• Volume 127, Issue 8

August 2015,   pages  1328a-1504

• Editorial Board

• Notes on the preparation of papers

• Contents

• Synthesis and unexpected reactivity of [Ru(𝜂6 -cymene)Cl2 (PPh2 Cl)], leading to [Ru(𝜂6 -cymene)Cl2 (PPh2H)] and [Ru(𝜂6-cymene)Cl2 (PPh2OH)] complexes

The reaction of [Ru(𝜂6-cymene)Cl2]2 and PPh2Cl in the ratio 1:2 gives a stable [Ru(𝜂6-cymene) Cl2(PPh2Cl)] complex. Attempts to make the cationic [Ru(𝜂6-cymene)Cl(PPh2Cl)2]Cl with excess PPh2Cl and higher temperatures led to adventitious hydrolysis and formation of [Ru(𝜂6-cymene)Cl2 (PPh2OH)]. Attempts to make a phosphinite complex by reacting [Ru(𝜂6-cymene)Cl2]2 with PPh2Cl in the presence of an alcohol results in the reduction of PPh2Cl to give [Ru(𝜂6-cymene)Cl2(PPh2H)] and the expected phosphinite. The yield of the hydride complex is highest when the alcohol is 1-phenyl-ethane-1,2-diol. All three half-sandwich complexes are characterized by X-ray crystallography. Surprisingly, the conversion of chlorodiphenylphosphine to diphenylphosphine is mediated by 1-phenyl-ethane-1,2-diol even in the absence of the ruthenium half-sandwich precursor.

• Synthesis and characterization of novel benzo[𝑑][1,3]dioxole substituted organo selenium compounds: X-ray structure of 1-((benzo[𝑑][1,3]dioxol-5-yl)methyl)-2-((benzo[𝑑] [1,3]dioxol-6-yl)methyl)diselane

An expeditious synthesis of novel organoselenium compounds (2–5) incorporating benzo[𝑑] [1,3]dioxole subunit has been reported. All these newly synthesized compounds have been characterized by elemental analysis and various spectroscopic techniques viz., multinuclear NMR (1H, 13C and 77Se), IR and mass spectrometry. Furthermore, single crystal X-ray crystallographic results and molecular geometry of 1-((benzo[𝑑][1,3]dioxol-5-yl)methyl)-2-((benzo[𝑑][1,3]dioxol-6-yl)methyl)diselane (2) are reported. Thermal decomposition behavior of compound (2) was studied by thermogravimetric analysis.

• Investigation of physicochemical properties and catalytic activity of nanostructured Ce0.7M0.3O2−𝛿 (M = Mn, Fe, Co) solid solutions for CO oxidation

In this work, nanosized Ce0.7M0.3O2−𝛿 (M = Mn, Fe, Co) solid solutions were prepared by a facile coprecipitation method and evaluated for CO oxidation. The physicochemical properties of the synthesized samples were investigated by various characterization techniques, namely, XRD, ICP-OES, BET surface area, SEM-EDX, TEM and HRTEM, Raman, XPS, and H2 -TPR. XRD studies confirmed the formation of nanocrystalline single phase Ce0.7M0.3O2−𝛿 solid solutions. ICP-OES analysis confirmed actual amount of metal loadings in the respective catalysts. The BET surface area of Ce0.7M0.3O2−𝛿 samples significantly enhanced after the incorporation of dopants. TEM studies confirmed nanosized nature of the samples and the average particle sizes of Ce0.7M0.3O2−𝛿 were found to be in the range of ~8–16 nm. Raman studies indicated that the incorporation of dopant ions into the CeO2 lattice promote the formation of more oxygen vacancies. The existence of oxygen vacancies and different oxidation states (Ce3+/Ce4+ and Mn2+/Mn3+, Fe2+/ Fe3+, and Co2+/Co3+) in the doped CeO2 samples were further confirmed from XPS investigation. TPR measurements revealed an enhanced reducibility of ceria after the incorporation of dopants. The catalytic activity results indicated that the doped CeO2 samples show excellent CO oxidation activity and the order of activity was found to be Ce0.7Mn0.3O2−𝛿 &gt; Ce0.7Fe0.3O2−𝛿 &gt; Ce0.7Co0.3O2−𝛿 &gt; CeO2. The superior CO oxidation performance of CeO2-MnOx has been attributed to a unique Ce-Mn synergistic interaction, which facilitates materials with promoted redox properties and improved oxidation activity.

