An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Zeolitic imidazolate frameworks Ald-ZIF were obtained by mixing two imidazole-based linkers with ... more Zeolitic imidazolate frameworks Ald-ZIF were obtained by mixing two imidazole-based linkers with zinc(ii). Post-synthetically modified Ald-ZIFs with thiosemicarbazide group improved mercury(ii) removal efficiency from water at a capacity of 1667 mg g−1.
Topologically nontrivial knots are fascinating entities on the macroscopic and molecular level. D... more Topologically nontrivial knots are fascinating entities on the macroscopic and molecular level. Due to their esthetic and practical properties, knots have been extensively investigated in different scientific fields ranging from mathematics, biology, and materials. On a molecular scale, chemists promoted the beauty of these structures by developing various synthetic approaches for the preparation and characterization of knots in a laboratory set-up. This chapter stresses on the fundamental properties of molecular knots and their potential use in real applications.
Dalton transactions (Cambridge, England : 2003), Jan 21, 2017
Topological transformation of a zinc-templated trefoil knot, Zn-TK, into a zinc-templated [2]cate... more Topological transformation of a zinc-templated trefoil knot, Zn-TK, into a zinc-templated [2]catenane, Zn-[2]C, was studied. The net reaction 2 Zn-TK→3 Zn-[2]C was accomplished in 89% yield by heating a solution of Zn-TK in D2O. Kinetic investigation by 1H NMR spectroscopy and high resolution mass spectrometry revealed that the mechanism is complex, involving a large pool of intermediates that form after imine bond cleavage. Bromide ions, which can occupy the central cavity of Zn-TK, inhibited the reaction. Two similar transformations were also studied, one of a cadmium-containing trefoil knot, Cd-TK, into a cadmium-containing catenane, Cd-[2]C, and the other of Cd-TK into Zn-[2]C. The latter transformation could be achieved in one step at high temperature or in two steps via transmetallation to form Zn-TK at room temperature followed by topological conversion of Zn-TK to Zn-[2]C at high temperature.
Cucurbit[7]uril-modified iron-oxide nanoparticles (CB[7]NPs) were loaded with doxorubicin hydroch... more Cucurbit[7]uril-modified iron-oxide nanoparticles (CB[7]NPs) were loaded with doxorubicin hydrochloride (Dox) and tested as a drug delivery system.
Three topologically non-trivial cadmium(ii)-based complexes—Cd-[2]C, Cd-TK and CD-SL—were self-as... more Three topologically non-trivial cadmium(ii)-based complexes—Cd-[2]C, Cd-TK and CD-SL—were self-assembled in a dynamic library, individually isolated and fully characterized and subjected to postsynthetic modification including demetallation and transmetallation.
We report the anion-recognition properties and anion-mediated templation of Metal-Organic knots a... more We report the anion-recognition properties and anion-mediated templation of Metal-Organic knots and links in aqueous solutions.
Driven by the need for delivering sustainable water purification solutions for the removal of hea... more Driven by the need for delivering sustainable water purification solutions for the removal of heavy metals from water, TETA functionalised electrospun PVC membranes were fabricated and used to remove lead(ii) ions selectively from water.
Different anionic templates act to give rise to four distinct Cd(II)-based architectures: a Cd2L3... more Different anionic templates act to give rise to four distinct Cd(II)-based architectures: a Cd2L3 helicate, a Cd8L12 distorted cuboid, a Cd10L15 pentagonal prism, and a Cd12L18 hexagonal prism, which respond to both anionic and cationic components. Interconversions between architectures are driven by the addition of anions that bind more strongly within a given product framework. The addition of Fe(II) prompted metal exchange and transformation to a Fe4L6 tetrahedron or a Fe10L15 pentagonal prism, depending on the anionic templates present. The equilibrium between the Cd12L18 prism and the Cd2L3 triple helicate displayed concentration dependence, with higher concentrations favoring the prism. The Cd12L18 structure serves as an intermediate en route to a hexafluoroarsenate-templated Cd10L15 complex, whereby the structural features of the hexagonal prism preorganize the system to form the structurally related pentagonal prism. In addition to the interconversion pathways investigated, we also report the single-crystal X-ray structure of bifluoride encapsulated within a Cd10L15 complex and report solution state data for J-coupling through a CH···F(-) hydrogen bond indicating the strength of these interactions in solution.
