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1.
Small ; 20(38): e2400712, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-38770994

RESUMO

As one of the main components of solid propellant, ammonium perchlorate (AP) shows slow sluggish decomposition kinetics with unconcentrated heat release. To achieve efficient catalytical decomposition, it is a significant challenge to design reasonable catalyst structure and explore the interaction between catalyst and AP. Herein, a series of porous carbon supported spinel-typed homogeneous heterometallic composites CuxCo3-xO4/C via pyrolysis of MOF-74-Co doped Cu. On basis of precise electronic-structure-tuning through modulating Cu/Co ratio in MOF-74, Cu0.15Co2.85O4/C with 5% Cu-doping featuring oxygen vacancy concentration of 26.25% exhibits the decrease to 261.5 °C with heat release up to 1222.1 J g-1 (456.9 °C and 669.2 J g-1 for pure AP). The detail process of AP accelerated decomposition is approved by TG-DSC-FTIR-MS technique. Density functional theory calculation revealed that in the Cu0.15Co2.85O4/C, the distinctive ability for NH3 catalyzed oxidation assisted with absorption performance of active porous C boosts accelerating AP decomposition. The findings would provide an insight for perceiving and understanding AP catalytic decomposition.

2.
Inorg Chem ; 63(29): 13484-13494, 2024 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-38990898

RESUMO

Transition metal phosphide/sulfide (TMP/TMS) heterostructures are attractive supercapacitor electrode materials due to their rapid redox reaction kinetics. However, the limited active sites and weak interfacial interactions result in undesirable electrochemical performance. Herein, based on constructing the NiCo-LDH template on Ni-MOF-derived Ni2P/NC, Ni2P/NC@CoNi2S4 with a porous heterostructure is fabricated by sulfurizing the intermediate and is used for supercapacitors. The exposed Ni sites in the phosphating-obtained Ni2P/NC coordinate with OH- to in situ form an intimate-connected Ni2P/NC@NiCo-LDH, and the CoNi2S4 nanosheets retaining the original cross-linked structure of NiCo-LDH integrate the porous carbon skeleton of Ni2P/NC to yield a hierarchical pore structure with rich electroactive sites. The conducting carbon backbone and the intense electronic interactions at the interface accelerate electron transfer, and the hierarchical pores offer sufficient ion diffusion paths to accelerate redox reactions. These confer Ni2P/NC@CoNi2S4 with a high specific capacitance of 2499 F·g-1 at 1 A·g-1. The NiCo-LDH template producing a tight interfacial connection, significantly enhances the stability of the heterostructure, leading to a 91.89% capacitance retention after 10,000 cycles. Moreover, the fabricated Ni2P/NC@CoNi2S4//NC asymmetric supercapacitor exhibits an excellent energy density of 73.68 Wh kg-1 at a power density of 700 W kg-1, superior to most reported composites of TMPs or TMSs.

3.
Inorg Chem ; 62(49): 20401-20411, 2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-38073496

RESUMO

Merging metal-organic frameworks (MOFs) and polyoxometalates (POMs) into heterogeneous heterojunction photocatalysts through in situ encapsulation is an effective approach to suppress the leachability of POMs and enhance their electron supply. The heterointerfacial connection in POMs@MOFs directly determines the performance of stability and charge separation, and the suited interaction between MOFs and POMs for POMs@MOFs heterojunctions photocatalyst is of vital importance. Here, a distinctive Keggin-type POM [(n-C4H9)N]10[SiW9Co3 (H2O)3O37]·17H2O (SiW9Co3) with near-total visible region absorption, narrow band gap of 2.23 eV, and powerful electron supply activity was prepared and tightly immobilized in the cavities of UiO-67-NH2 and UiO-68-NH2 to construct two Z-scheme heterojunctions SiW9Co3@UiO-67-NH2 and SiW9Co3@UiO-68-NH2, which were used for photocatalytic reduction of CO2 to CO. Their compositions, structures, and energy band features were fully characterized by a series of tests including XRD, FT-IR, SEM, XPS, UV-vis-DRS, UPS, and so forth. SiW9Co3@UiO-67-NH2 showed optimal photocatalytic performance with an excellent CO yield of 153.3 µmol-1·g-1·h-1 and a selectivity of 100%, which is 3.3-fold higher than that of SiW9Co3@UiO-68-NH2 and far superior to most reported POM-based heterojunctions. Comprehensive investigations with extensive photoelectric characterizations and microcalorimetric experiments demonstrated that the exceptional photocatalytic performances of SiW9Co3@UiO-67-NH2 could be attributed to the fact that (i) strong host-guest interactions were formed due to the well-matched dimensions between SiW9Co3 cluster and MOF cavity, which generated an intimate heterointerface to effectively accelerate interface electron transfer; (ii) the intimate heterointerface promoted SiW9Co3 to yield multielectron supply for efficient interfacial carrier neutralization owing to its donor-acceptor structure and narrow band gap. Additionally, the excellent durability of SiW9Co3@UiO-67-NH2 was also supported by the solidly locked SiW9Co3 and a stable MOF framework.

