Bis-silylated terephthalate as a building block precursor for highly fluorescent organic–inorganic hybrid materials

Abstract

A bis-silylated diethyl 2,5-bis [N,N-(3-triethoxysilyl)propylurea]terephthalate precursor (5) was synthesized from a terephthalate derivative (3) and successfully used to prepare highly fluorescent organosilicas by hydrolytic self-condensation (DPM1) and co-condensation (DPM2) with tetraethoxysilane. The dyes 3 and 5 present absorption in the UV-Vis region and fluorescence emission in the yellow and blue regions, respectively. The red-shifted bands in the absorption spectra of dye 3 with respect to dye 5 can be related to the formation of intramolecular charge transfer (ICT) state even in the ground-state due to the strong electron-donor amino groups and moderate electron-withdrawing carbonyl groups present in the benzenic ring. The small Stokes' shift, as well as the high fluorescence quantum yield values discards the intramolecular proton transfer mechanism in the excited state. The fluorescence emission dependence on the solvent polarity indicates that an intramolecular charge transfer (ICT) or a locally excited (LE) state is taking place in the excited state to the dyes 3 and 5, respectively. The new fluorescent hybrid materials (DPM1 and DPM2) show absorption maxima in the solid state located at around 390 nm, indicating that the electronic structure of the fluorescent precursor was not significantly perturbed in the ground state after its self-condensation or co-condensation with TEOS. The fluorescent material DPM2 presents a photophysical behavior quite similar to the precursor in solution. On the other hand, the self-condensed material DPM1 presents a fluorescence emission maximum red-shifted by 33 nm, which can be probably attributed to p-p stacking between the terephthalate cores. Any evidence of auto-organization could be observed in these materials.

Synthesis, Optical and Electrical Characterization of Amino-alcohol Based Sol-gel Hybrid Materials

“…The values obtained for the elements of the EEC proposed and reported in Table 1, i.e., the values of resistance (R Sample ), the constant phase element (CPE), and α, were used to obtain the C eff using Equation (3). The resistance (R) and capacitance (C) values were normalized to cell geometry dimensions and calculated using Equations (4) and (5), respectively. The conductivity (σ) and relative permittivity (ε r ) were also determined using Equations (6) and 7, respectively.…”

“…The most remarkable properties of such OIH materials include chemical stability, suitable dielectric properties, selective ion binding, and ion conducting ability, depending on their organic and inorganic components. Such materials have also been reported as interesting luminescent sources [ 1 , 2 , 3 , 4 , 5 ] and hosts of luminescent species [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. For instance, Severo Rodembusch et al reported for the first time the synthesis of fluorescent hybrid aerogels in the blue–green–yellow region.…”

Red-Emitting SBBF (Single-Benzene-Based Fluorophore)-Silica Hybrid Material: One-Pot Synthesis, Characterization, and Biomedical Applications

“…DCD showed other finger-print peaks at 1700–1600 cm −1 (B), which also correlated with the ν(C=O) from the ester and ketone [ 27 ]. APTES showed a strong peak at 1105 cm −1 (C) as a ν(Si–O) [ 28 , 29 ]. The reaction of DCD and APTES, under the aerobic condition in the presence of Lewis acid (acetic acid), generated a benzene ring within the SBBF core, and we observed that c-SSH had finger-print peaks for the bending mode (δ) of aromatic C–H at 700–600 cm −1 (D) [ 30 ].…”

Diaminoterephthalate Fluorescence Dyes – Versatile Tools for Life Sciences and Materials Science

“…The group of Franciscato Campo et al prepared the bisureyl DAT 59 from parent starting material 4a by reaction with triethoxysilylpropylisocyanate (Scheme ) . Compound 59 was successfully used to prepare highly fluorescent organosilicas by hydrolytic self‐condensation or co‐condensation tetraethoxysilane.…”