The extrinsic circular dichroism of J-aggregate species of achiral dyes

Saeva, F. D.; Olin, G. R.

doi:10.1021/ja00456a064

Cited by 44 publications

(30 citation statements)

References 15 publications

(27 reference statements)

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“…4 are measured in an ethyl cellulose polymer film ͑5 wt %, ϳ20 m film thickness͒. 64 Measurements on oriented PIC aggregates suggest that the absorption band at around 17 500 cm −1 is due to the absorption of light that is polarized parallel to the long axis of the aggregates ͑see, e.g., Ref. 5͒.…”

Section: Comparison With Experimentsmentioning

confidence: 99%

Theory of the absorption and circular dichroism spectra of helical molecular aggregates

Eisfeld

Kniprath

Briggs

2007

The Journal of Chemical Physics

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A theory of the electronic circular dichroism (CD) and optical rotatory dispersion (ORD) of infinite aggregates exhibiting cylindrical symmetry is presented in which, to the authors' knowledge, for the first time vibrational structure is included explicitly. It is shown that, with the coherent exciton scattering approximation in the Green function approach, the detailed vibrational structure of the aggregate absorption. CD and ORD bands can be calculated from a knowledge of the electronic coupling and the monomer absorption line shape alone. Detailed model calculations for a single helix are made and the results are used to expose the origin of different spectral features. A good reproduction of experimental J-aggregate spectra is obtained, using the same electronic interaction to fit both absorption and CD spectral line shapes. The theory allows some prediction of aggregate geometry to be made, but it is shown that an unambiguous geometrical assignment can only be made where experimental spectra for light of different propagation directions with respect to the cylinder axis are available.

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Section: Comparison With Experimentsmentioning

confidence: 99%

Theory of the absorption and circular dichroism spectra of helical molecular aggregates

Eisfeld

Kniprath

Briggs

2007

The Journal of Chemical Physics

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“…19.) This report was criticized on the basis that these findings might have been caused by an artifactual CD signal due to deficient calibration of the CD spectrometer20 or the effect of linear polarization 21. Therefore, previous reports17, 18 concerning the CD data have been considered erroneous.…”

Section: Introductionmentioning

confidence: 98%

Chirality generated by flows in pseudocyanine dye J‐aggregates: Revisiting 40 years old reports

et al. 2011

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Spontaneous symmetry breaking in J-aggregates of cyanine dyes has a long history in chemical literature. In 1976, Honda and Hada claimed that they had achieved chiral induction (CD) by stirring J-aggregates of pseudocyanine. However, this report is controversial, as the combinations of linear dichroism and birefringence can lead to artifactual circular dichroic signals that are unrelated to molecular chirality. A Mueller matrix spectroscopy study, with an approach for the application of a gradient of the shear rate (solution layer between a rotating and a fixed disk) that differs from the simple vortex stirring used in the original report, shows that true CD can be induced in the sample. The phenomenon is discussed, taking into account the flow dynamics that allows the alignment of the aggregate particles and the gradient of shear rates that determines their folding/torsion, which leads to a chiral excitonic transition.

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“…[40][41][42] In this work, the influence of the LD was eliminated by averaging at different angles with the similar procedure reported in literatures. 23,41,42 It has been found that the average of the CD spectra at eight angles (0 , 45 , 90 , 135 , 180 , 225 , 270 , 315 , and 360 ) results similar CD spectra as those in a rotating manner ( Figure 5). The CD spectra reported in this paper are measured by rotating the film during the measurement.…”

Section: Resultsmentioning

confidence: 99%

A Supramolecular Chiroptical Switch Based on Chitosan and Anionic Porphyrin Complex Film

Liao

Liu

Huang

2007

Polym J

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ABSTRACT:A supramolecular chiroptical switch based on chitosan and tetrakis (4-sulfonatophenyl) porphine (TPPS) complex films was prepared. The reversible changes of the chirality of the complex films were studied by UV-vis and circular dichroism (CD) spectra. It was found that the chirality of the complex films can be wiped off by being exposed to NH 3 gas and subsequently recovered by being exposed to moist HCl gas. The complex film is stable and can stand at least 20 cycles of the switching to NH 3 and HCl gases. There is no change in the above properties after the complex films were store in the air at room temperature. Chirality is an attractive issue in chemistry, biology, material science etc. and has been studied extensively. [1][2][3][4] The chiral switch, which shows the reversible change in chirality with an external stimulation, is particularly attractive due to the potential applications in data storage and sensor systems.5-9 Many chiral optical switches have been proposed, which are based on photochemically induced interconversions, 10,11 photochemically induced changes in liquid crystals, 12,13 stereoisomers of chiral photoresponsive molecules and chiral supramolecular systems, 14,15 etc. The most attractive one in this filed is the chiral optical supramolecular switch because it is easily controlled. [16][17][18][19] Tetrakis(4-sulfonatophenyl)porphine (TPPS, Figure 1) is a well investigated dye. It has two negative charges and forms stable J-and H-aggregates depending on the pH and ionic strength in the system. The TPPS J-and H-aggregates shows the property of induced chirality in many systems, such as multilayer and Langmuir-Schaefer (L-S) films prepared from chiral and achiral molecules, 20-23 the solutions containing polylutamic acid, polylysine, cationic porphyrin etc., [24][25][26][27][28][29][30] and even by mechanical stirring in solutions. 31 However, there is no report about the reversible chirality of TPPS aggregates in film.Chitosan, a chiral biopolymer, is used widely in many fields, e.g. biomedical 32-34 and chemical materials, 35 textiles, 36 pharmaceutics, 37,38 etc. Chitosan is a cationic polyelectrolyte and can interact with the anionic TPPS. More recently, Synytsya et al.39 studied the interaction of TPPS with chitosan in aqueous solutions at different pH value. The results confirmed that the formation of optically active species of TPPS in the presence of chitosan and the J-and H-aggregates depended on pH value and chitosan concentration. However, no work had been reported on the interactions between TPPS and chitosan on chitosan film.In this paper, the reversible change in chirality of chitosan/TPPS complex films when they are alternatively exposed in moist HCl and NH 3 gases was studied. The morphology of the complex films and the interaction between chitosan and TPPS were discussed. EXPERIMENTALWater-soluble anionic porphyrin TPPS was purchased from Dojindo Laboratories. Chitosan (M n ¼ 100 Kda, the degree of deacetylation was 91 mol %) was received from Professor Yanming D...

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The extrinsic circular dichroism of J-aggregate species of achiral dyes

Cited by 44 publications

References 15 publications

Theory of the absorption and circular dichroism spectra of helical molecular aggregates

Theory of the absorption and circular dichroism spectra of helical molecular aggregates

Chirality generated by flows in pseudocyanine dye J‐aggregates: Revisiting 40 years old reports

A Supramolecular Chiroptical Switch Based on Chitosan and Anionic Porphyrin Complex Film

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