Single Crystal Structure Research Articles

Facile synthesis of imidazolidinyl phenolate supported Dicopper(II/II) Complexes: Activation and fixation of atmospheric CO2 as MeOCO2− showing exogenous bridge modulating magnetic exchange coupling

Two imidazolidine grafted Schiff bases H3L2 and H3L3 have been utilized to fasten the Cu2 core in four new complexes [Cu2(μ-L2)(μ-O2CMe)]·H2O (1·H2O), [Cu2(μ-L2)(μ-O2COMe)]·H2O (2·H2O), [Cu2(μ-L2)(μ-NO3)]·H2O (3·H2O) and [Cu2L3(μ-OAc)]·5H2O (4·5H2O). Room temperature solution reaction of H3L2 with Cu2(OAc)4·2H2O provided 1·H2O in good yield. Follow-up reaction of 1·H2O with Et4NOH in air replaces μ-O2CMe (acetato) bridge by MeOCO2− (monomethyl carbonato) linker in 2·H2O. Single crystal X-ray structure established the individual complexes and confirmed the fixation of atmospheric CO2. Variable temperature (2 to 300 K) magnetic susceptibility measurements recognized the antiferromagnetic exchange interactions between the adjacent copper(II) centers in complexes 2 and 3. The amount of spin–spin interactions are found to be higher for ancillary NO3− bridge (−284 cm−1) compared to the in situ transformed MeOCO2− bridged (−1.64 cm−1).

β-Enaminones and organic salts from 3-benzoyl-4‑hydroxy-6-phenyl-2H-pyran-2-one: Synthesis, X-ray crystal structural studies and antimicrobial activity

The reactivity of pyran-2,4‑dione 1 towards primary amines (propylamine and p-toluidine) and secodary amines (morpholine and piperidine) were investigated. The reactions were proceeded by replacement of the external alcoholic hydroxyl group with primary amine accompanied by loss of water molecule to give β-enamino-pyran-2,4-diones 2 and 3. In case of secondary amines, a transfer of the phenolic proton of pyrone ring to the secondary amine nitrogen leading to the formation of the corresponding quaternary ammonium salts of morpholine 4 and piperidine 5, respectively. The X-ray single crystal structures of 2 and 4 proved with no doubt the proposed structure based on the spectral characterization. The percentages of the H…H, O…H, and C…H interactions are in the range of 49.2–50.6 %, 19.6–19.8 and 27.6–28.6 %, respectively in case of 2 based on Hirshfeld topology analysis. For the two cationic units in 4, the C…H (15.9–18.5 %), H…H (42.9–43.1) and O…H (38.2–40.5 %) are the most important. The two anionic units showed different types of intermolecular interactions. In one unit, the O…H (23.4 %), C…H (28.4 %) and C…C (1.3 %) contacts are the most important while in the other anionic unit the O…H (23.3 %), C…H (26.7 %), C…O (5.7 %) and C…C (1.6 %) interactions are the most significant. The inhibition zones of 1 (18 mm), 4 (22 mm), and 5 (20 mm) indicated greater activity against S. aureus, compared to streptomycin (16 mm) and neomycin (13 mm). Compounds 1–5 showed nearly two-fold as much antifungicidal activity against C. albicans compared to some conventional medicines such as Neomycin and Streptomycin.

An Unexpected Degradation Pathway of N-Hydroxy-5-Methylfuran-2-Sulfonamide (BMS-986231), a pH Sensitive Prodrug of HNO, in a Prototype Formulation Solution

