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~1H-NMR studies on cis-trans isomers of spheroidenes

Science China Chemistry 1996年第1期39卷 11-19页

作者：姜月顺小山泰 Department of Chemistry Jilin University Changchun 130023 China Faculty of Science Kwansei Gakuin University Nishinomiya 662 Japan

All-trans spheroidene was extracted from the cells of Rhodobacer sphaeroides 2.4.1 and a set of cis-trans isomers were isolated from an isomeric mixture obtained by iodine-sensitized photo-isomerization of the all-trans isomer by high-pressure liquid chromatography (HPLC). On the basis of assignment of the 1H-NMR spectra (COSY, long-range COSY, rekyed COSY, ROESY and NOESY) of the all-trans isomer, the configurations of cis isomers were determined by the isomerization shifts of the olefinic 1H signals. The peaks of HPLC could be assigned as follows: A: 9,13’-cis, B1: 5,13-cis, B2: 13,9’-cis, C: 13-cis, E: 9-cis, F: 13’-cis, G: 5,9’-cis, H: 9’-cis, I: all-trans.

关键词： spheroidene cis-trans isomers 2D 1H-NMR high-pressure liquid chromatography.

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Synthesis, Characterization and Photoinduced cis-trans Isomerisation Studies on Lignin Modified with 4-[(E)-2-(3-hydroxynaphthalen-2-yl)diazen-1-yl] Benzoic Acid

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Open Journal of Organic Polymer Materials 2012年第4期2卷 69-74页

作者： Ambily Chandran Sunny Kuriakose Tessymol Mathew Research and Post Graduate Department of Chemistry St.George College Mahathma Gandhi University Kerala India. Research and Post Graduate Department of Chemistry St.Thomas College Mahathma Gandhi University Kerala India

In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photoresponsive beha-vior of the green, environment friendly product was investigated. The end hydroxyl group of lignin was modified with the chromophoric systems by DCC coupling. The chromophoric systems as well as the chromophore-bound biopolymer core systems were purified by column chromatography. The products were characterized by UV-visible, fluorescence, FT-IR and NMR spectroscopic methods. The results of the studies show that incorporation of the chromophoric system on to the lignin core enhanced the light absorption, emission and light stabilization properties of the chromophoric system. The light fastening properties of chromophoric system and the modified product were compared. It shows that stability of the chromophoric system greatly enhanced on attaching to the polymeric system. The trans-cis photoisomerisation and the reverse cis-trans thermal conversions were also assisted by the lignin core. The remarkable stability on irradiation shows that this is a novel photoresponsive system with excellent light fastening properties which would find application in coating materials, dyes, paints, inks, therapeutic agents and many more.

关键词： Lignin Photoresponsive Environment Friendly Light Fastening cis-trans Isomerisation

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Photochromism of cis(z)-1,2-bispyrryl-substituted ethene derivatives

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Science China Chemistry 1996年第4期39卷 363-370页

作者：樊贵宝明阳福樊美公姚思德左志华 Institute of Photographic Chemistry Chinese Academy of Sciences Beijing 100101 China Laboratory of Radiation Chemistry Shanghai Institute of Nuclear Research Chinese Academy of Sciences Shanghai 201800 China

Photochromism of two bispyrryl-substituted ethenes, 2, 3-bis-(1-p-methoxyphenyl-5-phenyl-2-methyl-3-pyrryl)-2-butene (BPE1) and 2,3-bis(1-p-bromophenyl-4-phenyl-2-methyl-3-pyrryl)-2-butene (BPE2), was studied by laser flash photolysis technique. The results indicate that photocyclization of these compounds proceeds mainly via the excited triplet state, and the cis-trans isomerization proceeds mainly via the excited singlet state. After UV laser pulse irradiation, both photocylization and cis-trans isomerization of BPEl occur, but photocydization is the main reaction. On the other hand, laser photolysis of BPE2 leads mainly to photocydization. The effects of the substituents on the photochromic mechanism are also discussed.

关键词： bispyrryl-substituted ethene photochromic mechanism photocyclization cis-trans isomerization.

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Photochemical properties of carotenoids: what can we get from the VB model?

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Science China Chemistry 2003年第1期46卷 7-12页

作者：高嶷刘春根江元生 Institute of Mesoscopic Chemistry and Material Department of Chemistry Nanjing University Nanjing 210093 China

The empirical valence bond model, solved by the DMRG technique, is applied to the systematical study of the photochemical processes of carotenoids. The polyenes with five up to one hundred of C== C bonds are investigated. The probability of the state arrangement for the conjugated bond, Pij, is evaluated. It is a parameter to correlate the bond lengths, and could also be applied to rationalizing the quantum yields of the photo-isomerization and the reaction constant of the quenching of singlet-oxygen happened to the external C== C bond of the carotenoids. The maximum reaction constant in long chain limit is determined as about 2.92×1010 L·mol-1·s-1.

关键词： Pij , singlet oxygen quenching, cis-trans isomerization, DMRG.

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Irvingia Fat Ageing: Study of Chemical Characteristics Related to MIR Spectroscopy

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Spectral Analysis Review 2023年第1期7卷 1-12页

作者： Aristide H. W. Nakavoua Gadet M. Dzondo Aubin N. Loumouamou Louis Matos Gilles Figueredo Laboratory of Chemistry of Natural Substances (IRSEN) Brazzaville Congo Marien Ngouabi University National Polytechnic High School (ENSP) Laboratory for the Valorisation of Agri-Resources Brazzaville Congo Laboratory of Industrial Process Engineering UNESCO Chair-ENSP Marien Ngouabi University Brazzaville People’s Republic of Congo LEXVA Analytical 460 Montant Street 63540 Romagnat French or Henri Mondor Street Biopole Clermont Limagne 63360 Saint Beauzire French

The Irvingia gabonensis kernels, which have been extensively studied for their numerous virtues, including the ability to act against the accumulation of fats in the body[1], contain an oil. The aging of this oil under two different conditions of conservation was the subject of our work. One of the results was an increase in the content of long-chain carbonaceous fatty acids during aging for 11 months of storage at low temperature (6℃) and at 30℃. This behavior does not find a concordant explanation by the comparative analysis of the chemical indices. Hence, there is the need to use the Medium Infra-Red spectroscopy (MIR) which allowed to clarify the information of the saponification index, to justify the weakness of the formation of peroxides in the case of the conservation at 30℃ and to confirm the information given by the peroxide index. It also allowed to understand the formation of the long carbon chains by the “cis-trans” isomerization and the homolytic cuts which intervene within the matrix of the fat by the analysis of the number of -CH2 and -CH3 groups in the two conditions of conservation. This study reveals that the rapid solidification of Irvingia gabonensis oil at room temperature[2] is an advantage for its preservation at room temperature but a great weakness when the fat is stored at low temperature.

关键词： Ageing Irvingia gabonensis MIR cis-trans Isomerism

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