CrystEngComm最新文献

The work presented herein reports on the synthesis, structural and physicochemical characterization and luminescence properties of a family of isostructural coordination polymers (CPs) with a general formula {[Ln(6m2onic)₄Na(H₂O)₃]·8H₂O}_n (where Ln(III) = Nd (1_Nd), Sm (2_Sm), Dy (3_Dy), Er (4_Er), Tm (5_Tm), Yb (6_Yb) and Dy_0.77Eu_0.12Y_0.11 for the multi-metal compound (7_DyEuY) and 6m2onic = 6-methyl-2-oxonicotinate). The crystal structures consist of one-dimensional heterometallic arrays where octacoordinated lanthanide and hexacoordinated sodium centres are sequentially linked and which are held together into a 3D architecture by an extensive hydrogen bonding network formed by the crystallisation water molecules. Photoluminescence measurements in the solid state at variable temperature reveal good properties based on the capacity of the 6m2onic ligand to provide ligand-centred excitation, as suggested by time-dependent density functional theory (TDDFT), and promote efficient energy transfers to the lanthanide(III) ions, to eventually present intense emissions in both the visible and near-infrared (NIR) regions. On the one hand, compound 4_Er displays characteristic lanthanide-centred bands in the NIR region even at room temperature, meaning that the framework is able to isolate the excitons from the vibrational quenching component. On the other hand, regarding the compounds emitting in the visible region, the almost white light emitted by compound 3_Dy with a quantum yield (QY) of 6.2% should be noted. Both a purer white emission and an improved QY (up to 15.8%) may be achieved by means of a doping strategy of europium and yttrium ions into the Dy counterpart. Finally, taking advantage of white light emitted by compound 3_Dy, the chemical and optical stabilities in water have been confirmed by the photophysical study performed in solution.

Heating a single crystal of carbamazepine (III) (the thermodynamically stable form) in contact with solid palmitic acid resulted in the melting of palmitic acid and the growth of the crystals of carbamazepine (II) (the least stable polymorph) at the interface “carbamazepine (III) crystal–palmitic acid melt”. The study suggests a possible mechanism of the transformation of carbamazepine (III) into carbamazepine (II) on mechanical treatment with palmitic acid as an additive.

Metallic Ni catalysts often suffer from serious aggregation and poor stability during the process of catalysis. In this work, core–shell nanostructures with nanosized MoO₂–Ni nanoparticles (NPs) and mesoporous SiO₂(mSiO₂) shells were well designed to address these issues. The Ni–MoO₂ hybrid cores were converted from hierarchical NiMoO₄ microtubes inside the SiO₂ shell through carbonization treatment to remove the hexadecyl trimethyl ammonium bromide (CTAB) template under the protection of a nitrogen atmosphere. The mesoporous SiO₂ shells in Ni–MoO₂@mSiO₂ nanoreactors prevented the agglomeration/sintering of Ni NPs, while allowing the mass diffusion of small molecules. Owing to the high catalytic performance of Ni–MoO₂ cores, good protection of mesoporous silica, and the unique sandwich-like structure, the obtained Ni–MoO₂@mSiO₂ nanoreactors showed tremendous improvement in catalytic activity and stability.

Ten novel perrhenates of nitrogenous heterocycles have been generated throughout this investigation. The crystal structure of these compounds was thoroughly examined, and intermolecular non-covalent interactions were analysed using the Hirshfeld surface approach. Organic perrhenate cations interact primarily through intermolecular contacts of the H⋯H, O⋯H/H⋯O, and N⋯H/H⋯N types, whereas anions interact mostly via O⋯H/H⋯O interactions. Six of the eight structures with aromatic fragments had anion–π interactions, whereas four of the 11 structures had anion–anion interactions of the Re–O type. Previously unexplored subtypes of 2D networks composed of interacting tetrahedral perrhenate anions have been discovered in piperazinium and triazolium salts. Thermochemical analysis suggests that Re–O⋯Re anion–anion interactions provide additional stabilisation and impact phase transitions in perrhenates. The consistent patterns of organic salt perrhenate behaviour under MALDI-spectrometry settings have been identified. Characteristic multiplets for rhenium acid salts, which can be designated MALDI fingerprints, have been found. Potential formulae of oxorhenates corresponding to the listed multiplets have been specified.

