Search

The NUCLEUS experiment aims to perform a high-precision measurement of Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) at the EdF Chooz B nuclear power plant in France. CEvNS is a unique process to study neutrino properties and to search for physics beyond the Standard Model. The study of CEvNS is also important for light Dark-Matter searches. It could be a possible irreducible background for high-sensitivity Dark-Matter experiments. NUCLEUS is an experiment under construction based on ultra-low threshold ($\sim$20 eV$_{nr}$) cryogenic calorimeters, operated at tens-of-mK temperatures.

This work investigates the electron-donating capabilities of two 10-π electron nitrogen bridgehead bicyclic [5,6]-fused ring systems, imidazo[1,2- a ]pyridine and imidazo[1,5- a ]pyridine rings. Eight compounds with varying positions of electron-withdrawing moieties (TCF or DCI) coupled to the imidazopyridine ring were synthesized and studied. DCI-containing compounds ( Ib - IVb ) exhibited a purely dipolar nature with broad absorption bands, weak fluorescence, large Stokes shifts, and strong solvatochromism. In contrast, TCF-containing compounds ( Ia - IVa ) demonstrated diverse properties. Imidazo[1,2- a ]pyridine derivatives Ia and IIa were purely dipolar, while imidazo[1,5- a ]pyridine derivatives IIIa and IVa displayed a cyanine-like character with intense absorption and higher quantum yields of emission. The observed gradual red shift in optical properties with changing electron-donor groups ( IIb < Ib < IIIb < IVb ) and ( IIa < Ia < IIIa < IVa ) underscores the stronger electron-donor character of imidazo[1,5- a ]pyridine compared to that of imidazo[1,2- a ]pyridine. Furthermore, crystalline powders of imidazo[1,2- a ]pyridine derivatives exhibited fluorescence despite minimal emission in solution. Two compounds ( Ib and IVa ) were successfully formulated into nanoparticles for potential in vivo imaging applications in zebrafish embryos.

A series of molecules that possess two quinolines, benzoquinolines, or phenanthrolines connected in a chiral fashion by a biaryl junction along with their water-soluble derivatives was developed and characterized. The influence of the structure on the basicity of the nitrogen atoms in two heterocycles was examined and the photophysical and chiroptical switching activity of the compounds upon protonation was studied both experimentally and computationally. The results demonstrated that changes in the electronic structure of the protonated vs. neutral species, promoting a bathochromic shift of dominant electronic transitions and alternation of their character from π-to-π* to charge-transfer-type, when additionally accompanied by the high structural flexibility of a system, leading to changes in conformational preferences upon proton binding, produce particularly pronounced modifications of the spectral properties in acidic medium. The latter combined with reversibility of the read-out make some of the molecules in this series very promising multifunctional pH probes.

We report the synthesis and absolute configuration (AC) of a chiral isotopologue of syn -cryptophane-B. Low chiral signatures were measured by polarimetry and electronic circular dichroism, whereas most significant chiroptical effects were observed by vibrational circular dichroism (VCD) and Raman optical activity (ROA). The comparison of experimental VCD and ROA spectra with those predicted by DFT calculations allows the determination of the AC of the two enantiomers as (-) 589 - MP - syn - 2 and (+) 589 - PM - syn - 2 .

The title Schiff base, C 20 H 14 ClNO, obtained from the reaction of 4-chloro aniline with benzil, has an approximate T shape. The dihedral angle between the phenyl rings of the benzil unit is 74.14 (15)°. The extended structure features C-H⋯O hydrogen bonds., (© Ziani et al. 2023.)

We report in this article the synthesis, the X-ray crystal structure of compound syn - 2 , and its binding properties with cesium and thallium in aqueous solution under basic conditions. Compound syn - 2 is the diastereomeric compound of anti - 1 that shows very high affinity for cesium and thallium in aqueous solution under the same conditions. Despite the close structural similarities that exist between the syn - 2 and anti - 1 compounds, they show large discrepancy in their ability to bind cesium and thallium cations in the same conditions. Indeed, the syn - 2 derivative has a lower affinity for these two cationic species and the binding constants are several orders of magnitude lower than those found for its congener. The large differences in affinity observed with these two compounds can be explained by the relative position of the six hydroxyl groups to each other., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

