Aggregation of a Surfactant Squaraine in Langmuir-Blodgett Films, Solids, and Solution

Chen, Huijuan; Herkstroeter, William G.; Perlstein, Jerry; Law, Kock‐Yee; Whitten, David G.

doi:10.1021/j100070a033

Cited by 67 publications

(94 citation statements)

References 11 publications

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“…[14][15][16][17][18][19][20] Some bis(hydroxyphenyl)-squaraines were observed to form head-to-tail (J-type) aggregates due to intermolecular hydrogen bonding. 14 Complexation with iodine 14 and titanium dioxide 15 brought about an enhancement in the aggregate formation.…”

Section: Introductionmentioning

confidence: 99%

Aggregation Behavior of Water Soluble Bis(benzothiazolylidene)squaraine Derivatives in Aqueous Media^†

Das¹,

Thomas²,

Thomas³

et al. 1996

J. Phys. Chem.

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Two new water soluble squaraine dyes, bis[3-(p-carboxybenzyl)benzothiazol-2-ylidene]squaraine (Sq1) and bis [3-(carboxymethyl)benzothiazol-2-ylidene]squaraine (Sq2), have been synthesized and their photophysical properties have been characterized. Sq1 and Sq2 form dimer aggregates in water that have absorption bands blue-shifted to those of the monomeric forms. Aggregate formation is more preferred in D 2 O than in H 2 O. In the presence of low concentrations (<3 × 10 -4 M) of poly(vinylpyrrolidone) (PVP), enhancement in aggregate formation of Sq1 is observed, whereas that of Sq2 remains unaffected. Higher concentration (>3 × 10 -4 M) of PVP leads to the disruption of the aggregate and formation of a new species with absorption bands red-shifted to those of the corresponding monomers. The nature of these interactions has been investigated. It is proposed that hydrophobic interaction between the chromophoric units is the major driving force for the formation of the H-type (sandwich) aggregates in water. The red-shifted species are attributed to the monomeric forms, microencapsulated in a hydrophobic environment provided by PVP. Picosecond laser flash photolysis studies of the aggregates show clear evidence for the breakup of the aggregate from the excited state to yield an excited state-ground state monomer pair that rapidly recombines to reform the ground state dimer.

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Section: Introductionmentioning

confidence: 99%

Aggregation Behavior of Water Soluble Bis(benzothiazolylidene)squaraine Derivatives in Aqueous Media^†

Das¹,

Thomas²,

Thomas³

et al. 1996

J. Phys. Chem.

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“…Figure 2J). This NIR-emitting compound is particularly intriguing, as the ester moiety can be readily functionalized [84][85] and utilized for biological applications such as protein labeling. 75 Similarly, NIR terrylene fluorophores function as efficient energy acceptors in thin film blends with polymer 1 (Figure 2K-M).…”

mentioning

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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“…The J-aggregate phase of squaraines is also possible in their crystalline bulky films. 22,23 In this study, we report an observation of J-and H-aggregation of squaraines in confined solutions of a capillary thickness. We compare, on one hand, the behavior of different squaraines ( Figure 1) which do not form J-aggregates in the bulk solution and, on the other hand, the behavior of pseudoisocyanine (PIC) dye which readily forms J-aggregates in the bulk aqueous solution.…”

Section: Introductionmentioning

confidence: 87%

“…Such a spectral shift corresponds to the formation of H-aggregates. 22,23 (b) Thin Films Deposited in a Vacuum. To give more details of how different squaraines can aggregate, we present here results on vacuum-deposited films which have been described in detail in our previous work.…”

Section: Electronic Absorption Spectra Of Squaraines: General Behaviomentioning

confidence: 99%

Solvent-Induced Organization of Squaraine Dyes in Solution Capillary Layers and Adsorbed Films

et al. 2005

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Unusual behavior of indolenine and hydroxyphenyl squaraines has been observed in solution capillary layers and adsorbed films. The confined solutions showed anomalous aggregation of squaraine molecules in contrast to their monomer behavior in the bulk solutions of the same concentration, along with formation of a macroscopic cell-like structure in the confined solution layer, with the diameter of cells being 3-5 microm. The aggregate structure, as observed through electronic absorption spectra, was strongly dependent on the chemical structure of squaraine used and solvent used, and it also was different from squaraine aggregates observed in aqueous solutions and films prepared by vacuum evaporation. It has been found that indolenine squaraine is capable of forming H-aggregates in confined dimethylformamide solutions and hydroxyphenyl squaraine is capable of forming J-aggregates in confined dimethylformamide solutions and adsorbed films. The results were compared with pseudoisocyanine, which forms J-aggregates in aqueous bulk solutions readily; however, no J-aggregates have been found in their capillary layers. The interplay of dye-dye, dye-surface, and dye-solvent interactions resulting in the above effects is discussed.

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Aggregation of a Surfactant Squaraine in Langmuir-Blodgett Films, Solids, and Solution

Cited by 67 publications

References 11 publications

Aggregation Behavior of Water Soluble Bis(benzothiazolylidene)squaraine Derivatives in Aqueous Media^†

Aggregation Behavior of Water Soluble Bis(benzothiazolylidene)squaraine Derivatives in Aqueous Media^†

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

Solvent-Induced Organization of Squaraine Dyes in Solution Capillary Layers and Adsorbed Films

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Aggregation of a Surfactant Squaraine in Langmuir-Blodgett Films, Solids, and Solution

Cited by 67 publications

References 11 publications

Aggregation Behavior of Water Soluble Bis(benzothiazolylidene)squaraine Derivatives in Aqueous Media†

Aggregation Behavior of Water Soluble Bis(benzothiazolylidene)squaraine Derivatives in Aqueous Media†

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

Solvent-Induced Organization of Squaraine Dyes in Solution Capillary Layers and Adsorbed Films

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About

Aggregation Behavior of Water Soluble Bis(benzothiazolylidene)squaraine Derivatives in Aqueous Media^†

Aggregation Behavior of Water Soluble Bis(benzothiazolylidene)squaraine Derivatives in Aqueous Media^†