A family of heteroleptic paddlewheel diruthenium complexes has been designed to obtain a chiral arrangement of the donor atoms of their equatorial ligands around the metal–metal bond axis. In order to do so, the non-symmetric ligands 2-hydroxy-6-methylpyridinate (hmp) and 2-amino-6-methylpyridinate (amp) were employed to obtain the following four axially chiral compounds: cis-[Ru₂Cl(μ-DPhF)₂(μ-hmp)(μ-OAc)] (Ruhmp), cis-[Ru₂Cl(μ-DPhF)₂(μ-amp)(μ-OAc)] (Ruamp), cis-[Ru₂Cl(μ-DAniF)₂(μ-hmp)(μ-OAc)] (Ru′hmp) and cis-[Ru₂Cl(μ-DAniF)₂(μ-amp)(μ-OAc)] (Ru′amp) (DPhF = N,N′-diphenylformamidinate, DAniF = N,N′-bis(p-methoxyphenyl)formamidinate). All the compounds were studied by single crystal X-ray diffraction, confirming that a racemic mixture containing only one of the two possible regioisomers was obtained in all cases. A general nomenclature system for naming the full configuration of intrinsically chiral paddlewheel molecules is proposed using the C/A convention. In addition, electronic spectroscopy and cyclic voltamperometry data demonstrate the electronic tunable nature of this new platform. Overall, these results provide a novel example of robust and tunable chirality, which is of potential interest to be further exploited.

The exposed crystal facets of Cu have a profound effect on its electrocatalytic CO₂ reduction reaction (CO₂RR) activity and product selectivity. On the other hand, at present, most of the studies on Cu-based electrocatalysts for the CO₂RR focus on the synthesis of C₂₊ products. There are only a few reports involving methanol (CH₃OH) generation over Cu nanocrystals. Herein, CuO nanosheets (NSs) and nanorods (NRs) were synthesized through a controlled oxidation and dehydration route under mild reaction conditions, using Cu mesh as a Cu source and conductive substrate, respectively. The as-synthesized CuO NSs and NRs were further converted into Cu NSs and NRs through an in situ electrochemical reduction method, respectively. The experimental results showed that CH₃OH could be efficiently produced over Cu NSs with abundant (111) crystal facets through the electrocatalytic CO₂RR. The maximum CH₃OH faradaic efficiency (FE) obtained on Cu NSs is 68% at a relatively low applied potential of −0.6 V vs. reversible hydrogen electrode (RHE), which is 1.6 times larger than that achieved on Cu NRs with primarily exposed (200) crystal facets (42%). The crystal facet-dependent electrocatalytic CO₂RR activity toward CH₃OH production was elucidated based on theoretical calculations combined with experimental results.

Oxychalcogenides have been highly anticipated as nonlinear optical (NLO) crystals because of their excellent optical properties. Herein, a rare-earth oxychalcogenide Eu₂ZnGe₂OS₆ was successfully designed and synthesized. It crystallizes in the non-centrosymmetric P2₁m space group with highly polarized mixed-anion [GeOS₃] units and exhibits an indirect band gap of 2.22 eV, a moderate second harmonic generation (SHG) response (0.4 × AGS), and phase-matching properties. Additionally, Eu₂ZnGe₂OS₆ exhibits a significant calculated birefringence of 0.173@2090 nm. This research has enriched the rarely studied rare-earth oxychalcogenide system and provided new ideas for the design of promising IR NLO crystals.

Silver-containing heterometallic bromobismuthates(III) (3-BrPyC₃){[BiAgBr₆]} (1) and (ImC₄){[BiAgBr₆]} (2) and bromoantimonate (ImC₄)₃{[Sb₃Ag₂Br₁₇]} (3) (3-BrPyC₃ – 1,6-bis(3-bromopyridin-1-ium)propane dication, ImC₄ – diprotonated 1,4-bis(1H-imidazol-1-yl)butane) were synthesized. All compounds are composed of infinite chains, featuring yet unprecedented in halometalate(III) chemistry structural types. 1–3 reveal relatively high (>200 °C) thermal stability. Optical band gaps for 1–3 were estimated from UV-vis spectroscopy data.

The systems of intermolecular interactions, including hydrogen bonds, in the crystal structures of the cocrystal of L-ascorbic (L-Asc) and nicotinic (Nic) acids and individual coformers are considered, and the hemolytic and cytotoxic activities of these compounds are studied in vitro. The influence of conformational differences of L-Asc molecules (total effective charge) on the formation of a network of H-bonds in the supramolecular structure of pristine L-Asc is revealed. Calculation of regioselectivity descriptors shows that the conformer of the L-Asc molecule in the L-AscNic cocrystal has higher activity compared to conformer molecules of the pristine L-Asc. No hemolysis caused by the solutions of tested acids and L-AscNic is shown. Selective cytotoxicity (antimetabolic effect according to the MTT test) of solutions of L-AscNic cocrystals against a 72-hour culture of MCF-7 breast cancer cell line versus healthy cells (mesenchymal stem cells and embryonic fibroblasts) is revealed. The possible relationship between the initial conformational state of the L-Asc molecules in the composition/structure of the studied solid compounds and the biological activity of solutions of these compounds requires further studies.