Squaraine-Derived Rotaxanes:  Sterically Protected Fluorescent Near-IR Dyes

Arunkumar, Easwaran; Forbes, Christopher C.; Noll, Bruce C.; Smith, Bradley D.

doi:10.1021/ja042404n

Cited by 282 publications

(170 citation statements)

References 23 publications

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“…[63][64] They have been utilized in a variety of applications, including as chemosensors for metal ions [65][66][67][68] and thiols, 69 as indicators of membrane polarity, 70 and as guests encapsulated in aromatic macrocycles. [71][72][73] Squaraines have also been utilized extensively for biological imaging. [74][75] The absorption and fluorescence maxima of fluorophores in spin-cast PMMA films and their extinction coefficients a at their absorption maxima.…”

Section: Methodsmentioning

confidence: 99%

Photoluminescent energy transfer from poly(phenyleneethynylene)s to near‐infrared emitting fluorophores

Levine

Song

Andrew

et al. 2010

J. Polym. Sci. A Polym. Chem.

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Photoluminescent energy transfer was investigated in conjugated polymer-fluorophore blended thin films. A pentiptycene-containing poly(phenyleneethynylene) was used as the energy donor, and 13 fluorophores were used as energy acceptors. The efficiency of energy transfer was measured by monitoring both the quenching of the polymer emission IntroductionThe highly efficient energy transfer 1 and exciton migration processes 2 in conjugated polymers can be exploited in various electronic applications 3-11 and in amplifying sensor responses. [12][13][14][15][16][17][18][19] Highly sensitive, amplified quenching of polymer emission has been accomplished with various quenchers in solution as well as in the solid state. [20][21][22][23][24][25] Applications of this amplified quenching include the detection of chemical and biological analytes, 26-38 and explosives. 39 In contrast to turn-off sensors based on amplified polymer quenching, turn-on sensors have the advantage of potentially being even more sensitive and selective, 40-41 especially if the new signal can be generated on a completely dark background. Some examples of turn-on sensors have been developed previously. [42][43][44][45] In many of these sensors, the emission spectrum of the donor overlaps with the emission spectrum of the acceptor. This overlap leads to decreased sensitivity in turn-on sensory applications, as even in the absence of the acceptor there is background donor emission in the same spectral region, and hence not the desired completely dark background.Recent results from our group have demonstrated superior energy transfer with reduced spectral overlap between the absorption spectra of the streptavidin-functionalized fluorophore acceptors and the emission spectrum of the biotin-functionalized Additionally, turn-on sensors that display a new fluorescence emission in the nearinfrared (NIR) region (650-900 nm) are highly desirable for biological applications. [47][48] Biological chromophores exhibit low absorption and auto-fluorescence in this spectral region, which allows photons to penetrate biological tissue. 49 Some applications of NIR fluorophores in biological imaging have been reported; 50-55 however, the use of conjugated polymers as energy donors in combination with NIR energy acceptors allows for highly amplified fluorescence emission in a spectral region that is free of interfering signals (neither the polymer donor nor biological analytes fluoresce in this region).We report herein a thorough investigation of the energy transfer between a conjugated PPE and 13 commercially available and readily-synthesized fluorophores. These compounds have absorption maxima ranging from 537 nm to 686 nm, with many of the compounds absorbing and fluorescing in the NIR region. We show highly efficient energy transfer from the PPE to the fluorophores, with nearly 100-fold fluorescence amplification in the NIR region from exciting the PPE compared to exciting a squaraine chromophore directly. Experimental

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Section: Methodsmentioning

confidence: 99%

Photoluminescent energy transfer from poly(phenyleneethynylene)s to near‐infrared emitting fluorophores

Levine

Song

Andrew

et al. 2010

J. Polym. Sci. A Polym. Chem.

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“…Arunkumar and Smith introduced a smart supramolecular approach to solve both problems at the same time: the encapsulation of the squaraine as the thread component inside an interlocked rotaxane structure. [13] Scheme 13.…”

