Heptamethine Cyanine Dyes with a Large Stokes Shift and Strong Fluorescence:  A Paradigm for Excited-State Intramolecular Charge Transfer

Peng, Xiaojun; Song, Fengling; Lu, Erhu; Wang, Yanan; Zhou, Wei; Fan, Jiangli; Gao, Yanfang

doi:10.1021/ja043413z

Cited by 514 publications

(381 citation statements)

References 21 publications

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“…Extending Stokes Shift Structure−Property Relationships to Other Fluorophore Chemical Families. The "rotating" substituents that induce large Stokes shifts are present not only in coumarins but also in other chemical families, such as BODIPY dyes, 32,75−77 heptamethine cyanine dyes, 31 and stilbene derivatives. We first compare the molecular structures and properties of 12 and 13 (Scheme 4).…”

Section: Resultsmentioning

confidence: 99%

“…The great increase in the Stokes shifts has been attributed the "ICT" state of the new dyes. 31 The molecular origin of this "ICT" state is actually linked to substituent rotation upon the excitation of 18a and 18b. Because of their steric bulk, these substituents are forced to bend out of the molecular plane of the core chemical fragment in their ground state, as suggested by our DFT calculations ( Figure 9).…”

Section: Stokes Shift Trends In Heptamethine Cyanine Dyesmentioning

confidence: 99%

“…However, prior to chemical synthesis, one may not be sure which position to attach a substituent in the dye framework to maximize the spectral shift. An even more puzzling question concerns the Stokes shift: although it has been suggested that the rotation of a molecular structure upon its excitation leads to a large Stokes shift, such as in biphenyl, 29 9-t-butylanthracene, 30 pyrazolo-coumarin derivatives, 30 heptamethine cyanine dyes, 31 and BODIPY dyes, 32 there is a lack of detailed guidelines on how to design new fluorophores with such rotating structures and large Stokes shifts; moreover, introducing substituents to a fluorophore framework often shifts the UV−vis absorption and emission spectra of the dye in the same direction. Consequently, the overall change in the Stokes shift remains small.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Molecular Design of UV–vis Absorption and Emission Properties in Organic Fluorophores: Toward Larger Bathochromic Shifts, Enhanced Molar Extinction Coefficients, and Greater Stokes Shifts

2013

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Understanding the molecular origins of the optoelectronic properties of fluorophores provides rational guidelines for chemists to synthesize better-performing dyes. Factors affecting the UV−vis absorption spectral shift, molar extinction coefficients, and Stokes shift of fluorophores are herein examined at the molecular level, via both (time-dependent) density functional theory-based calculations and the empirical harmonic-oscillator-stabilization-energy (HOSE) and bond-lengthalternation (BLA) models. The importance of these factors is discussed using six coumarin dyes as exemplars. In particular, a special focus is devoted to the Stokes shift, a critical parameter in fluorophores. It is demonstrated that incorporating a "rotational" substituent in a fluorophore molecule with tailored steric hindrance effects and resonance effects leads to a substantial increase in the Stokes shift, not only in coumarins but also in other chemical dye families: boron-dipyrromethenes (BODIPYs), cyanines, and stilbenes. Structure−property relationships concerning the rotational substituent are discussed in detail with examples of several dye families. These findings lead to the proposal of molecular design criteria that enable one to tune the Stokes shift. Such criteria provide a foundation for the molecular engineering of fluorophores with improved optoelectronic properties.

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Section: Resultsmentioning

confidence: 99%

Section: Stokes Shift Trends In Heptamethine Cyanine Dyesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular Design of UV–vis Absorption and Emission Properties in Organic Fluorophores: Toward Larger Bathochromic Shifts, Enhanced Molar Extinction Coefficients, and Greater Stokes Shifts

2013

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“…state increase, leading to a blue shift in the absorption spectra. 24 From the Table 4, it could also be found, almost all the dyes (except D3 and D8), displayed a blue shift in the absorption spectra with increasing the polarity of the solvent in the protonic solvents. These hypsochromic shifts were most likely explained as follows: since these dyes were ionic dyes, which exhibited a polar character in the ground state, hence the solvent molecules were oriented in such a way as required by the polar character of the dye molecule.…”

Section: Resultsmentioning

confidence: 85%

Efficient One-Pot Three-Component Synthesis of Monomethine Cyanine Dyes with Quinoline Nucleus and Their Spectral Properties

