Synthesis, Structure, and Characterization of Chromo(fluoro)ionophores with Cation-Triggered Emission Based on N-Methylaza-Crown-Ether Styryl Dyes

Abstract

Novel 2-benzothiazole-, 4-pyridine-, and 2- and 4-quinoline-based styryl dyes containing an N-methylbenzoaza-15(18)-crown-5(6)-ether moiety were synthesized. A detailed electronic spectroscopy study revealed high performance of these compounds as optical molecular sensors for alkali and alkaline-earth metal cations. They were shown to considerably surpass analogous chromoionophores based on N-phenylaza-crown ethers regarding both the ionochromism and the cation-binding ability. In addition, they act as fluorescent sensors for the metal cations by demonstrating cation-triggered emission. Upon complexation with Ba(2+), the fluorescence enhancement factor reaches 61. The structural features of dyes and their metal complexes were studied by NMR spectroscopy and X-ray diffraction. The high degree of macrocycle preorganization was found to be one of the factors determining the high cation-binding ability of the sensor molecules based on N-methylbenzoaza-crown ethers.

On the Ion‐Pair Recognition and Indication Features of a Fluorescent Heteroditopic Host Based on a BODIPY Core

“…The magnitude of the observed shift follows the order NH 4 + ≈ K + > Na + > Li + , which is in agreement with the coordination preference of A18C6 2. In addition, Li + and Na + ions are also known to prefer oxygen over nitrogen coordination in such crowned dyes in acetonitrile, which leads to smaller spectral shifts that are frequently even accompanied by higher complexation constants 25,26a. The spectroscopic changes upon saturation with several cations and anions are summarized in Table 2.…”

The effect of ring sizes and alkali metal cations on interaction energy, charge transfer and nonlinear optical properties of crown ether derivatives

“…17 For example, the variation of ring sizes, 18 the oxygen atoms in the ring is replaced with nitrogen and sulfur heteroatoms, [19][20][21] the substituents of different functional groups in crown ether. 6 Due to the structural exibilities, thousands of crown compounds have been synthesized for specic goals. A novel compound 2 (Scheme 1) has been synthesized by condensation of 2,3,3-trimethylindolenine with substituted benzaldehydes in the presence of NaOMe in DMSO.…”

The Effect of Alkyl Substituent Length on Receptor Properties of Dithiaaza-Сrown-Hemicyanine MonolayersThe Effect of Alkyl Substituent Length on Receptor Properties of Dithiaaza-crown - Hemicyanine Monolayers

“…[1][2][3][4] From this standpoint, crown ether substituted fluoro-and chromophores capable of significant changes of photophysical properties upon selective binding of cations are of special interest. [5][6][7][8][9][10][11] Modification of the crown ether cycle allows achieving high selectivity and binding constants for biologically and environmentally important metal ions. For example, replacement of one or two oxygen atoms in this cycle by sulfur ones can lead to higher affinity for mercury and copper cations.…”

“…[12][13][14][15][16][17][18] Moreover, simultaneous inclusion of nitrogen atom into the crown-substituent of a coloured molecule as a part of both ionophoric and chromophoric moieties is an easy way to impart the chromoionophoric power to the dye molecule and obtain a spectral response to metal cation binding since their interaction with the nitrogen atom will reduce the overall chromophore conjugation and thus change the photophysical properties of the system. [5][6][7][8][9][10][11][19][20][21][22][23] In this regard, aza-crown substituted hemicyanines represent one of the most promising compounds for sensory applications due to the combination of hemicyanine spectral properties (absorbance and fluorescence in visible range), crown ether receptor ability and ease of chemical modification. [5,12,17,[24][25][26][27][28][29][30][31][32] However, most studies concerning the sensory properties of such crown-substituted hemicyanines were done in solution.…”

“…[5][6][7][8][9][10][11][19][20][21][22][23] In this regard, aza-crown substituted hemicyanines represent one of the most promising compounds for sensory applications due to the combination of hemicyanine spectral properties (absorbance and fluorescence in visible range), crown ether receptor ability and ease of chemical modification. [5,12,17,[24][25][26][27][28][29][30][31][32] However, most studies concerning the sensory properties of such crown-substituted hemicyanines were done in solution. At the same time, exploitation of the receptor properties of such compounds requires their immobilization onto the surface of the operational element of the sensor.…”