Graphene and graphene oxide as effective adsorbents toward anionic and cationic dyes

In the present study, exfoliated graphene oxide (EGO) and reduced graphene oxide (rGO) have been used for the adsorption of various charged dyes such as methylene blue, methyl violet, rhodamine B, and orange G from aqueous solutions. EGO consists of single layer of graphite decorated with oxygen containing functional groups such as carboxyl, epoxy, ketone, and hydroxyl groups in its basal and edge planes. Consequently, the large negative charge density available in aqueous solutions helps in the effective adsorption of cationic dyes on EGO while the adsorption is negligible for anionic dyes. On the other hand, rGO that has high surface area does not possess as high a negative charge and is found to be very good adsorbent for anionic dyes. The adsorption process is followed using UV-Visible spectroscopy, while the material before and after adsorption has been characterized using physicochemical and spectroscopic techniques. Various isotherms have been used to fit the data, and kinetic parameters were evaluated. Raman and FT-IR spectroscopic data yield information on the interactions of dyes with the adsorbent.     

Triazole-linked-thiophene conjugate of calix[4]arene: its selective recognition of Zn2+ and as biomimetic model in supporting the events of the metal detoxification and oxidative stress involving metallothionein

Supramolecular calix[4]arene conjugate (L) has been developed as a sensitive and selective sensor for Zn(2+) in HEPES buffer among the 12 metal ion by using fluorescence, absorption and ESI MS and also by visual fluorescent color. The structural, electronic, and emission properties of the calix[4]arene conjugates L and its zinc complex, [ZnL], have been demonstrated using ab initio density functional theory (DFT) combined with time-dependent density functional theory (TDDFT) calculations. The TDDFT calculations reveal the switch on fluorescence behavior of L is mainly due to the utilization of the lone pair of electrons on imine moiety by the Zn(2+). The resultant fluorescent complex, [ZnL], has been used as a secondary sensing chemo-ensemble for the detection of -SH containing molecules by removing Zn(2+) from [ZnL] and forming {Cys/DTT·Zn} adducts as equivalent to those present in metallothioneins. The displacement followed by the release of the coordinated zinc from its Cys/DTT complex by heavy metal ion (viz. Cd(2+) and Hg(2+)), as in the metal detoxification process or by ROS (such as H(2)O(2)) as in the oxidative stress, has been well demonstrated using the conjugate L through the fluorescence intensity retrieval wherein the fluorescence intensity is the same as that observed with [ZnL], which in turn mimics the zinc sensing element (MTF) in biology.     

Studies on the σ–hole bonds (halogen,chalcogen, pnicogen and carbon bonds) based on the orientation of crystal structure

ABSTRACT

The 4,7-dibromo-5,6-dinitro-2,1,3-benzothiadiazole (DDBT) crystal has two polymorphic forms [1 M.S. Pavan, A.K. Jana, S. Natarajan, and T.N. Guru Row, J. Phys. Chem. B 119, 11382 (2015).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]], where the close contacts between two electronegative atoms are identified and studied through Hirshfeld surface analysis. Br---Br and O---O cut-off distances are addressed and analysed. The σ–hole of bromine, sulphur, oxygen atoms and π-hole of carbon and nitrogen atoms were subjected to study using molecular electrostatic potential map and 3D-deformation density map. Sixteen types of dimers from the two forms of crystal structure (6 for form I and 10 for form II) were studied using the charge transfer properties and interaction energies and made detailed analysis of halogen bond (Br---N), dihalogen bond (Br---Br), chalcogen bond (O---Br and S---Br), dichalcogen bond (S---O, O---S and O---O), pnicogen bond (N---O) and carbon bond (C---O and C---Br) interactions. The impact of orientations is discussed to define the type of interaction and its strength through charge transfer mechanism. The contribution of bond angle values for the σ-hole and π–hole bonds are discussed. Utilisation of σ–hole in smaller bond angle values (above 30°) of |θ₁ ? θ₂| existing in type II halogen–halogen bond have been examined in the two forms.     

Polypyrazolylborate analogues without boron: Structural diversity in ligand design and metal complexes

Structural chemistry of organometallic complexes containing pyrazolederived polydentate ligands (without boron) has been reviewed in the context of current results from this laboratory. NCL Communication No. 6137     

A New Ent‐Trachylobane Diterpenoid from the Roots of Sapium Sebiferum

A new ent‐trachylobane diterpenoid, saposebifeic acid, together with thirteen known compounds, were isolated from the roots of Sapium sebiferum. Compounds, 5,7,8‐trimethoxycoumarin, baccatin, n‐alkyl trans‐ferulate and 2,6‐dimethoxyquinone, were reported for the first time from this plant. The structures of the new and known compounds were established on the basis of extensive 1D and 2D NMR spectral data.     

Reductive opening of glycal derived highly functionalized 2,3-epoxy-1-iodides with zinc dust: an efficient method for the synthesis of acyclic long chain polyhydroxylated terminal alkenic alcohols

The synthesis of densely functionalized acyclic long chain terminal alkenic alcohols was achieved by reductive opening of glycal derived 2,3-epoxy-1-iodides, with commercial zinc dust alone in a short reaction time with excellent yields involving a simple reaction procedure and easy work-up. A mechanism involving an organometallic intermediate is proposed.     

Meson spectroscopy with confined one gluon exchange potential

Confined gluons-exchange among relativistically confined quarks is used to calculate the ground state masses and the radially excited states of pseudo scalar and vector mesons. A good agreement is obtained with the experimental masses. The limitation of the perturbative treatment of estimating theN−Δ andπ−ρ splitting using one-gluon-exchange potential is pointed out.     

Nanostructured silicon as a photonic material

Photonics applications of silicon are presented. In particular it is demonstrated that silicon when rendered low dimensional, e.g. in form of nanocrystals or quantum wires, can be turned into an active photonic materials which shows light amplification characteristics, non-linear optical effects, photon confinement in both one and two dimensions, photon trapping with evidences of light localization, and gas sensing properties.     

Two new angular methyl dioxygenated D:A-fried-oleananes

Two new trioxygenated D:A-friedo-oleananes from Elaeodendron glaucum have been shown to be the angular methyl dioxygenated 25,28-dihydroxy-D:A-friedo-oleanan-3-one(1) and 3,28-dioxo-D:A-friedo-oleanan-25-ol(2) by interconversion and deoxygenation of the alcohol(2) using Lithium-ethyle diamine reduction coupled with spectroscopic methods.