alkyne C–C bond coupling and C–H bond activation

The reaction of the trimetallic clusters [H₂Os₃(CO)₁₀] and [Ru₃(CO)₁₀L₂] (L = CO, MeCN) with 2-ethynylpyridine has been investigated. Treatment of [H₂Os₃(CO)₁₀] with excess 2-ethynylpyridine affords [HOs₃(CO)₁₀(μ-C₅H₄NCH=CH)] (1), [HOs₃(CO)₉(μ₃-C₅H₄NC CH₂)] (2), [HOs₃(CO)₉(μ₃-C₅H₄NC CCO₂)] (3), and [HOs₃(CO)₁₀(μ-CH CHC₅H₄N)] (4) formed through either the direct addition of the Os–H bond across the C C bond or acetylenic C–H bond activation of the 2-ethynylpyridine substrate. In contrast, the dominant pathway for the reaction between [Ru₃(CO)₁₂] and 2-ethynylpyridine is C–C bond coupling of the alkyne moiety to furnish the triruthenium clusters [Ru₃(CO)₇(μ-CO){μ₃-C₅H₄NC CHC(C₅H₄N) CH}] (5) and [Ru₃(CO)₇(μ-CO){μ₃-C₅H₄NCCHC(C₅H₄N)CHCHC(C₅H₄N)}] (6). Cluster 5 contains a metalated 2-pyridyl-substituted diene while 6 exhibits a metalated 2-pyridyl-substituted triene moiety. The functionalized pyridyl ligands in 5 and 6 derive via the formal C–C bond coupling of two and three 2-ethynylpyridine molecules, respectively, and 5 and 6 provide evidence for facile alkyne insertion at ruthenium clusters. The solid-state structures of 1–3, 5, and 6 have been determined by single-crystal X-ray diffraction analyses, and the bonding in the product clusters has been investigated by DFT. In the case of 1, the computational results reveal a rare thermodynamic preference for a terminal hydride ligand as opposed to a hydride-bridged Os–Os bond (3c,2e Os–Os–H bond).

The reactivity of 2-ethynylpyridine at low-valent triosmium and triruthenium centers has been investigated.     

Bonding and stability of donor ligand-supported heavier analogues of cyanogen halides (L′)PSi(X)(L)

Fluoro- and chloro-phosphasilynes [X–Si P (X = F, Cl)] belong to a class of illusive chemical species which are expected to have Si P multiple bonds. Theoretical investigations of the bonding and stability of the corresponding Lewis base-stabilized species (L′)PSi(X)(L) [L′ = cAAC^Me (cyclic alkyl(amino) carbene); L = cAAC^Me, NHC^Me (N-heterocyclic carbene), PMe₃, aAAC (acyclic alkyl(amino) carbene); X = Cl, F] have been studied using the energy decomposition analysis-natural orbitals for chemical valence (EDA-NOCV) method. The variation of the ligands (L) on the Si-atom leads to different bonding scenarios depending on their σ-donation and π-back acceptance properties. The ligands with higher lying HOMOs prefer profoundly different bonding scenarios than the ligands with lower lying HOMOs. The type of halogen (Cl or F) on the Si-atom was also found to have a significant influence on the overall bonding scenario. The reasonably higher value and endergonic nature of the dissociation energies along with the appreciable HOMO–LUMO energy gap may corroborate to the synthetic viability of the homo and heteroleptic ligand-stabilized elusive PSi(Cl/F) species in the laboratory.

The bonding and stability of elusive heavier cyanogen halide analogues (L′)PSi(X)(L) have been theoretically investigated using EDA-NOCV method. Variation of ligands and halogen on Si atom had a significant effect on the stability of these species.     

A theoretical study of the hydrolysis mechanism of A-234; the suspected novichok agent in the Skripal attack

A-234, [EtO–P( O)(F)–N C(Me)–N(Et)₂], is the suspected A-type nerve agent used in the Skripal attack on the 4th of March 2018. Studies related to the structure and reactivity of this compound are limited. We, therefore, aimed at understanding the underlying hydrolysis mechanism of A-234 within the DFT framework. The attack of the water molecule can occur at the phosphinate and acetoamidine reactive centres. Our theoretical findings indicate that the hydrolysis at the acetoamidine centre is thermodynamically favoured compared to the hydrolysis at the phosphinate centre. The hydrolysis at the acetoamidine moiety may proceed via two pathways, depending on the nitrogen atom participating in the hydrolysis. The main pathway consists of four distinct channels to reach the final product, with the concerted 1,3-proton shift favoured kinetically and thermodynamically in the gas phase and water as solvent. The results are in good agreement with the literature, although some differences in the reaction mechanism were observed.

A theoretical study of the hydrolysis mechanism of A-234 [EtO–P( O)(F)–N C(Me)–N(Et)₂]; the suspected novichok agent in the Skripal attack.     

