Tubular J-aggregates of cyanine dyes in the near-infrared

Developing improved organic infrared emitters has wide-ranging applicability in fields such as bioimaging or energy harvesting. We synthesize redshifted analogues of C8S3, a well-known cyanine dye that self assembles into tubular aggregates which have attracted widespread attention as artificial photosynthetic complexes. Despite the elongated dye structure, the new pentamethine dyes retain their tubular self-assembly and emit at near-infrared wavelengths. Cryo-electron microscopy and detailed photophysical characterization of the new aggregates reveal similar absorption lineshapes with ~100 nm of redshift, as well as supramolecular morphologies that resemble their trimethine counterparts; the pentamethine aggregates generally show more disorder and decreased superradiance, suggesting that more ordered structures yield more robust photophysical properties. These results provide design principles of superradiant organic emitters, expand the chemical space of near-infrared aggregates, and introduce two additional wavelength-specific antennae as model systems for study.

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Principles for Self-Assembly of Cyanine Dyes into 2-Dimensional Excitonic Aggregates Across the Visible and Near-Infrared

10.26434/chemrxiv.12609398 ◽

2020 ◽

Author(s):

Arundhati Deshmukh ◽

Austin Bailey ◽

Leandra Forte ◽

Xingyu Shen ◽

Niklas Geue ◽

...

Keyword(s):

Self Assembly ◽

Near Infrared ◽

Dynamic Equilibrium ◽

Structural Information ◽

Photophysical Properties ◽

Cyanine Dyes ◽

Cyanine Dye ◽

Extensive Literature ◽

Solvent Ratio ◽

J Aggregates

<div>Cyanine dyes show a remarkable tendency to form non-covalent supramolecular aggregates with diverse morphologies (dimers, sheets, tubes and bundles). Specific molecular arrangements within these H- or J-aggregates dictate the extraordinary photophysical properties, including long-range exciton delocalization, extreme redshifts, and excitonic superradiance. Despite extensive literature on cyanine dye aggregates, design principles that drive the solution self-assembly to a preferred H- or J-aggregated state are unknown. We present a general approach to tune the thermodynamics of self-assembly, selectively stabilizing H- or J-aggregates and thereby achieving supramolecular control over aggregate photophysics. A simple interplay of solvent to non-solvent ratio, ionic strength or dye concentration yields a broad range of conditions that predictably and preferentially stabilize the monomer, H- or J-aggregate species that can be easily monitored using absorption spectroscopy. Diffusion ordered spectroscopy, cryo-electron microscopy and atomic force microscopy together reveal a dynamic equilibrium between monomers, H-aggregated dimers, and extended J-aggregated 2-dimensional monolayers. This structural information informs a three-component equilibrium model that describes the observed concentration dependence of spectral signatures, showing excellent fit with experimental data and yields the Gibb’s free energies of self-assembly for dimerization and 2D aggregate assembly. We further demonstrate the universality of this approach among several sheet forming cyanine dyes including the benzothiazole and benzimidazole families with absorptions spanning visible, near and shortwave infrared wavelengths.</div>

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Principles for Self-Assembly of Cyanine Dyes into 2-Dimensional Excitonic Aggregates Across the Visible and Near-Infrared

10.26434/chemrxiv.12609398.v1 ◽

2020 ◽

Author(s):

Arundhati Deshmukh ◽

Austin Bailey ◽

Leandra Forte ◽

Xingyu Shen ◽

Niklas Geue ◽

...

Keyword(s):

Self Assembly ◽

Near Infrared ◽

Dynamic Equilibrium ◽

Structural Information ◽

Photophysical Properties ◽

Cyanine Dyes ◽

Cyanine Dye ◽

Extensive Literature ◽

Solvent Ratio ◽

J Aggregates

<div>Cyanine dyes show a remarkable tendency to form non-covalent supramolecular aggregates with diverse morphologies (dimers, sheets, tubes and bundles). Specific molecular arrangements within these H- or J-aggregates dictate the extraordinary photophysical properties, including long-range exciton delocalization, extreme redshifts, and excitonic superradiance. Despite extensive literature on cyanine dye aggregates, design principles that drive the solution self-assembly to a preferred H- or J-aggregated state are unknown. We present a general approach to tune the thermodynamics of self-assembly, selectively stabilizing H- or J-aggregates and thereby achieving supramolecular control over aggregate photophysics. A simple interplay of solvent to non-solvent ratio, ionic strength or dye concentration yields a broad range of conditions that predictably and preferentially stabilize the monomer, H- or J-aggregate species that can be easily monitored using absorption spectroscopy. Diffusion ordered spectroscopy, cryo-electron microscopy and atomic force microscopy together reveal a dynamic equilibrium between monomers, H-aggregated dimers, and extended J-aggregated 2-dimensional monolayers. This structural information informs a three-component equilibrium model that describes the observed concentration dependence of spectral signatures, showing excellent fit with experimental data and yields the Gibb’s free energies of self-assembly for dimerization and 2D aggregate assembly. We further demonstrate the universality of this approach among several sheet forming cyanine dyes including the benzothiazole and benzimidazole families with absorptions spanning visible, near and shortwave infrared wavelengths.</div>

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New Insights on Near-Infrared Emitters Based on Er-quinolinolate Complexes: Synthesis, Characterization, Structural, and Photophysical Properties

Advanced Functional Materials ◽

10.1002/adfm.200600926 ◽

2007 ◽

Vol 17 (14) ◽

pp. 2365-2376 ◽

Cited By ~ 49

Author(s):

F. Artizzu ◽

L. Marchiò ◽

M. L. Mercuri ◽

L. Pilia ◽

A. Serpe ◽

...