Section: Squaraine-based Rotaxanesmentioning

confidence: 99%

“…All of these favourable features promote their exploitation in a number of technologically relevant applications including photoconductivity [3] data storage, [4] light emitting field-effect transistors, [5] solar cells [6][7][8] and nonlinear optics. [9] Recently, it has been shown that squaraines can also behave as very efficient two-photon absorbers, [10] fluorescent histological probes, [11] highly stable fluorescent near-IR dyes, [12,13] active media for fluorescence patterning [14] and possibly as second-generation photosensitizers for photodynamic therapy (PDT). [15,16] Aim of the present review is to summarize the most convenient strategies for squaraines and polysquaraines syntheses and to discuss the design strategies enabling for the preparation of squaraines having properties relevant for a given materials application.…”

Section: Introductionmentioning

confidence: 99%

Squaraine Compounds: Tailored Design and Synthesis towards a Variety of Material Science Applications

2010

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The interest in squaraine compounds, a relatively old class of dyes, has been recently renewed due to their potential usefulness in a large number of technologically relevant fields such as two-photon absorbing materials, field-effect transistors, solar cells, NIR-emitting fluorescent probes and sensitizers for photodynamic therapy. Aim of the present review is to summarize the most convenient strategies for squaraines and polysquaraines syntheses and to discuss the design strategies enabling for the preparation of squaraines having properties relevant for a given material application. In particular, in the first section of the review we will describe the various synthetic approaches for the preparation of squaraine and polysquaraine derivatives. The second section will

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“…[35] The thread component is a squaraine dye which emits potentially useful near-IR fluorescence, however, two drawbacks are the dye's suscep- tibility to nucleophilic attack [36] and aggregate formation. [37] These problems were rectified by converting the dye into a rotaxane.…”

Section: Rotaxane Dyesmentioning

confidence: 99%

Improving the Properties of Organic Dyes by Molecular Encapsulation

2005

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There is a demand for new methods of protecting organic dyes from aggregation effects and photochemical degradation. The purpose of this microreview is to summarize the recent attempts to improve the properties of dyes by molecular encapsulation. Organic dyes have been encapsulated inside inorganic matrices such as molecular sieves, and molecular containers such as cyclodextrins, cucurbiturils, dendrimers, and self-assembled gels. Another strategy is perma- IntroductionOrganic chromophores such as cyanines, squaraines, azo dyes and perylenediimide dyes are widely used as pigments in many commercial products. They are active ingredients in semiconducting materials, [1] textile products, [2] laser materials, [3] optical disks, [4] paints, [5] and probes for biological systems.[6] Modern research on organic dyes includes investigations of building blocks for conjugated polymers, hydrogen bonded assemblies, chromogenic sensors, molecular shuttles, solar energy cells, photonics and various approaches to photodynamic therapy. [7][8][9][10][11] A common limitation with organic dyes, especially those with long-wavelength absorption bands, is their susceptibility to chemical and photochemical degradation. The reason for the enhanced reactivity is the inherently small HOMO-LUMO energy gap, which means that the dyes are potentially reactive with both nucleophiles and electrophiles. Another potential drawback with organic dyes is their tendency to aggregate, which induces multichromophoric interactions that alter the color quality and quench the photoluminescence. In principle, these problems can be attenuated by supramolecular encapsulation strategies that isolate the individual dye molecules and prevent self-aggregation or similar interactions with the chemical environment. The purpose of this microreview is to summarize the recent literature on meth- Germany, 2005) ods to improve the properties of organic dyes by molecular encapsulation. The focus is on relatively "robust" molecular containers and does not include "soft" assemblies like micelles, emulsions or vesicles.

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Squaraine-Derived Rotaxanes: Sterically Protected Fluorescent Near-IR Dyes

Cited by 282 publications

References 23 publications

Photoluminescent energy transfer from poly(phenyleneethynylene)s to near‐infrared emitting fluorophores

Photoluminescent energy transfer from poly(phenyleneethynylene)s to near‐infrared emitting fluorophores

Squaraine Compounds: Tailored Design and Synthesis towards a Variety of Material Science Applications

Improving the Properties of Organic Dyes by Molecular Encapsulation

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