• Aggregation and electrochemical properties of 1-(4-chlorophenyl)-3-dodecanoylthiourea: A novel thiourea-based non-ionic surfactant

A novel thiourea-based non-ionic surfactant 1-(4-chlorophenyl)-3-dodecanoylthiourea (4CPDT) was synthesized from decanoyl chloride, potassium thiocyanate and 4-chloroanline in high yield. The structural chemistry of the compound was done by multiple nuclear NMR (1H, 13 C) and FT-IR. UV-Visible spectrophotometry and pendant drop methods were used to evaluate their critical micelle concentration in ethanol and hexane. This surfactant showed very low solubility in water, and interestingly low but well-defined, sub-millimolar critical micelle concentration (CMC) in ethanol and hexane, demonstrating that this is moderately amphiphobic. Its low value of critical micelle concentration indicates economical use for cleaning purposes and environment-friendly applications. It was also characterized by cyclic and square wave voltammetry and found to be electrochemically active giving sharp signal in different pH media.

• Crystal structure and solid-state properties of discrete hexa cationic trinuclear zinc triazole cluster

A linear trinuclear cluster of the type [{Zn3 (HTrz)6 (H2O)6}6+ (NO$_{3}^{−}$)6 (H2O)] (ZnT) has been synthesized by one-pot reaction between 1,2,4-triazole and Zn(NO3).6H2O. Molecule consists of three Zn2+ ions linearly connected by 1,2,4-triazole with tri-fold symmetry. The coordination geometry around the zinc centre is octahedral with zinc-zinc separation of 3.810 Å. The coordination environment of central Zn2+ ion is satisfied by nitrogen atoms of six 1,2,4-triazoles, while the geometry of terminal Zn2+ ions is fulfilled by nitrogen atoms of three 1,2,4-triazoles and three water molecules. The thermal and absorption properties of ZnT have been reported for the first time.

• DNA binding and cleavage activity of a structurally characterized Ni(II) Schiff base complex

Synthesis and characterization of a mononuclear Ni(II) compound [Ni(L)(H2O)2](NO3)2 [L = N,N'-bis((pyridine-2-yl)phenylidene)-1,3-diaminopropan-2-ol] (1) is reported. 1 crystallizes in triclinic P-1 space group with a = 8.1911(2) Å, b = 11.6624(3) Å, c = 16.5356(4) Å and𝛼 = 108.8120(10)° , 𝛽 = 91.2010(10)° , 𝛾 = 91.1500(10)° . The binding property of the complex with DNA has been investigated using absorption and emission studies, and viscosity experiment. The binding constant (Kb) and the linear Stern-Volmer quenching constant (Ksv) of the complex have been determined as 9.23 × 10 4 M−1 and 2.0 × 10 4 M−1, respectively. Spectroscopic and hydrodynamic investigations revealed groove or electrostatic nature of binding of 1 with DNA. 1 is also found to induce oxidative cleavage of the supercoiled pUC 18 DNA to its nicked circular form in a concentration dependent manner.

• Thiacalix[4]arene derivatives containing multiple aromatic groups: High efficient extractants for organic dyes

Click reaction of alkynylthiacalix[4]arene with ethyl 2-azidoacetate, followed by ammonolysis with hydrazine hydrate and Schiff-base condensation with benzaldehyde or salicyic aldehyde, afforded two novel thiacalix[4]arene derivatives containing multiple aromatic groups in yields of 86% and 90%. Their complexation properties for four organic dyes were investigated by liquid-liquid extraction experiments, complexation UV-Vis spectra and mass spectrum. The highest extraction percentage was 97% for Neutral red. The UV- Vis spectra and ESI-MS spectrum indicated the 1:1 complexes in DMSO solution. The association constants were as high as 1∼ 8 × 104 M−1. These complexation experiments showed that thiacalix[4]arene receptors possess excellent complexation capabilities for dyes.