We report the synthesis of C 3 -symmetric cryptophanes decorated with three aromatic amine groups on the same CTB cap and their interaction with xenon. The relative stereochemistry of these two stereoisomers syn and anti was assessed thanks to the determination of the X-ray structure of an intermediate compound. As previously observed with the tris-aza-cryptophanes analogs anti - 1 and syn - 2 ( J. Org. Chem . 2021 , 86 , 11, 7648-7658), both compounds anti - 5 and syn - 6 show a slow in-out exchange dynamics of xenon at 11.7 T. Our work supports the idea that the presence of nitrogen atoms grafted directly onto the cryptophane backbone has a strong impact on the in-out exchange dynamics of xenon whatever their stereochemistry. This result contrasts with the case of other cryptophanes decorated solely with methoxy substituents. Finally, we demonstrate that these new derivatives can be used to design new anti / syn cryptophanes bearing suitable ligands in order to constitute potent 129 Xe NMR-based sensors. An example is reported here with the synthesis of the tris-iodo derivatives anti - 13 and syn - 14 from compounds anti - 5 and syn - 6 .

Fast (60 kHz) magic angle spinning solid-state NMR allows very sensitive proton detection in highly paramagnetic organometallic powders. We showcase this technique with the complete assignment of 1 H and 13 C resonances in a high-spin Fe(ii) polymerisation catalyst with less than 2 mg of sample at natural abundance., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The synthesis and the QS modulation activity of diastereoisomerically pure 2-hydroxy-N-acyl-l-homoserine lactones (2-OH-AHLs) are unveiled. (2R)- and (2S)- 2-hydroxy-N-hexanoyl-l-homoserine lactone and 2-hydroxy-N-octanoyl-l-homoserine lactone have been identified as very potent QS agonists and antagonists on the Vibrio fischeri-quorum sensing system with opposite activities depending on the configuration of the carbon atom with the hydroxyl group. Flexible molecular docking showed that the (2R)-OH configuration in the antagonist isomer induces new hydrogen bonds with Tyr70 and Asp79, two importantly conserved residues in the LuxR protein family, while the (2S)-OH agonist configuration exhibits a binding mode comparable to the natural ligand 3-oxo-hexanoyl-l-homoserine lactone (OHHL). For the analogs with long alkyl chain 3a and 3b and aromatic analogs, all are antagonists with no effect of the configuration at C-2., (Copyright © 2020 Elsevier Inc. All rights reserved.)

We describe a large-scale synthesis of a series of helicene-like compounds based on a dibenzo[ c ]acridine fragment by the Friedlander reaction. The series includes targeted constrained (closed) derivatives comprising 11 rings that exhibit very intense circularly polarized luminescence (CPL) ( g lum = 8 × 10 -3 ) contrary to their nonconstrained (open) 10-ring precursors that are not CPL active. The relationship between structure and chiroptical properties in the series is discussed with the aid of quantum-chemical calculations.

In the context of molecular engineering of push-pull dipolar dyes, we introduce a structural modification of the well-known electron-accepting group 2-dicyanomethylidene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran ( TCF ). Introduction of a (benzo[ d ]thiazol-2-yl) moiety failed, and unexpected structures were obtained. On the other hand, phenylthio and phenylsulfonyl entities were successfully introduced at position 3 of the 2-(dicyanomethylidene)-2,5-dihydrofuran ring, giving access to new electron-acceptor groups and dipolar fluorophores displaying near-infrared emission in solution or in the solid state, brighter than their TCF analogues.

In this article, we present the synthesis of new cryptophane-type hosts capable of binding xenon in aqueous media and that may be useful for the development of xenon-based magnetic resonance imaging derivatives. The synthetic route proposed was chosen to facilitate both the introduction of water-solubilizing substituents and the functionalization of the host with a single arm showing recognition properties that constitute two crucial steps. This was made possible by preparing new cryptophane-223 derivatives bearing two different chemical functions that can be easily modified at a later stage. Thus, subsequent reactions allowed the design of a new cryptophane host able to bind zinc or nickel cations. The ability of this molecule to bind cationic species was assessed by calorimetric titration experiments and hyperpolarized 129 Xe NMR. The advantages and disadvantages of this approach are discussed.

Whereas the synthesis of the anti-cryptophane-A (1) derivative has been known for nearly 40 years, the preparation of its diastereomer (cryptophane-B according to Collet's nomenclature) has never been reported. Thus, the synthesis of the cryptophane-B derivative represents a real challenge for chemists interested in the preparation of these hollow molecules. Herein, we describe a synthetic route that allows us to prepare cryptophane-B (2), albeit in a low yield. The X-ray crystallographic structure of this compound is described, and it reveals the presence of an ethanol molecule inside the cavity of the host. Finally, the ability of cryptophane-B to bind xenon in 1,1,2,2-tetrachloroethane- d 2 is also studied via hyperpolarized 129 Xe NMR.

