Ecological and Economic Efforts in the Development of Molecular Sensors for the Optical Detection of Cyanide Ions

Abstract

Cyanide anions have wide use in industrial areas despite their high toxicity to the environment as waste; thus, numerous studies on the determination of this anion have been carried out. This review discusses recent progress in the colorimetric and fluorimetric detection of cyanide by nucleophilic addition or acid‐base reactions to different types of receptors by the chemodosimeter approach. Beyond sensor performance, we focus our analysis on the sustainable synthesis features of five representative families of probes based on small molecules. Some environmental and economic factors are considered (reaction mass efficiency, number of chemical changes, solvent greenness average, preliminary raw material cost, and energy implications), giving a complete picture of the current status of research in this detection field.

BF3-Mediated Acetylation of Pyrazolo[1,5-a]pyrimidines and Other π-Excedent (N-Hetero)arenes

“…Ultimately, the α-bromination of 2a afforded 3d and 3e with a 63 and 2% yield, respectively. Therefore, these results permitted novel 1,3-bis-electrophiles 3a–c or the 1,2-bis-electrophilic derivatives 3d–e , which are very useful synthons in organic synthesis and new organic material development. ,,− …”

“…Once the acetylated compounds 2a – x were obtained, some strategic functionalized compounds 3a – e for us , were synthesized from 3-acetyl-2-methyl-7-phenylpyrazolo­[1,5- a ]­pyrimidine ( 2a ) to explore the synthetic application of acetylated products (Scheme ). In this respect, considering the formation of the dioxaborinine derivate 3a , the methyl ketone 2a can be transformed into the corresponding β-diketone 3a′ through a second acylation reaction, this time on the methyl ketone group, under acidic conditions and the occurrence of acetic anhydride. , Then, 3a′ formed the dioxaborinine derivative 3a by complexation with BF 3 OEt 2 . − In the same line, a condensation reaction between 2a with N,N -dimethylformamide-dimethyl acetal (DMF-DMA) or benzaldehyde ( 4 ) allowed obtaining the β-enaminone 3b in an 82% yield or the conjugated enone 3c in a 90% yield.…”

“…In particular, pyrazolo­[1,5- a ]­pyrimidine (PP) derivatives have been identified as privileged N -heterocyclic compounds (NHCs) with those frequent applications. − For example, numerous derivatives have biological activities such as anticancer, − anti-inflammatory, and anti-infectious, among others. Some 3-acylpyrazolo­[1,5- a ]­pyrimidine derivatives are approved and commercialized as active pharmaceutical ingredients (APIs) in some health disorder treatments, , involving drugs such as Lorediplon, Ocinaplon, and Indiplon .…”

“…Some 3-acylpyrazolo­[1,5- a ]­pyrimidine derivatives are approved and commercialized as active pharmaceutical ingredients (APIs) in some health disorder treatments, , involving drugs such as Lorediplon, Ocinaplon, and Indiplon . Alternatively, more recent research has highlighted the use of the PP core in photophysical applications as molecular sensors for cyanide recognition , (Figure ).…”

“…In general, the acylation of the pyrazolo­[1,5- a ]­pyrimidine ring would be a functional synthetic transformation to improve the applicability of this family of compounds in the biological and optoelectronic fields , , .As a result, considerable advances have been achieved in the C–H functionalization of this fused ring at position 3; recently, a group of electrophilic aromatic substitution (EAS) reactions has been reported (halogenation, nitration, and formylation). , However, to the best of our knowledge, direct acetylation has not yet been reported for this scaffold; only a few examples of acylated products starting from materials that have already incorporated the acyl group are described. , Perhaps, the proven high nucleophilicity of the pyridine-type nitrogen at position 4 of the fused ring disfavors the Friedel–Crafts reactions.…”