Probing the supramolecular features via π–π interaction of a di-iminopyrene-di-benzo-18-crown-6-ether compound: experimental and theoretical study

A novel DPyDB-C N-18C6 compound was synthesised by linking a pyrene moiety to each phenyl group of dibenzo-18-crown-6-ether, the crown ether, through –HC N– bonds and characterized by FTIR, ¹H-NMR, ¹³C-NMR, TGA, and DSC techniques. The quantitative ¹³C-NMR analysis revealed the presence of two position isomers. The electronic structure of the DPyDB-C N-18C6 molecule was characterized by UV-vis and fluorescence spectroscopies in four solvents with different polarities to observe particular behavior of isomers, as well as to demonstrate a possible non-bonding chemical association (such as ground- and excited-state associations, namely, to probe if there were forming dimers/excimers). The interpretation of the electronic structure was realized through QM calculations. The TD-CAM-B3LYP functional, at the 6-311+G(d,p) basis set, indicated the presence of predominant π → π* and mixed π → π* + n → π* transitions, in line with the UV-vis experimental data. Even though DPyDB-C N-18C6 computational studies revealed a π-extended conjugation effect with predominantly π → π* transitions, thorough fluorescence analysis was observed a weak emission, as an effect of PET and ACQ. In particular, the WAXD analysis of powder and thin films obtained from n-hexane, 1,2-dichloroethane, and ethanol indicated an amorphous organization, whereas from toluene a smectic ordering was obtained. These results were correlated with MD simulation, and it was observed that the molecular geometry of DPyDB-C N-18C6 molecule played a defining role in the pyrene stacking arrangement.

Herein, we report the formation of a potential supramolecular arrangement mediated by inter- and intra-molecular interactions between di-iminopyrene-dibenzo-18-crown-6-ether molecules.     

Application of poly(vinylphosphonic acid) modified poly(amidoxime) in uptake of uranium from seawater

To enhance the anti-biofouling properties and adsorption capability of poly(amidoxime) (PAO), vinylphosphonic acid (VPA, CH₂ CH-PO₃H₂) was polymerized on poly(acrylonitrile) (PAN) surface by plasma technique, followed by amidoximation treatment to convert the cyano group (–C N) into an amidoxime group (AO, –C(NH₂) N–OH). The obtained poly(vinylphosphonic acid)/PAO (PVPA/PAO) was used as an adsorbent in the uptake of U(vi) from seawater. The effect of environmental conditions on the anti-biofouling property and adsorption capability of PVPA/PAO for U(vi) were studied. Results show that the modified PVPA enhances the anti-biofouling properties and adsorption capability of PAO for U(vi). The adsorption process is well described by the pseudo-second-order kinetic model and reached equilibrium in 24 h. Adsorption isotherms of U(vi) on PVPA/PAO can be well fitted by the Langmuir model, and the maximum adsorption capability was calculated to be 145 mg g⁻¹ at pH 8.2 and 298 K. Experimental results highlight the application of PVPA/PAO in the extraction of U(vi) from seawater.

Our modified poly(vinylphosphonic acid) (PVPA) enhances the anti-biofouling properties and adsorption capability of poly(amidoxime) (PAO); the PVPA/PAO presents exceptional ability in the selective uptake of U(vi) from seawater.     

Computational design and molecular modeling of the interaction of nicotinic acid hydrazide nickel-based complexes with H2S gas

The application of nickel complexes of nicotinic acid hydrazide ligand as a potential gas-sensor and adsorbent material for H₂S gas was examined using appropriate density functional theory (DFT) calculations with the ωB97XD/Gen/6-311++G(d,p)/LanL2DZ method. The FT-IR spectrum of the synthesized ligand exhibited a medium band at 3178 cm⁻¹ attributed to ν(NH) stretching vibrations and strong bands at 1657 and 1600 cm⁻¹ corresponding to the presence of ν(C O) and ν(C N) vibration modes. In the spectrum of the nickel(ii) complex, the ν(C O) and ν(C N) vibration bands experience negative shifts to 1605 cm⁻¹ and 1580 cm⁻¹, respectively, compared to the ligand. This indicates the coordination of the carbonyl oxygen and the azomethine nitrogen atoms to the Ni²⁺ ion. Thus, the sensing mechanism of the complexes indicated a short recovery time and that the work function value increases for all complexes, necessitating an excellent H₂S gas sensor material. Thus, a profound assertion was given that the complex sensor surfaces exhibited very dense stability with regards to their relevant binding energies corresponding to various existing studies.

We demonstrate the efficacy of nicotinic acid hydrazide as adsorbent/sensor materials for H₂S gas.     

