Crystal Engineering Approach To Design Colorimetric Indicator Array To Discriminate Positional Isomers of Aromatic Organic Molecules

Discriminating by color : A 2D colorimetric indicator array has been designed by a crystal engineering approach (N???H? O hydrogen bonding and charge‐transfer complexation) involving solid‐state co‐grinding for the visual discrimination of positional isomers of dihydroxynaphthalene. Factors governing the close packing of π planes, and hence color of the complex, were determined by single‐crystal X‐ray analysis, allowing fine tuning by crystal engineering.

     

Electronic property of SrFe2As2 under high pressure studied by 57Fe M?ssbauer spectroscopy

An illustrious complex [Fe(ptz)₆](BF₄)₂ (ptz = 1-propyl-tetrazole) (1) which was produced in the form of submicron crystals and thin film on Allium cepa membrane was probed by ⁵⁷Fe Mossbauer spectroscopy in order to follow its intrinsic spin crossover. In addition to a weak signal that corresponds to neat SCO compound significant amount of other iron compounds are found that could have morphed from 1 due to specific host-guest interaction on the lipid-bilayer of bio-membrane. Further complimentary information about biogenic role of membrane, was obtained from variable temperature Mossbauer spectroscopy on a ~5% enriched [⁵⁷Fe(H₂O)₆](BF₄)₂ salt on this membrane.     

Preparation of high oxygen permeable transparent hybrid copolymers with silicone macro-monomers

In this study, high oxygen permeable transparent hybrid copolymers were prepared with hydrophilic monomer such as 2-hydroxyethylmethacrylate (HEMA) or N,N-dimethylacrylamide (DMAA) and mono- or difunctional silicone macro-monomer introduced methacryl groups. In HEMA-based hybrid copolymers, difunctional silicone macro-monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker were required in order to prepare transparent hybrid materials, while high transparent DMAA-based hybrid copolymers could be prepared without EGDMA cross-linker. The polymerization kinetics investigation revealed that this difference between HEMA and DMAA in preparation condition to transparent hybrid material originated to monomer reactivity in copolymerization and DMAA showed high reactivity compared with HEMA. Moreover, DMAA-based hybrid copolymers indicated high water content and high oxygen permeability as against HEMA-based hybrid copolymers because of its low cross-linking density.     

Relationship between the distortion of polyene chains from planarity and the Raman activity of the in-phase CH out-of-plane wag

The relationship between the distortion of polyene chains from planarity and the Raman activity of the in-phase CH out-of-plane wag is examined by performing density functional theory calculations. The vibrational wavenumbers, vibrational modes, Raman activities and infrared absorption intensities of several oligoene (or polyene) molecules are calculated for model structures having various kinds of distortion around the CC double and/or single bond(s). The results of calculations show that the molecular distortion induces the Raman activity of the in-phase CH out-of-plane wag which should be Raman-inactive for the planar structure. The Raman activity of the in-phase CH out-of-plane wag is particularly enhanced when the molecule is uniformly helical. The origin of a weak Raman band at about 1010 cm⁻¹ of trans-polyacetylene is discussed on the basis of the calculated results.