Superfluorescent Squaraine with Efficient Two‐Photon Absorption and High Photostability

Belfield, Kevin D.; Bondar, Mykhailo V.; Haniff, Hafeez S.; Михайлов, И. В.; Luchita, Gheorghe; Przhonska, Olga V.

doi:10.1002/cphc.201300447

Cited by 33 publications

(86 citation statements)

References 81 publications

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“…Relatively weak 2PA efficiency (δ 2PA ∼ 100 GM) was observed in this spectral range with a noticeable increase to ∼1000 GM (long wavelength 2PA maximum) at the vibrational shoulder of the 1PA contour (at ≈600 nm). This is evidence of vibronic coupling with asymmetrical vibration modes, 11,21,71 which violates the selection rules. 72,73 The most intense short wavelength 2PA maximum with δ 2PA ≈ 8000 GM (at ≈820 nm) corresponded to the spectral range of the lowest 1PA (see insert in Figure 3a) and two-photon allowed S 0 →S n transitions (S 0 and S n are the ground and high excited electronic states of 1, respectively).…”

Section: Methodsmentioning

confidence: 87%

“…Table 1. The steady-state 1PA spectra of 1 were similar to corresponding centrosymmetric short squaraines, 11,56 and exhibited relatively narrow and sharp absorption contours (Figure 2a−c, curve 1), except for ACN where an additional H-aggregate absorbance 28 was observed at ≈606 nm ( Figure 2d, curve 1) due to low solubility. In TOL, THF, and DCM solutions no aggregation effects were observed in the concentration range C ≤ 10 −3 M (see, e.g., Figure 3a, curves 1 and 2).…”

Section: Methodsmentioning

confidence: 89%

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Linear Photophysics and Femtosecond Nonlinear Spectroscopy of a Star-Shaped Squaraine Derivative with Efficient Two-Photon Absorption

et al. 2016

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The synthesis, comprehensive linear photophysical and photochemical study, two-photon absorption (2PA) spectrum, ultrafast relaxation kinetics in the excited states, and efficient superluminescence properties of a new symmetrical three-armed star-shaped squaraine derivative (1) are presented. The steady-state spectral parameters of 1 in a number of organic solvents, including fluorescence excitation anisotropy spectra, revealed a weak interaction between the squaraine branches and the effect of symmetry breaking in the ground electronic state. The degenerate 2PA spectrum of 1 was obtained over a broad spectral range with a maximum cross section of ∼8000 GM using the open aperture Z-scan technique. The nature of the fast dynamic processes in the excited electronic states of 1 was investigated by the femtosecond transient absorption pump−probe method, revealing characteristic relaxation times of ∼3−4 ps. The efficient superluminescence emission of 1 was observed in relatively low concentration solution (≈ 2.3·10 −4 M) under femtosecond transverse pumping. A quantum-chemical study of 1 was performed using ZINDO/S//DFTB theory levels. Simulated 1PA and 2PA absorption spectra were found to be in a good agreement with experimental data. The figure of merit for 1 is ∼10 11 GM, 1 one of the highest values ever reported for two-photon fluorescence molecular probes, suggesting strong potential for its application in two-photon fluorescence microscopy and bioimaging.

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Section: Methodsmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 89%

Linear Photophysics and Femtosecond Nonlinear Spectroscopy of a Star-Shaped Squaraine Derivative with Efficient Two-Photon Absorption

et al. 2016

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“…We have found that the subtle changes of the number or position of the substituents close to the squaraine core influenced the twisting angle of the structure and led to significant variations in optical properties. [8b] Because of the twisted molecular structure and lower conjugation efficiency related to the intermolecular charge transfer interactions, it was reasonable to expect a modest 2PA cross section for AM‐1′ . [2a], , …”

Section: Resultsmentioning

confidence: 99%

“…[8b] Because of the twisted molecular structure and lower conjugation efficiency related to the intermolecular charge transfer interactions, it was reasonable to expect a modest 2PA cross section for AM‐1′ . [2a], , …”

Section: Resultsmentioning

confidence: 99%

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Far‐Red‐ to NIR‐Emitting Adamantyl‐Functionalized Squaraine Dye: J‐Aggregation, Dissociation, and Cell Imaging

Liu

Zhang

et al. 2018

Eur J Org Chem

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Squaraine dyes AM‐1′ and AM‐1 bearing adamantyl termini were synthesized and spectroscopically characterized. AM‐1′ exhibited intense absorption and sharp emission in the far‐red to near‐infrared (NIR) spectral region. The degenerate two‐photon absorption (2PA) spectrum of AM‐1′ was obtained over a broad spectral range with a maximum cross section of ca. 360 GM. In aqueous solutions, AM‐1′ displayed a strong tendency for J‐aggregation and the reference AM‐1 exhibited entirely different aggregation behavior. We conclude that both the terminal pendant groups and substituents adjacent to the squaraine core play important roles in determining the aggregation behaviors and optical properties of the resultant squaraine dyes. Further an AM‐1′/β‐cyclodextrin complex dramatically suppressed squaraine π–π stacking and dissociated the J‐aggregate. Fluorescence microscopy imaging of HCT 116 cells incubated with the complex was accomplished, suggesting the potential application of this complex in fluorescence bioimaging.

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Multiphoton Excited Fluorescent Materials for Frequency Upconversion Emission and Fluorescent Probes

Guo

Wong

2014

Advanced Materials

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Recent progress in developing various strategies for exploiting efficient MPA fluorophores for two emerging technological MPA applications including frequency upconversion photoluminescence and lasing as well as 2PA fluorescence bioimaging and biosensing are presented. An intriguing application of MPA frequency-upconverted lasing offers opportunity for the fabrication of high-energy coherent light sources in the blue region which could create new advantages and breakthroughs in various laser-based applications. In addition, multiphoton excitation has led to considerable progress in the development of advanced diagnostic and therapeutic treatments; further advancement is anticipated with the emergence of various versatile 2PA fluorescence probes. It is widely appreciated that the two-photon excitation offers significant advantages for the biological fluorescence imaging and sensing which includes higher spatial resolution, less photobleaching and photodamage as well as deeper tissue penetration as compared to the one-photon excited microscopy. To be practically useful, the 2PA fluorescent probes for biological applications are required to have a site-specificity, a high fluorescence quantum yield, proper two-photon excitation and subsequent emission wavelengths, good photodecomposition stability, water solubility, and biocompatibility besides large 2PA action cross-sections.

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Superfluorescent Squaraine with Efficient Two‐Photon Absorption and High Photostability

Cited by 33 publications

References 81 publications

Linear Photophysics and Femtosecond Nonlinear Spectroscopy of a Star-Shaped Squaraine Derivative with Efficient Two-Photon Absorption

Linear Photophysics and Femtosecond Nonlinear Spectroscopy of a Star-Shaped Squaraine Derivative with Efficient Two-Photon Absorption

Far‐Red‐ to NIR‐Emitting Adamantyl‐Functionalized Squaraine Dye: J‐Aggregation, Dissociation, and Cell Imaging

Multiphoton Excited Fluorescent Materials for Frequency Upconversion Emission and Fluorescent Probes

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