A hemicryptophane cage bearing amine and amide functions in its three linkers was synthesized in five steps. The X-ray molecular structure of the cage shows a triple-stranded helical arrangement of the linkers stabilized by intramolecular hydrogen bonds between amide and amine groups. The chirality of the cyclotriveratrylene unit controls the propeller arrangement of the three aromatic rings in the opposite part of the cage. 1 H NMR studies suggest that this structure is retained in solution.

In the title compound, C24H32BrN3O2, the six-membered cyclo-hexane ring adopts a chair conformation and the isoxasolidine ring adopts a twisted conformation. The mol-ecule has five chiral centres and the absolute configuration has been determined in this analysis. The mol-ecular structure is stabilized by weak intra-molecular C-H⋯O and C-H⋯N contacts. In the crystal, mol-ecules are linked by N-H⋯N and C-H⋯O hydrogen bonds, forming undulating sheets parallel to the bc plane.

The title compound, C15H18ClN5O2, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. In both mol-ecules, the isoxazolidine rings have an envelope conformation with the O atoms at the flap positions. Each mol-ecule has three stereogenic centres with configurations 2(S), 3(S) and 4(R), confirmed by resonant scattering. Their conformations are significantly different, for example in mol-ecule A the phenyl ring is inclined to the triazole ring by 32.5 (2)°, while in mol-ecule B the corresponding dihedral angle is 10.7 (2)°. In the crystal, the A and B mol-ecules are linked via an N-H⋯O and a C-H⋯O hydrogen bond. These units are linked by C-H⋯O and C-H⋯N hydrogen bonds, forming slabs parallel to the ab plane. There are C-H⋯π inter-actions present within the slabs.

Enantiopure cryptophane derivatives 1 and 2, possessing linkers of different nature (ethylenedioxy and propylenedioxy) connecting the two cyclotribenzylenes (CTB) units, were separated by HPLC using chiral stationary phases. X-ray crystallographic structures of the four enantiomers (+)-1, (-)-1, (+)-2, and (-)-2 have been obtained, allowing the unambiguous determination of their absolute configuration (AC) in the solid state. The chiroptical properties of compounds 1 and 2 were determined from polarimetry, electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) experiments and were compared to those of cryptophane-A (3) derivative. VCD, ROA and ECD spectra of 1 and 2 were calculated by density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations, respectively, to confirm the AC of the cryptophane derivatives in solution. The (+)-PP and (-)-MM configurations were established for compounds 1 and 2 in chloroform solution, as already reported for the two enantiomers of 3. This result is in agreement with the X-ray structures of the two enantiomers of 1 and 2.

We report the synthesis of new cryptophane derivatives 1-4 bearing nine (1, 2) and twelve (3, 4) methoxy substituents. These compounds represent the first examples of cryptophane derivatives bearing more than six substituents attached on the benzene rings. The preparation of these highly substituted cryptophanes was achieved due to the synthesis of a new cyclotrisyringyl derivative obtained from the reaction of a protected syringyl alcohol in the presence of a catalytic amount of scandium triflate Sc(OTf)3. This reaction also provides the protected cyclotetrasyringyl derivative in low yield (7%), which was fully characterized by (1)H NMR, IR, and X-ray crystallography. In contrast to what is observed for the cryptophane-A congener, the synthesis of these highly substituted cryptophanes gives rise to the two anti- and syn-diastereomers. These compounds have been fully characterized, and their X-ray structures have been obtained to ascertain the stereochemistry of these new cryptophane derivatives.

There are two crystallographically independent cations and two anions in the asymmetric unit of the title compound, C(4)H(5)NO(2) (+)·NO(3) (-). In the crystal, the 1-carb-oxy-propanaminium cations and nitrate anions are linked to each other through strong N-H⋯O and O-H⋯O hydrogen bonds, forming a three-dimensional complex network. C-H⋯O inter-actions also occur.

In the title complex, [Ni(C(5)H(9)NO(2))(2)(H(2)O)(2)], the Ni(II) atom, located on a centre of inversion, is trans-coordinated by two O atoms and two N atoms from d-bidentate valine and l-bidentate valine ligands and two water O atoms in an octa-hedral geometry. In the crystal, the discrete mononuclear units are linked into a three-dimensional network via O-H⋯O and N-H⋯O hydrogen bonds. C-H⋯O inter-actions are also observed.

