Functionalized diacetylenes for nonlinear optical applications: Synthesis, characterization, and the properties of their monolayers

Srikhirin, Toemsak; Cham, Pak-Meng; Mann, J. Adin; Lando, J. B.

doi:10.1002/(sici)1099-0518(19990615)37:12<1771::aid-pola6>3.0.co;2-o

Cited by 3 publications

(1 citation statement)

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“…Supramolecular structures of dyes used for optical layers, − active layers in organic, − dye sensitized, − or hybrid solar cells − (OSCs, DSSCs, HSCs, respectively), sensors, , as well as organic light emitting diodes ,− (OLEDs) essentially determine the resulting thin film − and device properties . While the molecular interactions between many dyes with extended π-systems are governed by dispersion interactions, the interactions between push–pull dyes, such as merocyanines, , are typically dominated by dipole–dipole interactions .…”

Section: Introductionmentioning

confidence: 99%

Photoannealing of Merocyanine Aggregates

et al. 2018

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In this work we elucidate the fundamental difference between aggregate formation of donor−π–acceptor merocyanines in their electronic ground and excited states. While increasing the π-bridge size favors formation of π-stacked aggregates in the dark, irradiation with visible light causes reorientation of the dyes to form prototype H-aggregates with compensating dipole moments. This photoannealing changes the supramolecular structure and its UV–vis spectroscopic properties dramatically, thus being of importance for the function of active layers composed of these dyes. Aggregates of the ground state dyes are bound cooperatively through ππ-London dispersion interactions and hydrogen bonds between the polar α-cyano-carboxylic acid groups. However, charge transfer upon photoexcitation leads to repulsion of the polar acid groups. Electronic excitation of the dyes approximately doubles the ground state dipole moment, thus driving molecular reorientation into prototype H-aggregate structures. We show that this photoinduced supramolecular rearrangement can disrupt the large polymeric aggregates formed in the dark. The photoinduced supramolecular structural changes reported in this work will influence the performance of optoelectronic devices composed of these structures and must be controlled to avoid morphological decomposition of active layers upon operation.

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Section: Introductionmentioning

confidence: 99%

Photoannealing of Merocyanine Aggregates

et al. 2018

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Synthesis and characterization of novel photoisomerizable liquid crystalline polymers containing cinnamoyl groups

Yang

Liu

2008

J. Polym. Sci. A Polym. Chem.

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A series of novel liquid crystalline monomers and polymers incorporating phenylbenzoate or phenylcinnamate segments as mesogenic cores have been synthesized to investigate the sensitivity of the photochromic cinnamoyl derivatives and to overcome the defects of the thermal instability of azobenzene. Their liquid crystalline, thermal, and photoinduced properties of all monomers and polymers were characterized. The polymers showed excellent solubility in common organic solvents such as CHCl3, toluene, and DMF and exhibited good thermal stability with decomposition temperatures (Td) at 5% weight loss greater than 340 °C and about 50% weight loss occurred beyond 430 °C under nitrogen atmosphere. The pitch length (about 574 nm) of the synthesized cholesteric polymeric film (CP2) was estimated using scanning electron microscopy. These photochromic polymers exhibited strong UV–vis absorption maxima at about 264 or 320 nm. Moreover, photo induced configurational E/Z isomerization further changed the π‐electron conjugation systems leading to a decrease at the π‐π* transition and an increase in the range of 300 nm to 400 nm for photochromic copolymers. The thermal stability of the Z‐structural segment was confirmed by heating the polymer at 50 °C for over 5 h. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1289–1304, 2008

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