Mechanoluminescence (ML) materials, such as CaZnOS and SrZnOS, show great potential in lighting, sensors, and wearable devices. Despite advances in the understanding of these materials, a detailed first-principles study of the strain-stress relationship and the effects on crystal structure and bandgap is lacking. In this work, we use first-principles calculations to investigate the elastic properties, crystal structure deformations, and bandgap responses under strain for both MZnOS (M = Ca, Sr) compounds, filling the gap in the current understanding of these materials. The elastic constants, elastic modulus and Poisson's ratios for SrZnOS and CaZnOS are calculated, revealing the influence of hydrostatic pressure on lattice parameters and atomic distances. Notably, the stress-strain relationships of SrZnOS and CaZnOS reveal distinct mechanical behaviors under tensile and compressive strains along the [100] and [001] directions. Under compressive stress, especially along the [100] direction, CaZnOS shows greater compressive resistance than SrZnOS. Additionally, strain-induced bandgap variations are observed: SrZnOS exhibits a decrease in bandgap with increasing strain, while CaZnOS shows an initial bandgap widening under compressive loading (0-2.34 GPa) along the [001] direction. Our findings provide new insights into the mechanical and electronic behavior of MZnOS materials, which are crucial for their application in mechanoluminescence and other related fields.

Four new copper(II)-flavonolate complexes of the type [Cu(L)(fla)](ClO4) 1-4, where L is the 3N ligand 4-methyl-(1-pyrid-2-ylmethyl)-1,4-diazacycloheptane (L1), 4-methyl-(6-methyl(1-pyrid-2-ylmethyl))-1,4-diaza-cycloheptane (L2), 4-methyl-1-(N-methylimidazol-2-ylmethyl)-1,4-diazacycloheptane (L3) or 4-methyl-1-(quinol-2-ylmethyl)-1,4-diazacycloheptane (L4), and H(fla) is 3-hydroxyflavone, have been prepared as functional models for the Cu(II)-containing quercetin 2,4-dioxygenase (2,4-QueD) enzyme. The single crystal X-ray structure of [Cu(L2)(fla)](ClO4) 2 comprises the CuN3O2 chromophore adopting a trigonal bipyramidal distorted square pyramidal coordination geometry around Cu(II) (TBDSP, tau = 0.47). The rate of dioxygenation of the ES model complexes, determined in DMF solution at 80 degrees C (k(obs): 1 (2.03 +/- 0.04) > 2 (0.58 +/- 0.04) < 3 (9.19 +/- 0.02) > 4 (0.56 +/- 0.05 x 10(-3) s(-1))), reveals that 3 reacts much faster than the other complexes in the presence of excess dioxygen. The replacement of the pyridyl nitrogen in 1 by an imidazolyl nitrogen with higher basicity to get 3 increases the pi-back bonding of flavonolate with Cu(II) located in a trigonally distorted square pyramidal coordination geometry, and enhances the activation of the flavonolate towards dioxygen. In contrast, the 6-methyl (2) and benzo (4) groups on the pyridyl moiety (1) lower the reaction rate by sterically hindering the approach of molecular oxygen. A computational study supports a reaction pathway involving a single-electron transfer (SET) from flavonolate to dioxygen to generate a superoxide radical. The latter reacts rapidly with the activated flavonoxy radical intermediate to give the dioxygenated products.

C24H20BN4OP, monoclinic, P21/n (no. 14), a = 14.1418(2) Å, b = 10.5821(1) Å, c = 15.4684(2) Å, β = 94.622(1)°, V = 2307.32(5) Å3, Z = 4, Rgt(F) = 0.0203, wRref = 0.0408, T = 293(2) K.

Multimodal luminescence materials are very important for advanced anti-counterfeiting, intelligent optical sensing, and so on. However, the integration of multimodal response and multicolor luminescence into a single material is still a huge challenge. Based on the Mn2+ and Er3+ dual-activator strategy, a multimodal luminescence material of piezoelectric SrZnOS with force, thermal, light, and high-energy radiation response is successfully designed and prepared. It is of note that the color-tunable ratiometric mechanoluminescence is realized under the stimulation of force. In addition, the microcrystal can be applied to the upconversion luminescence temperature measurement technology, achieving the non-contact real-time detection of temperature in the wide temperature range of 303 to 543 K with a relative sensitivity reaching 1.099%K-1. More importantly, the SrZnOS:Er/Mn@polydimethylsiloxane film exhibits a good linear response to X-ray dose, with the light yield of 26260 Ph MeV-1 (approximate to 2.6 times that of commercial BGO) and detection limit as low as 1.08 mu Gyair s-1. This work introduces an important reference for exploring advanced multimodal luminescence materials and shows great potential for integrated multifunctional optical sensing.

