Electronic properties of polymethine systems 7: soliton symmetry breaking and spectral features of dyes with a long polymethine chain

Molecular design of near infrared polymethine dyes: A review

“…For a long time it was experimentally observed that in absorption spectra of the polymethine dyes with the comparatively long chain the shape of the long-wavelength band undergoes substantial transformation: it becomes unusually broad [149,[165][166][167]. It should be noted that this distortion of the typical cyanine band with a sharp narrow maximum becomes M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 27 noticeably broader: the long-wavelength side of the spectral band remains similar to the band of the dyes with a shorter chain, whereas a new broad shoulder appears at the short-wavelength side.…”

Squaraine Compounds: Tailored Design and Synthesis towards a Variety of Material Science Applications

“…In fact, in cyanine-like compounds the absorption maximum position is not the only gauge of charge localization phenomena. [75] Symmetric squaraines most characteristic spectral feature is a particularly narrow band width, a direct consequence of their highly symmetric charge distribution. Conversely efficient push-pull chromophores are characterized by a strong charge-transfer transition connected with a major variation, and sometimes even a change in the sign, of their dipole moment.…”

Fluorescent J-aggregates of cyanine dyes: basic research and applications review

“…The color of these dyes is mainly determined by the length of their polymethine chain, so that its increase by one vinylene group shifts the spectra to longer wavelengths by ∼100 nm [84][85][86]. In this way the dyes with the same end-groups absorbing blue light with the chain elongation can become absorbers of the near-IR light [87], see figure 4.…”