J-Aggregates in Langmuir−Blodgett Films of a Merocyanine Dye without Metallic Cations: Using FT-IR to Observe Changes in the Electronic Structure of the Molecules upon Aggregation

Abstract

Langmuir−Blodgett films of mixtures of fatty acids (FA) and a merocyanine dye (DS), bearing one long alkyl chain and one carboxylic group, were prepared at a nitrogen−pure water interface. The films exhibit a distinct and highly anisotropic J-band near 605 nm, even though they do not contain any metallic or ammonium cations. Although an isotropic band was seen in the region of 500−550 nm, the contribution of the J-aggregates was extracted from the observed visible and IR absorption spectra by using the difference in the polarization of the bands. This analysis indicates a change in the electronic structure of DS in the J-aggregates, probably corresponding to intramolecular charge transfer. Furthermore, this analysis also suggests that in this metal-free case, the formation of the J-aggregates is strongly affected by the hydrogen bonding between the carboxylic groups in two DS and that between the carboxylic groups in DS and FA.

Temperature and concentration dependence of J-aggregate of a cyanine dye in a Laponite film fabricated by Langmuir–Blodgett technique

“…These building units should be controlled carefully in order to prepare the functional super-structures for their applications (Knoll et al, 1981). In particular, J-aggregates of dye molecules have been investigated under various conditions (Chibisov and Slavnova, 2008;Hussain and Schoonheydt, 2010a;Ikegami et al, 1999Ikegami et al, , 2001Kaiser et al, 2009;Kuhn and Kuhn, 1996;Lan and Ikegami, 2001;Lu et al, 2002;Saito, 1999;Tachibana and Matsumoto, 2000). The pioneering work by Kuhn et al (Czikkely et al, 1970;Kuhn and Kuhn, 1996) on surface active cyanine dyes has opened the studies of J-aggregation in the 2D structures formed in the LB films.…”

Modification of optical characteristics in langmuir-blodgett films of merocyanine dye by reduced pressure treatment

“…The data were taken around the center of the substrate. absorption band at 590 nm, which is red-shifted from that of the MS monomer band at around 540 nm [8,9]. The absorption maximum at 590 nm shows the optical anisotropy with dichroic ratio R > 1, where R is defined as R ¼ A k =A ?…”

“…. The red-shifted band with R > 1 at 590 nm is ascribed to J-aggregation elongated in shape, which is associated with MS chromophore alignments of head-to-tail type in the aggregates [5][6][7][8][9][10][11].…”

Structural Characterization of a Mixed Langmuir−Blodgett Film of a Merocyanine Dye Derivative−Deuterated Arachidic Acid Binary System and the Influence of Successive Hydrothermal Treatment in the Liquid Phase on the Film as Investigated by Polarized UV−Visible and IR Absorption Spectroscopy

“…[1][2][3][4][5][6][7][8][9][10][11] Because the J and H aggregates can be easily controlled in Langmuir-Blodgett (LB) films containing merocyanine dye (see Figure 1A; MS 18 , X ) S, 3-carboxymethyl-5-[2-(3-octadecylbenzothiazolin-2-ylidene)ethylidene]rhodanine), we have been using LB films containing MS 18 to investigate the abovedescribed topics. [12][13][14][15][16][17][18][19][20] The formation mechanisms of the J and H aggregates of MS 18 have been revealed by Ikegami et al [21][22][23] and our group, 19 respectively. On the other hand, when the LB film of an analogous merocyanine dye (see Figure 1A; MO 18 , X ) O) and arachidic acid (C 20 ) binary or pure MO 18 system is prepared under an aqueous subphase containing a cadmium ion, it is well-known that the absorption band with a maximum near 505 nm, which is broader in shape than the MS 18 J and H bands, is formed.…”