• Journal of Photoscience
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• 제9권2호
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• pp.33-36
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• 2002

In vertebrate rhodopsins the glutamic acid at position 113 serves as a counterion to stabilize the protonated retinylidene Schiff base linkage and to shift the spectrum to the visible region. Invertebrate rhodopsins and retinochrome have the amino acid residue different from glutamic acid or asparatic acid at this position and therefore, these pigments may have a counterion at different position. We first investigated the counterion in retinochrome by site specific mutagenesis. The results showed that the counterion is the glutamic acid at position 181, where almost of all the pigments including vertebrate and invertebrate rhodopsins in the rhodopsin family have a glutamic acid or an aspartic acid. In vertebrate rhodopsins, however, Glu 181 does not act as a counterion, and the red-sensitive cone pigments have a histidine at this position, which serves as a chloride-binding site for red-shift of the absorption spectrum. These findings suggested that the role of Glu181 as a counterion may be weakened by the newly acquired counterion at position 113. Taken together with our recent studies on an invertebrate-type rhodopsin, the rhodopsin diversity was discussed from viewpoint of counterion.

• Bulletin of the Korean Chemical Society
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• 제31권2호
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• pp.507-510
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• 2010

• 대한화학회지
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• 제31권2호
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• pp.184-189
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• 1987

역상 액체크로마토그래피에 의한 지방족 알코올, 케톤 및 에스테르를 분리하는데 검출 시약으로 brilliant green 에 관하여 연구하였다. 발색단을 가지고 있지 않은 이들 시료들을 brilliant green을 사용함으로써 가시영역인 625nm에서 분광광도 검출기로서 간접적으로 검출할 수 있었다. 또한 몇가지 혼합시료들을 좋은 분리도와 비교적 높은 감도로서 분리 및 검출할 수 있었다.

• 한국염색가공학회지
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• 제24권3호
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• pp.158-164
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• 2012

Rhodamine dyes belong to xanthene family has excellent photostability and photophysical properties. In rhodamine dyes, Rhodamine 6G and its precursors also have xanthene chromophore and it shows high fluorescent quantum yield. Rhodamine 6G derivates are simple to synthesis and its high sensitivity and water solubility are suitable as good chemosensor. In this regard, Rhodamine 6G derivates which have selectivity to specific metal cation can used to detect various heavy metal ions. In this study, rhodamine 6G derivatives were synthesized by reaction of rhodamine 6G hydrazide and glyoxal and 4-phenyl thiosemicarbazide and it showed colorimetric and fluorescence sensing toward $Hg^{2+}$ ion. This novel chemosensor was analyzed and measured on UV-Vis and fluorescence spectrophotometer. HOMO/LUMO values were also calculated by computational calculation.

• 한국염색가공학회지
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• 제18권5호
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• pp.30-34
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• 2006

Polypropylene fiber was dyed with 4 super hydrophobic dyes having different alkyl derivatives on the same chromophore. Double-tailed cationic surfactant, didodecyldimethylammonium bromide(DDAB), was used to make dye-dispersant complex to improve the dispersion of dyes. As the alkyl groups are longer and the hydrophobicity is increased, the dyeability onto polypropylene fiber was improved and deep coloration was obtained. As for the fastness properties, wash fastness was relatively good, while light fastness was bit low.

• 한국염색가공학회:학술대회논문집
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• 한국염색가공학회 2011년도 제44차 학술발표회
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• pp.62-62
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• 2011

Intramolecular charge transfer (ICT) system has received great attentions due to their promising optoelectronic properties For the efficient ICT of the chromophore, their organic compound mainly consists of strong electron donors (e.g. $NR_2$ or OR groups) and acceptors (e.g. CN or $NO_2$ groups). According to the molecular design and synthesis, the ICT compounds can be extended in many application fields. In this study, we have synthesized ICT compounds having a strong electron acceptor and donor. These novel ICT compounds were easily synthesized by a previously described method with some modifications. Their single crystals were grown and their structures were solved and described in this presentation.

• 한국식물학회:학술대회논문집
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• 한국식물학회 1994년도 94 Symposium on Plant science September 10, 1994 Ewha Womans University, Seoul, Korea 94 식물학 심포지움 환경 스트레스와 식물의 반응
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• pp.41-51
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• 1994

Tomato (Lycopersicon esculentum Mill.) has been chosen as a model species for the study of hotomorphogenesis. The aurea (au) and yellow-green-2 (yg-2) mutants which are severely photochrome deficient appear to be phytochrome chromophore mutants. Mutants modified with respect to specific members of the phytochrome gene family: the far-red light-insensitive mutant (fri, for phytochrome A) and the temporarily red light-insensitive mutant (tri, for phytochrome B1) have been identified. Mutants that exhibit an exaggerated phytochrome response are putative transduction-chain mutants affecting an amplification step in phytochrome signal transduction. These mutants are being used to understand the complexities of juvenile anthocyanin in the hypocotyl during seedling de-etiolation.

• Journal of Photoscience
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• 제7권3호
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• pp.79-86
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• 2000

Phytochromes are red and far-red light absorbing photoreceptors for photomorphogenesis in plants. The red/far wavelength reversible biliproteins are made up of two structural domains. The light-perceiving function of the photoreceptor resides in the N-terminal domain, whereas the signal transducing regulatory function is located within the C-terminal domain. The characteristic role of the phytochromes as phtosensory molecular switches is derived from the phototransformation between two distinct spectral forms, the red light absorbing Pr and the far-red light absorbing Pfr forms. The photoinduced Pr Pfr phototransformation accompanies subtle conformational changes throughout the phytochrome molecule. The conformational signals are subsequently transmitted to the C-terminal domain through various inter-domain crosstalks and induce the interaction of the activated C-terminal domain with phytochrome interacting factors. Thus the inter-domain crosstalks play critical roles in the photoactivation of the phytochromes. Posttranslational modifications, such as the phosphorylation of Ser-598, are also involved in this process through conformational changes and by modulating inter-domain signaling.

• Journal of Photoscience
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• 제1권1호
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• pp.67-68
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• 1994

INTRODUCTION : The photochemistry of nitro chromophore has been the subject of intense study only in recent years. Unlike the carbonyl functional group, of which the photochemistry has been quite extensively studied and fairly well understood, as a result of excellent work done by numerous physical and organic photochemists alike, the nature of photochemistry of nitro group has only recently been systematically explored. The photochemistry of nitro group exhibits general features of the photochemistry of the carbonyl groups such as hydrogen abstraction by the diradical species generated from the n-$\pi$$^*$ excited state of the nitro group. Other photochemical pathways common to the carbonyl group such as the biradical intermidiate formation, photocycloelimination, and cydoaddition reactions are also open for the nitro group. Of all the photochemical reactions of the nitro group mentioned above, hydrogen abstraction by the n-$\pi$$^*$ excited state of the nitro group has drawn much attention by synthetic organic chemists and polymer chemists. In the field of organic synthesis, above mintioned photochemical reaction has been utilized in the photoprotection-deprotection chemistry.

• Rapid Communication in Photoscience
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• 제3권4호
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• pp.73-75
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• 2014

Novel diphenylphenanthrenes (DPPs) were prepared by a photocyclization method, and the substituent effects of the phenyl groups on the photophysical properties of the phenanthrene chromophore were investigated based on measurements of fluorescence yields, lifetimes, and transient absorption. Fluorescence activities in DPPs are increased by introducing phenyl rings that can enhance the transition moment along the short axis of the phenanthrene skeleton. Intersystem crossing from the fluorescent states to the triplet manifolds is shown to be operative through the triplet-triplet absorption spectra obtained by laser photolysis techniques.