Chloride Binding Properties of a Macrocyclic Receptor Equipped with an Acetylide Gold(I) Complex: Synthesis, Characterization, Reactivity, and Cytotoxicity Studies
In this work, we report the synthesis and characterization of a mono-nuclear “two wall” aryl-extended calix[4]pyrrole receptor (<b>2Au</b>) decorated with an acetylide-gold(I)-PTA complex at its upper rim. We describe the <sup>1</sup>H NMR titration experiments of <b>2A...
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MDPI AG
2022-07-01
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| Series: | Inorganics |
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| Online Access: | https://www.mdpi.com/2304-6740/10/7/95 |
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| author | Andrea Rivoli Gemma Aragay María Concepción Gimeno Pablo Ballester |
| author_facet | Andrea Rivoli Gemma Aragay María Concepción Gimeno Pablo Ballester |
| author_sort | Andrea Rivoli |
| collection | DOAJ |
| description | In this work, we report the synthesis and characterization of a mono-nuclear “two wall” aryl-extended calix[4]pyrrole receptor (<b>2Au</b>) decorated with an acetylide-gold(I)-PTA complex at its upper rim. We describe the <sup>1</sup>H NMR titration experiments of <b>2Au</b> and its “two wall” aryl-extended calix[4]pyrrole synthetic precursors: the non-symmetric mono-iodo-mono-ethynyl <b>2</b> and the symmetric bis-iodo <b>3</b> with TBACl in dichloromethane and acetone solution. In acetone solution, we use isothermal titration calorimetry (ITC) experiments to thermodynamically characterize the formed 1:1 chloride complexes and perform pair-wise competitive binding experiments. In both solvents, we measured a decrease in the binding constant of the mono-nuclear <b>2Au</b> complex for chloride compared to the parent mono-iodo-mono-ethynyl <b>2</b>. In turn, receptor <b>2</b> also shows a reduction in binding affinity for chloride compared to its precursor bis-iodo calix[4]pyrrole <b>3</b>. The free energy differences (∆G) of the 1:1 chloride complexes cannot be exclusively attributed to their dissimilar electrostatic surface potential values either at the center of the <i>meso</i>-phenyl wall or its <i>para</i>-substituent. We conclude that solvation/desolvation processes play an important role in the stabilization of the chloride complexes. In acetone solution and in the presence of TBACl, <b>6Au</b>, a reference compound for the acetylide Au(I)•PTA unit, produces a bis(alkynyl)gold(I) anionic complex [<b>7Au</b>]<sup>−</sup>. Thus, the observation of two separate sets of signals for the bound aromatic calix[4]pyrrole protons, when more than 1 equiv. of the salt is added, is assigned to the formation of the chloride complexes of <b>2Au</b> and of the “in situ” formed calix[4]pyrrole anionic dimer [<b>8</b><b>Au</b>]<sup>−</sup>. Finally, preliminary data obtained in cell viability assays of <b>2Au</b> and <b>6Au</b> with human cancer cells lines assign them with moderate activities showing that the calix[4]pyrrole unit is not relevant. |
| first_indexed | 2024-03-09T13:39:33Z |
| format | Article |
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| language | English |
| last_indexed | 2024-03-09T13:39:33Z |
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| spelling | doaj.art-9e77830912aa47b98cfe3d0d151c39d12023-11-30T21:08:21ZengMDPI AGInorganics2304-67402022-07-011079510.3390/inorganics10070095Chloride Binding Properties of a Macrocyclic Receptor Equipped with an Acetylide Gold(I) Complex: Synthesis, Characterization, Reactivity, and Cytotoxicity StudiesAndrea Rivoli0Gemma Aragay1María Concepción Gimeno2Pablo Ballester3Institute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans 16, 43007 Tarragona, SpainInstitute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans 16, 43007 Tarragona, SpainDepartamento de Química Inorgánica, Instituto de Síntesis Química y Catálisis Homogénea (ISQCH) CSIC-Universidad de