A universally applicable synthesis route for the preparation of functionalized diazabicyclononane compounds was elaborated starting from a readily available 1,5-diphenyl-3,7-diazabicyclo[3.3.1] nonan-9-ol by alkylation of both secondary amines with modified benzyl residues containing a bromo, trimethylstannyl, trimethylsilyl, and pinacolboranyl residue. High yields (65-88 %) were achieved, supporting the intended purpose of these compounds: efficient mercuration reactions to stably bind Hg2+. Finally, the C-9 position of two functionalized diazabicyclononanes was further modified by introducing an azide functionality. This enables the conjugation to biomolecules of interest via click chemistry combined with a tracking by the introduced mercury isotopes. Mercury was safely caged into a dibenzyldiazabicyclononane scaffold to ensure the stable preparation of organomercurials for later radiotracer applications in nuclear medicine. The chosen synthesis route opens the easy introduction of different leaving groups for the mercuration process. A further functionalization of the diazabicyclononane C-9 position allows the connection of biomolecules via click chemistry. image

C31H26NO4P, monoclinic, P21/c (no. 14), a = 16.3835(2) Å, b = 14.5755(2) Å, c = 10.5388(2) Å, β = 95.694(1)°, V = 2504.22(7) Å3, Z = 4, Rgt (F) = 0.0435, wRref (F 2) = 0.1310, T = 173(2) K.

Ethylene glycol (EG) is a widely used material, but its vapor is harmful to human health already in low concentrations. Thus, highly sensitive EG gas sensors are urgently needed. Herein, a series samples of ZnO and carbon dots (CDs) were synthesized at different ratios through a simple mechanical grinding method. The senor made using ZnO/CDs2 exhibits an ultra-high response (Ra/Rg) to 100 ppm EG up to 2798, 1378 and 467, and extremely low detection limit as low as 21 ppb, 13 ppb and 2 ppb, under UV light, visible light, and infrared light, respectively, as well as excellent repeatability and long-term stability. Especially, under UV light irradiation, the response of ZnO/CDs2 to 100 ppm EG is 24 times that of pure ZnO (Ra/Rg=114.7), and more than 71 times that of 9 other gases. The outstanding gas sensing performance of ZnO/CDs2 can be attributed to the excellent light response ability of CDs at first, which greatly enriches the electron concentration in ZnO/CDs under light irradiation. Furthermore, the photo-induced electron transfer (PET) property of CDs and the p-n heterojunction formed at the interface between ZnO and CDs play a key role in rapid electron transport and transfer, avoiding a large number of electron hole recombination.

In chemical reactions of copper(II) acetate dihydrate with imidazolium azide salts in ethanol solution several new homoleptic azidocuprates(II) were obtained. In dependency of the used counter cation various different azidocuprate moieties were crystalized. The doubly charged DMMDIm2+ cation facilitates the formation of mononuclear [Cu(N3)4]2- complex anions, while the utilisation of the (PeMIm)+ ion enables the isolation of a dinuclear [Cu2(N3)6]2- salt. By using the unsymmetrical imidazolium ions (BMIm)+ or (EMIm)+ salts with the trinuclear [Cu3(N3)8]2- complex anion are obtained. With the (DML)+ cation an azidocuprate(II) crystallizes, which contains both [Cu(N3)4]2- and the [Cu2(N3)6]2- anion. The anions in the salt with the (PeMIm)+ cation are interconnected through further Cu-N bonds and form layers with a 2D-honeycomb structure. The trinuclear units in the (BMIm)+ and the (EMIm)+salts form coordination strands of different structures. image

A facile preparation of deprotonizable calix[4]crowns with enhanced properties to stably coordinate Ba2+ and Ra2+ inclusive radiolabeling is described. Binding properties of these ions were investigated by DFT calculations to support the findings.

