Anion⋅⋅⋅Anion Attraction in Complexes of MCl3− (M=Zn,Cd, Hg) with CN−

High-level ab initio calculations show that the MCl₃⁻ anions comprising Group 2B M atoms Zn, Cd, and Hg form a stable complex with the CN⁻ anion, despite the like charge of the two ions. The complexation occurs despite a negative π-hole region above the M atom of MCl₃⁻. The dimerization distorts the planar geometry of MCl₃⁻ into a pyramidal shape which reduces the negative potential above the M atom, facilitating a close approach of the two anions, with R(M⋅⋅⋅C)∼2 Å, and an overall attractive electrostatic attraction within the dimer. In the gas phase, this dimer is less stable than the pair of separated ions by some 30 kcal/mol. However, the dissociation must surmount an energy barrier of roughly 25 kcal/mol which occurs at an intermolecular distance of 4 Å. In aqueous solution, the dimerization process is exothermic and barrier-free, with a binding energy in the 11–18 kcal/mol range.     

DFT Studies on Second-order Nonlinear Optical Response of Ir(C∧N)2(pic)Complexes

Density flmctional theory(DFT)was employed to calculate the geometrical structures,UV-Vis absorption spectra and second-order nonlinear optical(NLO)properties of a family of iridium(Ⅲ)complexes,which possess of different cyclometallated ligands(C∧N)and ancillary ligands[pyridme-2-carboxylate(pic)].It was found that the mo-dification of the LUMO energy levels was achieved by changing pic ligands and the energy gaps between the HOMO and LUMO were notably increased or decreased.In addition,the degree of conjugation was significantly changed with the substituent groups varied,which led to that the first hyperpolarizabilityβcould be effectively modulated.Through the analysis of time-dependent DFT(TD-DFT)results,we predicted that these studied complexes withπ→π^*charge transfer was beneficial to the large second-order NLO properties.Therefore,we hope that these studied iridium(III)complexes can be considered as versatile second-order NLO materials.     

Synthesis and Nonlinear Optical Properties of New Quadrupolar Chromophores

Two-photon absorption (TPA) has recently received considerable attention because they offer opportunities for both fundamental research and technological applications. The potential applications, including optical data storage, two-photon photodanamic therapy and optical limiting mainly depend on the materials with large two-photon cross section (δTPA)1. Here, we reported two novel chromophores based on symmetric structure of “D-A-Core-A-D”, where D and A stand for electron-donor and e…     

A High-Performance Nonlinear Optical Crystal with a Building Block Containing Expanded π-Delocalization

Common nonlinear optical (NLO) crystals consist of traditional functional building blocks with inherent optical limitation. Herein, inspired by traditional (B₃O₆)³⁻ inorganic building block, we theoretically identified a new type of organic functional building blocks and then successfully synthesized the first cyamelurate NLO crystal, Ba(H₂C₆N₇O₃)₂ ⋅ 8 H₂O. To our surprise, the constituent (H₂C₆N₇O₃)⁻ building block is not in structurally optimal arrangement, but Ba(H₂C₆N₇O₃)₂ ⋅ 8 H₂O exhibits excellent optical properties including wide band gap of 4.10 eV, very large birefringence of 0.24@550 nm, and exceptionally strong second-harmonic generation (SHG) response of about 12×KH₂PO₄. Both the SHG response and birefringence are much larger than those of commercial NLO crystal β-BaB₂O₄ with optimally aligned (B₃O₆)³⁻ building block. Theoretical calculations suggest that the expanded π-conjugation delocalization within (H₂C₆N₇O₃)⁻ vs (B₃O₆)³⁻ should be responsible to the enhanced performance. This work implies that there is still much room to develop new NLO crystals with excellent functional building blocks that may be longly neglected.     

