CrystEngComm最新文献

Two isostructural nanosized coordination cages of formula [M^II₄SO₂TCA(μ₄-OH₂)]₆TATB₈·nS (M = Co or Ni, SO₂TCA = sulfonylcalix[4]arene, TATB = 4,4′,4′′-s-triazine-2,4,6-triyl-tribenzoate trisanion, S are solvent molecules) were obtained following a three-components strategy, using two different synthetic methods, leading to face-panelled octahedral coordination cages. The compounds were thoroughly analysed from a structural point of view, and for M = Co, the adsorption properties were measured, revealing a high surface area (SA = 742 m² g⁻¹) and a large CO₂ uptake for these types of compounds.

Blue light emitters are an important composition of the three primary colors. Considering the instability and toxicity of three-dimensional (3D) lead halide perovskites, it is significant to explore lead-free hybrid metal halides with high luminescence efficiency and green and pollution-free synthesis processes as solid blue light-emitting materials. In this work, a novel family of zero-dimensional (0D) hybrid zinc-based halides AZnX₄ (A = N-EtPipz, DMPZ, DAPr-Pipz, and MPPZ; X = Cl and Br) based on discrete [ZnX₄]²⁻ tetrahedrons were prepared by a simple method. When excited by UV light, all the four compounds exhibited bright blue light emissions, and among them, [DAPr-Pipz]ZnBr₆ had a photoluminescence quantum yield (PLQY) of 27.68%, indicating their potential as high-efficiency blue phosphors for assembling white light-emitting diodes (LEDs).

The electrochemical manipulation of organic compounds offers a promising alternative for the synthesis of valuable organic materials under mild conditions. In this study, the MoO₂@NiO heterostructure was successfully synthesized as an efficient thin-film electrode material for electrochemical ethanol oxidation, using amorphous Ni(OH)_x nanosheets as the precursor. During electrocatalytic ethanol oxidation, this electrode exhibited a significantly reduced overpotential, achieving a value of only 1.41 V at a current density of 50 mA cm⁻². Additionally, product analysis revealed that the heterojunction electrode demonstrated high faradaic efficiency (70%) and selectivity (80%) for acetaldehyde. The outstanding performance of this electrode can be attributed to the in situ transformation of MoO₂ species during the catalytic process. In the electrolyte, MoO₂ exists as MoO₄²⁻ and undergoes a series of processes including precipitation, dissolution, and redeposition on the electrode surface. These processes lead to the formation of a novel molecular outer layer, significantly enhancing the activity and stability of the electrode material. This study provides valuable insights into the potential replacement of anodes in the electrocatalytic oxidation of ethanol in aqueous solutions, thereby contributing to the development of more efficient and sustainable electrochemical systems.

In this work, BiOBr photocatalysts doped with zinc ions were manufactured to improve their photocatalytic degradation of methyl blue (MB). Among them, Zn²⁺/BiOBr-8 exhibited the highest photodegradation efficiency of MB after 100 min of illumination. After six-cycle experiments, it was found that its photocatalytic performance remained at a high level. The composition and microstructure of the materials were characterized by techniques such as XRD, FTIR, XPS, SEM, and TEM. The optical properties and the photodegradation performance of the materials were investigated by DRS, PL, photocurrent, and active species trapping experiments. The reasonable mechanism for photocatalytic degradation of MB was proposed.

Together with co-crystals, solid solutions of molecular systems are vital in the design of multicomponent solids that exhibit improved physical and chemical properties compared to those of pure substances. In this work, both the bulk and thin film phases of the molecular solid solutions of the active pharmaceutical ingredients (APIs) phenothiazine (PTZ) and iminostilbene (ISB) are characterized structurally, while low frequency Raman spectroscopy coupled with DFT simulations is employed to understand the impact of the loss of perfect periodicity of the mixed system on its lattice dynamics. X-ray diffraction methods show the statistical distribution of the two molecules in the structure, and the steady variation of the structural parameters with solution composition, confirming that we are dealing with monophasic mixtures. The spectroscopic properties are demonstrated to be different depending on the nature of the vibrational mode. While the vibrational spectra of molecules can always be decomposed into a superposition of the spectra of the two pure compounds, the lattice phonons exhibit a continuous evolution throughout the solution series.

Metal–organic frameworks (MOFs) can catalyze the oxygen evolution reaction (OER) process. Despite the established link between pristine MOFs and electrocatalysts, a number of limitations still hamper the understanding of the key factors that determine OER performance. In this paper, taking the ideal Co-MOF model as the structural basis (this MOF contains unsaturated coordinated metal centers and one-dimensional metal chains), nickel ions and/or iron ions are introduced to obtain isostructural bimetallic and trimetallic MOFs. Furthermore, the valence state of the iron element in the trimetallic MOF is regulated to improve the OER performance. The electrochemical performance test results confirm that the trimetallic (Co₁Ni₁)₂Fe₁(II)-MOF regulated by valence state shows excellent catalytic performance in the OER, which is superior to monometallic and bimetallic MOFs. Its enhanced catalytic performance can be attributed to the synergistic interactions between unsaturated Co, Ni and Fe sites as well as the faster charge transfer ability of the Fe^II/Fe^III mixed-phase system, which facilitates the optimization of the adsorption and activation processes of the reactants/intermediates. This exploration provides a new perspective for further studying the structure–performance relationship of metal–organic framework materials and developing more efficient OER catalysts.

