ZnI2 Research Articles

Photo-Assisted Rechargeable Battery Desalination.

Herein, we propose a novel design of photo-assisted battery desalination, which provides the tri-function within a single device including the photo-assisted charge (electrical energy saving), energy storage, and desalination (salt removal). The photoelectrode (N719/TiO2) is directly integrated into the zinc-iodide (Zn-I) battery with the desalination stream in the middle portion of the device. This architecture can provide a reduced energy consumption up to 50%, an energy output of 42 W h mol-1NaCl, and a desalination rate of 13 μg/cm2 min-1. This work is significant for the inter-discipline study of the redox flow energy storage and energy-saving desalination.

Synthesis, crystal structures and luminescent properties of three layered zinc complexes: Zn(1,10-phen)mI2 (m = 1, 2) and Zn2(1,10-phen)2C2O4Br2 (phen = phenanthroline)

Three 1,10-phenantroline zinc halide complexes were successfully synthesized under solvothermal method and structurally characterized by single-crystal X-ray diffraction analysis. The three title complexes Zn(1,10-phen)I2 (1), Zn(1,10-phen)2I2 (2) and Zn2(1,10-phen)2C2O4Br2 (3), crystallize in the triclinic space group P1¯(No.2) with different unit cell parameters, are isolated neutral molecules. The extra stretching force from another 1,10-phen ligand in 2 lead to the Zn−N bond lengths longer than the corresponding in 1. Meanwhile, the molecules of Zn(1,10-phen)I2 and Zn(1,10-phen)2I2 further connect each other via the π-π interactions between the adjacent phenanthrolines to form a pseudo-two-dimensional layer which parallel to b-axis. Their face-to-face distance of π-π stacking interactions between the adjoining 1,10-phen rings is 3.7264 Å and 3.4435 Å, respectively. The zinc bromide complex 3 contains C−H···O intramolecular and C−H···Br (2-D) interlayer hydrogen bonding, which contributed to the connection between the parallel zig-zag molecules. The distance of phenanthroline rings in intramolecular and interlayer is 2.6071 Å and 3.8125 Å.The luminescent emissions of free ligand 1,10-phen and its zinc halide complexes were measured in various solvents. These zinc halide complexes show the obvious luminescent phenomenon with grass-green, yellow-green and light yellow in Dimethyl sulfoxide (DMSO), respectively (the maximum emission wavelength is 530 nm, 539 nm and 496 nm). The maximum emission wavelength for 2 has a little red-shifted compared with 1. It can be concluded that the number of ligand and the electron density on coordinated Zn atoms influence the emission wavelength through charge transfer from ligand to the metal. The emission wavelengths of 3 are also slightly red-shifted compared with the free 1,10-phen ligand, which is attributed to the coordination effects of the 1,10-phen ligands to the Zn cations and [C2O4]2− group.

Modification of Poly(Styrene‐co‐Acrylonitrile) with Tetrazine by Inverse Electron Demand Diels‐Alder Reaction

AbstractPoly(styrene‐co‐acrylonitrile) [P(SAN)] copolymer was obtained by using styrene and acrylonitrile monomers via free‐radical polymerization. The tetrazine groups were formed in the P(SAN) copolymer backbone by using 2‐fluorobenzyl cyanide, hydrazine hydrate, zinc iodide as the catalyst, and sodium nitrile. The tetrazine groups in the copolymer backbone were modified using trans‐cyclooctenol by the Inverse Electron Demand Diels‐Alder reaction. The spectroscopic properties of the obtained products were determined by Fourier transform infrared and proton nuclear magnetic resonance and their thermal properties were determined by thermogravimetric analysis and differential scanning calorimetry techniques. The average molecular weights of the synthesized polymers were defined by using gel permeation chromatography method.

