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Comprehensive Summary: Herein, we describe a direct route for the synthesis of 3‐gem‐difluorovinyl lactams through Zn‐mediated reductive hydrodehalogenation. Importantly, by using inexpensive deuterium oxide (D2O), the high value‐added vicinal dideuterated gem‐difluoroalkenes with excellent deuterium (D) incorporation were prepared. Mechanism studies indicated a successive single electron transfer process: the reaction initially undergoes hydrodechlorination to give the intermediate α‐trifluoromethylidene lactams, which are then activated by the in‐situ generated zinc cations and reduced to the desired product via hydrodefluorination. [ABSTRACT FROM AUTHOR]

A convenient synthetic approach to Schiff bases based on 3-(4-methoxyphenyl)-6-formylpicolinonitrile as surrogates of 2,2′-bipyridine ligands is proposed. The synthesis was carried out using the "1,2,4-triazine" methodology, and a more efficient method for the preparation of 5-aryl-6-cyanopyridine-2-carbaldehydes was developed compared to the previously described one, which involves the use of isonitrosoacetophenone hydrazone and chloroacetonitrile as starting compounds. The resulting compounds exhibit fluorescence in solutions with a quantum yield of up to 15.4%, as well as a fluorescent response to the zinc cation in the form of dramatic fluorescence quenching. [ABSTRACT FROM AUTHOR]

New 4-methoxy-1,8-naphthalimide derivative containing a salicylideneamino receptor group at the imide nitrogen atom demonstrated selective fluorescent response to Zn2+ cations due to the formation of 1: 2 and 2: 1 ligand–metal complexes. [ABSTRACT FROM AUTHOR]

Scaling process is the main problem encountered in industrial plants using water. Several factors (pH, temperature, hydrodynamic conditions, metal surface, and especially, water composition) can affect the scaling kinetics of calcium carbonate (CaCO3), one of the main components of scaling. In addition, some foreign ions added can considerably modify the scaling rates. In this work, the inhibiting effects of Zn2+ and Cu2+ cations on CaCO3 precipitation were studied in a 50°F synthetic carbonic solution by using fast controlled precipitation (FCP) and scaling quartz crystal microbalance (SQCM) methods, for homogeneous and heterogeneous scaling deposition, respectively. Results showed that Zn2+ and Cu2+ ions are efficient, at high concentrations (=1 mg/L), to delay or even to prevent nucleation/growth of CaCO3. FCP measurements showed a complete inhibition of the homogeneous CaCO3 precipitation after 120 min in synthetic solution containing 5 and 4 mg/L of Cu2+ and Zn2+, respectively. SQCM measurements showed that the surface coverage of the metallic substrate by a layer of CaCO3 is reduced when the amount of these cations increased. Zn2+ cations inhibited the heterogeneous CaCO3 precipitation more efficiently than Cu2+. SEM and XRD results indicated that both cations affect calcium carbonate nucleation by changing the morphology of CaCO3 crystals. [ABSTRACT FROM AUTHOR]

Three mononuclear different-ligand Zn(II) complexes, [Zn(CHCOO)(PaoH)] ( I), [Zn(PaoH)(DMSO)][BF] ( II), and [Zn(NCS)(PaoH)] ( III) (DMSO = dimethylsulfoxide) were prepared by the reaction of zinc acetate and tetrafluoroborate with pyridine-2-aldoxime (PaoH). The composition and structure of the complexes were confirmed by IR spectroscopy and X-ray diffraction. All compounds crystallize in the monoclinic system, compounds I and II have space group P2/ n, while compound III has space group C2/ c. In all compounds, the Zn coordination polyhedron is a distorted octahedron, which is formed by the NO sets of donor atoms in I and II and by N in III. Complex I in the optimal concentration of 5-10 mg/L was found to stimulate the biosynthesis of standard (pH 4.7) amylases by the micromycete Aspergillus niger CNMN FD 06. [ABSTRACT FROM AUTHOR]

This study was focused on the determination of contaminant transport parameters of heavy metal Zinc moving through saturated soft Bangkok undisturbed clay under high hydraulic gradients. These parameters were compared with contaminant transport determined under concentration gradient alone (pure diffusion). In total fifteen column tests were conducted and a mathematical model was applied to determine the coefficients. Two different source concentrations conditions, constant and decreasing, were applied. Testing periods were ranged from 15-60 days while hydraulic gradients were ranged from 0-500. The curves between relative concentration and time and pore volume were developed for the constant source condition whereas curves between source reservoirs concentrations and time were developed for decreasing source condition. The effective diffusion and distribution coefficients, De and Kd, were determined by curve fitting using the computer code POLLUTE v 6.3. The results showed that diffusion coefficient increases and distribution coefficient decreases as hydraulic gradient increases from 0 to high value of 500 due to contribution of dispersion and additional molecular diffusion at high advective velocity. Thus, testing at high gradients ensures the safe performance of earthen barriers under worse conditions.

