While Nature often controls supramolecular processes through regulation giving multiple levels of activity,synthetic metallosupramolecular systems have generally been binary(e.g.on/off)when they have control over mole...While Nature often controls supramolecular processes through regulation giving multiple levels of activity,synthetic metallosupramolecular systems have generally been binary(e.g.on/off)when they have control over molecular recognition events,and have often relied upon drastic chemical transformations or com plete disassembly to enforce this control.We report here a new low symmetry ligand with a bidentate and a monodentate site(L).In combination with Pd^(2+),this ligand forms a[2+2]metallo-macrocycle,[Pd_(2)L_(2)L_(2)’]^(n+),where L’is the monodentate ancillary ligand that occupies the fourth andfinal coordination site of the metal ions.This assembly is structurally simple,but displays nuanced,multi-step binding affnity toward a neutral diplatinate vip employed for proof-of-concept.This complexity is introduced through varying the identity of L’,which can either be solvent(DMSO)or the halides chloride,bromide or iodide.The identity of L’alters the cationic charge of the complex(neutral DMSO versus monoanionic halides)or otherwise influences the electron deficiency of the binding site of the host through varied strength of halide-ligand intra-molecular hydrogen bonding.Cycling between these different complexes was demonstrated,except for L’=chloride which is non-reversible.This system therefore is able to interact with a platinate vip with four different graduations of affnity in response to stimuli,while still retaining the same simple core cationic structure.In addition to multi-setting binding affnity,we believe this is thefirst example of the use of variable intramolecular hydrogen bonding strength in switchable ancillary ligands to alter the electronic character and hence theπ–πrecognition characteristics of a metallosupra molecular host.展开更多
One of the most appealing features of[Pd_(2)L_(4)]^(4+)cages is their well-defined cavities,giving binding affinity for specific vips.If seeking to bind larger and more complex vips,an attractive strategy is to le...One of the most appealing features of[Pd_(2)L_(4)]^(4+)cages is their well-defined cavities,giving binding affinity for specific vips.If seeking to bind larger and more complex vips,an attractive strategy is to lengthen the ligand backbone and therefore the inter-palladium(Ⅱ)distance and cavity length.In comparison to large hollow[Pd_(n)L_(2n)]^(2n+)polyhedra,this approach retains a well-ordered cavity environment.We report here a novel ligand,1,3-bis(4-(4-ethynylpyridine)-phenyl)-adamantane,that has a hydrophobic bis(phenyl)adamantane core and forms[Pd_(2)L_(4)]^(4+)cages with a large 19Å inter-palladium(Ⅱ)cavity length.This cage binds long designer anions:naphthalimide sulfonates at≥15Å in length,which consist of two distinct domains:a naphthalimide and a phenyl sulfonate.This binding derives from hydrogen bonding between the endohedral pyridyl protons of the cage and the phenyl sulfonate group,and π-hydrophobic interactions between the adamantane core and the naphthalimide unit.The strength of binding depends on the degree of electron deficiency of the naphthalimide,brought about by the nature of substituents on this moiety,with binding constants for monoanionic vips ranging from 400 to 1800 M^(-1).The host/vip stoichiometry was found to be 1:2,unless the vip possessed a second sulfonate group,and was small enough to fit end-to-end within the cavity,in which case the stoichiometry was 1:1,and resulted in a high binding constant(for DMSO solvent)of 6100 M^(-1).This work demonstrates the subtle interplay and potential between cages and vips that are both large and that both have distinct dual zones able to interact with each other,and offers a pathway to specific and tunable binding of large vips.展开更多
文摘While Nature often controls supramolecular processes through regulation giving multiple levels of activity,synthetic metallosupramolecular systems have generally been binary(e.g.on/off)when they have control over molecular recognition events,and have often relied upon drastic chemical transformations or com plete disassembly to enforce this control.We report here a new low symmetry ligand with a bidentate and a monodentate site(L).In combination with Pd^(2+),this ligand forms a[2+2]metallo-macrocycle,[Pd_(2)L_(2)L_(2)’]^(n+),where L’is the monodentate ancillary ligand that occupies the fourth andfinal coordination site of the metal ions.This assembly is structurally simple,but displays nuanced,multi-step binding affnity toward a neutral diplatinate vip employed for proof-of-concept.This complexity is introduced through varying the identity of L’,which can either be solvent(DMSO)or the halides chloride,bromide or iodide.The identity of L’alters the cationic charge of the complex(neutral DMSO versus monoanionic halides)or otherwise influences the electron deficiency of the binding site of the host through varied strength of halide-ligand intra-molecular hydrogen bonding.Cycling between these different complexes was demonstrated,except for L’=chloride which is non-reversible.This system therefore is able to interact with a platinate vip with four different graduations of affnity in response to stimuli,while still retaining the same simple core cationic structure.In addition to multi-setting binding affnity,we believe this is thefirst example of the use of variable intramolecular hydrogen bonding strength in switchable ancillary ligands to alter the electronic character and hence theπ–πrecognition characteristics of a metallosupra molecular host.
基金the University of Canterbury,the Australian National University,Massey University Albany and the University of Otago for fundingthe MacDiarmid Institute for funding+1 种基金the Royal Society of New Zealand for a Rutherford Postdoctoral Fellowshipthe Australian Research Council for a DECRA Fellowship.
文摘One of the most appealing features of[Pd_(2)L_(4)]^(4+)cages is their well-defined cavities,giving binding affinity for specific vips.If seeking to bind larger and more complex vips,an attractive strategy is to lengthen the ligand backbone and therefore the inter-palladium(Ⅱ)distance and cavity length.In comparison to large hollow[Pd_(n)L_(2n)]^(2n+)polyhedra,this approach retains a well-ordered cavity environment.We report here a novel ligand,1,3-bis(4-(4-ethynylpyridine)-phenyl)-adamantane,that has a hydrophobic bis(phenyl)adamantane core and forms[Pd_(2)L_(4)]^(4+)cages with a large 19Å inter-palladium(Ⅱ)cavity length.This cage binds long designer anions:naphthalimide sulfonates at≥15Å in length,which consist of two distinct domains:a naphthalimide and a phenyl sulfonate.This binding derives from hydrogen bonding between the endohedral pyridyl protons of the cage and the phenyl sulfonate group,and π-hydrophobic interactions between the adamantane core and the naphthalimide unit.The strength of binding depends on the degree of electron deficiency of the naphthalimide,brought about by the nature of substituents on this moiety,with binding constants for monoanionic vips ranging from 400 to 1800 M^(-1).The host/vip stoichiometry was found to be 1:2,unless the vip possessed a second sulfonate group,and was small enough to fit end-to-end within the cavity,in which case the stoichiometry was 1:1,and resulted in a high binding constant(for DMSO solvent)of 6100 M^(-1).This work demonstrates the subtle interplay and potential between cages and vips that are both large and that both have distinct dual zones able to interact with each other,and offers a pathway to specific and tunable binding of large vips.
