3D Solid-State Network from Hierarchical Supramolecular Self-Assembly of Transition Metal Complexes of Pyridine Based Ligand

Abstract  The crystal structures of [Cu(py)₄(ClO₄)](ClO₄) (1), [V(pic)₂(OH)](NO₃)₂ · H₂O (2) and [Ni(H₂O)₆][Ni(dpa)₂] · 2H₂O (3) [py = Pyridine, picH = Pyridine-2-carboxylic acid, dpaH₂ = Pyridine-2,6-dicarboxylic acid] was determined by single-crystal X-ray diffraction techniques. Solid-state structural analysis shows that all these complexes from extensive 3D network structure via supramolecular self-assembly. The crystal structures are stabilized by extended hydrogen bonding interactions. The complex 2 forms orange V₂O₅ micro spheroids when heated at ~400 °C for 6 h. Graphical Abstract  Hierarchical supramolecular self-assembly of transition metal complexes of pyridine based ligands in crystal. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Beta-turn mimic in tripeptide with Phe(1)-Aib(2) as corner residues and beta-strand structure in an isomeric tripeptide: an X-ray diffraction study

A single crystal X-ray diffraction study of the tripeptide Boc-Phe-Aib-Leu-OMe (Aib = alpha-aminoisobutyric acid) reveals that it forms structurally one of the best type II beta-turns so far reported in tripeptides, stabilized by 10 atom intramolecular hydrogen bonding. In contrast, the isomeric tripeptide Boc-Phe-Leu-Aib-OMe adopts a beta-strand like conformation. Interestingly, a previously reported structure of another isomeric tripeptide, Boc-Leu-Aib-Phe-OMe, shows a double bend conformation without any intramolecular hydrogen bonding. These results demonstrate an example of the creation of structural diversities in the backbone of small peptides depending upon the co-operative steric interactions amongst the amino acid residues.     

One-pot sequential synthesis of 1,2-disubstituted benzimidazoles under metal-free conditions

An easy and inexpensive method has been developed to access 1,2-disubstituted benzimidazoles following a one-pot sequential coupling/reduction/cyclization process under metal-free neutral conditions.     

Information transfer using a single particle path-spin hybrid entangled state

The path-spin entangled state of a single spin-1/2 particle is considered which is generated by using a beam-spitter and a spin-flipper. Using this hybrid entanglement at the level of a single particle as a resource, we formulate a protocol for transferring of the state of an unknown qubit to a distant location. Our scheme is implemented by a sequence of unitary operations along with suitable spin-measurements, as well as by using classical communication between the two spatially separated parties. This protocol, thus, demonstrates the possibility of using intraparticle entanglement as a physical resource for performing information theoretic tasks.     

Strong coupled and doubly decoupled bands in the SU BF (3) ⊗ U F (2j + 1) limit of interacting boson — fermion — fermion model

The quantum numbers labelling the basis states and the corresponding strong coupled wavefunctions in the SU ^BF (3) ? U ^F (2j + 1) limit of interacting boson — fermion — fermion model are given. This dynamical symmetry limit is appropriate for heavy deformed odd — odd nuclei for configurations with one of the odd particle (proton or neutron) occupying all the natural parity orbits in the corresponding valence shell and the other particle occupying a single j — orbit. A boson — fermion — fermion interaction that can change the positions of the strong coupled bands without admixing and generate degenerate quadruplet of bands is constructed. A simple spin — spin and spin — orbital interaction that splits and changes the positions of the members of the quadruplet of bands is given. Adding a coriolis term to the hamiltonian generates doubly decoupled bands such as those seen in ¹⁷⁶Re nucleus.     

Self-assembling properties of lactic acid derivative with several ester linkages in the molecular core

The effect of several polar ester linkage groups incorporated in the molecular core of a chiral lactic acid derivative on self-assembling properties has been investigated by polarizing optical microscopy, small angle X-ray diffraction, differential scanning calorimetry, optical and electro--optical studies. The compound possesses the paraelectric smectic A* (SmA*) and ferroelectric smectic C* (SmC*) phases over a broad temperature range. Mesomorphic behaviour, spontaneous polarization, birefringence, optical transmission, dielectric anisotropy and structural properties of the self-assembled chiral material have been determined. The obtained results are discussed and compared with that of other liquid crystalline materials. Experimentally determined spontaneous polarization and tilt angle values are also used to elucidate the nature of SmC* to SmA* phase transition. The effect of polar ester linkages in the molecular core has also been discussed.     

Sonochemical synthesis and application of rhodium–graphene nanocomposite

Abstract  

Highly water dispersible rhodium–graphene nanocomposite have been successfully synthesized by the simple reduction of Rh³⁺ salt on poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) (PEO/PPO/PEO) triblock copolymer or pluronic-stabilized graphene oxide (GO) nanosheets with borohydride. Rhodium nanoparticles, having average size of 1–3 nm, are homogeneously distributed through out the graphene sheets. Some porous structures of graphene sheets have also been observed after the reduction of pluronic-stabilized GO in the presence of metal ions. The material is very effective for hydrogenation of arenes, especially for benzene as the substrate material at the room temperature and 5 atm pressure of hydrogen.     

Cu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Ni<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript> alloy nanoparticles embedded SiO<Subscript>2</Subscript> films: synthesis and structure

Cu–Ni fcc alloy nanoparticles (NPs) of tunable atomic ratios were generated in SiO₂ films. The films were prepared using the Cu(NO₃)₂ and Ni(NO₃)₂ co-doped inorganic–organic hybrid silica sols by single dipping. Transparent, crack-free, glassy SiO₂ films of 310 ± 10 nm in thickness embedded with high mol percent of Cu–Ni alloy NPs were yielded after annealing at 750 °C in 10% H₂-90% Ar atmosphere. Nominal compositions of the films were 20 mol% (Cu–Ni)-80 mol% SiO₂. Optical spectral study of the heat-treated films showed disappearance of Cu plasmon bands due to Cu–Ni alloy formation. Grazing incidence X-ray diffraction (GIXRD) studies revealed the formation of Cu–Ni alloy (2:1, 1:1 and 1:2) NPs inside the SiO₂ film. GIXRD showed a systematic shifting of the diffraction peaks with respect to the fcc Cu–Ni alloy composition, maintaining the nominal ratios. Transmission electron microscopy (TEM) studies of the representative Cu_0.5Ni_0.5-doped film showed existence of homogeneously dispersed Cu–Ni alloy NPs of average size 6.35 nm inside the SiO₂ matrix. The energy dispersive X-ray scattering (EDX) analysis of the individual NPs using the nano-probe (scanning TEM mode) confirmed the presence of both the Cu and Ni with the desired atomic ratio.     

SU(3) coupling schemes for odd-odd nuclei in the interacting boson – fermion – fermion model with both odd proton and odd neutron in natural parity orbits

The SU^BFF(3) dynamical symmetry limits of interacting boson – fermion – fermion model are identified and they are appropriate for heavy deformed odd – odd nuclei for configurations with both the odd proton and odd neutron occupying all the natural parity orbits in the corresponding valence shells. There are three symmetry limits and their correspondence with two quasi-particle (proton-neutron) Nilsson configurations is established; one of the limits mixes both Nilsson n_z's and Λ's and other two limits mix only Nilsson Λ's. The ¹⁹¹Ir (d,t) ¹⁹⁰Ir single nucleon transfer spectroscopic strengths are well described by one of the symmetry limits that mixes only Nilsson Λ's. Received: 22 June 1998