Rhodium(III) catalysis enabled C−H/N−H alkyne annulation of nonsymmetric imidazole derivatives. This study encompasses the synthesis of imidazoles from a naturally occurring quinoidal compound and their use for the preparation of rigid πextended imidazole derivatives with outstanding fluorescence. Our study also brings to light the photophysical aspects and the mechanism of the reaction studied via computational calculations. This method provided an efficient and versatile tool for the synthesis of fluorescent compounds with a wide range of chemical and biological applications.

Fluorescent and colorimetric sensors are important tools for investigating the chemical compositions of different matrices, including foods, environmental samples, and water. The high sensitivity, low interference, and low detection limits of these sensors have inspired scientists to investigate this class of sensing molecules for ion and molecule detection. Several examples of fluorescent and colorimetric sensors have been described in the literature; this Review focuses particularly on phenanthro [9,10d]imidazoles. Different strategies have been developed for obtaining phenanthro [9,10d]imidazoles, which enable modification of their optical properties upon interaction with specific analytes. These sensing responses usually involve changes in the fluorescence intensity and/or color arising from processes like photoinduced electron transfer, intramolecular charge transfer, intramolecular proton transfer in the excited state, and Forster resonance energy transfer. In this Review, we categorized these sensors into two different groups: those bearing formyl groups and their derivatives and those based on other molecular groups. The different optical responses of phenanthro [9,10-d]imidazole-based sensors upon interaction with specific analytes are discussed.

Diverse structural frameworks are found in natural compounds and are well known for their chemical and biological properties; such compounds include the imidazoles and oxazoles. Researchers worldwide are continually working on the development of methods for synthesizing new molecules bearing these basic moiety and evaluating their properties and applications. To expand the knowledge related to azoles, this review summarizes important examples of imidazole and oxazole derivatives from 1,2-dicarbonyl compounds, such as lapachones and phenanthrene-9,10-diones, not only regarding their synthesis and biological applications but also their photophysical properties and uses. The data concerning the latter are particularly scarce in the literature, which leads to underestimation of the potential applications that can be envisaged for these compounds.

Imidazoles constitute an important class of heterocyclic compounds with extensive potential use, from pharmaceuticals to optoelectronics. However, synthetic methodologies capable of producing novel nonsymmetric imidazoles are still scarce. In a combined synthesis, photophysical and computational investigation, we show that ruthenium(II) catalysis enables C−H/N−H alkyne annulation of nonsymmetric imidazoles derived from naturally occuring β‐lapachone and nor‐β‐lapachone. This method provides an efficient and versatile tool for synthesizing fluorescent compounds with a broad application range.

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