An Intervention into the Diverse Utilities of Fluorenes: A Brobdingnagian Family

The keyword "Fluorene" search in SciFinder found more than 57,000 results, including high-impact journal articles, review articles, patents, books, proceedings, etc. Against this background, a detailed enquiry has been made by our group on various classes of fluorenes and their relevancy. For the past several decades, fluorene and its related compounds have experienced extensive studies, which are attributed to the vast range of applications they possess in various fields like sensors, polymers, OLED devices and even in the pharmaceutical industries. Since fluorene is an important member of the 'polyaromatic-hydrocarbon' family and has proved its relevancy in multidisciplinary areas, summarising those milestones might be worthwhile for future researchers. Here, we intend to highlight the key applications of fluorene derivatives in the form of a review article and have put much effort into consolidating some of their most imperative applications, including those in sensors and medicinal, optoelectronic and electrochemical fields. The manuscript divides the fluorene family into multiple subclasses, counting mono- and polyfluorenes, spirofluorenes, silicon-cored fluorenes, indenofluorenes, etc., based on their structure, and portrays all the critical properties of each class. Since fluorenes are globally accepted as outstanding candidates for numerous applications and practicalities, our effort may find crucial acceptance in the near future.

Poly(arylene ether)s via Cu(II)-Catalysis

Poly(arylene ether)s (PAEs) are a versatile class of thermoplastic materials with commercial importance. Currently their synthesis relies predominantly on either nucleophilic or electrophilic aromatic substitution reactions, severely limiting the scope of available PAEs. Herein, we report the copper(II)-catalyzed polycondensation of electronically unactivated aryl bromides with bisphenols to afford a wide range of new PAEs. These PAEs are characterized by their thermal and mechanical properties. Functional PAEs were produced that have reversible acid- and redox-triggered chromophores incorporated into the backbone, which illustrates the utility of these methods.

Flexible and color-tunable poly(ether ether ketone) co-coordinated with Eu(III) and Tb(III) fluorescent films: Thermal stability and luminescence property

In this work, a novel kind of carboxyl-containing poly(ether ether ketone) (PEEK-COOH) was successfully synthesized and carefully characterized. Based on PEEK-COOH as macromolecular ligands, a series of luminescent rare earth polymer complexes (PEEKn-Eux-Tb1-x) were prepared and made into flexible films. The effects of the ratio of carboxyl ligand to rare earth ions on fluorescence intensity of complexes were studied and discussed. When the molar ratio was 6:1, the fluorescence emission intensity reached a maximum. Furthermore, the relative emission intensity of Tb3+ and Eu3+ binary system depended on their ratio and the intensity of fluorescence emission peak exhibited continuous change. Because of this, the color of the prepared fluorescent films could range from bright green to fire red, and each color has high purity. The fluorescence lifetime of complexes ranged from 0.428 to 0.511 ms. Absolute quantum yield of PEEK-Eu0.4-Tb0.6 was 8.4%. Beside this, these fluorescence films exhibited a high thermal stability with 5 wt. % in the range of 240–250°C, and its tensile strength was about 28 MPa. In addition, PEEKn-Eux-Tb1-x films possessed good optical transparency. All the interesting results suggested the potential application of the luminescent rare earth polymer complexes in display devices and photo-electronic devices.

A new nanomagnetic Pd-Co bimetallic alloy as catalyst in the Mizoroki-Heck and Buchwald-Hartwig amination reactions in aqueous media

A Pd-Co bimetallic alloy encapsulated in melamine-based dendrimer supported on magnetic nanoparticles denoted as γ-Fe2O3@MBD/Pd-Co was synthesized by a facile co-complexation-reduction method and characterized sufficiently. The catalytic evaluation of γ-Fe2O3@MBD/Pd-Co showed promising results in the Mizoroki-Heck and Buchwald-Hartwig amination reactions of various iodo-, bromo- and challenging chloroarenes in aqueous media. The synergetic cooperative effect of both Pd and Co and dispersion of the catalyst in water due to the encapsulation of γ-Fe2O3 by melamine-based dendrimer lead to high catalytic performance compared with the monometallic counterparts. The dispersion of the magnetic catalyst also facilitates the recovery and reuse of the catalyst by ten consecutive extraction and final magnetic isolation with no loss of catalytic activity, keeping its structure unaltered.