High Quantum Yield Blue InP/ZnS/ZnS Quantum Dots Based on Bromine Passivation for Efficient Blue Light‐Emitting Diodes

AbstractRed and green InP quantum dots (QDs) already have been demonstrated with excellent luminescence performance closing the gap with CdSe‐based QDs. However, the performance of blue InP QDs still lags behind that of red and green QDs. For blue InP QDs synthesized by aminophosphine and zinc iodide, the inherent I– possesses weak passivation ability. By introducing Br– with a smaller ion radius and larger binding energy, the quantum yield of blue InP QDs is increased from 54% to 93%, which is the highest value reported so far. Meanwhile, the long‐chain 1‐dodecanethiol is replaced by the short‐chain 1‐octanethiol through ligand exchange to increase the carrier injection efficiency. The blue quantum dot light‐emitting diodes (QLEDs) made of these QDs showed an external quantum efficiency of 2.6%, which is notably the highest blue InP QLED reported so far.

High‐Voltage Aqueous Zinc Batteries Achieved by Tri‐functional Metallic Bipolar Electrodes

Aqueous rechargeable zinc batteries are very attractive for energy storage applications due to their low cost and high safety. However, low operating voltages limit their further development. For the first time, this work proposes a unique approach to increase the voltages of aqueous zinc batteries by using tri‐functional metallic bipolar electrode with good electrochemical activity and ultrahigh electronic conductivity, which not only participates in redox reactions, but also functions as an electrical highway for charge transport. Furthermore, bipolar electrode can replace expensive ion selective membrane to separate electrolytes with different pH; thus, redox couples with higher potential in acid condition and couple with lower potential in alkaline condition can be employed together, leading to high voltages of aqueous zinc batteries. Herein, two types of metallic bipolar electrodes of Cu and Ag are utilized based on three kinds of aqueous zinc batteries: Zn–MnO2, Zn–I2, and Zn–Br2. The voltage of aqueous Zn–MnO2 battery is raised to 1.84 V by employing one Cu bipolar electrode, which shows no capacity attenuation after 3500 cycles. Moreover, the other Ag bipolar electrode can be adopted to successfully construct Zn–I2 and Zn–Br2 batteries exhibiting much higher voltages of 2.44 and 2.67 V, which also show no obvious capacity degradation for 1000 and 800 cycles, representing decent cycle stability. Since bipolar electrode can be applied in a large family of aqueous batteries, this work offers an elaborate high‐voltage concept based on tri‐functional metallic bipolar electrode as a model system to open a door to explore high‐voltage aqueous batteries.

Long-Life Aqueous Zn-I2 Battery Enabled by a Low-Cost Multifunctional Zeolite Membrane Separator.

Aqueous zinc iodide (Zn-I2) batteries are promising large-scale energy-storage devices. However, the uncontrollable diffuse away/shuttle of soluble I3- leads to energy loss (low Coulombic efficiency, CE), and poor reversibility (self-discharge). Herein, we employ an ordered framework window within a zeolite molecular sieve to restrain I3- crossover and prepare zeolite molecular sieve particles into compact, large-scale, and flexible membranes at the engineering level. The as-prepared membrane can confine I3- within the catholyte region and restrain its irreversible escape, which is proved via space-resolution and electrochemical in situ time-resolution Raman technologies. As a result, overcharge/self-discharge and Zn corrosion are effectively controlled by zeolite separator. After replacing the typically used glass fiber separator to a zeolite membrane, the CE of Zn-I2 battery improves from 78.9 to 98.6% at 0.2 A/g. Besides, after aging at the fully charged state for 5.0 h, self-discharge is restrained and CE is enhanced from 44.0 to 85.65%. Moreover, the Zn-I2 cell maintains 91.0% capacity over 30,000 cycles at 4.0 A/g.

