One‐Pot Synthesis of Spiro[fluorene‐9,9'‐xanthene] Derivatives

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.

Molecular Design of Hole Transport Materials to Immobilize Ion Motion for Photostable Perovskite Solar Cells

Poor operational stability is a crucial factor limiting the further application of perovskite solar cells (PSCs). Organic semiconductor layers can be a powerful means for reinforcing interfaces and inhibiting ion migration. Herein, two hole-transporting molecules, pDPA-SFX and mDPA-SFX, are synthesized with tuned substituent connection sites. The meta-substituted mDPA-SFX results in a larger dipole moment, more ordered packing, and better charge mobility than pDPA-SFX, accompanying with strong interface bonding on perovskite surfaces and suppressed ion motion as well. Importantly, mDPA-SFX-based PSCs exhibit an efficiency that has significantly increased from 22.5 % to 24.8 % and a module-based efficiency of 19.26 % with an active area of 12.95 cm2. The corresponding cell retain 94.8 % of its initial efficiency at maximum power point tracking (MPPT) after 1,000 h (T95=1,000 h). The MPPT T80 lifetime is as long as 2,238 h. This work illustrates that a small degree of structural variation in organic compounds leaves considerable room for developing new HTMs for light stable PSCs.

Ambipolar macrocycle derived from spiro-xanthene and carbazole: synthesis, structure-property relationships, electronic properties and host-guest investigation

For the first time, we present the detailed synthesis, photophysical, electrochemical, host-guest and charge transport properties of spiro[fluorene-9,9'-xanthene] (SFX) and carbazole macrocycle SPS-NR-02. The electron and hole transport values measured using the space charge limited current (SCLC) method resulted in ambipolar charge transport with an electron to hole mobility ratio of 0.39.

Spiro Derivatives in the Discovery of New Pesticides: A Research Review

Spiro compounds are biologically active organic compounds with unique structures, found in a wide variety of natural products and drugs. They do not readily lead to drug resistance due to their unique mechanisms of action and have, therefore, attracted considerable attention regarding pesticide development. Analyzing structure-activity relationships (SARs) and summarizing the characteristics of spiro compounds with high activity are crucial steps in the design and development of new pesticides. This review mainly summarizes spiro compounds with insecticidal, bactericidal, fungicidal, herbicidal, antiviral, and plant growth regulating functions to provide insight for the creation of new spiro compound pesticides.

Oxidation of BINOLs by Hypervalent Iodine Reagents: Facile Synthesis of Xanthenes and Lactones

Xanthene derivatives have broad applications in medicines, fluorescent probes, dyes, food additives, etc. Therefore, much attention was focused on developing the synthetic methods to prepare these compounds. Binaphthyl‐based xanthene derivatives were prepared through the oxidation of BINOLs promoted by the hypervalent iodine reagent iodosylbenzene (PhIO). Nine‐membered lactones were obtained through a similar oxidative reaction when iodoxybenzene (PhIO₂) was used. Additionally, one‐pot reactions of BINOLs, PhIO and nucleophiles such as alcohols and amines were also investigated to provide alkoxylated products and amides in good to excellent yields.