Complexation of Cobalt(II) at the Upper Rim of Two New Calix[4]arene/Bipyridine-Based Podands

Synthesis of a tube-like tetra-bipyridyl, tetra-ethylacetato-calix[4]arene in 1,3-alternate conformation and the unexpected crystal structure of its [bpy(CoCl 2 )] 3 -[bpy(CoCl 2 )(H 2 O)] complex

“…4. As in previous reports, 27,29,36 it shows two weak transitions with maxima at 569 nm (Abs = 0.198, ε = 985 mol −1 L cm −1 ) and 658 nm (Abs = 0.357, ε = 1775 mol −1 L cm −1 ), which are attributed to metal-to-ligand-charge-transfer (MLCT) and d–d metal-centered-transitions (MCT), respectively. The low absorptivity of those transitions required titration with a solution that was 20 times more concentrated (2.011 × 10 −4 M for 2 and 4.825 × 10 −2 M for the cobalt salt solution).…”

“…The complexation of the ligand 2 by cobalt(II) was followed by UV-visible-Near Infrared titration between 250 and 1000 nm, of 3 mL of a 1.006 10 Two isosbestic points are observed at 308 nm (0 to 25 µL -0 to 2 equivalents of metal ion) and 301 nm (30 to 50 µL-2.4 to 4 equivalents of metal ion) (Figure 3) which, albeit poorly resolute, tend to suggest the formation of LM and LM 2 species at 308 nm and LM 3 and LM 4 at 301 nm. The second domain, between 500 and 750 nm, is presented in Figure 4; it shows, as in precedent reports, 27,29,36 These observations point toward a CoA2B2 symmetry tetrahedral geometry around the cobalt ion, according to Banci et al 41 Of note, the same authors assume that a pentacoordination around Co(II) high spin generates transitions in the same range than our results, with a characteristic transition at 625 nm, within the envelope of the visible spectrum of 3 but also of 4 between 600 and 700 nm. It is not forbidden here to imagine, as future X-ray diffraction study will show in the solid state, that a part of Co/bipyridyl subunits in 3 is pentacoordinated.…”

Synthesis of a tube-like tetra-bipyridyl, tetra-ethylacetato-calix[4]arene in 1,3-alternate conformation and the unexpected crystal structure of its [bpy(CoCl 2 )] 3 -[bpy(CoCl 2 )(H 2 O)] complex

“…4. As in previous reports, 27,29,36 it shows two weak transitions with maxima at 569 nm (Abs = 0.198, ε = 985 mol −1 L cm −1 ) and 658 nm (Abs = 0.357, ε = 1775 mol −1 L cm −1 ), which are attributed to metal-to-ligand-charge-transfer (MLCT) and d–d metal-centered-transitions (MCT), respectively. The low absorptivity of those transitions required titration with a solution that was 20 times more concentrated (2.011 × 10 −4 M for 2 and 4.825 × 10 −2 M for the cobalt salt solution).…”

“…The complexation of the ligand 2 by cobalt(II) was followed by UV-visible-Near Infrared titration between 250 and 1000 nm, of 3 mL of a 1.006 10 Two isosbestic points are observed at 308 nm (0 to 25 µL -0 to 2 equivalents of metal ion) and 301 nm (30 to 50 µL-2.4 to 4 equivalents of metal ion) (Figure 3) which, albeit poorly resolute, tend to suggest the formation of LM and LM 2 species at 308 nm and LM 3 and LM 4 at 301 nm. The second domain, between 500 and 750 nm, is presented in Figure 4; it shows, as in precedent reports, 27,29,36 These observations point toward a CoA2B2 symmetry tetrahedral geometry around the cobalt ion, according to Banci et al 41 Of note, the same authors assume that a pentacoordination around Co(II) high spin generates transitions in the same range than our results, with a characteristic transition at 625 nm, within the envelope of the visible spectrum of 3 but also of 4 between 600 and 700 nm. It is not forbidden here to imagine, as future X-ray diffraction study will show in the solid state, that a part of Co/bipyridyl subunits in 3 is pentacoordinated.…”

Calixarenes in a Membrane Environment: A Monolayer Study on the Miscibility of Threep-tert-Butylcalix[4]arene β-Lactam Derivatives with 1,2-Dimyristoyl-sn-glycero-3-phosphoethanolamine

“…The electrospray mass spectrometry performed in the positive mode using MeOH with trace amounts of H 2 O as solvent yielded base peaks attributed to the monocharged, monosodio derivatives and to the dicharged, disodio derivatives. Elemental analyses were in accordance with the molecular formulas; some amount of CH 2 Cl 2 detected in Calix III with NMR was probably due to its complexation within the calixarene cavity, as already observed for other calixarene species …”

A Calix[4]arene-Based Bipyridine Podand as Versatile Ligand for Transition Metal Cations