Fu¹,

Zhang²,

Wang³

et al. 2013

Bulletin of the Korean Chemical Society

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An improved method for the preparation of monomethine cyanine dyes with quinoline nucleus by one-pot three-component using 1-methyl-2-quinolinethione, quaternized 2-or 4-methylheterocyclic compounds and methyl p-toluenesulfonate as starting materials was described. Compared with the traditional methods, the new synthetic method reduced the reaction steps, shortened the reaction time, avoided the separation and purification of the intermediate and reduced cost. The dyes absorbed in the region 478.0-563.0 nm and had molar extinction coefficients of 1.3 × 10 4 -9.4 × 10 4 L mol. Their fluorescence maxima and Stokes shifts were in the range of 525.2-594.4 nm and 16.2-80.6 nm in different solvents, respectively. From the spectral properties of the dyes in different solvents, it could be found that the λ max of the dyes were shorter in protonic solvents, and showed hypsochromic shifts with the increase of polarity of the solvents.

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“…For example, heptamethine cyanine dyes have been modified by introducing a chlorocyclohexenyl ring in the methine chain, which improves photostability and fluorescence QY and provides a site for further chemical modification. 13 In the present work, one of these heptamethine cyanine dyes (IR780) was modified with an aminoalkylcarboxylic acid; introducing an aminoalkyl group at the central position results in a relatively stronger fluorescent dye with a large Stokes shift (.110 nm) compared with IR780 itself. Due to this large Stokes shift, fluorescence resonance energy transfer among the dye molecules would be negligible, thus making encapsulation inside a solid matrix more viable while retaining high luminescence.…”

Section: Resultsmentioning

confidence: 99%

Multi-dye theranostic nanoparticle platform for bioimaging and cancer therapy

Singh¹,

Hahn²,

Gutwein³

et al. 2012

IJN

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Background: Theranostic nanomaterials composed of fluorescent and photothermal agents can both image and provide a method of disease treatment in clinical oncology. For in vivo use, the near-infrared (NIR) window has been the focus of the majority of studies, because of greater light penetration due to lower absorption and scatter of biological components. Therefore, having both fluorescent and photothermal agents with optical properties in the NIR provides the best chance of improved theranostic capabilities utilizing nanotechnology. Methods: We developed nonplasmonic multi-dye theranostic silica nanoparticles (MDT-NPs), combining NIR fluorescence visualization and photothermal therapy within a single nanoconstruct comprised of molecular components. A modified NIR fluorescent heptamethine cyanine dye was covalently incorporated into a mesoporous silica matrix and a hydrophobic metallonaphthalocyanine dye with large molar absorptivity was loaded into the pores of these fluorescent particles. The imaging and therapeutic capabilities of these nanoparticles were demonstrated in vivo using a direct tumor injection model. Results:The fluorescent nanoparticles are bright probes (300-fold enhancement in quantum yield versus free dye) that have a large Stokes shift (.110 nm). Incorporation of the naphthalocyanine dye and exposure to NIR laser excitation results in a temperature increase of the surrounding environment of the MDT-NPs. Tumors injected with these NPs are easily visible with NIR imaging and produce significantly elevated levels of tumor necrosis (95%) upon photothermal ablation compared with controls, as evaluated by bioluminescence and histological analysis. Conclusion: MDT-NPs are novel, multifunctional nanomaterials that have optical properties dependent upon the unique incorporation of NIR fluorescent and NIR photothermal dyes within a mesoporous silica platform.

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Heptamethine Cyanine Dyes with a Large Stokes Shift and Strong Fluorescence: A Paradigm for Excited-State Intramolecular Charge Transfer

Cited by 514 publications

References 21 publications

Molecular Design of UV–vis Absorption and Emission Properties in Organic Fluorophores: Toward Larger Bathochromic Shifts, Enhanced Molar Extinction Coefficients, and Greater Stokes Shifts

Molecular Design of UV–vis Absorption and Emission Properties in Organic Fluorophores: Toward Larger Bathochromic Shifts, Enhanced Molar Extinction Coefficients, and Greater Stokes Shifts

Efficient One-Pot Three-Component Synthesis of Monomethine Cyanine Dyes with Quinoline Nucleus and Their Spectral Properties

Multi-dye theranostic nanoparticle platform for bioimaging and cancer therapy

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