Evolution of Artificial Arginine Analogues—Fluorescent Guanidiniocarbonyl-Indoles as Efficient Oxo-Anion Binders

Molecules

卷:27

Christoph Wölper¹  Sarah Lampe²  Jens Voskuhl²  Till Nitschke²  Michael Giese²  Kevin Rudolph²  Daniel Sebena²  Bibhisan Roy² 

[1] Faculty of Chemistry (Inorganic Chemistry), University of Duisburg-Essen, 45117 Essen, Germany;

[2] Faculty of Chemistry (Organic Chemistry), University of Duisburg-Essen, 45117 Essen, Germany;

关键词: oxo-anion binders;    molecular recognition;    fluorescence;    supramolecular chemistry;   

DOI  :  10.3390/molecules27093005

来源: DOAJ

【 摘 要 】

In this article, we present fluorescent guanidiniocarbonyl-indoles as versatile oxo-anion binders. Herein, the guanidiniocarbonyl-indole (GCI) and methoxy-guanidiniocarbonyl-indole (MGCI) were investigated as ethylamides and compared with the well-known guanidiniocarbonyl-pyrrole (GCP) concerning their photophysical properties as well as their binding behavior towards oxo-anions. Hence, a variety of anionic species, such as carboxylates, phosphonates and sulfonates, have been studied regarding their binding properties with GCP, GCI and MGCI using UV-Vis titrations, in combination with the determination of the complex stoichiometry using the Job method. The emission properties were studied in relation to the pH value using fluorescence spectroscopy as well as the determination of the photoluminescence quantum yields (PLQY). Density functional theory (DFT) calculations were undertaken to obtain a better understanding of the ground-lying electronic properties of the investigated oxo-anion binders. Additionally, X-ray diffraction of GCP and GCI was conducted. We found that GCI and MGCI efficiently bind carboxylates, phosphonates and sulfonates in buffered aqueous solution and in a similar range as GCP (K_ass ≈ 1000–18,000 M⁻¹, in bis-tris buffer, pH = 6); thus, they could be regarded as promising emissive oxo-anion binders. They also exhibit a visible fluorescence with a sufficient PLQY. Additionally, the excitation and emission wavelength of MGCI was successfully shifted closer to the visible region of the electromagnetic spectrum by introducing a methoxy-group into the core structure, which makes them interesting for biological applications.

【 授权许可】

Unknown