• Sulfanilic acid functionalized mesoporous SBA-15: A water-tolerant solid acid catalyst for the synthesis of uracil fused spirooxindoles as antioxidant agents

Incorporating sulfanilic acid as a hydrophobic Brønsted acid inside the nanospaces of SBA-15 led to a water-tolerant solid acid catalyst, SBA-15-PhSO 3 H, which showed excellent catalytic performance in synthesis of uracil-fused spirooxindoles in aqueous ethanol. The synthesized compounds were evaluated for their antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay.

• Nickel(II) complexes having Imidazol-2-ylidene-N′-phenylurea ligand in the coordination sphere – syntheses and solid state structures

We report the syntheses and structural studies of two nickel(II) complexes of imidazol-2-ylidene- N'-phenylureate ligand of composition [{Im𝑡Bu NCON(H)Ph}2 Ni(acac)2] (1) and [(C6H5NH2)2 Ni(acac)2] [ImMes NCON(H)Ph] (2). The nickel complex 1 was readily prepared by the reaction of nickel(II) acetylacetonate [Ni(acac) 2 ] with imidazol-2-ylidene-N'-phenylureate ligand [Im𝑡Bu NCON(H)Ph] (L1) in THF under reflux condition for 72 h. The nickel complex 2 was obtained by the reaction of [Ni(acac)2], mesityl derivative of imidazol-2-ylidene-N′-phenylureate ligand [ImMes NCON(H)Ph] (L2) in the presence of aniline as base under reflux condition in THF. Both the paramagnetic complexes have been characterized by FT-IR spectroscopy and elemental analyses. Solid-state structures of both the new complexes were established by single crystal X-ray diffraction analysis. In the molecular structures of complexes 1 and 2, each nickel(II) ion is six fold coordinated and form a distorted octahedral geometry. The optical properties of both complexes have been explored. The Hirshfeld surfaces are used to view and analyze the intermolecular contacts in crystalline state for complex 2.

• Microwave assisted bi-functional activation of 𝛽-bromo-tert-alcohols

Microwave-assisted dehydration-oxidation of 𝛽-bromo-tert-alcohols to afford 2,3-unsaturated ketones in good yield is reported. The reaction of substrates with DMSO in 1:1 ratio (w/v) is promoted by ZnS in a solvent-free condition. A concurrent bi-functional activation of trans-vicinal bromo- and hydroxyl groups with ZnS is elucidated. This is a new observation under microwave and applies to 𝛽-bromo-tert-alcohols derived from 1,4-disubstitued-1-cyclohexenes. It is very useful in the synthesis of 2,3-unsaturated ketones derived from monoterpenes which are valuable flavour compounds.

• Significant improvement of electrochemical performance of Cu-coated LiVPO4F cathode material for lithium-ion batteries

In this paper, we reveal that the intrinsic low electronic conductivity of the pristine LiVPO4F is overcome with conductive Cu-coating. The existence of nano-Cu is confirmed with X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS). The morphology and particle size are observed by scanning electron microscopy (SEM). Galvanostatic charge/discharge test indicates that Cu coating is effective to improve the discharge capacity, cycle performance and rate capability. Analysis of electrochemical impedance spectra (EIS) shows that the addition of nano-Cu markedly decreases the charge transfer resistance of the pristine LiVPO4F electrode.

• An efficient and facile synthesis of divergent C-3/C-5 bis-functionalized 2-oxindoles from 5-formyl-Morita-Baylis-Hillman adducts of oxindole

An efficient and facile synthesis of divergent C-3/C-5 bis-functionalized 2-oxindole derivatives has been achieved from 3,5-bis-Morita-Baylis-Hillman (MBH) adducts of oxindole via nucleophilic substitution reaction for the first time. Wider scope of substrate and rate acceleration has been observed in second MBH reaction under typical reaction condition. The synthetic usefulness of bi-functionalized bis-allyl derivative has been demonstrated by the synthesis of potent bis-pyrazole via [3+2]-annulation strategy.

