Chalcone-Analogue Dyes Emitting in the Near-Infrared (NIR):  Influence of Donor−Acceptor Substitution and Cation Complexation on Their Spectroscopic Properties and X-ray Structure

Abstract

The photophysical properties of several newly synthesized 1-benzothiazole-3-(4-donor)-phenyl-substituted prop-2-en-1-ones (substituted chalcones) are studied as a function of solvent polarity, temperature, and metal ion by employing steady-state and time-resolved spectroscopy. To investigate the effect of bulkiness and donor strength of the anilino moiety on the spectroscopic properties of these dyes, the spectroscopic behavior of the 4-N-dimethylamino (DMA), the 4-N-tetraoxa-monoaza-15-crown-5 (A15C5), and the 4-N-tetrathiamonoaza-15-crown-5 (AT 4 15C5) derivatives as well as the 3-julolidino (Jul) analogue is compared. Absorption and fluorescence measurements reveal that the strength of the intramolecular charge transfer (ICT) process increases on the order of AT 4 15C5 < A15C5 ∼ DMA < Jul. The slight but significant differences between the two crowned dyes are well-supported by the results of the X-ray structure analysis, where oxa aza and thia aza crowns show essentially different geometries. For both fluoroionophores, this variation of heteroatom substitution pattern of the receptor induces specific cation selectivities. The spectroscopic effects accompanying complexation and the different binding sites are studied by steady-state and time-resolved optical spectroscopy as well as NMR spectroscopy. Whereas the probe carrying a tetraoxa monoaza 15-crown-5 receptor shows cation-induced fluorescence enhancement in the presence of alkali and alkaline-earth metal ions, its tetrathia analogue binds selectively to Hg II , Ag I , and Cu II in acetonitrile. Moreover, an increase in fluorescence is observed for the latter probe even upon coordination to the widely known fluorescence quencher Hg II . Besides receptor complexation, chelate formation in the benzothiazole-carbonyl acceptor part of these intrinsic fluorescent probes is possible, leading to a chromoionophoric signaling behavior in the near-infrared (NIR).

Synthesis and Characterization of an Efficient New Liquid Laser Dye Material - Chalcone (DMAPPP)

“…In spite of it there are versatile chemical and physical properties, and there are very limited data describing the photochemical and physical properties of these compounds. Recent reports related cocoons are widely used for various optical applications including second harmonic generation materials in nonlinear optics, photorefractive polymers, holographic recording materials and fluorescent probes for sensing of metal ions [9][10][11][12][13][14][15][16][17][18]. How- * corresponding author; e-mail: aminosman81@gmail.com ever, the photophysical properties of these chalcones such as solvent environment, temperature effect and quantum yield of fluorescence were not fully studied.…”

Structural characteristics and optical properties of a series of solvatochromic fluorescent dyes displaying long-wavelength emission

“…Similar observations have also been reported by Fayed for other types of fluorescent solvatochromic dyes [23], and can be explained by several mechanisms such as biradicaloid charge transfer, proximity effect and conformational changes. The dramatical decrease of the quantum yield in the protic polar alcohols is assumed to be due to hydrogen bonding interactions between the dye and the solvent, giving rise to enhanced non-radiative losses and quenching [19,24,25]. The existence of specific dye-solvent interactions in protic solvents is also supported by the particular spectral behavior of KSD-4 in alcohols, as mentioned above (Fig.…”

Ultrafast Dynamics of the Excited States of Hydrogen‐Bonded Complexes and Solvation

“…Copyright 2005 American Chemical Society responsible for the solvatochromic properties of these dyes in aprotic solvents, specific interaction involving formation of intermolecular hydrogen-bond provides stronger solvatochromic behavior of these dyes in protic solvents. Workers from different groups have also shown that the ketocyanine dyes form strong hydrogenbonded complexes both in the ground state and in the excited state [113][114][115][116]. However, the fluorescence efficiency of these dyes is seen to be reduced significantly in protic solvents due to hydrogen-bonding interaction with the solvent.…”