Uniform zinc electrodeposition directed by interfacial cation reservoir for stable Zn–I2 battery

Rough interfacial Zn electrodeposition and severe parasitic side reactions in aqueous electrolyte, resulting in increased internal resistance and limited reversibility, have significantly hindered the commercial deployment of Zn metal anode. Interfacial engineering offers a versatile platform for manipulating the zinc-ion flux and suppressing side reactions, via pre-formation of an artificial interlayer. Herein, we demonstrate a zincophile interphase based on metal-organic framework cation reservoir. The zinc hexacyanoferrate nanocubes with interconnected open cation transfer channels uniformize the interfacial electric field and render the protected electrode with faster zinc redox kinetic and higher exchange current density. The cations within the reservoir served as an ion-transfer mediator could regulate interfacial Zn2+ even distribution and lower zinc-ion nucleation energy barrier, consequently promoting the homogeneous Zn electrodeposition. Additionally, the in situ pre-formed film also enhances the thermodynamic stability of metal anode and avoids the water-induced side interfacial reaction. The protected anode exhibits an extremely low voltage hysteresis and achieves a high average Coulombic efficiency (∼99.6%) for 400 h with dendrite-free behaviors. When coupled with an iodine cathode, the favorable electrochemical performance of full Zn–I2 cells is realized, representing an advanced practical step toward stable Zn metal anode for real applications.

Coordination of an amino alcoholic Schiff base ligand toward the zinc(II) ion: spectral, structural, theoretical, and docking studies

A new zinc(II) complex of 2-(((2-((2-hydroxyethyl)amino)ethyl)imino)methyl)phenol (L), [Zn(Lz)Br2] (1), is prepared and identified by elemental analysis, FTIR and 1H NMR spectroscopy, and single crystal X-ray diffraction. The X-ray structure analysis of 1 reveals a tetrahedrally coordinated zinc(II) complex containing the NO-donor amino alcoholic Schiff base ligand and two bromo ligands. After complexation, the ligand (L) converts to its zwitterionc form (Lz) of phenol → phenolate; amine → ammonium. In this structure, hydrogen bonds between amine and alcohol units form different types of hydrogen bond motifs, including R21(7), R22(7), R22(10), R44(24), R44(30), R66(38), and R66(44). In addition to the hydrogen bonds in this crystal network, there are π—π stacking interactions between the phenyl ring and the imine group. The ability of the ligand and its isostructural complexes [Zn(Lz)Br2] (1), [Zn(Lz)Cl2] (2), and [Zn(Lz)I2] (3) to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II, and B-DNA) is investigated by docking studies. The results show that in some cases, the studied compound can interact with proteins and DNA better than doxorubicin. The charge distribution pattern of the ligand and complex 1 is studied by the NBO analysis.

Syntheses, crystal structures, and antimicrobial activities of zinc complexes derived from 2-amino-N'-(pyridin-2-ylmethylene)benzohydrazide

New zinc complexes, [ZnBr2(HL)] (1), [ZnBr(HL)(NCS)]·0.5H2O (2), [Zn(HL)I2] (3), and [ZnL2] (4), where L is the monoanionic form of 2-amino-N'-(pyridin-2-ylmethylene)benzo­hydrazide (HL), have been prepared and characterized by elemental analysis, IR and UV-Vis spectra, as well as single crystal X-ray diffraction. The Zn atoms in complexes 1—3 are in distorted trigonal-bipyramidal coordination, and that in complex 4 is in octahedral coordination. The crystal structures of the complexes are stabilized by hydrogen bonds. The antibacterial and antifungal activities of the compounds were evaluated.