• Synthesis, Crystal structure and Characterization of a New Oxalate Chromium (III) Complex

A new hybrid salt (C5H9N2)[Cr(C2O4)2 (H2O)2].3H2O, 3,5-dimethylpyrazole Cis diaquadioxala-tochromate(III) trihydrate, has been prepared by slow evaporation at room temperature and characterized by single crystal X-ray diffraction, IR, UV–visible spectroscopies, PXRD and thermogravimetric analyses. Furthermore, the observed crystal morphology was compared to the simulated one using the Bravais-Friedel, Donnay-Harker model. The structure of the title compound consists of [Cr(C2O4) 2 (H2O) 2] mononuclear anions, 3,5-dimethylpyrazole cations and three uncoordinated water molecules. The Cr3+ ion is six coordinated in a slightly distorted octahedral environment, by two O atoms from two water molecules and four O atoms of two oxalate anions acting as chelating ligands. The cohesion of the structure is established by intermolecular O–H...O, N–H...O hydrogen bonds which connect ionic entities and water molecules and also by 𝜋–𝜋 stacking interactions between the rings of 3,5-dimethylpyrazole cations. Hence, both coordinated and uncoordinated water molecules play an important role in the hydrogen-bonding system and stabilize the structure.

• Structural and vibrational spectral studies on hydrogen bonded salts: 4-chloroanilinium maleate and nitrate

In the present study, proton transfer from nitric and maleic acids to amine group (4-chloroaniline) led to hydrogen bonded crystals of 4-chloroanilinium maleate (4CAM) and 4-chloroanilinium nitrate (4CAN) which are investigated by the experimental and theoretical approaches. The molecular structures of these two compounds were optimized with the Density Functional Theory (DFT) using B3LYP function and the Hartree-Fock (HF) level with a6-311++G(d,p) basis set. Geometrical parameters of the molecules were also analyzed along with their intermolecular hydrogen bond, which tailors the ions. These analyses show that present molecules are stabilized through the N–H· · · O and O–H· · · O hydrogen bonds. The vibrational modes were computed by quantum chemical methods. Further, these modes are investigated by FT-IR and FT-Raman spectroscopy in the range of 4000–400 cm−1. The optimized molecular geometry and computed vibrational spectra are compared with experimental results, which show significant agreement. The natural bond orbital (NBO) analysis was carried out to interpret hyperconjucative interaction and intramolecular charge transfer (ICT). This analysis gives the precise insight into the nature of H-bond interactions. The chemical hardness, electronegativity and chemical potential of the molecules were determined by HOMO–LUMO plot. The frontier molecular orbitals have small band gap value, which signify the possible biological/pharmaceutical activity of the compounds.

• Synthesis and characterization of mononuclear copper(II) complexes of pyridine 2-carboxamide: Their application as catalyst in peroxidative oxidation and antimicrobial agents

Four water soluble copper(II) complexes, [Cu(HL)2 (H2O)2]Cl2 (1), [Cu(HL) 2 (ClO4)2 ] (2), [Cu(HL)2 (SCN)2] (3) and [CuL 2 ]·8H 2 O (4), where HL is pyridine 2–carboxamide, have been synthesized and characterized by various spectroscopic techniques. Structures have been determined by single crystal X-ray crystallography. The pH induced inter-conversion of Cu(HL)2 (H2O)2 ]Cl2 (1) and [CuL2]·8H2O (4) through co-ordination mode switching was investigated thoroughly with the help of absorption spectroscopy. Complexes 1–3 were found to be active catalysts for the oxidation of toluene, ethyl benzene and cyclohexane in the presence of hydrogen peroxide as the oxidant under mild conditions. Toluene was oxidized to benzyl alcohol and benzaldehyde, ethyl benzene was oxidized to 1-phenylethanol and acetophenone and cyclohexane was oxidized to yield cyclohexanol and cyclohexanone Antimicrobial activities have been investigated with these copper(II) complexes against gram + ve bacteria, gram − ve bacterial and fungal species.