Three new copper(II)-flavonolate complexes of the type [Cu(L)(fla)(ClO4)] 1-3, where L is the 2N ligand N(pyridin-2-ylmethyl)aniline (L1), 2,6-dimethyl-N-(pyridin-2-ylmethyl)aniline (L2) and 2,6-diisopropyl-N-(pyridin-2-ylmethyl)aniline (L3), and H(fla) is 3-hydroxyflavonone, have been isolated as functional models for Cu (II)-containing quercetin 2,4-dioxygenase (2,4-QueD). Single crystal X-ray structure of 3 contains a CuN2O2O' chromophore with a slightly distorted square pyramidal geometry (TBDSP, & tau; = 0.03). The pyridyl N1 and the tertiary amine N2 nitrogens of the 2N ligand occupy the two corners of the basal plane. The O1 (enolate) and the carbonyl O2 atoms of deprotonated 3-hydroxyflavanone (fla- ) occupy the remaining corners while the O3 of perchlorate anion (ClO4- ) occupies the axial position at a longer distance. The molecular structures of the complexes 1-3, their aquated species [Cu(L)(fla)(H2O)]+ 1a-3a and the square planar species [Cu(L)(fla)]+ 1c-3c have been computed by using DFT method. While 1-3 contain axially coordinated perchlorate 1a-3a contain axially coordinated water molecule with a slightly distorted square pyramidal geometry (CuN2O2O') with varying trigonality (& tau;, 0.03-0.05). The significantly high g|| (2.305) and low A|| (150 x 10-4 cm-1) values observed for 1-3 are consistent with & pi;-back bonding of Cu(II) with the conjugated carbonyl group of coordinated fla- and are typical of type-II copper enzymes. The electrochemical reduction of CuII to CuI and oxidation of flaoccur upon dissociation of axially coordinated water molecule in 1a-3a formed in DMF solution to give 1c-3c. Upon exposure to dioxygen, all the Cu(II)-flavonolate adducts undergo oxygenative degradation in DMF solution, as seen from the disappearance of the LMCT band at 430 nm at 80 degrees C to produce CO and the corresponding acids. The rate of dioxygenation, kO2, of the complexes decrease in the order, 1 (3.31 & PLUSMN; 0.53) > 3 (2.59 & PLUSMN; 0.36) > 2 (1.52 & PLUSMN; 0.13 x 10-1 M-1 s- 1), due to electron-donating substituents on the primary ligand.

The potential of designing irreversible alkyne-based inhibitors of cysteine cathepsins by isoelectronic replacement in reversibly acting potent peptide nitriles was explored. The synthesis of the dipeptide alkynes was developed with special emphasis on stereochemically homogeneous products obtained in the Gilbert–Seyferth homologation for C≡C bond formation. Twenty-three dipeptide alkynes and 12 analogous nitriles were synthesized and investigated for their inhibition of cathepsins B, L, S, and K. Numerous combinations of residues at positions P1 and P2 as well as terminal acyl groups allowed for the derivation of extensive structure–activity relationships, which were rationalized by computational covalent docking for selected examples. The determined inactivation constants of the alkynes at the target enzymes span a range of >3 orders of magnitude (3–10 133 M–1 s–1). Notably, the selectivity profiles of alkynes do not necessarily reflect those of the nitriles. Inhibitory activity at the cellular level was demonstrated for selected compounds.

Abstract The synthesis and the crystal structure of the double cluster compound [Nb6Cl14(MeCN)4][Nb6Cl14(pyz)4]·6CH3CN are described. The synthesis is based on a partial ligand exchange reaction, which proceeds upon dissolving [Nb6Cl14(pyz)4]·2CH2Cl2 in acetonitrile. The compound is built up of two discrete neutral cluster units, which consist of octahedra of Nb6 atoms coordinated by 12 edge-bridging chlorido and two terminal chlorido ligands, and four acetonitrile ligands on one and four pyrazine ligands on the other cluster unit. Co-crystallized acetonitrile molecules are also present. The single-crystal structure determination has revealed a cluster arrangement in which the [Nb6Cl14(pyz)4] units are connected by (halogen) lone-pair–(pyrazine) π interactions. These lead to chains of [Nb6Cl14(pyz)4] clusters. These chains are further connected to cluster layers by (nitrile-halogen) dipole–dipole interactions, in which the [Nb6Cl14(MeCN)4] and co-crystallized MeCN molecules are also involved. These cluster layers are arranged parallel to the crystallographic {011} plane.

