Solvatochromism of new tetraphenylethene luminogens: integration of aggregation-induced emission and conjugation-induced rigidity for emitting strongly in both solid and solution state.

In this study, we synthesized and characterized four tetraphenylethene (TPE) analogs, investigated their photophysical properties, and conducted quantum chemical calculations. Some molecules exhibited aggregation-induced emission enhancement behavior and showed efficient emission in both solid and solution states. Solvatochromism was observed in particular derivatives, with solvent polarity influencing either a bathochromic or hypsochromic shift, indicating the occurrence of photoinduced intramolecular charge transfer (ICT) processes. Quantum chemical calculations confirmed that variations in molecular packing and rigidity among the TPE analogs contributed to their diverse behavior. The study showcases aggregation in luminophores without significant impact on the excited state and highlights how minor alterations in terminal substituents can lead to unconventional behavior. These findings have implications for the development of luminescent materials. Furthermore, the synthesized compounds exhibited biocompatibility, suggesting their potential for cell imaging applications.

A post-sulfonated one-pot synthesized magnetic cellulose nanocomposite for Knoevenagel and Thorpe-Ziegler reactions.

The development of biodegradable and active cellulosic-based heterogeneous catalysts for the synthesis of different organic compounds would be attractive in pharmaceutical and petrochemical-related industries. Herein, a post-sulfonated composite of one-pot synthesized magnetite (Fe3O4) and cellulose nanocrystals (CNCs) was used as an effective and easily separable heterogeneous catalyst for activating the Knoevenagel and Thorpe-Ziegler reactions. The composite was developed hydrothermally from microcrystalline cellulose (MCC), iron chlorides, urea, and hydrochloric acid at 180 °C for 20 h in a one-pot reaction. After collecting the magnetic CNCs (MCNCs), post-sulfonation was performed using chlorosulfonic acid (ClSO3H) in DMF at room temperature producing sulfonated MCNCs (SMCNCs). The results confirmed the presence of sulfonated Fe3O4 and CNCs with a hydrodynamic size of 391 nm (±25). The presence of cellulose was beneficial for preventing Fe3O4 oxidation or the formation of agglomerations without requiring the presence of capping agents, organic solvents, or an inert environment. The SMCNC catalyst was applied to activate the Knoevenagel condensation and the Thorpe-Ziegler reaction with determining the optimal reaction conditions. The presence of the SMCNC catalyst facilitated these transformations under green procedures, which enabled us to synthesize a new series of olefins and thienopyridines, and the yields of some isolated olefins and thienopyridines were up to 99% and 95%, respectively. Besides, the catalyst was stable for five cycles without a significant decrease in its reactivity, and the mechanistic routes of both reactions on the SMCNCs were postulated.

Solid-State Luminescent Materials Containing Both Indole and Pyrimidine Moieties: Design, Synthesis, and Density Functional Theory Calculations.

Heterocyclic compounds with effective solid-state luminescence offer a wide range of uses. It has been observed that combining pyrimidine and indole moieties in a single molecule can enhance material behavior dramatically. Here, different heterocyclic compounds with indole and pyrimidine moieties have been synthesized effectively, and their structures have been validated using NMR, IR, and mass spectroscopy. The photoluminescence behavior of two substances was investigated in powder form and solutions of varying concentrations. After aggregation, one molecule displayed a redshifted luminescence spectrum, whereas another homolog showed a blueshift. Thus, density functional theory calculations were carried out to establish that introducing a terminal group allows modifying of the luminescence behavior by altering the molecular packing. Because of the non-planarity, intermolecular interactions, and tiny intermolecular distances within the dimers, the materials demonstrated a good emission quantum yield (Φem) in the solid state (ex. 25.6%). At high temperatures, the compounds also demonstrated a stable emission characteristic.

Base-Free Synthesis and Photophysical Properties of New Schiff Bases Containing Indole Moiety.