N-hydroxy-5-methylfuran-2-sulfonamide (BMS-986231, Cimlanod) was being developed as a pH-sensitive prodrug of HNO (nitroxyl) for the treatment of acute decompensated heart failure. During a stressed study of Cimlanod in a prototype formulation solution (pH 4.5) at 40°C, a predominant unknown degradant along with three previously identified degradants were observed. The unknown degradant was isolated from the stressed solution via preparative HPLC but totally decomposed during freeze-drying. LC-HRMS analysis of the isolated unknown degradant, prior to freeze-drying, revealed an empirical formula equivalent to the adduct of Cimlanod with SO2 even though SO2 was not added in the prototype formulation solution. The unknown degradant was synthesized from Cimlanod and DABSO ((1,4-diazabiscyclo[2,2,2]octane bis(sulfur dioxide) adduct) and isolated as a crystalline DABCO (1,4-diazabiscyclo[2,2,2]octane) salt for single crystal X-ray structure elucidation. The degradation of Cimlanod increased when the solution was exposed to air, as compared to N2 atmosphere. A plausible mechanism was postulated for the unexpected degradation pathway of Cimlanod. This study provided in-depth stability knowledge of Cimlanod, which will be beneficial to the subsequent stability indicating method development and validation as well as the registrational applications on the content and qualification of impurities in new drug products.

Assessing Structures and Solution Behaviors of Molecular and Ionic Cocrystals with a Common Bioactive Molecule: 2,4-Pyridinedicarboxylic Acid with Tranexamic Acid and Nicotinamide.

Cocrystals of 2,4-pyridinedicarboxylic acid (PDA) with either nicotinamide (NTD) or tranexamic acid (TXA) as (PDA)·(NTD) and 2(PDA)·(TXA), respectively, are reported, with the former being a molecular cocrystal and the latter being an ionic cocrystal. Single-crystal structure analyses showed that PDA and its coformers are sustained by neutral and ionic hydrogen bonds. Suspensions of (PDA)·(NTD) resulted in complete conversion to PDA monohydrate after 48 h, while 2(PDA)·(TXA) was thermodynamically stable at a lower pH and showed a 2-fold increase in the PDA concentration, relative to pure PDA monohydrate under similar conditions. Thermal characterization of 2(PDA)·(TXA) displayed a lower melting point and a lower heat of fusion, relative to the pure components. Powder dissolution studies were evaluated for PDA, (PDA)·(NTD), and 2(PDA)·(TXA) and the corresponding physical mixtures. The percent of PDA dissolved rapidly reached near 100% for most cases; however, for 2(PDA)·(TXA), complete dissolution was not achieved, and the amount of PDA dissolved decreased to 85% after 3 h. Instability of 2(PDA)·(TXA) was likely a result of a high solution pH during dissolution, and our results confirm that the solution pH plays a key role in determining the solution behavior and phase stability of the cocrystals.

Sequential Nucleophilic Aromatic Substitution Reactions of Activated Halogens.

Building blocks have been identified that can be functionalised by sequential nucleophilic aromatic substitution. Some examples are reported that involve the formation of cyclic benzodioxin and phenoxathiine derivatives from 4,5-difluoro-1,2-dinitrobenzene, racemic quinoxaline thioethers, and sulfones from 2,3-dichloroquinoxaline and (2-aminophenylethane)-2,5-dithiophenyl-4-nitrobenzene from 1-(2-aminophenylethane)-2-fluoro-4,5-dinitrobenzene. Four X-ray single-crystal structure determinations are reported, two of which show short intermolecular N-O…N "π hole" contacts.

Directional Electron Flow in a Selenoviologen-Based Tetracationic Cyclophane for Enhanced Visible-Light-Driven Hydrogen Evolution.

