Molecular Recognition of Imidazole Derivatives by Co(III)-Porphyrinsin Phosphate Buffer (pH = 7.4) and Cetylpyridinium Chloride Containing Solutions.

Galina Mamardashvili,Elena Kaigorodova,Olga Dmitrieva,Oscar Koifman,Nugzar Mamardashvili

doi:10.3390/molecules26040868

Galina Mamardashvili, Elena Kaigorodova + Show 3 more

Open Access

https://doi.org/10.3390/molecules26040868

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Abstract

By means of spectrophotometric titration and NMR spectroscopy, the selective binding ability of the Co(III)-5,15-bis-(3-hydroxyphenyl)-10,20-bis-(4-sulfophenyl)porphyrin (Co(III)P1) and Co(III)-5,15-bis-(2-hydroxyphenyl)-10,20-bis-(4-sulfophenyl)porphyrin (Co(III)P2) towards imidazole derivatives of various nature (imidazole (L1), metronidazole (L2), and histamine (L3)) in phosphate buffer (pH 7.4) has been studied. It was found that in the case of L2, L3 the binding of the “first” ligand molecule by porphyrinates Co(III)P1 and Co(III)P2 occurs with the formation of complexes with two binding sites (donor–acceptor bond at the center and hydrogen bond at the periphery of the macrocycle), while the “second” ligand molecule is added to the metalloporphyrin only due to the formation of the donor–acceptor bond at the macrocycle coordination center. The formation of stable complexes with two binding sites has been confirmed by density functional theory method (DFT) quantum chemical calculations and two-dimensional NMR experiments. It was shown that among the studied porphyrinates, Co(III)P2 is more selective towards to L1-L3 ligands, and localization of cobalt porphyrinates in cetylpyridinium chloride (CPC) micelles does not prevent the studied imidazole derivatives reversible binding. The obtained materials can be used to develop effective receptors for recognition, delivery, and prolonged release of drug compounds to the sites of their functioning. Considering that cetylpyridinium chloride is a widely used cationic biocide as a disinfectant, the designed materials may also prove to be effective antimicrobial agents.

Highlights

Molecular recognition processes, in which one molecule (“host” or receptor) recognizes and binds another molecule (“guest” or substrate) to form a system due to intermolecular interactions find broad application in the design of multifunctional devices for new molecular technologies
We previously found that the more effective method of influence and control of binding and elimination processes of hydrophilic Co(III)-porphyrins with various organic bases in aqueous media is micellization, namely the localization to the outer layer surfactant micelle [21], which gives them new properties
It was found that disulfoderivatives of Co(III)-tetraarylporphyrines with hydroxyl groups in two aryl fragments of the macrocycle have the ability to recognize the various imidazole derivatives due to the formation of additional hydrogen bonds upon their axial coordination on the cobalt cation in aqueous media

Summary

Introduction

In which one molecule (“host” or receptor) recognizes and binds another molecule (“guest” or substrate) to form a system due to intermolecular interactions find broad application in the design of multifunctional devices for new molecular technologies. We previously found that the more effective method of influence and control of binding and elimination processes of hydrophilic Co(III)-porphyrins with various organic bases in aqueous media is micellization, namely the localization to the outer layer (it may be intercalated among the CPC chains, most likely with the pyridinium group extending into the polar headgroup region of the micelle) surfactant micelle [21], which gives them new properties In this regard, the investigation of the recognition ability of the studied Co(III)-porphyrins hydroxy derivatives were carried out both in phosphate buffer (pH = 7.4) and in solutions containing cetylpyridinium chloride (CPC)

Results and Its

Materials and Methods

Spectrophotometric Studies

Quantum-Chemical Calculations

Conclusions