4.
Inorg Chem ; 62(20): 7954-7963, 2023 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-37154624

RESUMO

Efficient charge transfer has always been a challenge in heterogeneous MOF-based photoredox catalysis due to the poor electrical conductivity of the MOF photocatalyst, the toilless electron-hole recombination, and the uncontrollable host-guest interactions. Herein, a propeller-like tris(3'-carboxybiphenyl)amine (H3TCBA) ligand was synthesized to fabricate a 3D Zn3O cluster-based Zn(II)-MOF photocatalyst, Zn3(TCBA)2(µ3-H2O)H2O (Zn-TCBA), which was applied to efficient photoreductive H2 evolution and photooxidative aerobic cross-dehydrogenation coupling reactions of N-aryl-tetrahydroisoquinolines and nitromethane. In Zn-TCBA, the ingenious introduction of the meta-position benzene carboxylates on the triphenylamine motif not only promotes Zn-TCBA to exhibit a broad visible-light absorption with a maximum absorption edge of 480 nm but also causes special phenyl plane twists with dihedral angles of 27.8-45.8° through the coordination to Zn nodes. The semiconductor-like Zn clusters and the twisted TCBA3- antenna with multidimensional π interaction sites facilitate photoinduced electron transfer to render Zn-TCBA a good photocatalytic H2 evolution efficiency of 27.104 mmol·g-1·h-1 in the presence of [Co(bpy)3]Cl2 under visible-light illumination, surpassing many non-noble-metal MOF systems. Moreover, the positive enough excited-state potential of 2.03 V and the semiconductor-like characteristics of Zn-TCBA endow Zn-TCBA with double oxygen activation ability for photocatalytic oxidation of N-aryl-tetrahydroisoquinoline substrates with a yield up to 98.7% over 6 h. The durability of Zn-TCBA and the possible catalytic mechanisms were also investigated by a series of experiments including PXRD, IR, EPR, and fluorescence analyses.

5.
Inorg Chem ; 61(19): 7484-7496, 2022 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-35511935

RESUMO

Due to the inherent thermodynamic stability and kinetic inertness of CO2, heterogeneous catalytic conversion of CO2 to cyclic carbonates often requires harsh operating conditions, high temperature and high pressure, and the addition of cocatalysts. Therefore, the development of efficient heterogeneous catalysts under cocatalyst-free and mild conditions for CO2 conversion has always been a challenge. Herein, an infrequent tetracoordinated Cd-MOF was synthesized and used to catalyze CO2 cycloaddition reactions efficiently without the addition of any cocatalyst, and its catalytic mechanism was systematically investigated through a series of experiments, including fluorescence analysis, X-ray photoelectron spectroscopy, microcalorimetry, and density functional theory (DFT) calculation. Cd-MOF features a 3D supermolecule structure with 1D 11.6 × 7.7 Å2 channels, and the abundant Lewis acid/base and I- sites located in the confined channel boost efficient CO2 conversion with a maximum yield of 98.2% and a turnover number value of 1080.11 at 60 °C and 0.5 MPa, far surpassing most pristine MOF-based catalytic systems. A combined experimental and DFT calculation demonstrates that the exposed Cd(II) Lewis acid sites rapidly participate in coordination to activate the epoxides, and the resulting large steric hindrance facilitates leaving of the coordinated iodide ions in a reversibly dynamic fashion convenient for the rate-determining step ring-opening as a strong nucleophile. Such a pristine MOF catalyst with self-independent catalytic ring-opening overcomes the complicated operation limitation of the traditional cocatalyst-free MOF systems based on encapsulating/postmodifying cocatalysts, providing a whole new strategy for the development of simple, green, and efficient heterogeneous catalysts for CO2 cycloaddition.