Some new antimicrobial/antioxidant nanostructure zinc complexes: Synthesis, crystal structure, Hirshfeld surface analyses and thermal behavior

In this study, the synthesis and characterization of a new bidentate ligand and some its zinc halide/pseudohalide complexes and nano-structures are described. The crystal structures of the ligand and its zinc nitrate complex as typical examples were determined by single crystal X-ray diffraction. Hirshfeld surface analysis of these structures provided insight into the various intra and inter-molecular interactions and therefore a description of the supramolecular structure for the ligand and its zinc nitrate complex in solid state. Furthermore, the thermal behavior of the complexes was established by TG/DTG/DTA curves analysis. Moreover an antibacterial bioassay of the zinc complexes was been performed in vitro against two gram-positive (Staphylococcus aureus and Bacillus subtilis) and two gram negative (Escherichia coli and Pseudomonas aeruginosa)] bacterial strains. The antifungal activities of the compounds against two fungal strains of Aspergilus niger and Candida albicans were also investigated. The antioxidant capabilities of the Schiff base ligand and its zinc complexes were determined by the in vitro methods of ABTS and DPPH as compared with the standard Trolox. Finally, ZnO nanoparticles were synthesized by direct calcination of the zinc iodide complex at 550 °C under air atmosphere confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and energy dispersive X-ray analyses (EDX).

Accelerating the dissolution kinetics of iodine with a cosolvent for a high-current zinc–iodine flow battery

A cosolvent mitigates the rate-limiting step in the oxidation of iodide and boosts the current of an aqueous Zn–I2 flow battery.

Selective sulfonylation and isonitrilation of para-quinone methides employing TosMIC as a source of sulfonyl group or isonitrile group.

Chemoselective sulfonylation and isonitrilation reactions for the divergent synthesis of valuable diarylmethyl sulfones and isonitrile diarylmethanes starting from easy-to-synthesize para-quinone methides (p-QMs) and commercially abundant p-toluenesulfonylmethyl isocyanide (TosMIC) by using respectively zinc iodide and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as catalysts were developed. The distinguishing feature of this method is that TosMIC plays a dual role from the same substrates in the reaction: as a sulfonyl source or as an isonitrile source. The synthetic utility of this protocol was also demonstrated in the synthesis of difluoroalkylated diarylmethane 5 and diarylmethane ketone derivatives 6 and 7, which are important core structures in natural products and medicines.

I‐containing Polymer/Alloy Layer‐Based Li Anode Mediating High‐Performance Lithium–Air Batteries

AbstractLithium (Li)–air batteries with super‐high energy density have attracted wide attention, but they usually exhibit poor performance due to dendrite/passivation on anode and insoluble discharge products on cathode. Many recent works have just designed highly efficient catalysts or only prepared stable anodes to solve one aspect of the above issues. Herein, an iodine (I)‐containing polymer/alloy layer‐based Li (IPA‐Li) via the replacement reaction of zinc iodide (ZnI2) and Li and subsequent polymerization of ethyl α‐cyanoacrylate (ECA) is designed to tackle both the anode and cathode problems. The homogeneous polymer layer and LiZn alloy in IPA‐Li not only suppress the passivation caused by attack of O2/H2O, but also guide uniform Li plating/stripping behavior to inhibit dendrite formation. Moreover, soluble I‐containing species in IPA‐Li obviously promote decomposition of discharge products at low voltages. Compared with bare Li, IPA‐Li shows a longer lifespan (1200 h at 1 mA cm−2) in the symmetric cell. Hence, the electrochemical performance of IPA‐Li‐based Li–O2 batteries is also much better than Li‐based cells. Moreover, IPA‐Li‐based Li–air battery operates stably >120 cycles with low‐overpotential of <1.6 V in ambient air, while the Li–air battery fast decays only after 25 cycles. This strategy provides a new way to construct high‐performance Li–air batteries.