A New Synthetic Strategy to Prepare a Polyphosphazene with Charge－Transporting Agents and Nonlinear Optical Chromophores as Side Chains

A new strategy, a post coupling method to develop the polyphosphazene (P2) functionalized with carbazolyl groups and nonlinear optical (NLO) chromophores, has been ex-plored. P2 exhibits good solubility in common organic solvents. The poled film of P2 exhibits a resonant d33 value of 42 pm/V by second harmonic generation (SHG) measurements.     

A New Humidity-Sensitive Material Based on PPBT Prepared with Palladium Complex Catalyst

IntroductionIn recent years, there has been an increasing interest in humidity sensors in various fields such as air-conditioning systems, medical and industrial equipment, etc. The research on humidity sensors, which focused on looking for suitable polymeric humidity-sensitive materials, has attracted more and more attention with some encouraging results1.Poly(propargyl benzoate) is a hydrophilic polymer with (-conjugated structure. In the past 30 years, the synthesis of poly(propargyl alcoho…     

Switchable Nonlinear Optical Properties of η(5)-Monocyclopentadienylmetal Complexes: A DFT Approach

Density functional theory (DFT) calculations have been carried out to investigate the switching of the second-order nonlinear optical (NLO) properties of η(5)-monocyclopentadienyliron(II) and ruthenium(II) model complexes presenting 5-(3-(thiophen-2-yl)benzo[c]thiophen-1-yl)thiophene-2-carbonitrile as a ligand. The switching properties were induced by redox means. Both oxidation and reduction stimulus have been considered, and calculations have been performed both for the complexes and for the free benzo[c]thiophene derivative ligand in order to elucidate the role played by the organometallic fragment on the second-order NLO properties of these complexes. B3LYP, CAM-B3LYP, and M06 functionals were used for our calculations. The results show some important structural changes upon oxidation/reduction that are accompanied by significant differences on the corresponding second-order NLO properties. TD-DFT calculations show that these differences on the second-order NLO response upon oxidation/reduction are due to a change in the charge transfer pattern, in which the organometallic iron and ruthenium moieties play an important role. The calculated static hyperpolarizabilities were found to be strongly functional dependent. CAM-B3LYP, however, seems to predict more reliable structural and optical data as well as hyperpolarizabilities when compared to experimental data. The use of this functional predicts that the studied complexes can be viewed as acting as redox second-order NLO switches, in particular using oxidation stimulus. The β(tot) value of one-electron oxidized species is at least ～8.3 times (for Ru complex) and ～5.5 times (for Fe complex) as large as that of its nonoxidized counterparts.     

Synthesis and structural features of copper(II) complexes of N,N,N′,N′-tetramethylethylenediamine with 2-chlorobenzoate1− and 2-hydroxybenzoate1−

Abstract

Two copper(II) coordination complexes, formulated as [Cu(tmen)(Clba)₂] (1) and [Cu(tmen)(Hsal)₂·H₂O] (2) (where tmen?=?N,N,N′,N′-tetramethyl ethylenediamine (C₆H₁₆N₂), Clba^1? = 2-chlorobenzoate (C₇H₄ClO₂^1?), and Hsal^1? (C₇H₅O₃^1? = monoanion of o-hydroxybenzoic acid (salicylic acid)), have been synthesized and characterized by elemental combustion analysis, spectroscopic techniques, thermal studies, and single crystal X-ray analyses. Complex 1 consists of two distinct monomeric units in which the coordination environment around the central copper(II) ion is a distorted octahedron with a CuN₂O₄ chromophore, constituted by a chelating tmen molecule, and two 2-chlorobenzoate^1? anions coordinated through their carboxylate-O atoms in an asymmetrical bidentate fashion. Complex 2 is also a monomer and consists of an CuN₂O₃ chromophore, in which tmen is coordinated to Cu(II) through its two N atoms in a chelating bidentate fashion, and an aqua-O and the two o-hydroxybenzoate^1? (HSal^1?) anions are coordinated through one of their carboxylate-O atoms in a monodentate mode, forming a square pyramidal structure. Hydrogen bonding interactions especially of O–H…O, N–H…O, and C–H…Cl types interweave monomeric units and stabilize the overall crystal structures in both complexes. Thermal analysis and antibacterial activities of 1 and 2 against various bacterial strains were also investigated.     