This study reports the crystal structures of potassium and cesium salts of adenine (K-adenine and Cs-adenine) from the perspective of the interaction of alkali cations with purine nucleobases. Unlike previously-known guanine salts, both K-adenine and Cs-adenine are anhydrous, with the counter ions (K⁺ and Cs⁺) directly coordinating to the ring nitrogens of adenine anions. In both structures, the crystal packing is predominantly determined by cation–anion interactions, with additional stabilization through hydrogen-bonding of neighbouring adenines. Attempts to crystallise either the cesium salt of guanine or the sodium salt of adenine were unsuccessful. To explain this trend, quantum-chemical calculations were performed to rationalise the preferences of sodium, potassium, and cesium cations to coordinate either with water or adenylate/guanylate anions. The exchange energies of cation–anion complexes reveal that sodium cations exhibit a preference for water or guanylate coordination via oxygen, while cesium cations prefer adenylate coordination via nitrogen functions, avoiding water interaction. Potassium exhibits an intermediate trend. Overall, this research offers insights into interactions between alkali-cations and organic anions, aiding the development of new crystalline compounds and co-crystals.

We present the synthesis and detailed structural characterization of a cadmium-based metal–organic framework (Cd-MOF) with the formula [Cd(L^4-Py)(nipa)(H₂O)]_n, where L^4-Py stands for N,N′-(thiobis(4,1-phenylene))diisonicotinamide and anionic nipa²⁻ represents 5-nitroisophthalate. This Cd-MOF has been investigated for its potential application as a fluorescent probe, demonstrating highly selective recognition of nitroaromatic compounds (NACs). The Cd-MOF was synthesized using ligand L^4-Py, co-ligand H₂nipa, and cadmium iodide. Single crystal X-ray diffraction analysis revealed that the Cd-MOF forms a one-dimensional (1D) polymeric structure and is finally adapted into a three-dimensional (3D) supramolecular network through various C–H---π interactions. The 3D framework features channels with cross-sectional dimensions of 17.31 × 20.31 Ų, aligned along the crystallographic b-axis, and accommodates coordinated water molecules. Remarkably, the Cd-MOF exhibits high fluorescence stability in aqueous solutions and is capable of selectively detecting 4-nitrophenol (4-NP) and 4-nitrotoluene (4-NT). The detection is characterized by high quenching constants and low detection limits, specifically 3.09 × 10⁴ M⁻¹ and 0.166 μM for 4-NP, and 3.09 × 10⁴ M⁻¹ and 0.184 μM for 4-NT. We argued that the fluorescence quenching of Cd-MOF in the presence of NACs is driven by competitive absorption and a synergistic interaction between the amidic functionalities and hinged ‘S’ atom in the ligand framework of Cd-MOF and NACs. This powerful synergy enables quick detection of NACs through triggered fluorescence quenching response.

This study is committed to the synthesis and characterization of a series of bi-, tri- and tetranuclear coordination compounds. These compounds are produced through the reactions of zinc(II) or cadmium(II) ions as coordination centers with flexible bis(quinolyl) ligands HL1 (N,N′-bis-quinolin-2-ylmethylene-carbohydrazide) or HL2 (N,N′-bis-quinolin-2-ylmethylene-carbonothioic dihydrazide), in conjunction with chloride, thiocyanate, iodide or hydroxyl anions serving as the coordinated counterions. These compounds are denoted as [Zn₃(L1)₂Cl(NCS)₃]·2DMF·H₂O (1), [Zn₄(L1)₂Cl_3.8I_0.2(OH)₂]·8H₂O (2), [Cd₂(L1)I₃(H₂O)(DMF)]·DMF·0.25H₂O (3), [Zn₃(L2)₂Cl₄]·3DMF·2H₂O (4), [Zn₃(L2)₂Cl(NCS)₃]·3DMF (5), [Zn₄(L2)₂Cl₄(OH)₂]·3DMF·2H₂O (6), and [Cd₄(L2)₂I₆]·2DMF (7). An array of analytical techniques including elemental analyses, infrared (IR) spectroscopy, thermogravimetric (TG) analysis, powder X-ray diffraction (XRD) and comprehensive single crystal structure analyses have been utilized to elucidate the nature of these compounds. The crystal structures of compounds 1 to 7 exhibit complex supramolecular networks, arranged in zero, one, two, or three dimensions, primarily mediated by various interactions such as intermolecular π⋯π, C–H⋯π, C–H⋯Cl, and C–H⋯S weak interactions, in addition to hydrogen bonding. The structural diversity highlights the key roles of the variable coordinating counterions and the coordination modes of the iodide anions in shaping the architectures of the coordination compounds. Furthermore, the luminescence characteristics of compounds 1 to 7 have been assessed in the solid state.

The reaction of the precursors Eu(dbm)₃(H₂O) and Sm(dbm)₃(H₂O) with enantiopure monobidentate N-donor ligands (L_R/L_S), respectively, afforded two chiral Eu^III and Sm^III enantiomeric pairs, namely Ln(dbm)₃(L_R)/Ln(dbm)₃(L_S) (Ln = Eu^III, D-1/L-1 and Ln = Sm^III, D-2/L-2), where dbm⁻ = dibenzoylmethanate and L_R/L_S = (−)/(+)-4,5-pinenepyridyl-2-pyrazine. Compared with their precursors, D-1 and D-2 display highly enhanced photophysical properties under excitation with visible light. A study of nonlinear optical (NLO) response reveals that Eu(dbm)₃(H₂O) and Sm(dbm)₃(H₂O) only show moderate second-harmonic generation (SHG) responses, while D-1/L-1 and D-2/L-2 only exhibit strong third-harmonic generation (THG) responses. The THG intensities of D-1/L-1 and D-2/L-2 are 62/59 and 56/58 × α-SiO₂, respectively. These findings clearly indicate that introducing L_R and L_S into Eu(dbm)₃(H₂O) and Sm(dbm)₃(H₂O) can not only highly boost the photophysical performances but also lead to the switching of the NLO responses from SHG to THG.