Directional electron flow in the photocatalyst enables efficient charge separation, which is essential for efficient photocatalysis of H2 production. Here, we report a novel class of tetracationic cyclophanes (7) incorporating bipyridine Pt(II) and selenoviologen. X-ray single-crystal structures reveal that 7 not only fixes the distances and spatial positions between its individual units but also exhibits a box-like rigid electron-deficient cavity. Moreover, host-guest recognition phenomena are observed between 7 and ferrocene, forming host-guest complexes with a 1:1stoichiometryin MeCN. 7exhibits good redox properties, narrow energy gaps, and strong absorption in the visible range (370-500 nm) due to containing two selenoviologen(SeV2+)units.Meanwhile, the femtosecond transient absorption (fs-TA) reveals that 7 has stabilized dicationic biradical, efficient charge separation, and facilitates directional electron flow to achieve efficient electron transfer due to the formation of rigid cyclophane and electronic architecture. Then, 7 is applied to visible-light-driven hydrogen evolution with high hydrogen production (132 μmol), generation rate (11 μmol/h),turnover number (221), and apparent quantum yield (1.7%), which provides a simplified and efficient photocatalytic strategy for solar energy conversion.

Unexpected tunable photoluminescence and emission mechanism during the gradual increase of cyclic glucose units

Excitation-dependent (λex-dependent) emission is one of the most common emission characteristics of nonconventional luminophores. Previously, we have reported D-xylose crystals has an obvious λex-dependent color tunable persistent room temperature phosphorescence (p-RTP) from blue to green, but its p-RTP emission at long wavelength is very weak. To further explore this attractive multicolor p-RTP behavior, and to enhance its tunability, the photoluminescence (PL) behavior of three common cyclodextrins (CDs), namely α-CD, β-CD and γ-CD, including solution and single crystals, were studied. Their single crystals demonstrate λex-dependent multicolor p-RTP properties in the order of β-CD>α-CD>γ-CD, rather than the strongest with the least glucose units (α-CD). Among them, the λex-dependent tunable p-RTP of β-CD and α-CD is superior to that of D-(+)-xylose single crystal. The above unexpected phenomena could be explained reasonably through detailed single crystal structure analysis and theoretical calculations. The emission behavior of solution and single crystals of CDs can be reasonably explained by the clustering-triggered emission (CTE) mechanism. Furthermore, CD-based covalent organic frameworks (COF) and supramolecules are readily fabricated, which own significantly enhanced p-RTP emission. Due to the intriguing PL property as well as hydrophilic rim and low biotoxicity of CDs, successful imaging of HCT116 cells and encryption applications were demonstrated. It is believed that the intrinsic PL properties of CDs, especially their regularly adjustable multicolor p-RTP that varies with the number of glucose units, have significant guidance for the development of a series of multicolor luminescent materials.

Structural characteristics and crystalline nature of PZT powders topochemically synthesized from needle-like TiZrO4 precursors

Pb(Zr0.5Ti0.5)O3 (PZT) powders were synthesized from needle-like TiZrO4 (TZO) precursors by topochemical molten salt synthesis. The effects of the flux types, the raw powder sizes and the synthesis temperatures on the resultant particle morphologies and phase structures of both TZO and PZT were investigated. Via optimizing the synthesis conditions, needle-like TZO with a smooth surface and needle-like PZT with a rough surface were obtained. Transmission electron microscopy (TEM) analyses unveiled that TZO possesses a single-crystal structure with the axial direction along the [010] crystallographic orientation, while PZT exhibits a polycrystalline structure with a discernible degree of misorientation. Notably, the synthesized needle-like PZT from TZO were observed to be unstable and could not induce oriented grain growth of Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3 (PMN-PZT) ceramics. This study reveals that improving the thermal stability of needle-like PZT seeds is one of the key factors for the templated grain growth in textured piezoelectric ceramics.

Dislocation structures in micron-sized Ni single crystals produced via tension–compression cyclic loading

The strength and deformation characteristics of micron-sized metals under monotonic loading have long been investigated. In contrast, despite its practical significance, their fatigue behavior remains unexplored. To this end, tension–compression fatigue tests were conducted herein on micron-sized Ni single crystals to elucidate their fatigue behavior and internal dislocation structures. Specimens with square cross sections of 5 and 2 μm on a side were prepared and subjected to cyclic loading at low stress amplitudes, which did not induce fatigue cracking in bulk metals. Remarkably, fatigue cracks were not present in 5-μm-wide specimens, whereas intrusions/extrusions were observed in 2-μm-wide specimens, leading to crack initiation. Vein-like structures comprising edge dislocations were observed in 5-μm-wide specimens, which are commonly observed in bulk metals. Conversely, the dislocation structure in 2-μm-wide specimens resembled that associated with persistent slip bands, which cause intrusions/extrusions and fatigue cracking in bulk metals under high stress amplitudes. The experimental findings indicate that the fatigue behavior of small-sized metal single crystals is characterized by the absence of vein formation.