6.
Angew Chem Int Ed Engl ; 60(18): 10228-10238, 2021 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-33474801

RESUMO

Utilization of metal-organic frameworks (MOFs) as electrodes for energy storage/conversion is challenging because of the low chemical stability and poor electrical conductivity of MOFs in electrolytes. A nanoscale MOF, Co0.24 Ni0.76 -bpa-200, possessing ultrahigh stability with uncommon semiconductor behavior (σ=4.2×10-3  S m-1 ) was fabricated. The MOF comprises a robust hydrophobic paddlewheel and an optimized Co/Ni ratio, with consequent control over MOF size and the degree of conjugation of the coligand. A DFT study revealed that appropriate Ni2+ doping reduces the activation energy of the system, thus providing a higher carrier concentration, and the strongly delocalized N-donor ligand notably increases the metal-ligand orbital overlap to achieve efficient charge migration, leading to continuous through-bond (-CoNi-N-CoNi-)∞ conduction paths. These structural features endow the MOF with a good cycling stability of 86.5 % (10 000 cycles) and a high specific capacitance of 1927.14 F g-1 among pristine MOF-based electrodes.

7.
Inorg Chem ; 59(10): 7158-7166, 2020 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-32363861

RESUMO

It is a crucial challenge to address both magnetic anisotropy and stability for single-molecule magnets (SMMs) used in next-generation nanodevices. Highly axial lanthanide SMMs with neutral charge and moderate coordination numbers represent promising magnetic materials. Here, using iodide ions with large volume and low surface charge density as weak donors, we report a six-coordinate neutral dysprosium SMM [Dy(Cy3PO)2I3(CH3CN)] with a certain degree of stability exhibiting a huge thermal barrier of 1062 K and hysteresis loops open up to 9 K. Through the elaborate reduction of ligand field strength, an apparent strongly axial crystal field is provided which elicits prominent crystal-field splitting and high axiality with the thermally activated relaxation via the third-excited Kramers' doublet. Moreover, the profound influence of strong equatorial ligand substitution on the electronic structure and relaxation pathway is clearly explored in DyIII analogues. The result suggests the great potential of the reducing the transverse ligand field in the improvement of SMMs performance.

8.
J Am Chem Soc ; 141(49): 19252-19256, 2019 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-31762282

RESUMO

The first isolable Ge5-spiropentadiene 1 was synthesized via the reduction of (iPr3Si)2NGeCl (3) with potassium. The crystal structure of 1 reveals a spirocyclic Ge5 skeleton containing two Ge-Ge double bonds (avg. 2.34 Å), which are fettered in two Ge3 rings with a dihedral angle of 70.193°. The DFT calculations and orbital analysis show that the σ-delocalization of the Ge5 skeleton and the 2π-delocalized aromatic Ge3 rings enhance the stability of molecule 1.

9.
Inorg Chem ; 58(12): 8198-8207, 2019 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-31185542

RESUMO

Host-Guest interaction is crucial to the sensitivity of heterogeneous sensors. Here, a series of isomorphic three-dimensional lanthanide metal-organic frameworks (Ln-MOFs), [Ln(TCBA)(H2O)2]2·DMF [H3TCBA = tris(3'-carboxybiphenyl)amine; Ln = Tb (1), Eu (2), and Gd (3); DMF = dimethylformamide] was synthesized and characterized, in which the propeller-like TCBA3- ligands adopt special torsional link between Tb(III) ions to form one-dimensional triangular channels. Optical experiments show that 1 exhibits bright green luminescence with an overall quantum yield of 26%, a 5D4 lifetime of 478 µs, and can act as an excellent heterogeneous fluorescent sensor to detect 2,4,6-trinitrophenol (TNP) explosive with an extremely low detection limit of 1.64 ppb. Because the confined channels within 1 exhibit matched dimensions toward TNP and feature multiple guest-response sites including rich π-conjugated groups, electron-donating N centers, and open metal nodes, strong host-guest interactions between 1 and TNP are captured and accurately determined by online microcalorimetry, which provides a distinctive thermodynamic perspective to understand the heterogeneous sensing behaviors. Additionally, the finely modulated heterometallic isomorphism [Tb0.816Eu0.184(TCBA)(H2O)2]2·DMF emits bright white light when excited at 380 nm and could potentially be used as single-phase white light-emitting diode phosphors materials.