“…In the standard 1 H NMR spectrum of 3 (δ = 0−15), the absence of some resonance signals confirmed the paramagnetic nature of the [Co/bpy] subunit, as was previously observed 4f. Recording data in a larger frequency domain (65000 Hz; δ = 216 at 300 MHz, δ = 130 at 500 MHz) showed 11 new resonance signals that were correlated by a COSY experiment (Figure 2): two groups of three singlets integrating 2 H each at δ = 72.93 (Δν 1/2 = 32 Hz), 42.28 (Δν 1/2 = 34 Hz), −6.75 (s, Δν 1/2 = 77 Hz), and δ = 72.72 (s, Δν 1/2 = 25 Hz), 49.18 (s, Δν 1/2 = 28 Hz), −14.76 (s, Δν 1/2 = 21 Hz) were attributed to the bipyridyl groups; one group of two singlets integrating 4 H each at δ = −9.70 (s, Δν 1/2 = 40 Hz) and δ = −3.05 (s, Δν 1/2 = 22 Hz) was attributed to the Ar‐C H 2 ‐Ar protons.…”

“…At the end of the above‐mentioned investigations developed in solution, we obtained single crystals suitable for X‐ray analysis with the dinuclear cobalt, nickel and zinc complexes 3 , 4 and 5 . In each case the results of the X‐ray crystal structure analyses confirmed that two divalent metal ions are complexed by a podand unit in the expected, more or less distorted, tetrahedral mode,4f,10 with the participation of the two nitrogen atoms of each bipyridine unit and two coordinating chloride ions.…”

Synthesis of a tube-like tetra-bipyridyl, tetra-ethylacetato-calix[4]arene in 1,3-alternate conformation and the unexpected crystal structure of its [bpy(CoCl 2 )] 3 -[bpy(CoCl 2 )(H 2 O)] complex

“…4. As in previous reports, 27,29,36 it shows two weak transitions with maxima at 569 nm (Abs = 0.198, ε = 985 mol −1 L cm −1 ) and 658 nm (Abs = 0.357, ε = 1775 mol −1 L cm −1 ), which are attributed to metal-to-ligand-charge-transfer (MLCT) and d–d metal-centered-transitions (MCT), respectively. The low absorptivity of those transitions required titration with a solution that was 20 times more concentrated (2.011 × 10 −4 M for 2 and 4.825 × 10 −2 M for the cobalt salt solution).…”

“…The complexation of the ligand 2 by cobalt(II) was followed by UV-visible-Near Infrared titration between 250 and 1000 nm, of 3 mL of a 1.006 10 Two isosbestic points are observed at 308 nm (0 to 25 µL -0 to 2 equivalents of metal ion) and 301 nm (30 to 50 µL-2.4 to 4 equivalents of metal ion) (Figure 3) which, albeit poorly resolute, tend to suggest the formation of LM and LM 2 species at 308 nm and LM 3 and LM 4 at 301 nm. The second domain, between 500 and 750 nm, is presented in Figure 4; it shows, as in precedent reports, 27,29,36 These observations point toward a CoA2B2 symmetry tetrahedral geometry around the cobalt ion, according to Banci et al 41 Of note, the same authors assume that a pentacoordination around Co(II) high spin generates transitions in the same range than our results, with a characteristic transition at 625 nm, within the envelope of the visible spectrum of 3 but also of 4 between 600 and 700 nm. It is not forbidden here to imagine, as future X-ray diffraction study will show in the solid state, that a part of Co/bipyridyl subunits in 3 is pentacoordinated.…”

Calixarenes in a Membrane Environment: A Monolayer Study on the Miscibility of Threep-tert-Butylcalix[4]arene β-Lactam Derivatives with 1,2-Dimyristoyl-sn-glycero-3-phosphoethanolamine

“…The electrospray mass spectrometry performed in the positive mode using MeOH with trace amounts of H 2 O as solvent yielded base peaks attributed to the monocharged, monosodio derivatives and to the dicharged, disodio derivatives. Elemental analyses were in accordance with the molecular formulas; some amount of CH 2 Cl 2 detected in Calix III with NMR was probably due to its complexation within the calixarene cavity, as already observed for other calixarene species …”

A Calix[4]arene-Based Bipyridine Podand as Versatile Ligand for Transition Metal Cations

“…In the standard 1 H NMR spectrum of 3 (δ = 0−15), the absence of some resonance signals confirmed the paramagnetic nature of the [Co/bpy] subunit, as was previously observed 4f. Recording data in a larger frequency domain (65000 Hz; δ = 216 at 300 MHz, δ = 130 at 500 MHz) showed 11 new resonance signals that were correlated by a COSY experiment (Figure 2): two groups of three singlets integrating 2 H each at δ = 72.93 (Δν 1/2 = 32 Hz), 42.28 (Δν 1/2 = 34 Hz), −6.75 (s, Δν 1/2 = 77 Hz), and δ = 72.72 (s, Δν 1/2 = 25 Hz), 49.18 (s, Δν 1/2 = 28 Hz), −14.76 (s, Δν 1/2 = 21 Hz) were attributed to the bipyridyl groups; one group of two singlets integrating 4 H each at δ = −9.70 (s, Δν 1/2 = 40 Hz) and δ = −3.05 (s, Δν 1/2 = 22 Hz) was attributed to the Ar‐C H 2 ‐Ar protons.…”