Interaction between dislocation and heterogeneous interface in Cu/Fe laminated composites based on discrete dislocation dynamics

Bimetal laminated composites (BLCs) exhibit more outstanding mechanical properties than traditional alloys due to the interaction between heterogeneous interface boundary (HIB) and dislocation. However, the underlying physics of the dislocation motion and the strengthening effect has not been uncovered at mesoscopic scale. In this study, the detailed microstructure of the Cu/Fe HIB was obtained by transmission electron microscope (TEM) observation. The dislocation model was established using discrete dislocation dynamics (DDD), and several interactions between the dislocation and HIB were focused on, as well as the intrinsic strengthening mechanisms of the HIB. The results show that different HIB characteristics induce different interaction mechanisms such as absorption, slip transmission, slip on the HIB, emission from HIB and reflection by HIB, resulting in different strengthening effect on the BLCs. The HIB promotes slip of the dislocation emitted from the Fe, while prevents movement of the dislocation emitted from Cu. Since dislocation slip is more difficult in Fe, greater elastic deformation occurs before large-scale expansion of the dislocation, resulting in larger nominal yield strength. The presence of HIB increases the difficulty of dislocation movement compared to the single crystal structure, which in turn improves the overall strength of BLCs. Due to the different dislocation motion and strain gradient, the mechanism of that dislocation slip absorption by the HIB has optimal strengthening effect relative to other interaction mechanisms. The strengthening effect of other interaction mechanisms is influenced by the position of the dislocation emission, the type of interaction mechanism, and the angle between adjacent slip planes, etc. The outcome of present research sheds important insights into the design of HIB strengthening materials, such as multi- and nano- laminated composites.

Study on the properties of electrode materials for supercapacitors based on 1D Co-MOCPs

Three one-dimensional (1D) Co-MOCPs (23PCo–S1, 23PCo–S2, and 23PCo–S3; where 23P denotes the ligand, 2,3-pyridine dicarboxylic acid) were synthesized using a similar hydrothermal method. The molecular formulas for the isomers 23PCo–S1 and 23PCo–S2 are [Co(23P)3H2O], while that for 23PCo–S3 is [Co(23P)2H2O]. These single-crystal structures are classified into the P-1, Pca21, and P21/c space groups, displaying triclinic, orthogonal, and monoclinic symmetries, respectively. Techniques such as S-XRD, P-XRD, XPS, and SEM were applied to analyze the structures and valence states of the materials. Additionally, the electrochemical properties of the structures were evaluated using a three-electrode setup. Among these, 23P–Co–S2 demonstrated a remarkable specific capacitance of 458.5 F g−1 at a current density of 1 A g−1. In contrast, 23P–Co–S1 and 23P–Co–S2 showed specific capacitances of 192.2 and 270.6 F g−1, respectively, under the same experimental conditions.