10.
Inorg Chem ; 53(20): 10952-63, 2014 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-25286250

RESUMO

Hydrothermal reactions of europium(III) salt with 2-(4-carboxyphenyl)imidazo[4,5-f]-1,10-phenanthroline and dicarboxylic acid as coligands-benzene-1,4-dicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 2,5-dibromoterephthalic acid, and naphthalene-1,4-dicarboxylic acid-lead to four europium fluorescent materials (1-4). Structural analyses reveal that 1-4 have binuclear 3D metal-organic frameworks with different channels, void volumes, and conjugated structures tuned by ditopic carboxylates. There are no latticed and coordinated water molecules occurring in 1-3, while the free water molecules fill in 1D channels of 4. 4' was readily obtained via water removal of 4. Thermal analyses of all compounds show the high thermal stability of the main framework up to 450 °C. Optical studies indicate that 1-4 and 4' show the characteristic red luminescence emission of the Eu(III) ion in the visible regions at room temperature. On the basis of emission spectra, their luminescence lifetimes were determined. In particular, compound 4' shows a longer lifetime (τ = 0.942 ms) and significantly enhanced quantum yield (39%) compared with those of 1 (11%, 0.770 ms), 2 (4%, 0.414 ms), 3 (18%, 0.807 ms), and 4 (26%, 0.858 ms).

11.
Spectrochim Acta A Mol Biomol Spectrosc ; 325: 125145, 2024 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-39299072

RESUMO

Luminous imaging of latent fingerprints (LFPs) necessitates the possession of high-brightness aggregation-state luminescence by developers to ensure sufficient imaging contrast and resolution. A novel strategy involving incremental rotor modification is presented for AIE activation of the iridium developer. The rotor proliferation prominently improves the rotational activity of groups and facilitates high-efficiency RIM, thereby prompting the AIE activation of iridium developer with high luminous efficiency. Subsequently, a prompt, high-contrast, and robust LFP imaging protocol is developed utilizing the high-brightness AIE-active iridium developer. This innovative protocol realizes the luminous imaging and quantification of microscopic features in fingerprint ridges and furrows, including ridge widths, edge morphology of ridges, included angles, pores, and pore pitches with exceptional imaging contrast and refined detail resolution. Moreover, it allows for accurate identification of individual traits across diverse substrates without any pre-/post-processing to LFPs. The high-brightness AIE-active iridium developer provides outstanding aging resistance to developed fingerprints, thereby strongly supporting the acquisition, transfer, and preservation of fingerprint evidence. The luminous imaging protocol of LFPs based on high-brightness AIE exhibits robust adaptability to actual scenes and offers a premium scheme for facilitating forensic investigation.

12.
Talanta ; 264: 124775, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37311327

RESUMO

Creation of AIEgens with high brightness is compactly related to acquiring optimum AIE capabilities and still faces challenges. This study proposes an ingenious structurally regulative approach for preparing ultrabright AIEgens, taking iridium complexes as the model. The incremental rotational activity of substituents obtained by fine adjustment of the stereoscopic configuration efficaciously activates the AIE of iridium complexes and synchronously imparts high-brightness luminescence. Subsequently, benefitting from the ultrabright AIE, high-resolution visualization of latent fingerprints (LFPs) is achieved on diverse substrates by transient immersion in a solution of the AIE-active iridium complex (Ir3) for 60 s. The LFPs stained by Ir3 are integral and distinct enough to possess level 1-3 detail features, which allow precisely realizing personal identification. The LFP photograph emerges inconspicuous attenuation of contrast when aged under ambient light for 10 days and then being continuously irradiated with high-power ultraviolet light for 1 h, reflecting extraordinary aging resistance. Notably, the ultrabright AIE of Ir3 with room-temperature phosphorescence feature successfully achieves enhanced visualization of local fingerprint details with ultrahigh contrast. This LFP visualization protocol based on the ultrabright AIEgens is practical and provides a reliable solution for forensic investigations in actual scenarios.


Assuntos
Irídio , Luminescência , Raios Ultravioleta
13.
Dalton Trans ; 52(46): 17458-17469, 2023 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-37953710

RESUMO

In this work, using tri(5-aminotetrazolium)triazine (H3TATT) as an energetic ligand, two new energetic complexes (ECs), Cu(HTATT)(H2O)2 (EC-Cu1) and [Cu3(TATT)2(H2O)2]n (EC-Cu2), have been synthesized under hydrothermal conditions. Their crystal structures, thermal decomposition behaviors and specific heat capacities were determined respectively. In addition, two ECs were combined with GO (graphene oxide) and an MXene (Ti3C2TX) respectively by an in situ growth strategy to obtain four carbon nanomaterials/EC composites, which were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The effects of two ECs and four composites on the thermal decomposition of AP were studied by differential scanning calorimetry (DSC). Among them, the sample containing 8 wt% composite (GO/EC-Cu2) has the best promoting effect on AP, causing the high temperature decomposition peak to overlap with the low temperature decomposition peak of AP, reducing the decomposition peak temperature of AP from 443.6 °C to 308.9 °C, and the heat release is up to 4875 J g-1. Compared with ECs acting solely on AP, composite materials have stronger synergistic and promoting effects. This study provides a new example of the synthesis of carbon nanomaterial/EC composites and the improvement of the performance of AP-based solid propellants.

