Spectroscopic, dark and photoconductive properties of some polyene-iodine charge-transfer complexes

Ghosh, Dilip Kumar; Hazra, S.; Pal, Prabir; Misra, T. N.

doi:10.1007/bf02745328

Cited by 5 publications

(7 citation statements)

References 14 publications

(13 reference statements)

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“…These include conjugated and unconjugated ones and are: the natural rubber (poly(cisisoprene), polystyrene, styrene butadiene rubber, polyacetylene, polyphenylacetylene, poly(phenylene vinylene), polybutadiene, graphite, carbon nanotubes, and fullerene C 60 . Several conjugated polyenic naturally occurring molecules such βcarotene, β apo8′carotenal, astacene, methyl bixin, lycopene, lutein, retinoic acid, vitamin A acetate, zeaxanthin, and fucoxan thin, were reported to develop CTCs with molecular iodine in the solid state [267][268][269][270][271]. A remarkable finding was that these iodinetreated molecules were endowed with high electrical conductivity, and were found, therefore, appli cations in solid state batteries [25,269,270]; there was an electrical conductivity of 10 6 S·cm 1 for the iodinated mol ecules against 10 14 S·cm 1 for the virgin molecules.…”

Section: Iodine Carbon/hydrocarbon Polymers Complexesmentioning

confidence: 99%

Molecular iodine/polymer complexes

Moulay

2013

Journal of Polymer Engineering

164

127

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A unique feature of molecular iodine by far, is its ability to bind to polymeric materials. A plethora of natural and synthetic polymers develop complexes when treated with molecular iodine, or with a mixture of mole cular iodine and potassium iodide. Many unexpected findings have been encountered upon complexation of iodine and the polymer skeleton, including the color formation, the polymer morphology changes, the compl exation sites or regions, the biological activity, and the electrical conductivity enhancement of the complexes, with poly iodides (I n¯) , mainly I 3¯ and I 5¯, as the actual binding species. Natural polymers that afford such complexes with iodine species are starch (amylose and amylopectin), chitosan, glycogen, silk, wool, albumin, cellulose, xylan, and natural rubber; iodinestarch being the oldest iodinenatural polymer complex. By contrast, numerous synthetic polymers are prone to make com plexes, including poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), nylons, poly(Schiff base)s, poly aniline, unsaturated polyhydrocarbons (carbon nano tubes, fullerenes C 60 /C 70 , polyacetylene; iodinePVA being the oldest iodinesynthetic polymer complex.

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Section: Iodine Carbon/hydrocarbon Polymers Complexesmentioning

confidence: 99%

Molecular iodine/polymer complexes

Moulay

2013

Journal of Polymer Engineering

164

127

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“…m/z (EI) 604 (M ϩ , 27%), 578 (29 (6), 394 (11), 339 (19), 313 (7), 262 (35), 243 (12), 223 (11), 165 (15), 119 (17), 109 (21), 95 (36), 83 (41), 55 (59), 28 (100).…”

Section: Eims Analysisunclassified

The charge delocalised β,β-carotene dication—preparation, structure elucidation by NMR and reactions with nucleophiles

et al. 2003

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The reaction between beta,beta-carotene and BF3-etherates has been investigated, leading to structural elucidation of the blue product, formed in appropriate organic solvents, as a symmetrical charge delocalised dication (lambda(max) 985 nm at room temperature in CHCl3) with considerable stability. The reaction, monitored by EPR studies at -25 degrees C, occurred via free radical intermediates. A C40H56BF3 intermediate was captured by EIMS. The detailed structure of the dication was established by COSY, HSQC, HMBC and 1D and 2D ROESY NMR techniques (600 MHz, CDCl3, -20 degrees C) leading to complete assignments of 1H and 13C chemical shifts and 3J(H,H) coupling constants. The effects of the two delocalised charges on chemical shift (charge distribution) and bond distance (3J(H,H)) were considered. The results are consistent with charge delocalisation mainly in the C-5-C-9 and C-5'-C-9' regions and with bond inversion to retro shifted double bonds in the central C-13-C-13' region. A convention for denoting the charge delocalisation and bond types is presented. The experimental results are discussed relative to previous theoretical calculations of the beta,beta-carotene dication structure. (All-E) and (15-Z)-beta,beta-carotene provided the same dication. The NIR spectra and stability of dications prepared in the same manner from the related carotenes 20,20'-dinor-beta,beta-carotene, heptapreno-beta,beta-carotene and nonapreno-beta,beta-carotene were examined for comparison. Reactions of the beta,beta-carotene dication with selected nucleophiles provided products including isocryptoxanthin, isocarotene and mutatochrome with H2O as nucleophile, and isocryptoxanthin methyl ether, 8-methoxy-7,8-dihydro-beta,beta-carotene and isocarotene with CH3ONa as nucleophile. The formation of these products is rationalised from the structure assigned to the dication.

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“…Several carotenoids have been used as substrates. 12,13 Doping of various carotenoids with iodine vapour, providing charge transfer complexes, [15][16][17][18] has been used in conductivity studies.…”

Section: Introductionmentioning

confidence: 99%

On the structure of carotenoid iodine complexes

2004

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Previous work on carotenoid-iodine complexes is briefly reviewed. The formation of iodine complexes of beta,beta-carotene and of (3R,3' R )-beta,beta-carotene-3,3'-diol (zeaxanthin) has been studied by modern methods including UV/VIS/NIR, IR MS, EPR, ENDOR and NMR (1H, 1H-1H COSY, TOCSY, 2D ROESY, 1H-13C HSQC and 1H-13C HMBC) spectroscopy, and chemical reactions monitored by HPLC, TLC and spectral analysis (VIS, MS, 1H NMR). beta,beta-Carotene formed a solid complex C40H56 x 4I with iodine in hexane and a solvent complex with lambdamax 1010 nm in chlorinated solvents. Iodine was not covalently bound to the carotene. Spectroscopic and chemical evidence is consistent with the representation of the beta,beta-carotene-iodine complex containing iodine in a pi complex with cationic/radical cationic properties. Extensive E/Z isomerisation was noted for all quenching products obtained in acetone, with thiosulfate, by dilution, or by reaction with nucleophile (MeOH). Key products obtained from the beta,beta-carotene-iodine complex were 4',5'-didehydro-4,5'-retro-beta,beta-carotene (isocarotene) and 4-methoxy-beta,beta-carotene. The zeaxanthin-iodine complex was not suitable for a practical synthesis of (3S,3'S)-4',5'-didehydro-4,5'-retro-beta,beta-carotene-3,3'-diol (eschscholtzxanthin).

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Spectroscopic, dark and photoconductive properties of some polyene-iodine charge-transfer complexes

Cited by 5 publications

References 14 publications

Molecular iodine/polymer complexes

Molecular iodine/polymer complexes

The charge delocalised β,β-carotene dication—preparation, structure elucidation by NMR and reactions with nucleophiles

On the structure of carotenoid iodine complexes

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