Two triphenylamine chalcone derivatives, compound 1 and compound 2, were successfully synthesized via the Vilsmeier-Haack reaction followed by Claisen-Schmidt condensation. The structural integrity and purity of both compounds were confirmed through 1H NMR, 13C NMR, and HR-MS analyses. UV-Vis absorption and fluorescence emission spectroscopy were employed to investigate their photophysical properties in various solvents, particularly in ethanol/water mixtures. Results revealed that both compounds exhibit significant aggregation-induced emission (AIE) characteristics: their fluorescence intensity dramatically increases upon aggregation, especially when the water volume fraction exceeds 40% for compound 1 and 50% for compound 2. This enhancement is attributed to the restriction of intramolecular rotation and the occurrence of excited-state intramolecular proton transfer (ESIPT), which are facilitated in the aggregated state due to reduced molecular mobility and stabilization of hydrogen bonding between the hydroxyl and carbonyl groups.
The solvent effect on optical behavior was further evaluated using a Lippert-Mataga plot, which demonstrated a linear relationship between Stokes shift and solvent orientation polarizability. This indicates that the electronic transition in both compounds is sensitive to solvent polarity, with greater stabilization of the excited state observed in more polar environments. Additionally, the fluorescence emission spectra in different solvents showed red-shifted maxima in nonpolar media such as toluene and chloroform, suggesting enhanced conjugation or charge transfer in less polar conditions.Vinculin Antibody manufacturer
Solid-state fluorescence measurements indicated weak emission for both compounds, with maximum peaks at 610 nm (compound 1) and 620 nm (compound 2), compared to 550 nm and 541 nm, respectively, in ethanol solution.TUBB1 Antibody Technical Information This red shift in the solid state is primarily caused by intermolecular π-π stacking interactions, which promote close molecular packing and quench fluorescence through energy transfer. Density functional theory (DFT) calculations supported this finding, revealing a planar molecular conformation that favors stacking, thereby reducing radiative decay efficiency.
pH responsiveness studies showed that the fluorescence intensity remains stable under acidic conditions (pH < 7), as the phenolic OH group remains protonated and capable of forming a stable hydrogen bond. However, in alkaline environments (pH > 7), deprotonation of the OH group disrupts the ESIPT process, leading to a sharp decrease in fluorescence intensity.PMID:34918343 This pH-dependent behavior highlights the potential of these compounds as environmental sensors.
Electrochemical analysis via cyclic voltammetry revealed that compound 1 exhibits a lower oxidation onset potential (1.06 V) than compound 2 (1.08 V), indicating higher electron-donating ability and easier oxidation. Thermal stability assessments using TGA showed that compound 1 decomposes at a higher temperature (Td = 410°C) than compound 2 (Td = 340°C), suggesting improved thermal robustness due to increased steric hindrance from additional branching.
In conclusion, the triphenylamine chalcone derivatives display strong AIE behavior, excellent pH sensitivity, favorable electrochemical properties, and enhanced thermal stability—particularly in the case of compound 1. These features make them promising candidates for applications in optoelectronic devices, biological imaging, and chemical sensing.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com