Anion-controlled morphologies and spectral features of cyanine-based nanoGUMBOS – an improved photosensitizer

Abstract

The ability to control the morphologies and spectral properties of organic low-dimensional nanomaterials is of paramount importance. The research reported herein demonstrates a template-free approach to tailored morphological and optical properties for a novel class of pseudoisocyanine (PIC)-based fluorescent organic nanoparticles derived from a group of uniform materials based on organic salts (GUMBOS). The synthesized nanoscale PIC-based particles (termed nanoGUMBOS), [PIC][NTf(2)] and [PIC][BETI], exhibit interesting adaptability as a function of the associated anion. The diamond-shaped nanostructures of [PIC][NTf(2)] and [PIC][BETI] nanorods exhibit enhanced fluorescence quantum yields relative to the parent compound, [PIC][I]. As supported by fluorescence lifetime measurements, these enhanced spectral properties can be attributed to differences in molecular self-assembly ordering (e.g., H- vs. J-aggregation) and restricted molecular rotation leading to reduced twisted intramolecular charge transfer in the nanoGUMBOS. The electrochemical properties of the PIC-based GUMBOS suggest their potential use in dye-sensitized solar cells.

Increasing Photovoltaic Performance of an Organic Cationic Chromophore by Anion Exchange

“…At the same time new features like enhanced thermal stability and solubility were introduced 24. Salt metathesis using two‐phase liquid/liquid systems is the most commonly used technique 25, 26, 27. However, it often requires several purification steps either by recrystallization or column chromatography, which lowers the yield of the desired organic salt.…”

Hierarchial Coassembly of a Cyanine Dye in Poly(vinyl alcohol) Fibrous Films by Electrospinning

“…1 The aggregation patterns of the dye molecules exhibit red shift (J-type) and blue shift (H-type) in absorption bands. 2,3 TTBC is a twodimensional planar molecule that can form secondary interactions, yielding intriguing supramolecular structure. This cyanine dye undergoes both H-and J-type aggregation by shortrange noncovalent interactions, such as dipole−dipole interactions, π−π stacking, and hydrogen bonding.…”

Strategies for controlled synthesis of nanoparticles derived from a group of uniform materials based on organic salts

“…Nevertheless, the size-control of melt-emulsionquench-derived nanoparticles was still considered a major challenge. In some of our more recent studies, a reprecipitation approach commonly employed in the synthesis of organic nanoparticles [22,23] was extended to the preparation of nanoGUMBOS in an aqueous medium [12,14,18,19]. Although this method can be used to produce nanoparticles with average sizes in the nanometer regime, it is difficult to deliver nanoparticles smaller than 20 nm without using additives such as surfactants or polymers [24].…”

“…NanoGUMBOS thus combine the versatility of GUMBOS with the enhanced properties often obtained at the nanoscale, offering the flexible design of organic nanomaterials. Within the last few years, nanoGUMBOS which possess fluorescent [12][13][14], magnetic [15], luminescent [16], pHsensitive [17], optoelectronic [18], and anticancer [19] properties have been described. Previous studies from our laboratory have demonstrated the wide tunability in the spectral and physical properties, as well as the morphologies of nanoGUMBOS through variation in the associated counter ion [14,18,20].…”