Recent developments in the chemistry of halogen-free flame retardant polymers

Because of its fundamental importance in many branches of science, hydrogen bonding is a subject of intense contemporary research interest. The physical and chemical properties of hydrogen bonds in the ground state have been widely studied both experimentally and theoretically by chemists, physicists, and biologists. However, hydrogen bonding in the electronic excited state, which plays an important role in many photophysical processes and photochemical reactions, has scarcely been investigated.Upon electronic excitation of hydrogen-bonded systems by light, the hydrogen donor and acceptor molecules must reorganize in the electronic excited state because of the significant charge distribution difference between the different electronic states. The electronic excited-state hydrogen-bonding dynamics, which are predominantly determined by the vibrational motions of the hydrogen donor and acceptor groups, generally occur on ultrafast time scales of hundreds of femtoseconds. As a result, state-of-the-art femtos...

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Hydrogen Bonding in the Electronic Excited State

Preparation and applications of ion exchange membranes by radiation-induced graft copolymerization of polar monomers onto non-polar films

Metal−organic polyhedra and frameworks (MOPs and MOFs) were prepared by linking square units M2(CO2)4 (M = Cu and Zn) with a variety of organic linkers designed to control the dimensionality (periodicity) and topology of the resulting structures. We describe the preparation, characterization, and crystal structures of 5 new MOPs and 11 new MOFs (termed MOP-14, -15, -17, -23, -24 and MOF-114, -115, -116, -117, -118, -119, -222, -601, -602, -603, -604) and show how their structures are related to the shape and functionality of the building blocks. The gas uptake behaviors of MOP-23 and MOF-601 to -603 are also presented as evidence that these structures have permanent porosity and rigid architectures.

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Control of vertex geometry, structure dimensionality, functionality, and pore metrics in the reticular synthesis of crystalline metal-organic frameworks and polyhedra.

From monomers to polymers from renewable resources: Recent advances

Co-ordination polymers

One-pot synthesis and the fluorescent behavior of 4-acetyl-5-methyl-1,2,3-triazole regioisomers

Chalcone based materials are widely used in many industrial applications. The two new similar chalcone based single crystals, namely (E)-3-(4-(benzyloxy)phenyl)-1-(4-hydroxyphenyl)prop-2-en-1-one (Crystal A) and (E)-1-(4-(benzyloxy)phenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one (Crystal B) were synthesized and grown as single crystals by slow evaporation solution growth technique in acetone. The structures of the grown crystals were solved and refined by single crystal XRD and this demonstrates that crystal A shows an orthorhombic system with a space group of Pca21 and crystal B crystallizes in a monoclinic system with a space group of C2/c. The morphology of the crystals A and B was predicted using WINXMORPH. The hyperpolarizability studies were carried out for the chalcone single crystals using density functional theory (DFT) - triply parameter hybrid model DFT/B3LYP using GAUSSIAN 03. The calculated first order hyperpolarizability was found as 0.1314 × 10−30 e.s.u. for crystal A and 0.188 × 10−30 e.s.u. for crystal B. The second harmonic generation was studied by Kurtz–Perry test. The comparison statement of the enone shifted material properties enumerates interesting results in all the studies.

Synthesis, single crystal growth, characterization and comparison of two new enone shifted chalcones and their NLO behaviour

Two series of new sudan dye based poly(alkyloxymethacrylate)s were synthesized with varying even number of methylene spacers The structure of the polymers was confirmed by FT-IR, 1H and 13C-NMR spectroscopy Thermal stability, glass transition and melting temperatures of the polymers were investigated with thermogravimetric analysis and differential scanning calorimetry respectively Thermal stability of the polymers decrease with the increasing chain length of the methylene chain The substituent on the azo moiety in the pendant side chain polymers has less thermal stability than the unsubstituted counterpart The optical characterization of the polymers was done by formation of the holographic grating using 5145 nm line of the Ar ion laser as source The diffraction efficiency of the grating on the polymeric film was studied by varying the length of the methylene spacer, concentration and writing beam power

Azo dye based poly(alkyloxymethacrylate)s and their spacer effect on optical data storage

A Cu2+-specific colorimetric sensor of bis-triazole-appended azobenzene receptors I and II was designed and synthesized. Receptor II shows high selectivity toward Cu2+ in acetonitrile/water (80:20, v/v) solution based on the internal charge transfer (ICT) mechanism. The tridentate coordination behavior was proposed with 1:1 stoichiometry between receptor II and Cu2+. Herein, the Cu2+ gives rise to a large change in the absorption spectra (from red to pale yellow) that is clearly visible to the naked eye.

Palaninathan Kannan

Papers

Co-ordination polymers

One-pot synthesis and the fluorescent behavior of 4-acetyl-5-methyl-1,2,3-triazole regioisomers

Synthesis, single crystal growth, characterization and comparison of two new enone shifted chalcones and their NLO behaviour

Azo dye based poly(alkyloxymethacrylate)s and their spacer effect on optical data storage

Bis-Triazole-Appended Azobenzene Chromophore for Selective Sensing of Copper(II) Ion