Zaragoza, 50009 Zaragoza, SpainInstitute of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology (BIST), Av. Països Catalans 16, 43007 Tarragona, SpainIn this work, we report the synthesis and characterization of a mono-nuclear “two wall” aryl-extended calix[4]pyrrole receptor (<b>2Au</b>) decorated with an acetylide-gold(I)-PTA complex at its upper rim. We describe the <sup>1</sup>H NMR titration experiments of <b>2Au</b> and its “two wall” aryl-extended calix[4]pyrrole synthetic precursors: the non-symmetric mono-iodo-mono-ethynyl <b>2</b> and the symmetric bis-iodo <b>3</b> with TBACl in dichloromethane and acetone solution. In acetone solution, we use isothermal titration calorimetry (ITC) experiments to thermodynamically characterize the formed 1:1 chloride complexes and perform pair-wise competitive binding experiments. In both solvents, we measured a decrease in the binding constant of the mono-nuclear <b>2Au</b> complex for chloride compared to the parent mono-iodo-mono-ethynyl <b>2</b>. In turn, receptor <b>2</b> also shows a reduction in binding affinity for chloride compared to its precursor bis-iodo calix[4]pyrrole <b>3</b>. The free energy differences (∆G) of the 1:1 chloride complexes cannot be exclusively attributed to their dissimilar electrostatic surface potential values either at the center of the <i>meso</i>-phenyl wall or its <i>para</i>-substituent. We conclude that solvation/desolvation processes play an important role in the stabilization of the chloride complexes. In acetone solution and in the presence of TBACl, <b>6Au</b>, a reference compound for the acetylide Au(I)•PTA unit, produces a bis(alkynyl)gold(I) anionic complex [<b>7Au</b>]<sup>−</sup>. Thus, the observation of two separate sets of signals for the bound aromatic calix[4]pyrrole protons, when more than 1 equiv. of the salt is added, is assigned to the formation of the chloride complexes of <b>2Au</b> and of the “in situ” formed calix[4]pyrrole anionic dimer [<b>8</b><b>Au</b>]<sup>−</sup>. Finally, preliminary data obtained in cell viability assays of <b>2Au</b> and <b>6Au</b> with human cancer cells lines assign them with moderate activities showing that the calix[4]pyrrole unit is not relevant.https://www.mdpi.com/2304-6740/10/7/95calix[4]pyrroleanion receptorsacetylide gold(I) complexescytotoxicity studies |
| spellingShingle | Andrea Rivoli Gemma Aragay María Concepción Gimeno Pablo Ballester Chloride Binding Properties of a Macrocyclic Receptor Equipped with an Acetylide Gold(I) Complex: Synthesis, Characterization, Reactivity, and Cytotoxicity Studies Inorganics calix[4]pyrrole anion receptors acetylide gold(I) complexes cytotoxicity studies |
| title | Chloride Binding Properties of a Macrocyclic Receptor Equipped with an Acetylide Gold(I) Complex: Synthesis, Characterization, Reactivity, and Cytotoxicity Studies |
| title_full | Chloride Binding Properties of a Macrocyclic Receptor Equipped with an Acetylide Gold(I) Complex: Synthesis, Characterization, Reactivity, and Cytotoxicity Studies |
| title_fullStr | Chloride Binding Properties of a Macrocyclic Receptor Equipped with an Acetylide Gold(I) Complex: Synthesis, Characterization, Reactivity, and Cytotoxicity Studies |
| title_full_unstemmed | Chloride Binding Properties of a Macrocyclic Receptor Equipped with an Acetylide Gold(I) Complex: Synthesis, Characterization, Reactivity, and Cytotoxicity Studies |
| title_short | Chloride Binding Properties of a Macrocyclic Receptor Equipped with an Acetylide Gold(I) Complex: Synthesis, Characterization, Reactivity, and Cytotoxicity Studies |
| title_sort | chloride binding properties of a macrocyclic receptor equipped with an acetylide gold i complex synthesis characterization reactivity and cytotoxicity studies |
| topic | calix[4]pyrrole anion receptors acetylide gold(I) complexes cytotoxicity studies |
| url | https://www.mdpi.com/2304-6740/10/7/95 |
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