Sam-Rok Keum

Synthesis and characterization of unsymmetrical bis-indolinospirobenzopyrans, a new class of thermo- and photo-chromic dyes

Abstract A new class of unsymmetrical bis-indolinobenzospiropyran dyes (U-BSP) and their precursors have been synthesized. Unsymmetrical bis-indolinobenzo-spiropyrans are obtained by condensation of the precursor, Fischer base-spiropyran derivatives (FB-SPx), with substituted salicylaldehydes. The alternative Fischer base-spiropyran precursor (FB-SPy), which has an electron-withdrawing substituent, was not found to be suitable for the synthesis of U-BSPs. The synthesized U-BSPs have been characterized by 1H NMR, UV-Vis, and mass spectroscopy; they show abnormal solvatokinetic behavior in nonpolar solvents, suggestive of aggregate formation.

Indium-mediated highly regioselective reaction of prop-2-ynyl bromides with acyl cyanides in aqueous media: a convenient synthesis of allenic and propargylic ketones

Abstract Indium-mediated reaction of acyl cyanides 1 with prop-2-ynyl bromides 2 in aqueous media occurs regioselectively to afford either allenic 3 or propargylic ketones 4 depending on the γ-substituent of the prop-2-ynyl bromide under the mild conditions.

Synthesis and properties of new liquid crystalline compounds containing an indolinobenzospiropyranylazo group. Part 3

Abstract Two series of liquid crystalline dyes (series 1 and 2) containing novel mesogens incorporating a non-activated spiropyranylazo group have been synthesized. Those mesogens are derived from [1′,3′,3′-trimethylspiro(2H-1-benzopyran-2,2′-indoline)-6-yl] azobenzoic acid and 6-(p-hydroxyphenylazo)-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] for the series 1 and 2, respectively. Their liquid crystalline properties were studied by differential scanning calorimetry, optical polarizing microscopy and electro-optical measurement. Most of the compounds in series 1 form the enantiotropic nematic phase, while compounds in series 2 form the monotropic nematic and SmA phase.

Synthesis and characterization of liquid crystals containing a non-activated 1',3',3'-trimethylspiro\[2H-1-benzopyran-2,2-indoline] group

Two series of mesogens derived from the non-activated spiropyran dyes 6-hydroxy-1,3,3-trimethylspiro\[2H -1-benzopyran-2,2-indoline] (series trimethylspiro\[2 H -1-benzopyran-2,2-indoline] (series 2) have been synthesized. Analysis by differential scanning calorimetry, polarizing microscopy and X-ray diffraction showed compounds in series 1 form monotropic nematic and SmA phases, while compounds in series 2 form only a monotropic nematic phase.

Synthesis and properties of thermo- and photochromic bisindolinobenzospiropyrans linked by thio- and carbonyl groups

Abstract Novel thermo- and photochromic thio- and carbonylated bisspiropyrans have been synthesized by the reaction of 5,5′-thiobissalicylaldehydes or the 5,5′-carbonyl analogue and Fischers base derivatives in 1:2.5 mole ratios. For the synthesis of 5,5′-thio- or carbonylbissalicylaldehyde, 4,4′-thiodiphenol or 4,4′-carbonylbisphenol was formylated with paraformaldehyde. The synthesized dyes were characterized using 1H NMR, IR, UV–vis and mass spectroscopy. The thio-bisspiropyrans showed no thermo- and photochromism whereas the carbonylated dyes showed weak thermo- and photochromism.

1H and 13C NMR assignments for new heterocyclic TAM leuco dyes, (2Z,2′E)-2,2′-(2-phenyl propane-1,3-diylidene) bis(1,3,3-trimethylindoline) derivatives. Part II†

The 1H and 13C NMR spectra of the novel heterocyclic Leuco‐TAM dyes, (2Z, 2′E)‐2,2′‐(2‐phenyl propane‐1,3‐diylidene) bis(1,3,3‐trimethylindoline) derivatives 1–4 as precursors of triarylmethane (TAM)+ (Malachite Green FB‐analog) dyes were completely assigned by 1D and 2D NMR experiments, including DEPT, COSY, HSQC, HMBC, and NOESY. Especially, the diastereotopic gem‐dimethyl protons at the C3 and C3′ positions of the FB rings were definitively assigned. The (Z,E) isomers adopt the energetically favored three‐bladed propeller conformation in solution. Copyright

Synthesis and characterization of new liquid crystalline materials containing a non-activated arylazoindolinobenzospiropyranyl group as a chiral unit. Part II

Two series of new liquid crystalline compounds containing a non-activated arylazoindolinobenzospiropyran, ABP-SPAB 1a-1e (series 1) and SPAP-ABPC 2a-2e (series 2), have been synthesized. These LC dyes were characterized by a differential scanning calorimetry polarizing optical microscopy, X-ray diffraction and electro-optical measurements. All but one of the series 1 compounds examined exhibit monotropic second and/or third transition liquid crystal phases on cooling from the isotropic liquid. In particular, ABP-SPAB 1b shows a monotropic SmC phase, in addition to a SmA phase. In series 2, most of the compounds exhibit a monotropic nematic phase on cooling. SPAP-ABPC 2c forms an enantiotropic nematic phase and a monotropic SmA phase; 2e shows enantiotropic nematic and SmA phases.

Resolution and circular dichroism of a non-activated spiropyran dye: 6-(p-Chlorophenylazo)-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline]

Abstract The non-activated spiropyran dye 6-( p -chlorophenylazo)-1′,3′,3′-trimethylspiro[2H-1-benzopyran-2,2′-indoline] ( 2 ) was synthesized and resolved by chiral stationary phase HPLC. The chiroptical properties of the optically active dye were determined by circular dichroism spectropolarimetry.

Novel Fischer’s Base Analogous of Leuco-TAM and TAM+ Dyes – Synthesis and Spectroscopic Characterization

The development of material engineering is accompanied by a growing demand for routine, nondestructive techniques for material and product testing. These techniques are to be used for the assessment of chemical and physical structure of new materials as well as for a systematic control of their manufacturing processes. Nowadays nanotechnologies fulfill a particular role in creating new materials of nanometric dimensions. The products of nanotechnology are made in various forms, mostly such as coatings and fibers. Coatings are of great practical importance while deposited on conventional substrates, such as metals, ceramics and polymers to impart new functions, e.g. anticorrosive, reflexive, sensory properties, etc., to them. Coatings are mostly made of polymers and hence their functional properties and durability mainly depend on polymer chemical and supermolecular structure. The current control tests of the chemical properties and supermolecular characteristic of materials are carried out with the use of IR absorption spectroscopy. Currently, these are dedicated to test the surface of materials. This paper concerns the spectroscopic technique FTIR used to test the surface of polymeric materials and coatings formed on polymeric substrates. The general characteristics, advantages and drawbacks of this technique in testing polymer surfaces have been presented.© 2012 Keum et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Novel Fischer’s Base Analogous of Leuco-TAM and TAM Dyes – Synthesis and Spectroscopic Characterization

Rearrangement mechanisms for azoxypyridines and azoxypyridine N-oxides in the 100% H2SO4 region - The Wallach rearrangement story comes full circle

Kinetic studies of the Wallach rearrangements of four azoxypyridines, four azoxypyridine N-oxides, and one azoxypyridine N-methiodide have been carried out in the 100% H2SO4 acidity region. For all...