Orthogonal Action of Noncovalent Interactions for Photoresponsive Chiral Columnar Assemblies

Vera, Francisco; Barberá, Joaquín; Romero, Pilar; Serrano, José Luís; Ros, M. Blanca; Sierra, Teresa

doi:10.1002/anie.201000580

Cited by 46 publications

(30 citation statements)

References 50 publications

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“…For example, the 13 C signals of the triazine core are shifted to higher frequencies by 4 or 5 ppm and the 13 C signals of the carboxylic acid groups and of the methylene groups in the β-position to the carboxylic acid group are shifted by +0.2-0.8 ppm after complexation (Figure 1). We previously reported similar systems [22] and demonstrated that the stoichiometry of these complexes in solution is 1:1. Titration NMR experiments in [D2]dichloromethane are shown in Figure 2 and allowed the estimation of the binding constant (718 ± 98 M -1 at 25 ºC) for the complexation of the triazine derivative and the Ac-G1A2 dendron.…”

Section: Nmr Characterizationmentioning

confidence: 71%

Multifunctional Supramolecular Dendrimers with an s‐Triazine Ring as the Central Core: Liquid Crystalline, Fluorescence and Photoconductive Properties

Bucoş

Sierra

Golemme

et al. 2014

Chemistry A European J

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Novel liquid crystal (LC) dendrimers have been synthesised by hydrogen bonding between an s‐triazine as the central core and three peripheral dendrons derived from bis(hydroxymethyl)propionic acid. Symmetric acid dendrons bearing achiral promesogenic units have been synthesised to obtain 3:1 complexes with triazine that exhibit LC properties. Asymmetric dendrons that combine the achiral promesogenic unit and an active moiety derived from coumarin or pyrene structures have been synthesised in order to obtain dendrimers with photophysical and electrochemical properties. The formation of the complexes was confirmed by IR and NMR spectroscopy data. The liquid crystalline properties were investigated by differential scanning calorimetry, polarising optical microscopy and X‐ray diffractometry. All complexes displayed mesogenic properties, which were smectic in the case of symmetric dendrons and their complexes and nematic in the case of asymmetric dendrons and their dendrimers. A supramolecular model for the lamellar mesophase, based mainly on X‐ray diffraction studies, is proposed. The electrochemical behaviour of dendritic complexes was investigated by cyclic voltammetry. The UV/Vis absorption and emission properties of the compounds and the photoconductive properties of the dendrons and dendrimers were also investigated

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Section: Nmr Characterizationmentioning

confidence: 71%

Multifunctional Supramolecular Dendrimers with an s‐Triazine Ring as the Central Core: Liquid Crystalline, Fluorescence and Photoconductive Properties

Bucoş

Sierra

Golemme

et al. 2014

Chemistry A European J

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“…This 1 H-NMR result was in accordance with that of the earlier work. 28 When the PCDA/T complex solution was subjected to UV-Vis absorption characterization, the absorption band for melamine unit (at 280 nm) was found to be obviously redshifted relative to the corresponding band in pure T solution (at 260 nm, as shown in Fig. S2).…”

Section: Characterization Of the Pcda/t Hydrogen-bonded Complexmentioning

confidence: 92%

“…This ability was ascribed to the synergistic action of the π-π stacking tendency of the melamine-derived core and the strong lateral interactions between V-shaped azobenzene molecules. [27][28][29] However, the relationship between the helical packing of the aromatic cores and the peripheral flexible chains are still not fully understood. It is anticipated that the helical packing of the rigid aromatic core might impact the packing of the peripheral diacetylene chains, and control the subsequent formation of helical PDA backbone, which has not yet been realized.…”

Section: Introductionmentioning

confidence: 99%

Chirality Transfer and Modulation in LB Films Derived From the Diacetylene/Melamine Hydrogen‐Bonded Complex

Zhu

Zou

et al. 2015

Chirality

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Introduction of hydrogen-bonding interaction into π-conjugated systems is a promising strategy, since the highly selective and directional hydrogen-bonding can increase the binding strength, provide enhanced stability to the assemblies, and position the π-conjugated molecules in a desired arrangement. The helical packing of the rigid melamine cores seems to play a dominating role in the subsequent formation of the peripheral helical PDA backbone. The polymerized Langmuir-Blodgett (LB) films exhibited reversible colorimetric and chiroptical changes during repeated heating-cooling cycles, which should be ascribed to the strong hydrogen-bonding interaction between the carboxylic acid and the melamine core. Further, the closely helical packing of the melamine cores could be destroyed upon exposure to HCl or NH(3) gas, whereas the peripheral helical polyaniline and polydiacetylene (PDA) backbone exhibited excellent stability. Although similar absorption changes could be observed for the films upon exposure to HCl or NH(3) gas, their distinct circular dichroism (CD) responses enabled us to distinguish the above two stimuli.

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“…No photo-orientation process has been observed. Recently, the same research group reported photo-modulation in the columnar phase formed by supramolecular aggregates, which result by hydrogen bonding between a melamine derivative and an azo-containing bent-core mesogen bearing a free carboxylic group [51].…”

Section: Introductionmentioning

confidence: 98%

Photochromic azobenzene functionalised banana–calamitic dimers and trimers: mesophase behaviour and photo-orientational phenomena

et al. 2011

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Azobenzene functionalised banana-calamitic dimers and a novel type of banana-calamitic-banana trimers have been synthesised. Their thermotropic behaviour and the structure of the mesophases have been characterised by differential scanning calorimetry, polarising optical microscopy and X-ray diffractions measurements. Electro-optical studies evidence the polar properties of the smectic phases. A rare anticlinic-synclinic smectic CP (SmCP) phase transition could be proven for two of the twins upon cooling without an electric field although the molecules are not optically active. Remarkably, the phase sequence SmC a -SmC s has been observed upon cooling, the inverse sequence to that reported for non-chiral compounds up to now. A comparative study of the photochemical properties of dilute solutions and of thin films of two compounds has been performed. Irradiation with polarised ultra-violet (365 nm) and visible light (473 nm) induces a photo-orientation process of the chromophores in a direction perpendicular to the polarisation plane of the exciting light. For a trimeric compound bearing an azobenzene bridge between both bent-core mesogenic units this process is associated with cycles of the E-Z-E isomerisation of the azobenzene groups followed by rotational diffusion of molecules in the films. For a bis(azobenzene) containing dimer the E-Z isomerisation in films is strongly suppressed and the photo-induced orientation has a rotational diffusion mechanism.

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Orthogonal Action of Noncovalent Interactions for Photoresponsive Chiral Columnar Assemblies

Cited by 46 publications

References 50 publications

Multifunctional Supramolecular Dendrimers with an s‐Triazine Ring as the Central Core: Liquid Crystalline, Fluorescence and Photoconductive Properties

Multifunctional Supramolecular Dendrimers with an s‐Triazine Ring as the Central Core: Liquid Crystalline, Fluorescence and Photoconductive Properties

Chirality Transfer and Modulation in LB Films Derived From the Diacetylene/Melamine Hydrogen‐Bonded Complex

Photochromic azobenzene functionalised banana–calamitic dimers and trimers: mesophase behaviour and photo-orientational phenomena

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