Exploring the self-assembly of dumbbell-shaped polyoxometalate hybrids, from molecular building units to nanostructured soft materials

Abstract

The formation of hierarchical nanostructures using supramolecular dumbbell-like species made of organic–inorganic polyoxometalate-based hybrids is investigated by combination of SAXS and computational methods.

Supramolecular assemblies of organo-functionalised hybrid polyoxometalates: from functional building blocks to hierarchical nanomaterials

“…Following their initial work with ditopic hybrids, Izzet and co-workers reported the aggregation of dumbbell-shaped polyoxometalate hybrids, using organotin derivatives of monovacant Keggin-or Dawson-type POMs terminated with a remote terpyridine function. 90 They observed the formation of dumbbell-like species in DMSO and showed using ITC that the metal coordination to the POM-based building unit was reinforced by coulombic interactions between the POMs and the metal linker and counter balanced by an entropic cost associated to the POM (the entropic contribution being higher for the Dawson than for the Keggin). They also evaluated the effect of the nature of the POM (Keggin vs Dawson) and the charge of the metal linker (2+ and 3 +) on the aggregation of the dumbbell species.…”

“Host in Host” Supramolecular Core–Shell Type Systems Based on Giant Ring‐Shaped Polyoxometalates

“…[3], [4] As self-assembly is one of the most relevant approaches for the bottom-up construction of multifunctional materials, fundamental understanding of the molecular interactions is still critical for the rational design of specific supramolecular architectures. [5] Among contributing phenomena that include usual weak attractive forces such as coulombic, hydrogen bonding or dispersion forces, solvent effects are often underestimated, while they may contribute significantly to the stability of seemingly fragile supramolecular complexes. In context, unique solvation properties of water has been pinpointed out within numerous aggregation phenomena, [6], [7] and recent observations evidence the predominant role of water self-organization within supramolecular architectures associating ionic hydrophilic inorganic components and non-ionic molecules.…”

“…Important breakthroughs in this area have been reported leading to nanostructures efficient for energy conversion, storage or transport, drug delivery, gas capture or separation [3, 4] . As self‐assembly is one of the most relevant approaches for the bottom‐up construction of multifunctional materials, fundamental understanding of the molecular interactions is still critical for the rational design of specific supramolecular architectures [5] . Among contributing phenomena that include usual weak attractive forces such as dipolar, hydrogen bonding or dispersion forces, solvent effects are often underestimated, while they may contribute significantly to the stability of seemingly fragile supramolecular complexes.…”

“…[3,4] As self-assembly is one of the most relevant approaches for the bottom-up construction of multifunctional materials,fundamental understanding of the molecular interactions is still critical for the rational design of specific supramolecular architectures. [5] Among contributing phenomena that include usual weak attractive forces such as dipolar, hydrogen bonding or dispersion forces,s olvent effects are often underestimated, while they may contribute significantly to the stability of seemingly fragile supramolecular complexes.I nc ontext, unique solvation properties of water has been pinpointed out within numerous aggregation phenomena, [6,7] and recent observations evidence the predominant role of water within self-assembly processes associating ionic inorganic components and non-ionic molecules.F or instance,h ost-guest assemblies involving dodecaborate anions [B 12 X 12 ] 2À (X = Cl, Br or I) or ac ationic tantalum cluster [Ta 6 Br 12 (H 2 O) 6 ] 2+ with g-cyclodextrin have revealed exceptional high stability in water,even larger than those usually found with hydrophobic guests. [8,9] Thepioneering works of Hofmeister in the end of the 19 th century allowed discriminating two distinct behaviours of solvated ions regarding their effect on co-solutes,namely the salting-in for chaotropes and the salting-out for kosmotropes, characterized, respectively by al oosely and strongly bound hydration shell.…”

Unlocking Phase Diagrams for Molybdenum and Tungsten Nanoclusters and Prediction of their Formation Constants

“…However, it is becoming more and more apparent that a deeper understanding of metal-oxo speciation, and thus of the self-assembly process, is needed. 24 Currently, different techniques are used to study POMs in solution: electronic 25 and vibrational 26 spectroscopy, nuclear magnetic resonance 27 , massspectrometry experiments 28 , small-angle X-ray scattering 29 and kinetic investigations 30 . Despite that, the experimental determination of unstable metal-oxo equilibrium constants is proving to be difficult.…”