Molecular dynamics study on the effect of cementite structure on the mechanical properties of pearlite

The effect of cementite structure on the mechanical properties of pearlite were investigated using molecular dynamics simulations. Three types of cementite structures were considered: single crystal, nanocrystalline, and a mixture of nanocrystalline and amorphous structures. The study found that regardless of the cementite structure, the ferrite phase in the pearlite exhibited plastic deformation first due to the activation of its internal {112} 〈111〉 slip system during tensile loading, resulting in macroscopic yielding of the pearlite. However, the difficulty of plastic deformation in the ferrite phase varied with different cementite structures. Compared to the other two types of cementite structures, the ferrite phase in the pearlite containing single crystal cementite exhibited the most difficult plastic deformation, leading to the highest peak stress. As the strain increased, the plastic deformation in the ferrite transferred through the ferrite-cementite interface to the cementite. After the plastic deformation transferred to the cementite, the different cementite structures exhibited distinct mechanical responses: the single crystal cementite structure experienced cleavage fracture, the nanocrystalline cementite structure underwent plastic deformation induced by grain boundary slip, while the nanocrystalline-amorphous mixture cementite structure showed shear deformation in the amorphous cementite and plastic deformation induced by grain boundary slip in the nanocrystalline cementite. Due to the influence of cementite mechanical response mechanism, the flow stress of the pearlite was minimal when the cementite in the pearlite were in single crystal structure. The study also revealed that when the cementite was in nanocrystalline structure, the flow stress of pearlite decreases with the grain size decreasing from 4.25 nm to 2.68 nm. When the cementite is a mixture of nanocrystalline and amorphous structure, the flow stress of pearlite decreases as the thickness of amorphous layer increases from 1 nm to 2 nm.

Rational design of dual-ion doped cobalt-free Li-rich cathode materials for enhanced cycle stability of lithium-ion pouch cell batteries.

The synergistic effect of single-crystal structure and dual doping in Li-rich cobalt-free cathode materials was thoroughly investigated. Lithium-ion pouch cells employing Sb/Sn doped Li1.2Mn0.6Ni0.2O2 and graphite exhibited a specific capacity of 191.01 mA h g-1 at 1C rate and exceptionally stable performance upon cycling, with capacity retention of 87.24% of their initial capacity after 250 cycles at 1C rate. The strategic combination of morphology manipulation and dual ion doping has markedly diminished cation mixing and expanded the Li interstitial sites within the cathode lattice. This work offers significant insights into the mechanisms responsible for the structural decline of Li-rich cobalt-free cathodes, emphasizing the importance of stabilizing the cathode lattice structure at high potential. These findings suggest promising potential for this material to meet the demanding energy density criteria for electric vehicles. Finally, this research provides practical strategies for effectively implementing high-voltage cobalt-free cathodes, offering valuable guidance for future applications.

Single-crystallinity of large-sized tungsten ingots obtained by plasma-induction additive technology

Obtaining large ingots of refractory metals with a single-crystal structure is still a difficult technical task. Large-sized tungsten ingots up to 15 cm cross-section can be obtained at rates of 17…70 mm/min using the technology of additive plasma-induction layer-by-layer growth. The most single-crystalline repeated structure of the tungsten ingot was obtained at 26 mm/min. Some deterioration in the structure of the ingot is associated with a technological change in the rate of surfacing and technical pauses. Volumetric single-crystallinity in the layers of the tungsten ingot is confirmed by research with such analytical criteria as the misorientation angle of the subgrain structure is less than 2°, the deviations in growth directions specified by the primary single-crystal base (seed) not exceeding 0,053° according to reflection Laue, and the volumetric repeatability of physical and mechanical properties.

Two-Dimensional Cu-Based MOF for Selective Staining of the Cellular Nucleus through Fluorescence Imaging and Selective Sorption of Dye Molecules in Aqueous Medium.