The behaviour of metal-organic cages upon guest encapsulation can be difficult to elucidate in so... more The behaviour of metal-organic cages upon guest encapsulation can be difficult to elucidate in solution. Paramagnetic metal centres introduce additional dispersion of signals that is useful for characterisation of host-guest complexes in solution using nuclear magnetic resonance (NMR). However, paramagnetic centres also complicate spectral assignment due to line broadening, signal integration error, and large changes in chemical shifts, which can be difficult to assign even for known compounds. Quantum chemical predictions can provide information that greatly facilitates the assignment of NMR signals and identification of species present. Here we explore how the prediction of paramagnetic NMR spectra may be used to gain insight into the spin crossover (SCO) properties of iron(II)-based metal organic coordination cages, specifically examining how the structure of the local metal coordination environment affects SCO. To represent the tetrahedral metal-organic cage, a model system is generated by considering an isolated metal-ion vertex: fac-ML3(2+) (M = Fe(II), Co(II); L = N-phenyl-2-pyridinaldimine). The sensitivity of the (1)H paramagnetic chemical shifts to local coordination environments is assessed and utilised to shed light on spin crossover behaviour in iron complexes. Our data indicate that expansion of the metal coordination sphere must precede any thermal SCO. An attempt to correlate experimental enthalpies of SCO with static properties of bound guests shows that no simple relationship exists, and that effects are likely due to nuanced dynamic response to encapsulation.
A new class of Fe(II)4L4 capsules, based upon a tritopic trialdehyde subcomponent, is reported. O... more A new class of Fe(II)4L4 capsules, based upon a tritopic trialdehyde subcomponent, is reported. One such capsule was prepared diastereoselectively through the incorporation of a chiral amine residue. This amine was displaced by an achiral one, while maintaining the stereochemistry of the cage framework (99% ee); this cage retained its stereochemistry even after 4 days at 90 °C. Mechanistic studies indicate the memory displayed by this capsule to be the result of effective stereochemical communication between the metal centers mediated by the rigid 3-fold-symmetric faces, in combination with a stepwise substitution mechanism.
How much should we switch? Two FeII₄L₄ tetrahedral capsules were shown to undergo thermally induc... more How much should we switch? Two FeII₄L₄ tetrahedral capsules were shown to undergo thermally induced spin crossover (SCO). Guest binding to one of these capsules was observed to affect the thermodynamics of its SCO in solution, leading to different spin transition temperatures between the empty host (blue) and the host-guest complex (red). HS: high spin; LS: low spin.
ABSTRACT Formsache: Abhängig von den Reaktionsbedingungen baut ein symmetrisches Triamin entweder... more ABSTRACT Formsache: Abhängig von den Reaktionsbedingungen baut ein symmetrisches Triamin entweder die neuartige ikosaedrische [FeII12L12]‐Kapsel 1 oder die tetraedrische [FeII4L4]‐Kapsel 2 auf. Die beiden Kapseln umschließen Hohlräume mit stark unterschiedlichen Volumina und Formen und können daher Gastspezies verschiedener Größe, Gestalt und Ladung aufnehmen.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Zeolitic imidazolate frameworks Ald-ZIF were obtained by mixing two imidazole-based linkers with ... more Zeolitic imidazolate frameworks Ald-ZIF were obtained by mixing two imidazole-based linkers with zinc(ii). Post-synthetically modified Ald-ZIFs with thiosemicarbazide group improved mercury(ii) removal efficiency from water at a capacity of 1667 mg g−1.
Topologically nontrivial knots are fascinating entities on the macroscopic and molecular level. D... more Topologically nontrivial knots are fascinating entities on the macroscopic and molecular level. Due to their esthetic and practical properties, knots have been extensively investigated in different scientific fields ranging from mathematics, biology, and materials. On a molecular scale, chemists promoted the beauty of these structures by developing various synthetic approaches for the preparation and characterization of knots in a laboratory set-up. This chapter stresses on the fundamental properties of molecular knots and their potential use in real applications.
Dalton transactions (Cambridge, England : 2003), Jan 21, 2017
Topological transformation of a zinc-templated trefoil knot, Zn-TK, into a zinc-templated [2]cate... more Topological transformation of a zinc-templated trefoil knot, Zn-TK, into a zinc-templated [2]catenane, Zn-[2]C, was studied. The net reaction 2 Zn-TK→3 Zn-[2]C was accomplished in 89% yield by heating a solution of Zn-TK in D2O. Kinetic investigation by 1H NMR spectroscopy and high resolution mass spectrometry revealed that the mechanism is complex, involving a large pool of intermediates that form after imine bond cleavage. Bromide ions, which can occupy the central cavity of Zn-TK, inhibited the reaction. Two similar transformations were also studied, one of a cadmium-containing trefoil knot, Cd-TK, into a cadmium-containing catenane, Cd-[2]C, and the other of Cd-TK into Zn-[2]C. The latter transformation could be achieved in one step at high temperature or in two steps via transmetallation to form Zn-TK at room temperature followed by topological conversion of Zn-TK to Zn-[2]C at high temperature.
Cucurbit[7]uril-modified iron-oxide nanoparticles (CB[7]NPs) were loaded with doxorubicin hydroch... more Cucurbit[7]uril-modified iron-oxide nanoparticles (CB[7]NPs) were loaded with doxorubicin hydrochloride (Dox) and tested as a drug delivery system.
