Sung Hoon Kim

Synthesis and photostability of functional squarylium dyes

Abstract Various symmetrical and unsymmetrical squarylium dyes have been synthesized and characterized with the aid of IR spectroscopy and solvatochromism. The photofading of squarylium dyes has been investigated in solution and in polyvinylbutyral (PVB) film with carbon arc Fade-Ometer. The photostability of squarylium dyes increases with the electron-with-drawing power of substituent groups at the indoline moiety. The rates of photofading of these dyes were remarkably suppressed in the presence of hydroxycarboxylic acid metal salt, while the addition of UV-absorber afforded little retardation of the rate of fading.

Syntheses and Properties of Functional Aminosquarylium Dyes

Abstract Aminosquarylium dyes(6a–d) were prepared by condensation of aminosquarates (3a–d) and 1-ethyl-2,3,3-trimethylindolenium iodide (5) and structure of dye 6 was discussed on the basis of IR and solvatochromism. A new aminosquarylium dye 6a absorbed at a longer wavelength (18xa0nm) than the corresponding squarylium dye 7. The light absorption characteristics of representative examples are well accounted for with the PPP-MO calculation. The photostability properties of dye 6d was also investigated in solution with a high pressure mercury lamp when iodine was replaced by benzene dithiol metal complex as a counter anion, the photochemical stability being better than that of dye 7.

Absorption Spectra and Electrophotographic Properties of Squarylium Dyes Containing a Nitro group

Abstract Squarylium dye containing a nitro group, absorbs at 676xa0nm in chloroform and showed a bathochromic shift of 22xa0nm in comparision to the unsubstituted analogue. The reaction between squaric acid and 2,3,3-trimethyl-5-nitroindolenine proceeded readily giving a product in 97% yield. Electrophotographic characteristic of negatively charged dual-layered photoreceptors with squarylium dyes for charge generation materials and five charge transport materials have been investigated. Photoreceptors that used squarylium dyes containing a nitro group, exhibited high sensitivity under light exposure.

Electrochromic Properties of Functional Squarylium Dyes

Abstract The electrochromic properties of some squarylium dye (S Q ) were studied by using BuOH CH 2 Cl 2 (4:6/v:v) solution with Bu4NClO4 as supporting electrolyte. The electrochromic display (ECD) cell of these squarylium dyes coloured blue in open-circuit condition, but changed to a green colour at 1.41 ∼ 1.8 volt. At an applied voltage in the range higher than 2.1 volt, the absorbance at 480 nm and 630 nm decreases rapidly and the reversible colour change in open-circuit condition disappeared. The cyclic voltametric behaviour of the dyes was investigated and the first and second oxidation potentials measured. Decolouration rates in open-circuit were found to be first-order processes.

Synthesis and characterization of symmetric and non-symmetric bis-spiropyranylethyne

Abstract Symmetric bis -spiropyrans have been synthesized by the reaction of 5-[2-(3-formyl-4-hydroxyphenyl)ethynyl]-2-hydroxybenzaldehyde, which had previously been prepared by a palladium-catalyzed reaction of 2-hydroxy-5-iodo-benzaldehyde and 5-ethynyl-2-hydroxybenzaldehyde, with 2 equiv. of Fischers bases. Non-symmetric bis -spiropyrans were synthesized by palladium-catalyzed reaction of 6-iodospiropyrans with 6-ethynylspiropyrans, which had been prepared by reaction of 2-hydroxy-5-iodobenzaldehyde with 1 equiv. of Fischers base, and the reaction of 5-ethynyl-2-hydroxybenzaldehyde with 1 equiv. of Fischers base respectively. The bis -spiropyrans obtained were characterized by 1 H NMR, IR spectroscopy, UV and GC-MS.

Syntheses, characteristics and electrophotographic properties of new dithiosquarylium dyes

Abstract A new class of dithiosquarylium dyes (DTSQ) has been synthesized by the reaction of squarylium dye (SQ) with Lawessons reagent or P 4 S 10 . The λ max , of DTSQ dyes undergoes a bathochromic shift of about 25 nm compared with corresponding SQ dyes. The visible absorption spectra of DTSQ dyes are well accounted for by Pariser-Parr-Pople Molecular Orbital (PPP-MO) calculations. Electrophotographic characteristics of negatively charged dual layered photoreceptors with DTSQ for charge generation materials (CGM) and 1-phenyl-1,2,3,4-tetrahydroquinoline-6-carboxyaldehyde-1′,1′-diphenylhydrazone as a charge transport material (CTM) have been investigated. The photoreceptor that used DTSQs exhibited high photosensitivity at white light.

Dimer formation of viologen derivatives and their electrochromic properties

The electrochromic properties of 1,1′-diethyl-4,4′-bipyridinium dibromide (EV), 1,1′-dipropyl-4,4′-bipyridinium dibromide (PV), 1,1′-dibutyl-4,4′-bipyridinium dibromide (BV) and 1-ethyl-1′-butyl bipyridium dibromide (EBV) were studied using a propylenecarbonate/methanol solution with Bu4NBF4 as the supporting electrolyte. A monomer-dimer equilibrium is proposed to explain the observation that the EV and EBV cation radical solutions are violet at an applied voltage of 1.7-3.0 V, but become blue in the open-circuit condition.

A new dithiosquarylium dye for use as an electron transport material in an organic electroluminescent device having poly(p-phenylene vinylene) as an emitter

Abstract A new dithiosquarylium (DTS Q ) dye was examined as an electron transport material in organic EL devices. We fabricated the EL cell with poly(p-phenylene vinylene) (PPV) as the emission layer. DTS Q was found to be useful as a novel electron transport material. The EL device with DTS Q as the electron transport layer was more efficient than that with only the PPV layer.

Synthesis of Conjugated Spiropyran Dyes via Palladium-Catalyzed Coupling Reaction

Spiropyrans (5a-h) conjugated at 6 position have been conveniently and efficiently prepared by palladium-catalyzed coupling of 6-iodospiropyran (4a, 4b) with olefins or alkynes in moderate to high ...

Crystal Structure of a photoconductive dithiosquarylium dye: 2,4-Bis(1,3,3-trimethyl-2-indolinylidenemethyl) cyclobutenediylium-1,3-dithiolate

Abstract The crystal structure of a new dithiosquarylium dye (DTSQ), viz, 2,4-bis(1,3,3-trimethyl-2-indolinylidenemethyl) cyclobutenediylium-1,3-dithiolate, has been determined by X-ray crystallography. A crystal was grown from chloroform/ethylacetate (8:1/v:v) and found to exist in the monoclinic space group P2 1 /n (no. 14). The molecule is roughly planar and adopts the trans conformation.