Stabilization of Dynamic Covalent Architectures by Multivalence

Abstract

The formation of imine bond is reversible. This feature has been taken advantage of by chemists for accomplishing high yielding self-assembly. On the other hand, it also jeopardizes the intrinsic stability of these selfassembled products. However, some recent discoveries demonstrate that some of these imine bond containing molecules could be rather stable or kinetically inert. A deep investigation indicated that such enhanced stability results from, at least partially, multivalence. Such results also inspire chemists to use imine condensation for self-assembly in water, a solvent that is considered not compatible with imine bond for a long time.

Key structural features to favour imines over hydrates in water: pyridoxal phosphate as a muse

“…12 As a consequence, many research efforts have been devoted in the last years toward the implementation of chemical methods that increase the stability of imines in water, mainly using covalent/supramolecular multivalency and hydrophobic effects. 13–17 In nature, imitation reactions are achieved in the sophisticatedly-arranged active sites of enzymes, using pyridoxal phosphate ( PLP ) as the aldehyde. 18 The mode-of-action of this cofactor has been extensively studied as it plays an essential role in numerous enzymatic processes ( e.g.…”

Supramolecular multivalency effects enhance imine formation in aqueous medium allowing for dynamic modification of enzymatic activity

“…1b). 29 Despite the promising advances reached, most of the reported systems are only stable at basic pH or in the presence of certain thermodynamic templates, hampering the use of such designs for dynamic biological applications. 30,31 The most common approach for overcoming these limitations relies on the coupling of fast and site-selective reversible imination steps with irreversible post-modification reactions ( e.g.…”

Crystalline Nanoparticles of Water‐Soluble Covalent Basket Cages (CBCs) for Encapsulation of Anticancer Drugs

“…Alternatively, others sought to construct covalent organic cages directly in water by using reversible condensation of hydrazones, [31] oximes [32] and acyl hydrazones [33] with carbonyls or exchange of disulfides [34] . So far, these approaches resulted in the formation of water‐soluble cages that are either interlocked [31a] or smaller in size [31b] but also capable of complexing organics, [30] micropollutants [33a] or ions [25c,34] . In line with these advances, [35] the lack of large covalent organic cages operating in water [35] at physiological pH and with the ability to trap multiple [36] pharmaceuticals and toxins [37] inspired our study.…”