The crystal structure of the cluster complex salt, (C6H13N2)4[Nb6(NCS)6Cl12] or (H-DABCO)4[Nb6Cl12(NCS)6] (DABCO = tri-ethyl-enedi-amine or 1,4-di-aza-bicyclo-[2.2.2]octa-ne), comprises octa-hedral Nb6 cluster cores, which are μ2-coordinated by 12 chloride ligands (bridging the octa-hedral edges, inner ligand sphere). Furthermore, each Nb atom is N-bonded to a terminal thio-cyanate ligand (outer ligand sphere). The discrete clusters carry a charge of -4, which is compensated by four monoprotonated DABCO mol-ecules. These are arranged in rows, which are N-H⋯Cl and N-H⋯N hydrogen bonded to the anions and among each other.

Two 2,4-difluorobenzyl functionalized piperazine derivatives were synthesized and fully characterized by 1H/13C/19F NMR and MS. Both piperazine compounds occur as syn/anti conformers resulting from the partial amide double bond resulting in one solvent-dependent coalescence point. Furthermore, a second conformational shape was observed for the mono-substituted derivative due to the limited change of the piperazine chair conformation. Thus, two coalescence points were determined and their resulting two activation energy barriers were calculated using temperature-dependent 1H NMR techniques. To support this result, single crystals of N,N-bis(2,4-difluorobenzoyl)piperazine 3b (monoclinic, space group P21/c, a = 7.2687(3), b = 17.2658(8), c = 6.9738(3) Å, β = 115.393(2)°, V = 790.65(6) Å3, Z = 4, Dobs = 1.530 g/cm3) were obtained from a saturated chloroform solution. The rotational conformation of this compound was additionally verified by XRD.

Four new compounds were synthesized which belong to the so far very small group of hexanuclear niobium cluster alcoholates. These are [Mg(HOCH3)(6)](3)[Nb6Cl12(OCH3)(6)](2) center dot 6CH(3)OH (1), (Ph4P)(2)[Nb-6(OC2H5)(12)Cl-6] (2), (Ph4P)(2)[Nb-6(OC3H7)(4)(Cl8Cl6a)-Cl-i-Cl-i] (3) and (NC5H6)(2)[Nb-6(OC3H7)(12)Cl-6] (4). The last two compounds represent the first examples with isopropanolato ligands on the inner coordination sites of the octahedral metal atom cores. The X-ray structures of 1-3 have been determined. All cluster units with alcoholato ligands on the inner sites carry 14 cluster-based electrons (CBEs), as do all other so far known cluster alcoholates. The cluster unit in Compound 1, which carries chloride ligands on the inner coordination sites, is a 15 CBE unit. The cluster anion in 3 has four inner ligand sites occupied by isopropanolate anions, which are arranged trans to each other and define a common plane. Because of the smaller size of the alcoholato O donor atom compared to halogenido ligands matrix effects are not much or not at all present in the cluster anions of 2 and 3 (and 4) and thereby the Nb-Nb distances are much smaller than found in cluster units with halogenido ligands.

The compound [Nb6Cl14(pyrazine)4]·2CH2Cl2 (1) was investigated for its suitability as a starting compound for new ligand-supported hexanuclear niobium cluster compounds. The synthesis, stability to air and increased temperature, solubility and usability for subsequent reactions of 1, and purification and separation of the reaction products are discussed. The compounds with cluster units [Nb6Cl14L4], where L = iso-quinoline N-oxides (2), 1,1-dimethylethylenediamines (3), or thiazoles (4), and [Nb6Cl14(PEt3)3.76(Et3PO)0.24][Nb6Cl14(MeCN)4]·4MeCN (5) are presented as follow-up products. The crystal structures of compounds 1-5 are analyzed, and the structures are discussed with respect to their intra- and intermolecular bonding situations and crystal packing. In addition to hydrogen bonds and π-π interactions, the appearance of chalcogen and halogen bonds and lone pair-π interactions between Nb6 cluster units was observed for the first time.