New Complex Nonlinear optical Crystal-Bis(4-methoxybenzaldehyde thiosemicarbazone) Zinc Chloride(ZnL_2Cl_2)

ExtensivestudyoftheSecondHarmonicGeneration(SHG)oforganicmo1ecularcrystalshavebeenmadeinrecentyears.'SomeofthemhavequadraticnonlinearityatIeastoneorderofmagnitudehigherthanthatofclassicalinorganiccrystaIssuchasKDPandLiNbO32Furthermore,organicmaterialsgenerallyhavehigherIaserdamagethresholdsthanthatofinorganicmaterials.However,organiccrystalsareoftenmechanicalIyandthermallyunstabIe.Therefore,wehavemadeattemptstoincorPorateorganicmoleculesintocomplexcompoundsandfoundthattheorganometallic…     

Stabilization Of The CN35− Anion In Recoverable High-pressure Ln3O2(CN3) (Ln=La,Eu, Gd,Tb, Ho,Yb) Oxoguanidinates

A series of isostructural Ln₃O₂(CN₃) (Ln=La, Eu, Gd, Tb, Ho, Yb) oxoguanidinates was synthesized under high-pressure (25–54 GPa) high-temperature (2000–3000 K) conditions in laser-heated diamond anvil cells. The crystal structure of this novel class of compounds was determined via synchrotron single-crystal X-ray diffraction (SCXRD) as well as corroborated by X-ray absorption near edge structure (XANES) measurements and density functional theory (DFT) calculations. The Ln₃O₂(CN₃) solids are composed of the hitherto unknown CN₃⁵⁻ guanidinate anion—deprotonated guanidine. Changes in unit cell volumes and compressibility of Ln₃O₂(CN₃) (Ln=La, Eu, Gd, Tb, Ho, Yb) compounds are found to be dictated by the lanthanide contraction phenomenon. Decompression experiments show that Ln₃O₂(CN₃) compounds are recoverable to ambient conditions. The stabilization of the CN₃⁵⁻ guanidinate anion at ambient conditions provides new opportunities in inorganic and organic synthetic chemistry.     

Stabilization of Pancake Bonding in (TCNQ)2.− Dimers in the Radical-Anionic Salt (N−CH3−2-NH2−5Cl−Py)(TCNQ)(CH3CN) Solvate and Antiferromagnetism Induction

We report a new antiferromagnetic radical-anion salt (RAS) formed from 7,7,8,8-tetracyanquinonedimethane (TCNQ) anion and 2-amino-5-chloro-pyridine cation with the composition of (N−CH₃−2-NH₂−5Cl−Py)(TCNQ)(CH₃CN). The crystallographic data indicates the formation of (TCNQ)₂^.− radical-anion π-dimers in the synthesized RAS. Unrestricted density functional theory calculations show that the formed π-dimers characterize with strong π-stacking “pancake” interactions, resulting in high electronic coupling, enabling efficient charge transfer properties, but π-dimers cannot be stable in the isolated conditions as a result of strong Coulomb repulsions. In a crystal, where (TCNQ)₂^.− π-dimers bound in the endless chainlets via supramolecular bonds with (N−CH₃−2-NH₂−5-Cl−Py)⁺ cations, the repulsion forces are screened, allowing for specific parallel π-stacking interactions and stable radical-anion dimers formation. Measurements of magnetic susceptibility and magnetization confirm antiferromagnetic properties of RAS, what is in line with the higher stability of ground singlet state of the radical-anion pair, calculated by means of the DFT. Therefore, the reported radical-anion (N−CH₃−2-NH₂−5Cl−Py)(TCNQ)(CH₃CN) solvate has promising applications in novel magnetics with supramolecular structures.     