• FeCl3 catalysed regioselective allylation of phenolic substrates with (𝛼-hydroxy)allylphosphonates

Electrophilic allylation of phenolic substrates including salicylaldehydes with (𝛼-hydroxy) allylphosphonates is presented. It is observed that catalytic FeCl3 is sufficient to accomplish the allylation. Interestingly, the reaction led to the formation of allylphosphonates in addition to vinylphosphonates, depending upon the substituent. The vinylphosphonates obtained here are 𝐸-isomers. More importantly, the reaction occurred regioselectively with respect to the phenolic substrates. Substituted allylphosphonates are formed when salicylaldehyde or (2-hydroxy-phenyl)arylmethanones are used. Conclusive proof for the formation of allylphosphontates as well as vinylphosphonates has been provided by single crystal X-ray crystallography.

• Mechanism for the Reaction of a Tungsten-Germylyne Complex with 𝛼, 𝛽-Unsaturated Ketones: A DFT Study

In this report we present results of theoretical analysis for the reaction mechanism involving a tungsten-germylyne complex with 𝛼, 𝛽-unsaturated ketones. Three different substituents, namely H, Me and CF3 in 𝛼-position of the unsaturated ketones have been selected to account for a variety of experimental observations. The computed results for different unsaturated ketones are in good agreement with experimental evidence and suggest that the formation of the final product can be achieved through steric as well as electronic effects.

• Silica functionalized Cu(II) catalysed selective oxidation of benzyl alcohols using TEMPO and molecular oxygen as an oxidant

A general scheme for the oxidation of benzyl alcohols catalyzed by silica functionalized copper (II) has been designed. TEMPO, a free radical, assists this oxidation that was initiated by molecular oxygen which converts it to a primary oxidant. This catalytic combination i.e. SiO2 -Cu(II) in presence of TEMPO and oxygen provides excellent results in terms of yields and reaction time. SiO2 -Cu(II) was very well characterized by different spectroscopic techniques such as FTIR, XRD, TGA, XPS, EDAX, SEM, TEM and AAS and is recyclable upto five times which makes it economically beneficial.

• Theoretical study on the molecular and crystal structures of nitrogen trifluoride and it's adduct with BF3

The molecular and crystal structure of the adduct NF3·BF3 was studied computationally using density functional theory. It shows that the adduct exists in the form of a complex but is not ionic. The heats of formation in the gas and the condensed phase of the adduct are −1266.09 and −1276.37 kJ·mol−1, respectively, which indicates that it is stable under atmospheric conditions. The crystal form belongs to 𝑃21/𝑐 space group. The calculated large band gap (𝛥 𝐸g) of the crystal proves that it is stable. The conduction band (LUCO) is mainly contributed by the 𝑝 orbital of N atom and the valence band (HOCO) from the 𝑝 orbital of F atom.

• Influence of collision energy and vibrational excitation on the dynamics for the H+HBr $\rightarrow$ H2 + Br reaction

Quasi-classical trajectory (QCT) calculations of H+HBr $\rightarrow$ H2 + Br reaction have been performed on a recently proposed ab initio potential energy surface. The reaction probability and integral cross section are found to be in fairly good agreement with the available quantum mechanical (QM) results on this surface. The behavior of reactivity is well consistent with properties of exothermic reaction. Once the energy of vibrational excited HBr is larger than the barrier height, the integral cross sections for the reaction diverge at very low collision energies close to the threshold, similarly to capture reaction. In addition, differential cross sections show that scattering of the product H2 shift from backward to forward directions as the collision energy and vibrational quantum number increase. All the theoretical findings are reasonably explained by the properties of the surface, as well as reactive mechanisms.

• # Journal of Chemical Sciences

Volume 132, 2020
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019

Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.