A two-dimensional copper-based metal-organic framework, [Cu(C23H14O6)(C10H8N2)2]·H2O·DMSO, 1, was synthesized using pamoic acid (C23H16O6) and 4,4'-bipyridine (C10H8N2) as an organic ligand and Cu(II) as a metal ion. Single-crystal structure X-ray diffraction studies of the as-synthesized compound showed a two- dimensional structure with free hydroxyl groups. Upon excitation at 370 nm, the aqueous dispersion of [Cu(C23H14O6)(C10H8N2)2]·H2O·DMSO, 1, showed emission centered at 525 nm resulting from the intraligand energy transfer. Fluorescence microscopic experiments using a human epithelioid cervix carcinoma HeLa cell line were carried out, clearly showing that our compound selectively stained the cellular nucleus. To utilize the porous nature of [Cu(C23H14O6)(C10H8N2)2]·H2O·DMSO, 1, its dye sorption behavior in aqueous solution was determined, and a high affinity for methylene blue (MB) dye was confirmed. Our synthesized compound sorbed 88% MB dye with an initial concentration of 32 mg L-1, and its sorption capacity for MB was found to be 29.79 mg g-1. The possible mechanism of the dye sorption behavior was discussed in terms of the size and charge of dye molecules with respect to molecular-level interactions between the framework and the dye molecules.

Ultra-low stress-hysteresis and huge superelasticity in NiMn-based shape memory microwire

Hysteresis related to first-order phase transformation in shape memory alloys, which is the macroscopic manifestation of energy dissipation, is detrimental to the precise control of actuation and causes structural and functional fatigue of components. It is of vital importance to explore high-performance shape memory alloys with low stress-hysteresis, large superelasticity, and wide temperature range operation in practical applications. Here, we have developed a Ni-Mn-Fe-In shape memory microwire, exhibiting an ultra-low stress-hysteresis and huge tensile superelasticity in a wide temperature range. The microwire shows a smooth surface and a single crystal structure (with ⟨001⟩A-oriented along the axial direction of microwire), and the microstructure of the microwire contains austenite matrix and sparsely distributed precipitates with an average size of 20–80 nm, all of which may be beneficial to obtain low hysteresis and large strains in the microwire. As a result, the microwire exhibits a minimum stress-hysteresis of as low as 8.5 MPa (with overall strain of 15.3%) and corresponding energy dissipation as low as 1.44 MJ/m3. The microwire always shows a low stress-hysteresis (less than 24 MPa) and low energy dissipation (less than 2.86 MJ/m3) above room temperature. The microwire shows a huge superelasticity with recoverable strains higher than 15% in the wide temperature range from 218 to 418 K. Together with the advantages of easy fabrication and no post-processing required, this microwire shows a tremendous potential for cyclic actuators and energy conversion devices under multi-field coupling.

Investigation on characteristic of vanadium trioxide insulation mixed with metal powder for rare-earth barium copper oxide coils

This study examined the turn-to-turn contact resistance (R ct) between rare-earth barium copper oxide (REBCO) tapes and layers of vanadium trioxide (V2O3) and V2O3 mixed with metal powder mixture. V2O3 in single crystal structure was electrically characterised to exhibit resistivity with negative temperature dependence, allowing the turn-to-turn insulation to self-regulate the current bypass between REBCO tapes. To facilitate effective quench protection of V2O3-insulated REBCO magnets above the metal-insulator transition temperature (T rt), R ct must be further reduced to a level similar to those of non- and metal as insulated (NI and MI) REBCO magnets. Thus, we explored the mixing of conductive metal powders such as molybdenum (Mo) with V2O3 paste and investigated the transition properties of R ct. The resistance versus temperature characteristics, microscopic morphologies of the V2O3 layers, and thermal conductivity (k v) were appropriately assessed to determine the effects of mixing the metal powder with V2O3. The R ct of virgin V2O3 exhibited variations of 107–105 μΩ cm2 under 77–293 K. As the mixing concentration of the metal powder was increased, the reduction magnitude on R ct increased for > T rt (approximately 150 K). Furthermore, the transition slope became gentler for a wider temperature range of < T rt. For metal powder concentrations exceeding 50 wt%, R ct decreased by approximately 2 orders of magnitude (∼103 μΩ cm2) for > 150 K compared with that for virgin V2O3 paste. Moreover, compared to that of pure V2O3, k v demonstrated a remarkable increase of approximately 352% at 91 K for Mo powder mixed at a concentration of 60 wt%. The improved electrical and thermal properties of the V2O3 insulation layer owing to the mixing of metal powders can help REBCO magnets operate in an insulated state under normal conditions and effectively convert to a non-insulated state under quenching.