The asymmetric unit of the title compound, (C(7)H(7)N(2)S)(2)[ZnCl(4)], contains a network of 2-amino-benzothia-zolium cations and tetra-hedral [ZnCl(4)](2-) anions. The crystal packing is influenced by cation-to-anion N-H⋯Cl and C-H⋯Cl hydrogen bonds. The [ZnCl(4)](2-) anions have a distorded tetra-hedral geometry. Inter-molecular π-π stacking inter-actions are present between neighboring benzene rings, thia-zole and benzene rings and neighboring thia-zole rings [centroid-centroid distances = 3.711 (2), 3.554 (1), 3.536 (2) and 3.572 (1) Å].

A new noncentrosymmetric organic-inorganic hybrid material, (C(8)H(12)N)(2)[ZnCl(4)], has been synthesized as single crystals at room temperature and characterized by X-ray diffraction and solid-state NMR spectroscopy. Its novel structure consists of two 4-methylbenzylammonium cations and one [ZnCl(4)](2-) anion connected by N-H···Cl and C-H···Cl hydrogen bonds, two of which are three-centre interactions. The Zn(II) metal centre has a slightly distorted tetrahedral coordination geometry. Results from (13)C CP-MAS NMR spectroscopy are in good agreement with the X-ray structure. Density functional theory calculations allow the assignment of the carbon peaks to the independent crystallographic sites., (© 2011 International Union of Crystallography)

The asymmetric unit of the title compound, (C(5)H(6)ClN(2))(2)[ZnCl(4)], contains two 2-amino-5-chloro-pyridinium cations and one [ZnCl(4)](2-) dianion which are held together by N-H⋯Cl and C-H⋯Cl hydrogen bonds. The [ZnCl(4)](2-) anions have a distorted tetra-hedral geometry. Weak inter-molecular π-π stacking inter-actions exist between neighbouring aromatic rings of the cations with a centroid-centroid distance of 3.712 (7) Å.

In the title compound, [ZnCl(HPO(4))](C(5)H(8)NO), polymeric inorganic layers constructed from ZnO(3)Cl and PO(4) tetra-hedra are linked by O atoms: O-H⋯O hydrogen bonds occur within the layers. The organic cations occupy the interlayer regions and interact with the layers by way of N-H⋯O, N-H⋯Cl, and C-H⋯Cl hydrogen bonds.

The asymmetric unit of the title compound, (C(11)H(18)N(2))(2)[CdCl(6)]·2H(2)O, consists of one 1-benzyl-piperazine-1,4-diium dication, one water mol-ecule and one-half of a [CdCl(6)](4-) anion, located on an inversion centre. The crystal packing is governed by an extensive three-dimensional network of inter-molecular O-H⋯Cl, C-H⋯Cl, N-H⋯O and N-H⋯Cl hydrogen bonds, two of them bifurcated.

In the title compound, C(11)H(18)N(2) (2+)·2ClO(4) (-)·H(2)O, one perchlor-ate anion is disordered over two orientations in a 0.66 (3):0.34 (3) ratio. Inter-molecular O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds link the cations, anions and water mol-ecules into ribbons extending along [100].

The title compound, (C(8)H(12)NO)(C(16)H(18)NO(2))[ZnCl(4)]·H(2)O, was obtained as a by-product of the Zn(2+) and HCl catalyzed condensation of (2-meth-oxy-phen-yl)methanamine in water. Both cations feature an intra-molecular N-H⋯O hydrogen bond. In the crystal, the components are linked by an extensive three-dimensional network of N-H⋯O, O-H⋯Cl and N-H⋯Cl hydrogen bonds (three of them bifurcated). Weak C-H⋯O intera-ctions also occur.

In the title compound, C(4)H(8)N(3)O(4)P(+)·H(2)PO(3) (-), the cytosine mol-ecule is monoprotonated and the phospho-ric acid is in the monoionized state. Strong hydrogen bonds, dominated by N-H⋯O inter-actions, are responsible for cohesion between the organic and inorganic layers and maintain the stability of this structure.

In the title compound, (C(7)H(18)N(2)O)[ZnCl(4)], the Zn(II) ion is coordinated by four Cl atoms in a close to tetra-hedral geometry. The crystal packing exhibits C-H⋯Cl, N-H⋯Cl and N-H⋯O hydrogen bonds.