Cobalt doped graphitic carbon nitride as an effective catalyst for peracetic acid to degrade sulfamethoxazole

In this study, cobalt doped graphitic carbon nitride (Co–CN) was prepared and applied as a catalyst to activate peracetic acid (PAA) for sulfamethoxazole (SMX) degradation at neutral pH. PAA could be efficiently activated by Co–CN resulting in the efficient degradation of SMX. Characterization results of fresh and used Co–CN suggested that cobalt was successfully doped in graphitic carbon nitride (g-C₃N₄) through chemical bonding (Co–N bond) and the surface cobalt species in Co–CN (i.e., Co(ii) and Co(iii)) were the main activators for PAA. Organic radicals (i.e., CH₃C(O)O˙ and CH₃C(O)OO˙) were proved to be the dominant reactive species for SMX removal in the Co–CN/PAA system by radical scavenging experiments. The increase of cobalt doping content, PAA dosage or Co–CN dosage could accelerate SMX degradation and the neutral condition was highly favorable to SMX removal in Co–CN/PAA system. Co–CN exhibited a good stability and reusability for PAA activation in degrading SMX. Four possible degradation pathways of SMX (i.e., hydroxylation, nitration, bond cleavage and coupling reaction) were proposed in the Co–CN/PAA system according to eight identified transformation products.

An efficient advanced oxidation process (AOP) for sulfamethoxazole (SMX) removal: peracetic acid activated with cobalt doped graphitic carbon nitride.     

FTIR product study of the Cl-initiated oxidation products of CFC replacements: (E/Z)-1,2,3,3,3-pentafluoropropene and hexafluoroisobutylene

A product study of the reactions of (E/Z)-1,2,3,3,3-pentafluoropropene ((E/Z)-CF₃CF CHF) and hexafluoroisobutylene ((CF₃)₂C CH₂) initiated by Cl atoms were developed at 298 ± 2 K and atmospheric pressure. The experiments were carried out in a 1080 L quartz-glass environmental chamber coupled via in situ FTIR spectroscopy to monitor the reactants and products. The main products observed and their yields were as follows: CF₃C(O)F (106 ± 9)% with HC(O)F (100 ± 8)% as a co-product for (E/Z)-CF₃CF CHF, and CF₃C(O)CF₃ (94 ± 5)% with HC(O)Cl (90 ± 7)% as a co-product for (CF₃)₂C CH₂. Atmospheric implications of the end-product degradation are assessed in terms of their impact on ecosystems to help environmental policymakers consider HFOs as acceptable replacements.

An experimental product distribution study and the atmospheric implications of the reactions of Cl with two fluorinated alkenes is provided.     

Theoretical screening of bistriazole-derived energetic salts with high energetic properties and low sensitivity

We designed four series of energetic anions by replacing nitro group (NO₂) with trinitromethyl group (C(NO₂)₃) or by inserting N-bridging groups (–NH–, –NH–NH–, –N N–, –N N(O)–) into the bistriazole frameworks. The properties of 40 energetic salts, based on the bistriazole-derived anions and hydroxylammonium cation, were studied by density functional theory (DFT) and volume-based thermodynamics calculations (VBT). It is found that the newly designed energetic salts have good detonation properties due to their larger nitrogen content and better oxygen balance. And one of their corresponding hydroxylammonium salts exhibits better detonation performance (D = 10.06 km s⁻¹ and P = 48.58 GPa) than CL-20 (D = 9.54 km s⁻¹ and P = 43.36 GPa). Moreover, 10 energetic salts not only exhibit excellent energetic properties superior to CL-20, but also have lower sensitivity than CL-20 (h₅₀ = 13.81 cm). In addition, we rationally selected salt B6 from the 10 salts to predict its crystal structure under pressures. By converting energetic molecules with excellent detonation properties into energetic ions, some highly bistriazole-derived energetic salts with both excellent performance and low sensitivity could be developed strategically.

We designed four series of energetic anions by replacing nitro group (NO₂) with trinitromethyl group (C(NO₂)₃) or by inserting N-bridging groups (–NH–, –NH–NH–, –N N–, –N N(O)–) into the bistriazole frameworks.     

Co-ligand triphenylphosphine/alkynyl-stabilized undecagold nanocluster with a capped crown structure

We report the synthesis and crystal structure of novel co-ligand phosphine/alkynyl protected Au nanoclusters, with composition [Au₁₁(PPh₃)₈(C CPh–CF₃)₂](SbF₆) (1). The gold atoms in the cluster as a capped crown structure subtend C_3v symmetry with one deriving from a central icosahedron and 10 peripheral Au atoms, and all alkynides are exclusively σ coordination bonding. The mean core diameter is about 5.1 Å and the overall van der Waals diameter can be estimated to be 20.5 Å. The optical absorbance of 1 in solution reveals characteristic peaks at 384 and 426 nm and a shoulder between 450 and 550 nm.

We synthesized novel co-ligand phosphine/alkynyl-stabilized Au nanoclusters with a capped crown structure, and all alkynides are exclusively in the μ₁-η¹-end-on coordination mode which is unlike the other undecagold system.