14.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 4): o989, 2012 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-22590040

RESUMO

The asymmetric unit of the title compound, C(4)H(6)N(8), contains a quarter of the mol-ecule, which possesses a crystallographically imposed centre of symmetry with all non-H atoms situated on a mirror plane. The crystal packing exhibits inter-molecular N-H⋯N hydrogen bonds and π-π stacking inter-actions between the tetra-zole rings of adjacent mol-ecules [centroid-centroid distance = 3.4402 (10) Å].

15.
Acta Crystallogr Sect E Struct Rep Online ; 68(Pt 5): o1330, 2012 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-22590231

RESUMO

In the title mol-ecule, C(3)H(5)N(5)O(2), the tetra-zole ring and carboxyl group form a dihedral angle of 82.25 (14)°. In the crystal, adjacent mol-ecules are linked through O-H⋯N, N-H⋯O and N-H⋯N hydrogen bonds into layers parallel to the bc plane.

16.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 7): o1669, 2011 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-21837068

RESUMO

The title compound, C(6)H(10)N(8)S(2), was prepared by the nucleophilic substitution reaction of 5-mercapto-1-methyl-tetra-zole and dichloro-ethane. In the crystal, the mol-ecule possesses an approximate non-crystallographic twofold symmetry axis. The crystal packing is stabilized by weak inter-molecular C-H⋯N and π-π inter-actions [centroid-centroid distances = 3.448 (6), 3.5085 (5) and 3.4591 (2) Å]. The two five-membered rings form a dihedral angle of 1.9 (2)°.

17.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 9): o2481, 2011 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-22059036

RESUMO

In the two anions of the title salt, C(2)H(10)N(2) (2+)·2C(8)H(5)N(8) (-)·2H(2)O, the central aromatic rings make dihedral angles of 13.53 (6) and 6.53 (7)° with the deprotonated tetra-zole rings, and 11.39 (6) and 10.41 (9)° with the other tetra-zole groups. In the crystal, the cations, anions and water mol-ecules are linked by an extensive O-H⋯N, N-H⋯O and N-H⋯N hydrogen-bond network into two-dimensional wave-like duplex sheets extending parallel to the bc plane. π-π stacking inter-actions between benzene rings [inter-centroid distances are 3.8482 (4) and 3.9621 (5) Å] and between tetra-zole rings [inter-centroid distances are 3.4350 (4) and 3.7169 (4) Å] further consolidate the crystal structure.

18.
Acta Crystallogr Sect E Struct Rep Online ; 67(Pt 4): o999, 2011 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-21754254

RESUMO

The mol-ecule of the title compound, C(5)H(8)N(8)S(2), lies on a twofold rotation axis that relates on 1-methyl-tetra-zolyl group to the other; the five-membered rings are twisted by 53.1 (1)°.

19.
ACS Appl Mater Interfaces ; 13(1): 563-569, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33373185

RESUMO

In this work, a new energetic coordination polymer (ECP), [Cu(HBTI)(H2O)]n (1) (H3BTI = 4,5-bistetrazole-imidazole), was synthesized by a hydrothermal method. Due to the existence of coordination water molecules in 1, however, its energy density was limited, which led to the insufficient detonation performance. To further improve its detonation performance, [Cu(H2BTI)(NO3)]n (2) was then obtained by substituting the coordinated water molecule in 1 with nitrate through the coordination substitution reaction under acidic conditions. The structures of two ECPs were respectively characterized using X-ray single-crystal diffraction, and the theoretical density of 2 (2.227 g·cm-3) was greater than 1 (1.851 g·cm-3). Thermogravimetric analyses showed that 2 has a one-step rapid weight loss process compared with the two-step slow weight loss process of 1. The theoretical calculations indicated that the detonation performances of 2 were better than those of 1. Moreover, the promotion effects of two ECPs on the combustion decomposition of ammonium perchlorate were studied using a differential scanning calorimetry method.

20.
Chem Commun (Camb) ; 57(3): 371-374, 2021 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-33325464

RESUMO

We report here a dinuclear DyIII iodine-bridged single-molecule magnet self-assembled by cis/trans coordination chemistry that displays a large anisotropy barrier of ca. 1300 K and a hysteresis opening temperature of 16 K. High temperature quantum tunnelling of magnetization is observed up to 56 K in zero-field and explained by the combination of the large anisotropy barrier and the local transverse field at the trans site. The results provide a model for thorough understanding of the effect of electronic structure on the magnetic behavior of lanthanide complexes.

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