Synthesis, crystal structure, density functional theory, and vibration analysis of 4-nitro-N-[(4-nitrophenyl) methyl]-N-phenylbenzenemethanamine

In this study, N, N-dibenzylaniline, an essential intermediate with broad significance in organic syntheses organic synthesis, was synthesized and characterized based on its spectrum. The single-crystal structure of the compound was confirmed using X-ray. The crystal structure of the compound, as calculated and optimized by DFT, was consistent with the crystal structure obtained by X-ray single-crystal diffraction. The functional groups of the compound were analyzed using vibrational analysis. Molecular docking analysis revealed the potential pharmacological effects of the compound. The molecular electrostatic potential and frontier molecular orbitals of the compound were studied, and its physical and chemical properties were revealed.

Innovative two-dimensional porphyrin-integrated metal-organic frameworks for enhanced photocatalytic hydrogen peroxide generation in pure water

In the quest for eco-friendly and efficient synthesis of hydrogen peroxide (H2O2), a chemical with extensive applications, photocatalytic production emerges as a promising clean technique. Metal-organic frameworks (MOFs), known for their exceptional porosity and geometric customizability, stand at the forefront of potential photocatalytic materials. Yet, the conventional three-dimensional topologies of MOFs pose a challenge, impeding the swift transit of photogenerated electrons and thereby curbing performance enhancements. In this vein, we have engineered novel 2D porphyrin-based MOFs, specifically Ce-TCPP and La-TCPP, utilizing diverse metal sources while maintaining a consistent topological framework. This design strategy streamlines the electron and hole transport pathways, thus elevating the photocatalytic activity. Delving into the structural nuances of these MOFs, our research unveiled that the photocatalytic activity experienced a marked shift upon altering the metal cluster types. Notably, La-TCPP, as an efficacious catalyst, demonstrated an H2O2 yield of 79.75 μmol/g/h in pure water, sans any sacrificial agents. Rigorous testing confirmed the robust stability of both MOFs. This study marks the inaugural design and synthesis of a single crystal structure of La-TCPP. By strategically varying metal cluster compositions, we have fine-tuned the architecture of two-dimensional MOFs. This approach sheds light on the intricate structure-activity relationship governing the photocatalytic synthesis of H2O2, paving the way for future advancements in the field.

Helicene Appended Benzothiadiazoles as Chiral Emitters.

A homologous series of 4,7-bis(aryl) substituted benzothiadiazole (BTD) compounds, containing the helicenic derivatives bis([4]helicene), bis([5]helicene) and bis([6]helicene), have been prepared upon a double Suzuki coupling between 3,6-bis(pinacolyl-borane)-BTD and the corresponding bromo-aryl precursors. The single crystal X-ray structure of the bis([4]helicene) compound shows the existence of both helicities (M) and (P) on the same molecule. All the compounds of the series are highly emissive in solution, with quantum yields of the emission ranging from 50 to 91 %. The enantiopure compounds (M,M) and (P,P) for the BTD-bis([6]helicene) have been prepared from the corresponding enantiopure 2-bromo-[6]helicene precursors. Their chiroptical properties have been investigated in correlation with density functional theory (DFT) calculations, which allowed to confidently assign the absolute configuration of the helicene arms and to characterize the different electronic transitions, including the low energy charge transfer excitation from helicenes to BTD. The enantiomerically pure fluorophores (M,M)- and (P,P)-BTD-bis([6]helicene), which exist in solution as two main conformers, according to the DFT calculations, show CPL activity in solution, with glum factors of ≈1.7×10-3 at λem=525 nm, and also in the solid state, with glum factors of ≈1.2×10-3 in spite of the strong decrease of the quantum efficiency.