Numerous adsorbent materials are developed and are able to face specific types of pollution, but none of them can manage the whole pollution. The purpose of this work is to develop a novel hybrid adsorbent, based on chitosan (CS) biopolymer, clay minerals and activated carbon (AC), having complementary adsorption properties and achieving a wide-spectrum water decontamination in a single treatment. Hybrid CS beads, containing dispersed clay and AC, were prepared from dispersions of solid adsorbents in a CS solution and its further coagulation in a basic medium. The porosity and the homogeneity of the hybrid beads were characterized by N2 adsorption at 77 K and Cryo-Scanning Electron Microscopy respectively. The interaction between CS and clay was characterized using X-ray diffraction. Water content and the amount of each adsorbent in the hydrogel beads were determined by thermogravimetric analysis. Such a composite material was still porous and presented a wide adsorption spectrum. As shown by their adsorption kinetics, hydrophobic anionic clofibric acid (CBA) and cationic metoprolol (MTP) were well adsorbed on AC containing beads (21 and 26 mg/g), respectively. Clays containing beads showed interesting adsorption properties towards cationic Zn2+ and MTP. The obtained composite beads were able to adsorb all the pollutant types: Zinc cations, and hydrophobic-charged organic molecules, such as pharmaceutical derivatives (clofibric acid and MTP).

A novel type of selective and sensitive fluorescent sensor having triazole rings as the binding sites on the lower rim of a hexahomotrioxacalix[3]arene scaffold in a cone conformation is reported. This sensor has desirable properties for practical applications, including selectivity for detecting Zn 2+ and Cd 2+ in the presence of excess competing metal ions at low ion concentration or as a fluorescence enhancement type chemosensor due to the cavity of calixarene changing from a ‘flattened-cone’ to a more-upright form and inhibition of PET. In contrast, the results suggested that receptor 1 is highly sensitive and selective for Cu 2+ and Fe 3+ as a fluorescence quenching type chemosensor due to the photoinduced electron transfer (PET) or heavy atom effect. [ABSTRACT FROM AUTHOR]

We report a DFT study (M06L/cc-pVDZ) of the interactions between the Si(OH) group in three simplified gem-silanediols [i.e., N-[dihydroxy(methyl)silyl] methyl}formamide (DHSF), 3-[dihydroxy (methyl) silyl] propanamide (DHSP), and 3,3′-(dihydroxysilanediyl)dipropanamide (DHSDP)], which have a similar structure to silanediol-based inhibitors of metalloproteases, and simplified active site models: [Zn(Imdz)-OH] and [Zn(Imdz)R-OH], where R can be a formaldehyde, an acetone, or an acetic acid molecule. These models partly resemble the structure of the first coordination sphere of some metalloproteases (e.g., angiotensin I converting enzyme and thermolysin). Different types of bonding patterns were found for the systems into study. The three related silanediols may coordinate with the zinc dication in monodentate, pseudo-bidentate, and pseudo-tridentate way. Pseudo-bidentate interaction was reported to be that corresponding to the silanediol transition-state-analog of the thermolysin enzyme as confirmed by the X-ray structural study (Juers et al., Biochemistry 44:16524-16528, ). The binding ability of the mentioned silanediols was determined as the energy of the water displacement reaction for the mentioned active sites models in gas phase and in water solution (PCM model). The calculated binding energies point out to the higher strength of the pseudo-bidentate Zn-MBG interaction. Moreover, DHSDP ligand is calculated to be the strongest MBG for Zn in both active sites models. NBO population analysis and the AIM methodology were implemented as a tool for evaluating electronic structure of the complexes. The results obtained may point out to the fact that the higher the electronic delocalization around the metal center is, the stronger the interaction between the MBG and the active site, bringing about a higher binding energy. [ABSTRACT FROM AUTHOR]