The title compound, C(4)H(8)N(3)O(+)·ClO(4) (-), is built up from creatininium cations and perchlorate anions. Crystal cohesion and perchlorate stability are ensured by N-H⋯O hydrogen bonds that together with weak C-H⋯O inter-actions build up a three-dimensional network.

The title compound, C(6)H(10)N(2) (2+)·2Cl(-), contains a network of 4-(ammonio-meth-yl)pyridinium cations and chloride anions which are inter-connected by N-H⋯Cl hydrogen bonds. The crystal packing is also influenced by inter-molecular π-π stacking inter-actions between identical anti-parallel organic cations with a face-to-face distance of ca 3.52 Å.

The title compound, C(12)H(19)N(2) (+)·Cl(-)·H(2)O, contains a network of 4-(2,3-dimethyl-phen-yl)piperazin-1-ium cations, water mol-ecules and chloride anions. The crystal packing is influenced by O-H⋯Cl, N-H⋯Cl, N-H⋯O, C-H⋯O and C-H⋯Cl hydrogen bonds, resulting in structure with an open-framework architecture.

In the crystal structure of the title compound, (C(10)H(15)ClN(2))[ZnCl(4)]·H(2)O, the Zn atom is coordinated by four Cl atoms in a tetrahedral geometry. The water mol-ecules and the 1-(4-chloro-phen-yl)piperazine-1,4-diium cations inter-act with the [ZnCl(4)](2-) anions through O-H⋯Cl, N-H⋯Cl, N-H⋯O and C-H⋯Cl hydrogen bonds (five simple and one bifurcated). Inter-molecular π-π stacking inter-actions are present between adjacent aromatic rings of 1-(4-chloro-phenyl)-piperazine-1,4-diium cations (the centroid-centroid distance is 3.453 Å).

The title compound, C(18)H(33)NO(3), was prepared according to a highly diastereoselective hydrogenation procedure from 3,5,7-triallyl-1-aza-adamantane-4,6,10-trione. The crystal structure of the title compound contains two crystallographically independent mol-ecules (Z' = 2), which are linked by inter-molecular hydrogen bonding into chains. In contrast to the aza-adamantanones, the aza-adamantanetriol core of the title compound does not show any particular C-C bond elongation.

In the presence of bases, trifluoroacetone is known to trimerize leading to configurationally labile 6-methyl-2,4,6-tris(trifluoromethyl)tetrahydro-2H-pyran-2,4-diols 1a,b and 2a,b, structurally close to fluorinated carbohydrates. We report herein a complete study of their behavior in solution. The remarkable solvent effect on the two equilibria (1a <--> 1b; 2a <--> 2b) was rationalized using solvent basicity measures and polarity scales. Solvents of weak donor number were found to favor the diastereoisomers 1a and 2a, which were subsequently isolated. According to their X-ray analyses, they both possess a concave structure with 1,3-cis-diaxial hydroxyl groups. A complementary kinetic study illustrated that acidic conditions can drastically reduce the equilibration rate, allowing the use of a wide range of solvents. Finally, a reexamination of previously published trimerization conditions using sodium or magnesium amalgam revealed that, contrary to the suggestion by two independent reports, 1,3,5-tris(trifluoromethyl)cyclohexane-1,3,5-triol 3/4 was neither formed as the principal product in place of 1a,b and 2a,b nor could it be detected as a minor product.

Deprotonation of benzoxazole, benzothiazole, benzo[b]thiophene, benzo[b]furan, N-Boc-protected indole and pyrrole, and N-phenylpyrazole using an in situ mixture of ZnCl(2).TMEDA (0.5 equiv) and lithium 2,2,6,6-tetramethylpiperidide (1.5 equiv) in THF at room temperature is described. The reaction was evidenced by trapping with iodine, regioselectively giving the expected functionalized derivatives in 52-73% yields. A mixture of mono- and disubstituted derivatives was obtained starting from thiazole. Cross-coupling reactions of 2-metalated benzo[b]thiophene and benzo[b]furan with heteroaromatic chlorides proved possible under palladium catalysis. A reaction pathway where the lithium amide and zinc diamide present in solution behave synergically was proposed for the deprotonation reaction, taking account of NMR and DFT studies carried out on the basic mixture.

Crystals of anhydrous cadmium oxalate, beta-[Cd(C(2)O(4))], have been synthesized hydrothermally and the crystal structure solved using single-crystal X-ray diffraction data. The Cd and oxalate ions lie about independent inversion centres. The structure consists of a three-dimensional framework built from sheets of cadmium octahedra linked together by oxalate groups.