Anion effect on properties of Zn-doped CH3NH3PbI3 based perovskite solar cells

High-quality perovskite films are crucial for developing efficient planar perovskite solar cells (PSCs). As-prepared perovskite films have low crystallinity and high level of trap densities, resulting in the deterioration of PSCs performances. Herein, a facile approach is adopted to fabricate high-quality CH 3 NH 3 PbI 3 films by incorporating different types of zinc salt, including zinc iodide (ZnI 2 ), zinc chloride (ZnCl 2 ), and zinc acetate (Zn(Ac) 2 ). It is demonstrated that zinc ions (Zn 2+ ) substitute a part of the lead ion (Pb 2+ ) sites, enlarging the grain size, and suppressing the formation of metallic lead. Moreover, the acetate anion bearing the carbonyl species (C O) effectively passivates the under-coordinated Pb 2+ defects and further reduces the defect densities at both the grain boundaries and interfaces. As a result, the planar PSCs with the Zn(Ac) 2 additive yield a champion power conversion efficiency (PCE) of 19.32%, which is 15% higher than that of the control device. Simultaneously, the outperforming device delivers remarkable stability, retaining 87% of its original efficiency after aging for 500 h under ambient conditions. • Enhanced Gibbs free energy of nucleation induced by zinc salt leads to larger grains. • A more stable perovskite lattice was obtained due to the partly replacement of Zn 2+ and Ac − . • The Ac − group takes superior role than I − and Cl − in passivating the under-coordinated Pb 2+ defects. • The synergistic effect of the Zn(Ac) 2 yields a PCE of 19.32%, enhancement of ∼15%.

Crystal structures of Zn(cyclam)I2 (second monoclinic polymorph) and Zn(cyclam)I(I3).

The asymmetric unit of the first title compound iodido-(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ4 N 1,N 4,N 8,N 11)zinc(II) iodide, [ZnI(C10H24N4)]I, I, consists of the zinc-cyclam macrocyclic cation with one iodide anion coordinated to the metal ion [Zn-I = 2.6619 (5) Å] and the second present as a counter-ion. The asymmetric unit of the second title compound iodido-(1,4,8,11-tetra-aza-cyclo-tetra-decane-κ4 N 1,N 4,N 8,N 11)zinc(II) triiodide, [ZnI(C10H24N4)]I3, II, consists of half of the centrosymmetric macrocyclic cation, in which the ZnII ion coordinated to an iodide anion [Zn-I = 2.766 (2) Å] is disordered over two positions [Zn⋯Zn = 0.810 (3) Å], and of the two halves of the crystallographically non-equivalent, non-coordinated, centrosymmetric triiodide anions. In both compounds, the N,N,N,N-tetra-dentate macrocyclic ligand is present in the most energetically favored trans-III conformation. In the crystals of I, the [Zn(C10H24N4)I]+ cations and the non-coordinated iodide anions are linked by N-H⋯I and bifurcated N-H⋯(I,I) hydrogen bonds, resulting in the formation of two-dimensional networks lying parallel to the (001) and (101) planes. In contrast, the crystals of II are built up from infinite chains of the five-coordinate macrocyclic units arranged along the b-axis direction and perpendicular sheets formed of the triiodide counter-ions without significant hydrogen bonding between them.

Highest Ever Achieved Current Densities for Zinc/Polyiodide Redox Flow Batteries

With the aim of environment protection and security of energy supply in the coming decades, electricity is increasingly generated from renewable sources. Since availability of these sources such as solar and wind power and therefore electricity generation varies with time, importance of energy storage also increases tremendously. Rechargeable batteries represent an excellent technology for that purpose, as they convert electrical to chemical energy quickly and efficiently and are independent of geographical conditions. The market is currently dominated by lithium ion batteries, but they are expensive, especially on a larger scale. Redox flow batteries (RFBs) have therefore received a lot of interest in the recent years. However, the most commonly used RFB, the all-vanadium system, suffers from a low energy density with only around 30 Wh/l.A promising alternative is the recently suggested zinc/polyiodide RFB. In this system, an aqueous solution of zinc iodide is used as electrolyte. This compound contains the active species for both half-cells, while zinc ions also act as charge carriers since they can diffuse through the cation exchange membrane. These properties lead to enhanced energy density in three ways. First, zinc iodide is soluble in water up to 5 mol/l, which is about two and a half times the solubility of vanadium ions. Secondly, two electrons are transferred in each redox process and thirdly, the anolyte volume can be kept very small. This adds up to almost 10 times higher energy density for zinc/polyiodide RFBs in comparison to all-vanadium RFBs. Up to 200 Wh/l has already been reached experimentally as reported in literature.Here, a novel 100 cm² cell design for this battery type is presented. Graphite compound plates with three different flow field types (flow-through, serpentine, interdigitated) were fabricated. Their electrochemical performances were investigated with the help of current-voltage curves and charge/discharge cycle experiments. In this cell, the highest ever reported current densities for zinc/polyiodide flow batteries at more than 500 mA cm-2 could be achieved. These experimental results were accompanied by CFD simulations, which provided further insights. The results will be reported at the conference.