From extraction experiments and γ-activity measurements, the exchange extraction constant corresponding to the equilibrium Zn2+ (aq) + 1 ⋅ Sr2+ (nb) ⇔ 1 ⋅ Zn2+(nb) + Sr2+(aq) taking place in the two--phase water--nitrobenzene system (1 = beauvericin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex (Zn2+, 1 ⋅ Sr2+) = -0.3 ± 0.1. Further, the stability constant of the beauvericin -- zinc complex (abbrev. 1 ⋅ Zn2+) in nitrobenzene saturated with water was calculated for a temperature of 25 °C: log βnb (1 ⋅ Zn2+) = 9.1 ± 0.2. Finally, by using quantum mechanical DFT calculations, the most probable structure of the 1 ⋅ Zn2+ complex species was predicted. [ABSTRACT FROM AUTHOR]

Using embedded cluster models and the hybrid density functional–molecular mechanics scheme covEPE, we studied computationally various Zn species in ZSM-5 zeolites: Zn2+, [Zn(OH)]+, [Zn(H2O)]2+, and [ZnOZn]2+. The covEPE embedding approach accounts for the flexibility of the zeolite framework and long-range electrostatic interactions. Due to this flexibility of the embedded models, the mononuclear Zn-species in zeolite structures showed more (four) Zn-O contacts or shorter average Zn-O distances compared to the corresponding isolated cluster models. Comparing protonic and Zn-exchanged forms of the zeolites rings suggests that upon Zn-substitution O centers shift farthest, extending bonds in the five-ring and contracting distances in the six-ring. We also calculated energies of two types of formal reactions for exchanging protons in H-ZSM-5 by zinc ions: a reaction with zinc vapor which is exothermic by −73 to −112 kJ/mol and ion-exchange with an aqueous solution of a zinc salt which is exothermic by −33 to −124 kJ/mol; the latter value corresponds to [Zn(H2O)]2+ coordinated at a six-ring. Cluster embedding stabilizes the zinc exchanged form with respect to the protonic one in both types of reactions. [ABSTRACT FROM PUBLISHER]

It is suggested that the abnormal methane IR frequency shift observed in ZnZSM‐5 zeolites is caused by adsorptive interaction of CH4 with particularly strong Zn2+ Lewis sites. Various molecular structures of zinc ion species in high‐silica zeolites are discussed, and it is concluded that increased Lewis acidity of a site is associated with decreased structural stability. It is shown that Zn2+ in zeolite cationic position with distantly placed A1 ions can produce observed shift of vibrational frequencies for adsorbed methane molecule. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 [ABSTRACT FROM AUTHOR]

By doing first-principles based simulations, a reaction of zinc cation catalyzing the carbonyl hydrazine C N bond cleavage was verified by investigating the flash pyrolysis processes of carbohydrazide, carbohydrazide perchlorate and zinc carbohydrazide perchlorate (GTX) crystals. We propose a mechanism of nitrogen gas generation that, perchlorate anions release oxygen radicals to seize hydrogen atoms of carbohydrazide, then coordination with zinc facilitates the C N bond cleavage in carbohydrazide. The center single zinc cation of GTX decreases the barrier of C N bond cleavage. The lowest energy barrier of breaking C N bond is 127.33 kJ mol−1. The simulations reveal how the oxidizing perchlorate anion and the center metal contribute to the flash pyrolysis of GTX via the zinc cation catalyzed carbonyl hydrazine C N bond cleavage. The catalytic mechanism of transition metal in primary explosives opens new windows for designing coordination energetic compounds. [Display omitted] A reaction of zinc cation catalyzed the carbonyl hydrazine C−N bond cleavage in dehydrogenated carbohydrazide molecule accelerates the pyrolysis of GTX (zinc carbohydrazide perchlorate). The results reveal why a majority of primary explosives contain metal elements and how metal elements accelerate the deflagration to detonation transition (DDT) of primary explosives. The catalytic mechanism of transition metal in primary explosives opens new windows for designing coordination energetic compounds. • The flash pyrolysis of a transition metal complex was performed by AIMD method. • The mechanism of nitrogen release was proposed during the flash pyrolysis of zinc carbohydrazide perchlorate. • Zinc cation catalyzed carbonyl hydrazine C−N bond cleavage was revealed. • The catalytic mechanism was investigated by analyzing the electronic structures of critical bonds. • The catalysis of metal during the flash pyrolysis of complex-based primary explosive was confirmed theoretically. [ABSTRACT FROM AUTHOR]

