Amphiphilic Squaraine Dye Aggregates: Evidence for a Cyclic Chiral Structure as a General Supramolecular Structure for Aggregates of Dyes and Aromatic Molecules

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

doi:10.1021/ja00132a031

Cited by 67 publications

(78 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[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.

View full text Add to dashboard Cite

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.

show abstract

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.

View full text Add to dashboard Cite

show abstract

“…Basic units in aggregates have rarely been reported, [45,46] for example, the monomers of the mentioned styrylthiophene phospolipid create a tetramer unit. [12] The formation of aggregation units is consistent with the observation of quantized aggregation numbers (AN), [47] where the total aggregation number can only be a multiple of monomers in the primary aggregation unit.…”

Section: Resultsmentioning

confidence: 99%

Optically Active Oligomer Units in Aggregates of a Highly Unsaturated, Optically Inactive Carotenoid Phospholipid

Foss

Sliwka

Partali

et al. 2005

Chemistry A European J

View full text Add to dashboard Cite

Enantiomers of glycerophospholipids show low or no optical activity. Accordingly, optical activity was not observed with the R enantiomer of a highly unsaturated carotenoyl lysophospholipid in solution. In spite of this, strong Cotton effects are detected in water. The amphiphilic carotenoid-phospholipid monomers associate to form aggregates, whose optical activity is attributed to oligomeric entities. These small helical assemblies cannot exist independently. Yet, the calculated octamer represents the simplest repeating primary unit that sufficiently expresses the absorption properties and supramolecular optical activity.

show abstract

“…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: 84%

“…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

View full text Add to dashboard Cite

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.

show abstract

Amphiphilic Squaraine Dye Aggregates: Evidence for a Cyclic Chiral Structure as a General Supramolecular Structure for Aggregates of Dyes and Aromatic Molecules

Cited by 67 publications

References 0 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^†

Optically Active Oligomer Units in Aggregates of a Highly Unsaturated, Optically Inactive Carotenoid Phospholipid

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

Contact Info

Product

Resources

About

Amphiphilic Squaraine Dye Aggregates: Evidence for a Cyclic Chiral Structure as a General Supramolecular Structure for Aggregates of Dyes and Aromatic Molecules

Cited by 67 publications

References 0 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†

Optically Active Oligomer Units in Aggregates of a Highly Unsaturated, Optically Inactive Carotenoid Phospholipid

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

Contact Info

Product

Resources

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^†