Synthesis and Characterization of Water-Soluble Phenylene−Vinylene-Based Singlet Oxygen Sensitizers for Two-Photon Excitation

Abstract

[reaction: see text] The synthesis and characterization of water-soluble singlet oxygen sensitizers with a phenylene-vinylene motif is presented. The principal motivation for this study was to better understand specific features of a water-soluble molecule that influence the photosensitized production of singlet oxygen upon nonlinear, two-photon excitation of that molecule. To achieve water solubility, sensitizers were synthesized with ionic as well as nonionic substituents. In the ionic approach, salts of N-methylated pyridine, benzothiazole, and 1-methyl-piperazine moieties were used, as were aryl-substituted sulfonic acid moieties. In the nonionic approach, aryl-substituted triethylene glycol moieties were used. Selected photophysical properties of the compounds synthesized were determined, including singlet oxygen quantum yields. Of the molecules examined, the most efficient singlet oxygen sensitizers had triethylene glycol units as the functional group that imparted water solubility. Molecules containing the ionic moieties did not make singlet oxygen in appreciable yield nor did they efficiently fluoresce. Rather, for these latter molecules, rapid charge-transfer-mediated non-radiative processes appear to dominate excited state deactivation.

Formation of Metal‐Assisted Stable Double Helices in Dimers of Cyclic Bis‐Tetrapyrroles that Exhibit Spring‐Like Motion

“…[17] (100 mg, 0.106 mmol) and the mixture was stirred at room temperature for 30 min. The solvent was evaporated to dryness and the residue was purified by alumina (CH 2 Cl 2 ) and silica gel column chromatography (Wakogel C300, CH 2 Cl 2 /hexane = 2:1) and recrystallized from CHCl 3 /MeOH to afford 3OC 16 5-(3,4,5-Tri-TEG-phenyl)dipyrromethane (3TEGPh-DPM): 3,4,5-Tri-TEG-benzaldehyde [18] (1.78 g, 2.93 mmol) was dissolved in pyrrole (1.22 mL, 17.6 mmol) and CH 2 Cl 2 (10 mL) and degassed by bubbling with nitrogen for 30 min. Trifluoroacetic acid (22 mL, 0.293 mmol) was added and the solution was stirred under N 2 at room temperature for 30 min and then quenched with triethylamine (1 mL).…”

Two-photon Absorbing Photonic Materials: From Fundamentals to Applications

“…This is an area that has attracted increased attention. Some recent examples of two-photon photosensitized production of singlet oxygen are difuranonaphthalenes [97], porphyrin [98,99], phenylene-vinylene-based molecules [100], and fluorene [75] derivatives. However, these PS either possess low efficiency of 2PA or poor compatibility with the biological environment.…”

Enhanced Two‐Photon Absorption of Organic Chromophores: Theoretical and Experimental Assessments

“…Even though TPA based approaches hold a considerable advantage over conventional one-photon absorption (OPA) technique due to spatial resolution and deep penetration of long wavelength irradiation into tissues, few organic photosensitizers based on a TPA mechanism have been suggested. [53,[62][63][64][65][66][67] Among the other applications in the field of biology, the technique of two-photon laser scanning fluorescence microscopy [9,[17][18][19]68] is well-spread. For example, it enables in vivo imaging of calcium dynamics [20,69,70] or intracellular zinc.…”