A series of neutral nonenzymatic receptors have been synthesized for the recognition of creatinine in a nondegrative way. The receptors contain different heterocyclic moieties for better interactions between host and guest. Among these, 1, 4, and 5 are fluorescent receptors for creatinine. From this study, it was found that the receptors 1 and 4 containing the naphthyridine moiety have higher binding affinity to the guest creatinine than receptors containing other heterocyclic moiety. Theoretical studies for the calculation of binding energy were carried out using discrete Fourier transform (DFT) for the hosts and their complexation with creatinine in both gas phase and acetonitrile medium.
The recognition of different monocarboxylic acids by a group of substituted imidazoles containing pyridyl moiety has been studied. This work highlights the substituent effects as well as the position of “nitrogen” in the attached pyridine moiety of the hosts during the recognition process. The strongest recognition ability is observed if the receptor contains the 2‐pyridyl moiety. The binding ability is weak for the imidazoles with a 3‐pyridyl unit, and it is close to the phenyl‐substituted imidazoles. The size of the monocarboxylic acids also plays a crucial role in the formation of the host–guest complexes. In all the cases, host and guest bind in 2:1 mode of complexation. This type of interaction is due to the angular supramolecular arrangement of two host molecules generating a cavity to bind the carboxylic acid through three‐ or four‐point hydrogen bonding. The phenyl substituents at the imidazole also slightly enhance the association of hosts and guests. The 1H NMR studies clearly demonstrate a host–guest interaction without any proton transfer in a neutral organic medium.
The cover image is based on the Research Article Recognition of monocarboxylic acids by imidazole‐containing receptors by Sunita Prajapati, Puspita Sinha, Kishor Kumar Suryavanshi and Subrata Jana, https://doi.org/10.1002/poc.4397.
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