Three topologically non-trivial cadmium(ii)-based complexes—Cd-[2]C, Cd-TK and CD-SL—were self-as... more Three topologically non-trivial cadmium(ii)-based complexes—Cd-[2]C, Cd-TK and CD-SL—were self-assembled in a dynamic library, individually isolated and fully characterized and subjected to postsynthetic modification including demetallation and transmetallation.
We report the anion-recognition properties and anion-mediated templation of Metal-Organic knots a... more We report the anion-recognition properties and anion-mediated templation of Metal-Organic knots and links in aqueous solutions.
Driven by the need for delivering sustainable water purification solutions for the removal of hea... more Driven by the need for delivering sustainable water purification solutions for the removal of heavy metals from water, TETA functionalised electrospun PVC membranes were fabricated and used to remove lead(ii) ions selectively from water.
Different anionic templates act to give rise to four distinct Cd(II)-based architectures: a Cd2L3... more Different anionic templates act to give rise to four distinct Cd(II)-based architectures: a Cd2L3 helicate, a Cd8L12 distorted cuboid, a Cd10L15 pentagonal prism, and a Cd12L18 hexagonal prism, which respond to both anionic and cationic components. Interconversions between architectures are driven by the addition of anions that bind more strongly within a given product framework. The addition of Fe(II) prompted metal exchange and transformation to a Fe4L6 tetrahedron or a Fe10L15 pentagonal prism, depending on the anionic templates present. The equilibrium between the Cd12L18 prism and the Cd2L3 triple helicate displayed concentration dependence, with higher concentrations favoring the prism. The Cd12L18 structure serves as an intermediate en route to a hexafluoroarsenate-templated Cd10L15 complex, whereby the structural features of the hexagonal prism preorganize the system to form the structurally related pentagonal prism. In addition to the interconversion pathways investigated, we also report the single-crystal X-ray structure of bifluoride encapsulated within a Cd10L15 complex and report solution state data for J-coupling through a CH···F(-) hydrogen bond indicating the strength of these interactions in solution.
The behaviour of metal-organic cages upon guest encapsulation can be difficult to elucidate in so... more The behaviour of metal-organic cages upon guest encapsulation can be difficult to elucidate in solution. Paramagnetic metal centres introduce additional dispersion of signals that is useful for characterisation of host-guest complexes in solution using nuclear magnetic resonance (NMR). However, paramagnetic centres also complicate spectral assignment due to line broadening, signal integration error, and large changes in chemical shifts, which can be difficult to assign even for known compounds. Quantum chemical predictions can provide information that greatly facilitates the assignment of NMR signals and identification of species present. Here we explore how the prediction of paramagnetic NMR spectra may be used to gain insight into the spin crossover (SCO) properties of iron(II)-based metal organic coordination cages, specifically examining how the structure of the local metal coordination environment affects SCO. To represent the tetrahedral metal-organic cage, a model system is generated by considering an isolated metal-ion vertex: fac-ML3(2+) (M = Fe(II), Co(II); L = N-phenyl-2-pyridinaldimine). The sensitivity of the (1)H paramagnetic chemical shifts to local coordination environments is assessed and utilised to shed light on spin crossover behaviour in iron complexes. Our data indicate that expansion of the metal coordination sphere must precede any thermal SCO. An attempt to correlate experimental enthalpies of SCO with static properties of bound guests shows that no simple relationship exists, and that effects are likely due to nuanced dynamic response to encapsulation.
A new class of Fe(II)4L4 capsules, based upon a tritopic trialdehyde subcomponent, is reported. O... more A new class of Fe(II)4L4 capsules, based upon a tritopic trialdehyde subcomponent, is reported. One such capsule was prepared diastereoselectively through the incorporation of a chiral amine residue. This amine was displaced by an achiral one, while maintaining the stereochemistry of the cage framework (99% ee); this cage retained its stereochemistry even after 4 days at 90 °C. Mechanistic studies indicate the memory displayed by this capsule to be the result of effective stereochemical communication between the metal centers mediated by the rigid 3-fold-symmetric faces, in combination with a stepwise substitution mechanism.
How much should we switch? Two FeII₄L₄ tetrahedral capsules were shown to undergo thermally induc... more How much should we switch? Two FeII₄L₄ tetrahedral capsules were shown to undergo thermally induced spin crossover (SCO). Guest binding to one of these capsules was observed to affect the thermodynamics of its SCO in solution, leading to different spin transition temperatures between the empty host (blue) and the host-guest complex (red). HS: high spin; LS: low spin.
ABSTRACT Formsache: Abhängig von den Reaktionsbedingungen baut ein symmetrisches Triamin entweder... more ABSTRACT Formsache: Abhängig von den Reaktionsbedingungen baut ein symmetrisches Triamin entweder die neuartige ikosaedrische [FeII12L12]‐Kapsel 1 oder die tetraedrische [FeII4L4]‐Kapsel 2 auf. Die beiden Kapseln umschließen Hohlräume mit stark unterschiedlichen Volumina und Formen und können daher Gastspezies verschiedener Größe, Gestalt und Ladung aufnehmen.
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