Electrode Materials for Enhancing the Performance of a Zinc Iodide Flow Battery at High Current Density

The zinc-iodide flow battery (ZIFB) has a high energy density and uses a benign electrolyte material [1]. However, the energy density and cyclability the ZIFB is hindered by zinc dendrite growth and electrode polarization in this battery [2]. In our previous work a new flow field design was used to mitigate dendrite formation and enhance the performance of the ZIFB [3]. Despite the enhancement achieved, capacity fade and limited cyclability at current densities greater than 20 mA cm- 2 remain a challenge for ZIFBs. In this study, the use of a high electrical conductivity material for the negative (zinc) electrode, combined with an electrocatalyst on the positive (iodide) electrode was investigated, in order to improve the cyclability and energy density of the ZIFB at high current densities.The use of a high electrical conductivity electrode has been shown to enable rapid transfer of surface charge, and maintain a uniform interfacial electric field [4]. A uniform interfacial electric field can reduce surface charge accumulation and enable a more uniform zinc deposition [5]. This leads to uniform zinc deposition and high rechargeability of the zinc electrode. In this study a copper foil was used as a high conductivity electrode material at the negative (zinc) side of the ZIFB. Scanning electron microscopy (SEM) images of the zinc deposit show that epitaxially layered deposition was obtained on the electrode surface. For all the experiments, charge/discharge of a Zn-I battery were carried out using a 3.0 M ZnI2 electrolyte on both sides of the battery, the charge and discharge current density was 40 mA cm-2, and charging was carried out to 60% state of charge. A Nafion 117 membrane was used to separate the electrolyte compartments.Nitrogen doped carbon obtained by carbonizing polyaniline (PANI) is a promising electrocatalyst material for the next generation energy storage technologies [6]. A carbonized PANI-graphite felt composite was used as the electrode material on the positive (iodide) side of the ZIFB. PANI was uniformly coated on graphite felt using brush, followed by heating to 850 °C for 2 hours under the N2 atmosphere. The use of the carbonized PANI modified graphite felt electrode material in the positive side of the ZIFB (with a graphite felt negative electrode), led to an enhancement of the energy efficiency of around 4% (from 67 % to 71%) at a current density of 40 mA cm-2. The carbonized-PANI modified electrode was characterized using X-ray diffraction, Raman spectroscopy, nitrogen adsorption, and SEM. SEM results indicated that agglomerated nano-grains of carbonized PANI were distributed on the graphite felt fibers. Nitrogen adsorption analysis confirmed that the carbonized PANI-graphite felt electrode had a higher specific surface area than the pristine graphite felt.The performance of a ZIFB using a carbonized PANI-graphite felt positive electrode, and a copper foil negative electrode was evaluated by cycling for over 100 cycles. Stable cycling was observed, with a coulombic efficiency of 99%. When compared with using pristine graphite felt on the negative and positive electrodes, a significant improvement in the charge-discharge energy efficiency of around 10 % (from 67 % to 76%) was obtained.

Zn Coordination and the Identity of the Halide Ancillary Ligand Dramatically Influence the Excited-State Dynamics and Bimolecular Reactions of 2,3-Di(pyridin-2-yl)benzo[g]quinoxaline.