Schiff bases represent an essential class in organic chemistry with antitumor, antiviral, antifungal, and antibacterial activities. The synthesis of Schiff bases requires the presence of an organic base as a catalyst such as piperidine. Base-free synthesis of organic compounds using a heterogeneous catalyst has recently attracted more interest due to the facile procedure, high yield, and reusability of the used catalyst. Herein, we present a comparative study to synthesize new Schiff bases containing indole moieties using piperidine as an organic base catalyst and Au@TiO2 as a heterogeneous catalyst. In both methods, the products were isolated in high yields and fully characterized using different spectral analysis techniques. The catalyst was reusable four times, and the activity was slightly decreased. The presence of Au increases the number of acidic sites of TiO2, resulting in C=O polarization. Yields of the prepared Schiff bases in the presence of Au@TiO2 and piperidine were comparable. However, Au@TiO2 is an easily separable and recyclable catalyst, which would facilitate the synthesis of organic compounds without applying any hazardous materials. Furthermore, the luminescence behavior of the synthesized Schiff bases exhibited spectral shape dependence on the substituent group. Interestingly, the compounds also displayed deep-blue fluorescence with Commission Internationale de l'Éclairage (CIE) coordinates of y < 0.1. Thus, these materials may contribute to decreasing the energy consumption of the emitting devices.

Synthesis of Novel Biocompatible Thienopyrimidine Chromophores with Aggregation-Induced Emission Sensitive to Molecular Aggregation.

Biocompatible luminogens with aggregation-induced emission (AIE) have several applications in the biology field, such as in detecting biomacromolecules bioprobes and in bio-imaging. Due to their bioactivities and light-emitting properties, many heterocyclic compounds are good candidates for such applications. However, heterocyclic π-conjugated systems with AIE behavior remain rare as strong intermolecular π-π interactions usually quench their emission. In this work, new thienopyrimidine heterocyclic compounds were synthesized and their structures were verified by elemental analysis and Fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (NMR), and 13C NMR spectra. The photophysical properties of some compounds were investigated in the solution and solid states. Density functional theory calculations were also performed to confirm the observed photophysical properties of the compounds. The studied dyes displayed AIE properties with spectral shapes related to the aggregate structure and a quantum yield up to 10.8%. The emission efficiency of the powder is attributed to the incorporation of multiply rotatable and twisted aryl groups to the fused heterocyclic moieties. The dyes also showed high thermal stability and potent antimicrobial activities against numerous bacterial and fungal strains. Additionally, the cytotoxicity of the new compounds was evaluated against the Caco-2 cell line, and molecular docking was used to investigate the binding conformation of the most effective compound with the MNK2 enzyme. Therefore, the presented structures may potentially be used for bioapplications.

Correction to "Synthesis and Antimicrobial Activity of Novel Piperidinyl Tetrahydrothieno[2,3-c]isoquinolines and Related Heterocycles".

[This corrects the article DOI: 10.1021/acsomega.9b02604.].

Synthesis and Antimicrobial Activity of Novel Piperidinyl Tetrahydrothieno[2,3-c]isoquinolines and Related Heterocycles.

A novel series of 1-amino-2-substituted-5-piperidinyl-6,7,8,9-tertahydrothieno[2,3-c]isoquinolines (4a-e) was synthesized upon treatment of 4-cyano-1-piperidinyl-5,6,7,8-tetrahydroisoquinline-3(2H)-thione (2) with α-halo carbonyl compounds such as chloroacetone, ethyl chloroacetate, 2-bromoacetophenone, chloroacetamide, and chloroacetanilide. Construction the pyrrolyl ring associated with the thienotetrahydroisoquinoline moiety was achieved by treatment of compounds 4a, b with 2,5-dimethoxytertahydrofuran in acetic acid. 1-Pyrrolyl-2-substituted-thieno[2,3-c]isoquinolines 5a and 5b which in turn were used as multipurpose precursors for synthesis of other new heterocycles. Assignments of the chemical structures of the respectively synthesized thienotetrahydroisoquinolines and their derivatives were established on the bases of elemental and spectral techniques (Fourier transform infrared, 1H NMR, 13C NMR, and mass spectroscopy). Furthermore, certain compounds were screened for their antimicrobial activity which revealed promising activities against various pathogenic strains of bacteria and fungi.