Keyword(s):

Near Infrared ◽

Photophysical Properties ◽

Infrared Emitters

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Two-Dimensional Near-Infrared and Shortwave Infrared Molecular Aggregates: Taking Kasha’s Model to the Next Dimension

10.26434/chemrxiv.7699358.v3 ◽

2019 ◽

Author(s):

Arundhati Deshmukh ◽

Danielle Koppel ◽

Chern Chuang ◽

Danielle Cadena ◽

Jianshu Cao ◽

...

Keyword(s):

Near Infrared ◽

Photophysical Properties ◽

Satellite Telemetry ◽

Transition Dipole Moment ◽

Short Wave ◽

Tissue Imaging ◽

Transition Dipole ◽

Deep Tissue Imaging ◽

Excitonic States ◽

Shortwave Infrared

Technologies which utilize near-infrared (700 – 1000 nm) and short-wave infrared (1000 – 2000 nm) electromagnetic radiation have applications in deep-tissue imaging, telecommunications and satellite telemetry due to low scattering and decreased background signal in this spectral region. However, there are few molecular species, which absorb efficiently beyond 1000 nm. Transition dipole moment coupling (e.g. J-aggregation) allows for redshifted excitonic states and provides a pathway to highly absorptive electronic states in the infrared. We present aggregates of two cyanine dyes whose absorption peaks redshift dramatically upon aggregation in water from ~ 800 nm to 1000 nm and 1050 nm with sheet-like morphologies and high molar absorptivities (e ~ 10<sup>5 </sup>M<sup>-1</sup>cm<sup>-1</sup>). To describe this phenomenology, we extend Kasha’s model for J- and H-aggregation to describe the excitonic states of <i> 2-dimensional aggregates</i> whose slip is controlled by steric hindrance in the assembled structure. A consequence of the increased dimensionality is the phenomenon of an <i>intermediate </i>“I-aggregate”, one which redshifts yet displays spectral signatures of band-edge dark states akin to an H-aggregate. We distinguish between H-, I- and J-aggregates by showing the relative position of the bright (absorptive) state within the density of states using temperature dependent spectroscopy. Our results can be used to better design chromophores with predictable and tunable aggregation with new photophysical properties.

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Self-assembling behaviour of a modified aromatic amino acid in competitive medium

Soft Matter ◽

10.1039/d0sm00584c ◽

2020 ◽

Vol 16 (28) ◽

pp. 6599-6607 ◽

Cited By ~ 1

Author(s):

Pijush Singh ◽

Souvik Misra ◽

Nayim Sepay ◽

Sanjoy Mondal ◽

Debes Ray ◽

...

Keyword(s):

Amino Acid ◽

Self Assembly ◽

Aromatic Amino Acid ◽

Photophysical Properties ◽

Solvent Mixture ◽

The Self ◽

Solvent Ratio ◽

Self Assembling

The self-assembly and photophysical properties of 4-nitrophenylalanine (4NP) are changed with the alteration of solvent and final self-assembly state of 4NP in competitive solvent mixture and are dictated by the solvent ratio.

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Electromechanically reconfigurable optical nano-kirigami

Nature Communications ◽

10.1038/s41467-021-21565-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Shanshan Chen ◽

Zhiguang Liu ◽

Huifeng Du ◽

Chengchun Tang ◽

Chang-Yin Ji ◽

...

Keyword(s):

Near Infrared ◽

Large Range ◽

Three Dimensional ◽

High Contrast ◽

Si Substrate ◽

High Modulation ◽

Gold Nanostructure ◽

Infrared Wavelengths ◽

On Chip ◽

Nano Electromechanical System

AbstractKirigami, with facile and automated fashion of three-dimensional (3D) transformations, offers an unconventional approach for realizing cutting-edge optical nano-electromechanical systems. Here, we demonstrate an on-chip and electromechanically reconfigurable nano-kirigami with optical functionalities. The nano-electromechanical system is built on an Au/SiO2/Si substrate and operated via attractive electrostatic forces between the top gold nanostructure and bottom silicon substrate. Large-range nano-kirigami like 3D deformations are clearly observed and reversibly engineered, with scalable pitch size down to 0.975 μm. Broadband nonresonant and narrowband resonant optical reconfigurations are achieved at visible and near-infrared wavelengths, respectively, with a high modulation contrast up to 494%. On-chip modulation of optical helicity is further demonstrated in submicron nano-kirigami at near-infrared wavelengths. Such small-size and high-contrast reconfigurable optical nano-kirigami provides advanced methodologies and platforms for versatile on-chip manipulation of light at nanoscale.

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