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

Author(s):  
Arundhati Deshmukh ◽  
Austin Bailey ◽  
Leandra Forte ◽  
Xingyu Shen ◽  
Niklas Geue ◽  
...  

<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>

2020 ◽  
Author(s):  
Arundhati Deshmukh ◽  
Austin Bailey ◽  
Leandra Forte ◽  
Xingyu Shen ◽  
Niklas Geue ◽  
...  

<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>


2021 ◽  
Author(s):  
Austin Bailey ◽  
Arundhati Deshmukh ◽  
Timothy Atallah ◽  
Ulugbek Barotov ◽  
Monica Pengshung ◽  
...  

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.


2021 ◽  
Author(s):  
Austin Bailey ◽  
Arundhati Deshmukh ◽  
Timothy Atallah ◽  
Ulugbek Barotov ◽  
Monica Pengshung ◽  
...  

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.


Soft Matter ◽  
2020 ◽  
Vol 16 (28) ◽  
pp. 6599-6607 ◽  
Author(s):  
Pijush Singh ◽  
Souvik Misra ◽  
Nayim Sepay ◽  
Sanjoy Mondal ◽  
Debes Ray ◽  
...  

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.


Nanoscale ◽  
2021 ◽  
Author(s):  
Matias Luis Picchio ◽  
Julian Bergueiro Álvarez ◽  
Stefanie Wedepohl ◽  
Roque J Minari ◽  
Cecilia Ines Alvarez Igarzabal ◽  
...  

After several decades of development in the field of near-infrared (NIR) dyes for photothermal therapy (PTT), indocyanine green (ICG) still remains the only FDA-approved NIR contrast agent. However, upon NIR...


Author(s):  
Wesley Tillmann ◽  
Hussein Samha

The effect of polyvinylsulfate (PVS) on the spectroscopy of the cyanine dye, 1,1’-diethyl-2,2’-cyanine iodide (PIC), has been investigated using UV-vis spectroscopy. J-aggregates of the PIC dye were formed upon addition of PVS to the monomers of the dye in solution. The appearance of only one isosbestic point in the UV-vis spectra suggests that the dye monomers are quantitatively converted to J-aggregates and equilibrium was reached. Using Benisi-Hildebrand kinetics, aggregation number of 4 was calculated for the dye. In addition, a 1:2 mole ratio of PIC/PVS was calculated at the maximum capacity of the polymer.


Author(s):  
Andrew Dixon ◽  
Clint Duncan ◽  
Hussein Samha

The effect of Ca-montmorillonite (clay) on the aggregation behavior of the cyanine dye, 1,1’-diethyl-2,2’-cyanine iodide (PIC), in aqueous solutions has been investigated using UV-vis spectroscopy. The absorbance of the monomeric dye in aqueous solutions is compared with the absorbance of the aggregates formed after adding the clay. The appearance of a sharp “red-shifted” band centered at 574 nm, after the addition of clay to the aqueous solutions of the dye, indicates the formation J-aggregates on the charged surfaces of the clay particles. The spontaneous and quantitative transformation of monomers into J-aggregates was controlled by the concentration of the clay in the solution. Successive addition of clay to the dye solution causes an increase in the absorbance intensity of the J-band and consequently, a decrease in the absorbance intensity of the monomer. These changes occur linearly which suggests that the dye monomers are quantitatively being converted to J-aggregates.


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