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Octupolar Merocyanine Dyes: A New Class of Nonlinear Optical Chromophores
Author(s) -
Poronik Yevgen M.,
Hugues Vincent,
BlanchardDesce Mireille,
Gryko Daniel T.
Publication year - 2012
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201200718
Subject(s) - chromophore , cyanine , merocyanine , photochemistry , two photon absorption , chemistry , absorption (acoustics) , absorption band , hyperpolarizability , bathochromic shift , wavelength , absorption spectroscopy , molecular physics , optoelectronics , fluorescence , materials science , photochromism , optics , molecule , physics , organic chemistry , polarizability , laser
Abstract A set of new octupolar merocyanine chromophores was designed and synthesized. These compounds were prepared from the reaction of 1,3,5‐triformyl‐2,4,6‐trihydroxybenzene with heterocyclic nucleophiles. Octupolar dyes were formed exclusively in their open‐dye form. The one‐ and two‐photon‐absorption spectra of the dyes consist of two bands: The long‐wavelength band in the two‐photon absorption spectrum (a few hundreds GM above 1000 nm) matches well with the intense, long‐wavelength‐absorption band that is located in the visible region in the linear spectrum. Interestingly, an additional, much‐more‐intense TPA band in the NIR region is observed at higher energy, which corresponds to a weakly allowed one‐photon electronic transition. Changing the peripheral heterocyclic moieties allows tuning of the optical properties to approach the cyanine limit (i.e., polymethine state), thus resulting in a red‐shift of the low‐energy one‐photon‐absorption band as well as to the rise of an intense two‐photon‐absorption band in the NIR region. To the best of our knowledge, this is the first synthesis and TPA characterization of octupolar merocyanine chromophores with typical low‐bond‐length alternation.