Chemical reactions of ball-mill activated [Nb 6 I 11 ] with alcohol solutions of Mg alcoholates result in the formation of the three new hexanuclear Nb cluster compounds [Nb 6 I 8 (HOCH 3 ) 6 ][Nb 6 (OCH 3 ) 18 ]·2CH 3 OH ( 1 ), (PPh 4 ) 2 [Nb 6 (OC 2 H 5 ) 12 I 6 ]·C 2 H 5 OH ( 2 ) and (PPN) 2 [Nb 6 (OC 2 H 5 ) 12 I 6 ] ( 3 ). They contain cluster anions, which have the edges of the Nb 6 octahedra, i.e. the inner coordination sites, μ 2 -bridged by the O atoms of methanolato or ethanolato ligands. Thereby, they represent further characterized members of the so far very small group of hexanuclear cluster alcoholates. The terminal metal sites are bonded to further methanolato ( 1 ) or iodido ligands ( 2 and 3 ). Sterically demanding organic cations (PPh 4 + , PPN + , 2 and 3 ) or a cationic Nb 6 cluster complex with terminal methanol ligands [Nb 6 I 8 (HOCH 3 ) 6 ] 2+ in 1 compensate the negative charges of the cluster anions. Compound 1 is the first example of a M 6 cluster ion pair of both the text-book known edge-bridged [ M 6 X 12 ] and face-bridged [ M 6 X 8 ] cluster units. The structures of the three title compounds were determined by means of single-crystal X-ray structure analysis. Graphical Abstract

The cluster compounds [Nb6I8Py6] and [Nb6I8Py6]I . 9Py, both with octahedral Nb-6 metal atom cores, were obtained from the reaction of [Nb6I11] with pyridine (Py). Both compounds are rare examples of iodide supported hexanuclear cluster compounds, which are obtained through solvent-based chemical reactions. The Nb-6 cluster core is surrounded by mu(3)-bridging iodido and apical-bonded pyridine ligands. [Nb6I8Py6] contains 22 cluster-based electrons (CBE's), whereas [Nb6I8Py6]I . 9Py is the oxidized version with 21 CBE's. The oxidation happens just by lowering the temperature from room temperature to -20 degrees C of the same starting materials as used for [Nb6I8Py6]. The structures of the two cluster compounds were determined by single-crystal X-ray diffraction.

Six cluster salts which consist of hexanuclear cluster anions [Nb6Cl12iX6a]2- (X = Cl or Br) and protonated crown ether molecules (15-crown-5 (15cr5) and 12-crown-4 (12cr4)) or crown ether-stabilized oxonium cations as well as one compound consisting of neutral cluster units, [Nb6Cl16(H2O)2]·4 dioxane, were synthesized in good to high yields. The single-crystal X-ray structures of six of these compounds were determined. The cation/anion ratios and the bond distances confirm in all cases oxidized cluster cores with 14 cluster-based electrons. The cations of the cluster salts are either sandwich-type dimers of the formula [(15cr5)H]22+ or [(15cr5)(H3O)]22+ with the protons or oxonium ions embedded in between the crown ether rings or monomeric units in the case of [(12cr4)H]+. 1H NMR investigations show that the cluster salts are strong Brønsted acids. The fact that the cluster core of [Nb6Cl16(H2O)2]·4 dioxane is oxidized but still carries water ligands indicates that within the multi-step reaction sequence of the formation of the cluster-supported acids, the oxidation step happens much faster than the ligand exchange steps. Temperature-dependent 2H MAS NMR spectra of deuterium-exchanged [(15cr5)H]2[Nb6Cl18]·2 CHCl3 are indicative of dynamic processes of the hydrogen-bonded protons within the crown ether molecule.

The title compound, [Nb6Cl12I2(H2O)4]·8THF (THF is tetrahydrofuran, C4H8O), comprises an uncharged niobium cluster unit surrounded by THF solvent molecules. The edges of the {Nb6} octahedron are μ2-coordinated by twelve chlorido ligands. Four in-plane (equatorial plane) aqua ligands and two iodido ligands coordinating above and below the plane are bound at the corners of the {Nb6} atomic octahedron. O—H...O hydrogen bonds are formed between the aqua ligands and the THF solvent molecules; one THF molecule is disordered over two positions with the major component having a site occupancy of 0.64 (2).