Structural switching in self-assembled metal–ligand helicate complexes via ligand-centered reactions

Abstract

Ligand centered reactions are capable of conferring structural switching between a metastable, self-assembled Fe–iminopyridine aggregate and a stable M2L3 helicate.

A Self‐Assembled Cage with Endohedral Acid Groups both Catalyzes Substitution Reactions and Controls Their Molecularity

“…Four differenta ctivated electrophiles were tested that vary in reactivity;t riphenylmethanol 4a,i ts ethyl (4b)a nd trifluoroethyl (4c)e thers, and benzhydrol 4d.T hese electrophiles are well-known "S N 1" substrates that can undergo various substitution reactions via their highly stabilized cationic intermediates. [31] As cage 1 is sensitivet oavariety of different nucleophiles, some as mild as chloride, [32] we focused on mild, neutraln ucleophiles for the reactivity tests. The combination of tri-or diphenylmethyl electrophiles with thiols in highly acidic media is aw ell-precedented method of thioether synthesis, [33,34] ando ccurs via an acid-catalyzed dissociative substitution mechanism.…”

No, Not That Way, the Other Way: Creating Active Sites in Self-Assembled Host Molecules

“…We synthesized the doubly activated chloro ligand L7 (Scheme 7, a), and attempted form a helicate from that, with the intention of performing a nucleophilic substitution at the CHCl center. 61 Interestingly, diaminosuberyl chloride L7 did not form a helicate complex when reacted with PyCHO and Fe(ClO 4 ) 2 . The reactive alkyl chloride group is intact and does not react under the assembly conditions, but the product is a disordered aggregate, rather than a defined helicate.…”

“…46 When the analogous reaction was performed on a nonassembled ligand equivalent, only the alcohol was formed via substitution. 61 The stability of the suberone helicate drives the reaction to the lowest energy product, diverting the outcome of a relatively simple reaction. The 'how' is far more complex.…”

Self-Assembly of a [1 + 1] Ionic Hexagonal Macrocycle and Its Antiproliferative Activity

“…Coordination driven self-assembly has been used conveniently in contemporary research for the construction of wide range of discrete supramolecular architectures (Chakrabarty et al, 2011 ; Cook et al, 2013b ; Li et al, 2013 ; Schmidt et al, 2014 ; Schoedel and Zaworotko, 2014 ; Tanaka et al, 2014 ; Bhowmick et al, 2015a , b ; Cook and Stang, 2015 ; Wang et al, 2016 ; Jana et al, 2017 ). In such complex frameworks, the building blocks ( aka supramolecular tectons) are held together by using multiple ligand-metal coordination bonds (Lehn, 1995 ; Chakrabarty et al, 2011 ; Cook et al, 2013b ; Li et al, 2013 ; Ward and Raithby, 2013 ; Han et al, 2014 ; Schmidt et al, 2014 ; Schoedel and Zaworotko, 2014 ; Tanaka et al, 2014 ; Bhowmick et al, 2015a , b ; Cook and Stang, 2015 ; Johnson et al, 2015 ; Holloway et al, 2016 , 2017 ; Wang et al, 2016 ; Jana et al, 2017 ). The dimensions of resultant abiotic supramolecules are guided by chemical information (stereo and geometric) contained in precursor moieties (Oliveri et al, 2008 ; Newkome and Shreiner, 2010 ; Inokuma et al, 2011 ; Cook et al, 2013b ; Harris et al, 2013 ; Yoshizawa and Klosterman, 2014 ; Cook and Stang, 2015 ; Wang et al, 2015 ; Xu et al, 2016 ; Jana and Das, 2017 ).…”