Search

We propose post-metalation modification as a useful strategy to control the guest recognition behavior of a metal-containing macrocyclic host. This is based on the ligand exchange of the axial ligands of a cobalt(III) dinuclear macrocyclic host, [LCo 2 X 4 ] 2+ (X=axial amine ligand). Four piperidine ligands in [LCo 2 (pip) 4 ] 2+ (pip=piperidine) were site-selectively replaced with primary amines. The competitive experiments revealed that the order of the affinity toward the cobalt centers in [LCo 2 X 4 ] 2+ is primary amine > secondary amine > tertiary amine and that the piperidine-coordinating complex, [LCo 2 (pip) 4 ] 2+ , was reasonably reactive among the isolable complexes. Indeed, two piperidine ligands at the diagonal positions in [LCo 2 (pip) 4 ] 2+ were site-selectively replaced with pyridine or acetate ion. The replacement of piperidine with acetate ion significantly enhanced the recognition ability towards Na + ., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Dynamic M/P invertible helicity was successfully induced at a SiO2 surface immobilized with a dynamic helical trinuclear cobalt complex, [LCo3(NHMe2)6](OTf)3, using chiral ((R) or (S))-1-phenylethylamine. Solid-state CD spectra and theoretical calculations suggested that the fixation of the M/P helical complex on the surface via coordination interactions was the key factor of the induced chirality at the surface. [ABSTRACT FROM AUTHOR]

Host–guest binding behavior of macrocyclic hosts is significantly influenced by the shapes and sizes of the hosts. In particular, closing/opening the apertures of the hosts controls the guest uptake/release. A post‐metalation modification method was used to achieve the open/close conversions. The starting open complex, [LCo2(pip)4](OTf)2, was efficiently converted to the closed complex, [LCo2(hda)2](OTf)2, which has a doubly bridged structure. The conversion of this closed complex to the open complex [LCo2(hda)2(OAc)]+ was too slow to be completed, but this gate‐opening was dramatically accelerated by the addition of Na+. The Na+ binding was also significantly enhanced by the gate‐opening, that is, conversion of [LCo2(hda)2]2+ to [LCo2(hda)2(OAc)]+. [ABSTRACT FROM AUTHOR]

We propose post‐metalation modification as a useful strategy to control the guest recognition behavior of a metal‐containing macrocyclic host. This is based on the ligand exchange of the axial ligands of a cobalt(III) dinuclear macrocyclic host, [LCo2X4]2+ (X=axial amine ligand). Four piperidine ligands in [LCo2(pip)4]2+ (pip=piperidine) were site‐selectively replaced with primary amines. The competitive experiments revealed that the order of the affinity toward the cobalt centers in [LCo2X4]2+ is primary amine > secondary amine > tertiary amine and that the piperidine‐coordinating complex, [LCo2(pip)4]2+, was reasonably reactive among the isolable complexes. Indeed, two piperidine ligands at the diagonal positions in [LCo2(pip)4]2+ were site‐selectively replaced with pyridine or acetate ion. The replacement of piperidine with acetate ion significantly enhanced the recognition ability towards Na+. [ABSTRACT FROM AUTHOR]

We developed a new strategy, ligand exchange strategy, for tuning the response speeds of helicity inversion of a metal‐containing helical structure. This is based on the exchange of the two axial amine ligands of the octahedral Co3+ centers in the metallocryptands [LCo3X6] (X=axial amine ligand). The response speeds of the helicity induction were controlled by using different combinations of achiral and chiral amines as the starting and entering ligands, respectively. The response speeds of the helicity inversion from P to M were also tuned by using different combinations of chiral amines. The response speeds of helicity inversion were efficiently controlled by the ligand exchange strategy using a metal‐containing helical structure. The ligand exchange between different kinds of achiral and chiral amines as the starting and entering ligands resulted in a variation of the response speeds both in the helicity induction and helicity inversion. [ABSTRACT FROM AUTHOR]

Keywords: cobalt; host-guest systems; ion recognition; macrocyclic ligands; metallohost EN cobalt host-guest systems ion recognition macrocyclic ligands metallohost 2220 2220 1 02/03/21 20210201 NES 210201 B The recognition of a guest Na SP + sp ion b significantly accelerated the AcO SP - sp -mediated gate-opening of a closed dicobalt(III) macrocyclic metallohost [LCo SB 2 sb (hda) SB 2 sb ] SP 2+ sp , which has two bridging 1,6-hexanediamine (hda) ligands, yielding an open host - guest complex [LCo SB 2 sb (hda) SB 2 sb (OAc) B - b Na] SP 2+ sp . Cobalt, host-guest systems, ion recognition, macrocyclic ligands, metallohost. [Extracted from the article]

Keywords: cobalt; ion recognition; ligand exchange; macrocycles; structural conversion EN cobalt ion recognition ligand exchange macrocycles structural conversion 7513 7513 1 06/22/20 20200618 NES 200618 B Post-metalation modification b based on ligand exchange on the metal centers is a useful strategy to control the guest recognition behavior of a metal-containing macrocyclic host. The two axial piperidine ligands at diagonal positions in the cobalt(III) dinuclear macrocyclic host, [LCo SB 2 sb (pip) SB 4 sb ] SP 2+ sp (pip=piperidine), were site-selectively replaced with pyridine or acetato ligands. Cobalt, ion recognition, ligand exchange, macrocycles, structural conversion. [Extracted from the article]

A ligand exchange strategy was successfully utilized for tuning the response speeds of helicity induction and inversion of a metal‐containing helical structure. The helicity changes were driven by the exchange of six axial amine ligands that are introduced into the three Co3+ centers in the metallocryptands, and the response speeds were efficiently controlled by using different combinations of the starting and entering amine ligands. More information can be found in the Communication by Shigehisa Akine et al. on page 2962. [ABSTRACT FROM AUTHOR]

Dynamic M/P invertible helicity was successfully induced at a SiO2 surface immobilized with a dynamic helical trinuclear cobalt complex, [LCo3(NHMe2)6](OTf)3, using chiral ((R) or (S))-1-phenylethylamine. Solid-state CD spectra and theoretical calculations suggested that the fixation of the M/P helical complex on the surface via coordination interactions was the key factor of the induced chirality at the surface. [ABSTRACT FROM AUTHOR]