“…At the end of the above‐mentioned investigations developed in solution, we obtained single crystals suitable for X‐ray analysis with the dinuclear cobalt, nickel and zinc complexes 3 , 4 and 5 . In each case the results of the X‐ray crystal structure analyses confirmed that two divalent metal ions are complexed by a podand unit in the expected, more or less distorted, tetrahedral mode,4f,10 with the participation of the two nitrogen atoms of each bipyridine unit and two coordinating chloride ions.…”

Synthesis of a tube-like tetra-bipyridyl, tetra-ethylacetato-calix[4]arene in 1,3-alternate conformation and the unexpected crystal structure of its [bpy(CoCl 2 )] 3 -[bpy(CoCl 2 )(H 2 O)] complex

“…4. As in previous reports, 27,29,36 it shows two weak transitions with maxima at 569 nm (Abs = 0.198, ε = 985 mol −1 L cm −1 ) and 658 nm (Abs = 0.357, ε = 1775 mol −1 L cm −1 ), which are attributed to metal-to-ligand-charge-transfer (MLCT) and d–d metal-centered-transitions (MCT), respectively. The low absorptivity of those transitions required titration with a solution that was 20 times more concentrated (2.011 × 10 −4 M for 2 and 4.825 × 10 −2 M for the cobalt salt solution).…”

“…The complexation of the ligand 2 by cobalt(II) was followed by UV-visible-Near Infrared titration between 250 and 1000 nm, of 3 mL of a 1.006 10 Two isosbestic points are observed at 308 nm (0 to 25 µL -0 to 2 equivalents of metal ion) and 301 nm (30 to 50 µL-2.4 to 4 equivalents of metal ion) (Figure 3) which, albeit poorly resolute, tend to suggest the formation of LM and LM 2 species at 308 nm and LM 3 and LM 4 at 301 nm. The second domain, between 500 and 750 nm, is presented in Figure 4; it shows, as in precedent reports, 27,29,36 These observations point toward a CoA2B2 symmetry tetrahedral geometry around the cobalt ion, according to Banci et al 41 Of note, the same authors assume that a pentacoordination around Co(II) high spin generates transitions in the same range than our results, with a characteristic transition at 625 nm, within the envelope of the visible spectrum of 3 but also of 4 between 600 and 700 nm. It is not forbidden here to imagine, as future X-ray diffraction study will show in the solid state, that a part of Co/bipyridyl subunits in 3 is pentacoordinated.…”

Calixarenes in a Membrane Environment: A Monolayer Study on the Miscibility of Threep-tert-Butylcalix[4]arene β-Lactam Derivatives with 1,2-Dimyristoyl-sn-glycero-3-phosphoethanolamine

“…The electrospray mass spectrometry performed in the positive mode using MeOH with trace amounts of H 2 O as solvent yielded base peaks attributed to the monocharged, monosodio derivatives and to the dicharged, disodio derivatives. Elemental analyses were in accordance with the molecular formulas; some amount of CH 2 Cl 2 detected in Calix III with NMR was probably due to its complexation within the calixarene cavity, as already observed for other calixarene species …”

A Calix[4]arene-Based Bipyridine Podand as Versatile Ligand for Transition Metal Cations

“…In the standard 1 H NMR spectrum of 3 (δ = 0−15), the absence of some resonance signals confirmed the paramagnetic nature of the [Co/bpy] subunit, as was previously observed 4f. Recording data in a larger frequency domain (65000 Hz; δ = 216 at 300 MHz, δ = 130 at 500 MHz) showed 11 new resonance signals that were correlated by a COSY experiment (Figure 2): two groups of three singlets integrating 2 H each at δ = 72.93 (Δν 1/2 = 32 Hz), 42.28 (Δν 1/2 = 34 Hz), −6.75 (s, Δν 1/2 = 77 Hz), and δ = 72.72 (s, Δν 1/2 = 25 Hz), 49.18 (s, Δν 1/2 = 28 Hz), −14.76 (s, Δν 1/2 = 21 Hz) were attributed to the bipyridyl groups; one group of two singlets integrating 4 H each at δ = −9.70 (s, Δν 1/2 = 40 Hz) and δ = −3.05 (s, Δν 1/2 = 22 Hz) was attributed to the Ar‐C H 2 ‐Ar protons.…”

“…At the end of the above‐mentioned investigations developed in solution, we obtained single crystals suitable for X‐ray analysis with the dinuclear cobalt, nickel and zinc complexes 3 , 4 and 5 . In each case the results of the X‐ray crystal structure analyses confirmed that two divalent metal ions are complexed by a podand unit in the expected, more or less distorted, tetrahedral mode,4f,10 with the participation of the two nitrogen atoms of each bipyridine unit and two coordinating chloride ions.…”