The optical properties of coordination complexes with ligands containing nitrogen heterocycles have been extensively studied for decades. One subclass of these materials, metal complexes utilizing substituted pyrazines and quinoxalines as ligands, has been employed in a variety of photochemical applications ranging from photodynamic therapy to organic light-emitting diodes. A vast majority of this work focuses on characterization of the metal-to-ligand charge-transfer states in these metal complexes; however, literature reports rarely investigate the photophysics of the parent pyrazine or quinoxaline ligand or perform control experiments utilizing metal complexes that lack low-lying charge-transfer (CT) states in order to determine how metal-atom coordination influences the photophysical properties of the ligand. With this in mind, we examined the steady-state and time-resolved photophysics of 2,3-di(pyridin-2-yl)benzo[g]quinoxaline (dpb) and explored how the coordination of ZnX2 (X = Cl-, Br-, I-) affects the photophysical properties of dpb. In dpb, we find that the dominant mode of deactivation from the singlet excited state is intersystem crossing (ISC). Coordination of ZnX2 perturbs the relative energies of the ππ* and nπ* excited states of dpb, leading to drastically different rates of ISC as well as radiative and nonradiative decay in the [Zn(dpb)X2] complexes compared to dpb. These differences in the rates change the dominant singlet-excited-state decay pathway from ISC in dpb to a mixture of ISC and fluorescence in [Zn(dpb)Cl2] and [Zn(dpb)Br2] and to nonradiative decay in [Zn(dpb)I2]. Coordination of ZnX2 and the choice of the halide ligand also have profound effects on the rate constants for excited-state bimolecular reactions, including triplet-triplet annihilation and oxygen quenching. These results demonstrate that metal coordination, even in complexes lacking low-lying CT states, and the choice of the ancillary ligand can dramatically alter the photophysical properties of chromophores containing nitrogen heterocycles.

Anion Induced Synthesis, Structural Characterization and Antibacterial Activity of Zinc(II) Complexes Derived from 5-Bromo-2-((2-(diethylamino)ethylimino)methyl) phenol

By changing the anions of zinc salts, three different zinc(II) complexes, [Zn2(HL)2(NCS)4]·2CH3OH (1), [Zn2L(μ2-η1:η1-CH3COO)2(NCS)] (2) and [Zn(HL)I2]·CH3OH (3), where L = 5-bromo-2-((2-(diethylamino)ethylimino)methyl)phenolate, HL = 5-bromo-2-((2-(diethylammonio)ethylimino)methyl)phenolate, have been synthesized and characterized by IR and UV-Vis spectroscopy, as well as single-crystal X-ray diffraction. X-ray analysis indicates that the Zn atoms in the complexes are in trigonal bipyramidal, square pyramidal and tetrahedral coordination. The anions of the zinc salts lead to the formation of different structures of the complexes. Antibacterial activity of the complexes against Staphylococcus aureus, Escherichia coli, Klebsielle pneumoniae and Candida albicans strains was studied.

Zinc Iodide Catalyzed Synthesis of Trisubstituted Allenes from Terminal Alkynes and Ketones.

A straightforward, user-friendly, efficient protocol for the one pot, ZnI2-catalyzed allenylation of terminal alkynes with pyrrolidine and ketones, toward trisubstituted allenes, is described. Trisubstituted allenes can be obtained under either conventional heating or microwave irradiation conditions, which significantly reduces the reaction time. A sustainable, widely available, and low-cost metal salt catalyst is employed, and the reactions are carried out under solvent-free conditions. Among others, synthetically valuable allenes bearing functionalities such as amide, hydroxyl, or phthalimide can be efficiently prepared. Mechanistic experiments, including kinetic isotope effect measurements and density functional theory (DFT) calculations, suggest a rate-determining [1,5]-hydride transfer during the transformation of the intermediate propargylamine to the final allene.