[Display omitted] • Basil leaf extract was used to synthesize a novel Zn2+ based hybrid pigment. • The synthesized pigment was analyzed by SEM-EDS, TGA, FTIR, and UV–vis. • Mechanism of corrosion inhibition of Zn-Basil was studied on bare steel samples. • Epoxy coatings showed considerable corrosion protection in the presence of Zn-Basil. A hybrid corrosion inhibitive pigment based on zinc cation-basil leaf extract was synthesized for application in protective construction coatings. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), UV–vis spectroscopy, and thermal gravimetric analysis (TGA) were used for characterization of the hybrid pigment. Electrochemical impedance spectroscopy (EIS) was utilized to evaluate the corrosion inhibition efficiency of the hybrid pigment in 3.5 wt% NaCl solution on mild steel. The protective functioning of the synthesized pigment as incorporated into the epoxy coating was studied via salt spray test and EIS. Results showed a significant corrosion inhibition by the hybrid pigment in the solution phase. Besides, the hybrid pigment provided considerable improvement in corrosion protection in intact and artificially scratched coatings. [ABSTRACT FROM AUTHOR]

Two-photon fluorescent probes CHP-H and CHP-CH 3 were synthesized and applied to explore the mutual regulation between Zn2+ and nitrosyl (HNO) in cells and in vivo models. The probes consist of two moieties: coumarin derivative as the two-photon fluorescence transducer, 2-hydrazino pyridine as the fluorescence modulator and Zn2+ chelator. Both probes exhibit excellent analytical properties for Zn2+ detection in simulated physiological systems. Utilizing CHP-H and an HNO probe Cyto-JN , we perform fluorescent imaging of cell I/R models. The results confirm that HNO can stimulate Zn2+ release from labile Zn2+ pool, whereas, the increase of intracellular Zn2+ cannot upregulate the level of HNO. Combining with the deep tissue imaging of mice hippocampus tissues, our probes may provide potential approaches for the medical diagnostic assessment of HNO regulation effect on Zn2+ release in clinical cerebral I/R-related diseases. • We designed and synthesized two-photon fluorescent probes CHP-H and CHP-CH 3 for Zn2+ detection. • The two probes exhibited high sensitivity, selectivity, and low limit of detection towards Zn2+ (19 and 25 nM). • CHP-H was chosen to track the changes of intracellular Zn2+ in cells and in ischemia/reperfusion mice models. • The two probes featured deep tissue penetration and real-time imaging of Zn2+ in mice hippocampus specimens. • We verified the mutual regulatory interaction between Zn2+ and HNO in cells and in mice models. The homeostatic disorder of intracellular Zn2+ pool is closely associated with severe diseases. It has been reported that the high level of free Zn2+ during ischemia/reperfusion (I/R) process can result in oxidative stress damage on nerve cells. Given that nitrosyl (HNO) can aggravate the nerve injury during cerebral I/R process, we assume that there may exist a mutual regulation between Zn2+ and HNO under certain physiological conditions. To reveal this potential small-signaling-molecule crosstalk, we synthesized two-photon fluorescent probes CHP-H and CHP-CH 3 to monitor intracellular Zn2+ in cell and mice hippocampus I/R models. The probes consist of two moieties: coumarin derivative as the two-photon fluorescence transducer, 2-hydrazino pyridine as the fluorescence modulator and Zn2+ chelator. Both probes exhibit excellent analytical properties for Zn2+ detection in simulated physiological systems. Utilizing CHP-H and an HNO probe Cyto-JN , we perform fluorescent imaging of cell I/R models. The results confirm that HNO can stimulate Zn2+ release from labile Zn2+ pool, whereas, the increase of intracellular Zn2+ cannot upregulate the level of HNO. Combining with the deep tissue imaging of mice hippocampus tissues, our probes may provide potential approaches for the medical diagnostic assessment of HNO regulation effect on Zn2+ release in clinical cerebral I/R-related diseases. [ABSTRACT FROM AUTHOR]