Rhodium(III)-Catalyzed C−H/N−H Functionalization with Hydrogen Evolution

A rhodium(III)-catalyzed C−H/N−H bond functionalization of benzimidates with α-chloroaldehydes to afford isoquinolin-3-ol derivatives is reported. No external oxidants are needed in this process, and interestingly, evolution of hydrogen gas is observed.     

New multicomponent organic semiconductors based on ET with polymeric Anions: α″-(ET)2N(CN)2·2H2O and α‴-(ET)6(NO3)3·2C2H5O2N3

New multicomponent radical cation salts derived from bis(ethylenedithio)tetrathiafulvalene (ET) were prepared: bis(ethylenedithio)tetrathiafulvalene dicyanamide dihydrate α″-(ET)₂N(CN)₂·2H₂O and bis-(ethylenedithio)tetrathiafulvalene nitrate α?-(ET)₆(NO₃)₃·2C₂H₅O₂N₃ containing two biuret molecules (C₂H₅O₂N₃). The crystal structures of the compounds were determined, and their conducting properties were examined. Both salts have layered structures in which radical cation layers alternate with nonconducting anionic layers. The radical cation layers in the salts α″-(ET)₂N(CN)₂·2H₂O and α?-(ET)₆(NO₃)₃·2C₂H₅O₂N₃ are packed in the α″ and α? fashion, respectively. Anionic layers consist of polymeric chains formed by hydrogen bonding between [N(CN)₂]? anions and water molecules in α″-(ET)₂N(CN)₂·2H₂O or between NO?₃ anions and biuret molecules in α?-(ET)₆(NO₃)₃·2C₂H₅O₂N₃. Both salts show semiconductor conductivity.     

A New Luminescent Cd(Ⅱ) Coordination Polymer Constructed with 2-(Carboxymethoxy) benzoic Acid

In this work, we synthesized a new Cd(Ⅱ) coordination polymer, [Cd(L)(cmb)H_2O]· H_2O(1), by using mixed 2-(carboxymethoxy)benzoic acid(H2 cmb) and typical chelating N-donor ligands 2-(2-fluoro-6-fluorophenyl)-1 H-imidazo[4,5-f][1,10]phenanthroline ligand(L). 1 crystallizes in monoclinic, space group P21/c with a = 17.6150(8), b = 9.7811(4), c = 18.1603(8) ?, β = 118.9150(10)o, V = 2738.9(2) ?~3, Z = 4, C28 H20 CdF2 N4 O7, Mr = 674.88, Dc = 1.637 g/cm3, F(000) = 1352, μ(Mo Ka) = 0.865 mm–1, R = 0.0643 and w R = 0.1976. In 1, the cmb2– anions link neighboring Cd(Ⅱ) atoms in a bis-chelating mode, yielding a one-dimensional chain structure along the b axis. The L ligands are attached on one side of the chain through chelating the Cd(Ⅱ) atoms, and are stacked with those of an adjacent chain through π-π interactions to generate a one-dimensional double-chain structure. Furthermore, the one-dimensional double-chains are stacked by C–H???π interactions between the carbon atom of L ligand and the benzene ring of cmb2–ligand to give a layer structure. Moreover, the solid state luminescent property of 1 was also investigated at room temperature.     

Enantioselective Synthesis of N−N Biaryl Atropisomers through Iridium(I)-Catalyzed C−H Alkylation with Acrylates

Enantioselective synthesis of N−N biaryl atropisomers is an emerging area but remains underexplored. The development of efficient synthesis of N−N biaryl atropisomers is in great demand. Herein, the construction of N−N biaryl atropisomers through iridium-catalyzed asymmetric C−H alkylation is reported for the first time. In the presence of readily available Ir precursor and Xyl-BINAP, a variety of axially chiral molecules based on indole-pyrrole skeleton were obtained in good yields (up to 98 %) with excellent enantioselectivity (up to 99 % ee). In addition, N−N bispyrrole atropisomers could also be synthesized in excellent yields and enantioselectivity. This method features perfect atom economy, wide substrate scope, and multifunctionalized products allowing diverse transformations.     

