Copper(II) Ion Promoted Reverse Solvatochromic Response of the Silatrane Probe to Spectral Shifts: Preferential Solvation and Computational Approach

Abstract

The unique solvatochromic attitude of an analyte owing to its coordination with metal ions in solvents of different polarities is challenging. Herein, we introduce two new solvatochromic 4-(pentan-3-yl) benzaldehyde-based triazolyl silatrane probes (5 and 6). The solvatochromic behavior of both probes 5 and 6 was studied using Reichardt’s E (30) and the Kamlet–Taft empirical scale by UV–visible spectra in 14 solvents (hydrogen-bond donor (HBD) and non-HBD), and the results show that probes 5 and 6 exhibit reverse solvatochromism. Probe 5 witnessed an enhancement in this behavior upon coordination with the Cu2+ ion in MeCN/MeOH solvents due to the intramolecular charge transfer (ICT) process. Interestingly, the binding of probe 5 with Cu2+ ions resulted in an instant color change in MeCN and MeOH from pale yellow to light blue and brown-red, respectively, which can be easily detected by the “naked eye”. A solvatochromic study of the complex 5–Cu2+ in binary mixtures of polar aprotic and polar protic solvents (MeCN/MeOH) discloses that the latter are more preferred over polar aprotic solvents in the solvation microsphere. The entire metal coordination process of probe 5 toward the Cu2+ ion can be visualized and was further evaluated by UV–vis/fluorescence spectral titrations, Fourier transform infrared (FT-IR) spectroscopy, and theoretical calculations employing density functional theory (DFT) and time-dependent-DFT (TD-DFT). The proposed analytical approach is believed to play a crucial role in the solvatochromic study of higher coordinated silicon compounds, which may be utilized to develop a solvent-dependent sensor.

Aryl sulfonate anion stabilized aromatic triangular cation [Pd3]+: syntheses, structures and properties

“…36 Basically, the excited states possessed greater polarity and was more benecial from increasing solvent polarity. [38][39][40] Generally, complex 7 conformed to the rule of uorescence intensity enhancement with increasing solvent polarity and presented apparently stronger emission in CH 3 OH. Meanwhile, the uorescence wavelengths also presented red shi when the polarity of organic solvents were increased.…”

A turn-on fluorescent Zn(ii) metal–organic framework sensor for quantitative anthrax biomarker detection

“…That is, the hydrogen bonding between DPA and 2,6-H 2 NBC ligands will increase the electron-accepting affinity and favor the charge flow for the ligandto-ligand charge transfer process, resulting in a fluorescence turn-on phenomenon at 400 nm. 66 Correspondingly, due to the weak intermolecular interactions, the fluorescence decay of 1 in the presence of DPA follows a biexponential decay dynamic with good fitting (Fig. 7 and Table S3 †).…”

“…That is, the hydrogen bonding between DPA and 2,6-H 2 NBC ligands will increase the electron-accepting affinity and favor the charge flow for the ligand-to-ligand charge transfer process, resulting in a fluorescence turn-on phenomenon at 400 nm. 66…”

Synthesis of Schiff base functionalized organosilatranes for the detection of Zirconium (IV) ion: Their cytotoxicity evaluation and anti‐inflammatory activity against cyclooxygenase‐2 via computational approach

“…The linear calibration curve was plotted between absorbance at λ max and increasing concentration of Zr(IV). The value of LOD was obtained from equation 3σ/k, where σ denotes standard deviation and k signifies slope 41 . The value of LOD calculated is 10.89 × 10 −7 M, indicating good sensitivity of 2a for the detection of Zr(IV) as shown in Figure 1d.…”