Smart Macrocyclic Molecules: Induced Fit and Ultrafast Self‐Sorting Inclusion Behavior through Dynamic Covalent Chemistry

Abstract

A family of macrocycles with oligo(ethylene glycol) chains, 4O, 5O, and 6O, was developed to construct a series of new incorporated macrocycles through dynamic covalent chemistry. These flexible macrocycles exhibited excellent "self-sorting" abilities with diamine compounds, which depended on the "induced-fit" rule. For instance, the host macrocycles underwent conformational modulation to accommodate the diamine guests, affording [1+1] intramolecular addition compounds regardless of the flexibility of the diamine. These macrocycles folded themselves to fit various diamines with different chain length through modulation of the flexible polyether chain, and afforded intramolecular condensation products. However, if the chain of the diamine was too long and rigid, oligomers or polymers were obtained from the mixture of the macromolecule and the diamine. All results demonstrated that inclusion compounds involving conformationally suitable aromatic diamines were thermodynamically favorable candidates in the mixture due to the restriction of the macrocycle size. Furthermore, kinetic and thermodynamic studies of self-sorting behaviors of both mixed 4O-5O and 4O-6O systems were investigated in detail. Finally, theoretical calculations were also employed to further understand such self-sorting behavior, and indicated that the large enthalpy change of H(2)NArArNH(2)@4O is the driving force for the sorting behavior. Our system may provide a model to further understand the principle of biomolecules with high specificity due only to their conformational self-adjusting ability.

Inducing Social Self‐Sorting in Organic Cages To Tune The Shape of The Internal Cavity

“…[50] However,i ti se xtremely hard to predict-either intuitively or computationally-which outcome will be observed for ag iven pair of aldehyde reactants.F or simple cases,such as two linear aldehydes,one could expect that narcissistic self-sorting is likely due to the mismatch in the aldehyde lengths and strain in the resultant cages. [48,[51][52][53] It is much more difficult to predict the outcome when al inear aldehyde is combined with ab ent aldehyde, such as B1 (see Figure 1ii). W ehypothesised that the greater conformational degrees of freedom of non-linear aldehydes compared to linear aldehydes would aid social self-sorting or scrambling by accommodating aw ider range of options for the cage geometry.…”

Enabling Technology for Supramolecular Chemistry

“…Supramolecular chemists seek to develop materials and systems made of multiple molecular building blocks where the whole is “more than the sum of its parts.” Many have exploited the reversibility of both non-covalent and dynamic covalent systems to form multicomponent structures under thermodynamic equilibrium ( Whitesides et al, 1991 ; Rowan et al, 2002 ; Otto and Severin, 2007 ; Han et al, 2010 ; Okesola and Mata, 2018 ). Under fully reversible equilibrium conditions, the final outcome of such processes only depends on the molecular building blocks being used and the overall stability of the products: the thermodynamic product is often observed, representing the global energy minimum ( Rowan et al, 2002 ).…”

Dynamic combinatorial/covalent chemistry: a tool to read, generate and modulate the bioactivity of compounds and compound mixtures

“…319 In a further example, reversible imine formation between a host and a guest has been used for the self-sorting of macrocyclic hosts bearing two aldehyde functions, which selected the best-fitting and conformationally most suitable guest from a library of different diamines. 320 Recently, the self-sorting of a library of hydrazides as a result of non-covalent interactions with a target being immobilised on a resin has been reported. 321 Osowska and Miljanic ´applied a kinetic self-sorting process to a dynamic library of imines by using a slow irreversible oxidation of the mixture as the kinetic step.…”