A New Two-dimensional Copper(Ⅱ)Complex with p-PhDTA Bridges

A new p-PhDTA bridged Cu(Ⅱ) complex [Cu2(p-PhDTA)(DMSO)2]·4DMSO (pPhDTA = p-phenylenediamine-N,N,N,N'-tetraacetic acid) has been synthesized and structurally characterized.The crystal belongs to orthorhombic, space group Pca21 with a = 19.572(4), b=19.552(4), c = 10.156(2)(A), C26H48N2O14Cu2S6, Mr = 932.10, V = 3886.4(13)(A)3, Z = 4, Dc = 1.593 g/cm3, F(000) = 1936, λ(MoKα) = 0.71073 (A),μ= 1.480, R = 0.0487 and wR = 0.1151 for 8464 observed reflections (I ＞2σ(I)).In the complex, the oxygen atoms of carboxylate of p-PhDTA connect the Cu atoms in a syn-anti type, giving one-dimensional chains which are further linked by the benzene groups of p-PhDTA to form a novel two-dimensional structure.     

Mesoporous TiO2−xAy (A = N,S) as a visible-light-response photocatalyst

Mesoporous TiO_2?xA_y (A = N, S) thin films were fabricated using thiourea as a doping resource by a combination of sol-gel and evaporation-induced self-assembly (EISA) processes. The results showed that thiourea could serve two functions of co-doping nitrogen and sulfur and changing the mesoporous structure of TiO₂ thin films. The resultant mesoporous TiO_2?xA_y (A = N, S) exhibited anatase framework with a high porosity and a narrow pore distribution. The formation of the O–Ti–N and O–Ti–S bonds in the mesoporous TiO_2?xA_y (A = N, S) were substantiated by the XPS spectra. A new bandgap in visible light region (520 nm) corresponding to 2.38 eV could be formed by the co-doping. After being illuminated for 3 h, methyl orange could be degraded nearly completely by the co-doped sample under both ultraviolet irradiation and visible light illumination. While pure mesoporous TiO₂ could only degrade 60% methyl orange under UV illumination and showed negligible photodegradation capability in the visible light range. Furthermore, the photo-induced hydrophilic activity of TiO₂ film was improved by the co-doping. The mesoporous microstructure and high visible light absorption could be attributed to their good photocatalytic acitivity and hydrophilicity.     

Kinetic studies on the reactions of Ru(II) tetraammines with CS2N−3

The kinetics of the reactions of Ru(II) complexes with CS₂N⁻₃ ions were studied spectrophotometrically. The formation rate constants data for trans-[Ru(NH₃)₄L(CS₂N₃)] are 2.2 × 10², 1.8 × 10 and 1.3 × 10² M⁻¹ s⁻¹ for L = SO^2-₃, HSO⁻₃ and P(OEt)₃), respectively [μ = 1.0 M (NaCF₃COO), 25°C]. Under the same experimental conditions, the values of k⁻¹ (specific rate for the aquation reaction) are 1.5 × 10⁻², 5.0 × 10⁻² and 4.5 × 10 s⁻¹ for L = SO²⁻₃, HSO⁻₃ and P(OEt)₃, respectively. The free-energy change (ΔG^≠) for the systems where L = P(OEt)₃ and SO²⁻₃ are in agreement within the experimental error. It was observed that the affinity of the CS₂N⁻₃ ion decreases with the increasing π-acidity of the auxiliary ligand L. The order of affinity of the CS₂N⁻₃ ion for the Ru(II) center studies is SO²⁻₃ > HSO⁻₃ > P(OEt)₃ >SO₂.