Recent Advances towards the Synthesis and Material Applications of Indoloindoles

An important class of N -heteroacenes is indoloindoles which are air-stable, electron-rich and possesses many tuneable properties. Initially, indoloindoles were explored for potential biological applications but current interest is based on their performance as photovoltaic materials. With growing applications of indoloindoles across multiple facets as organic functional materials, the need for efficient methods to synthesize and functionalize indoloindoles has taken a centre stage. Over the years, synthetic routes leading to indoloindoles have evolved from multistep protocols to one-pot multicomponent synthesis. Present literature boasts of a variety of reports that employ metals such as Cu, Ru, Rh, Pd, or Au to mediate the reaction towards indoloindoles. As alternatives to such metal-mediated methods, researchers have also developed metal-free and catalyst-free conditions. Indoloindoles, which are fundamentally fused-indoles, are often synthesized by transforming indole derivatives but methods that employ anilines or arynes as the starting substrates are equally abundant. The present review highlights the rich diversity and versatility of recent literature for the synthesis of indolo[3,2- b ]indoles, indolo[2,3- b ]indoles, indolo[7,6- g ]indoles, and indolo[5,4- e ]indoles. This review discusses protocols that were explicitly designed to obtain the above-mentioned indoloindoles and also explores several other methods that can be adapted to access said heteroacenes. Available mechanistic details pertaining to novel transformations have been detailed for the readers. Various applications where indoloindoles function as organic light-emitting diodes, organic field-effect transistors, solar cells, etc. have also been delved into before concluding with an outlook on future research.

Essential Oil and Bioactive Compounds Variation in Myrtle (Myrtus communis L.) as Affected by Seasonal Variation and Salt Stress

The effect of different NaCl concentrations (control, 2, 4 and 6 dS/m) and three harvesting times in different seasons including spring (9 April), summer (5 July), and fall (23 September) was evaluated on essential oil (EO) yield, composition, phenolic, flavonoid content, and antioxidant activity of myrtle. Essential oil yield ranged from 0.2% in control and fall to 1.6% in moderate salinity (4 dS/m) and spring season. The main constituents obtained from gas chromatography/mass spectrometry analysis were α-pinene, 1,8-cineole, limonene, linalool, α-terpineol, and linalyl acetate in which α-pinene ranged from 11.70% in moderate and fall to 30.99% in low salinity (2 dS/m) and spring, while 1,8-cineole varied from 7.42% in high salinity (6 dS/m) and summer to 15.45% in low salinity and spring, respectively. Salt stress also resulted in an increase in total phenolic, flavonoid content, and antioxidant activity. The highest antioxidant activity based on DPPH radical scavenging activity, reducing power (FTC) and β-carotene/linoleic acid model systems was found in plants harvested in spring and summer in high stress condition. The lowest IC₅₀ values obtained in 6 dS/m in spring (375.23 μg/ml) followed by summer (249.41 μg/ml) and fall (618.38 μg/ml). Eight major phenolic and flavonoid compounds were determined in three harvesting times using high performance liquid chromatography analysis. In overall, late harvesting time of myrtle in fall can lead to reduce the most of major EO components, while it can improve the amount of phenolic acids.