Transient equilibrium mapping: A new tool for measuring the thermodynamics of slowly assembling supramolecular systems

Abstract

Supramolecular chemistry involves the non-covalent assembly of monomers into materials with unique properties and wide-ranging applications. Thermal analysis is one of the key analytical tools in this field, as it provides quantitative thermodynamic information on both the structural stability and nature of the underlying molecular interactions. However there exist many supramolecular systems whose kinetics are so slow under conditions approaching chemical equilibrium that thermodynamic data are inaccessible. We have developed a simple, general, and rapid spectroscopic method for extracting thermodynamic parameters from such slowly assembling systems. It is based on repeatedly raising and lowering the temperature during assembly and identifying the points of transient equilibrium as they are passed on the up-and down-scans. In a proof-of-principle application to the slow co-assembly of polydeoxyadenosine containing 15 adenosines (polyA15) and cyanuric acid (CA), we found that roughly 30% of the CA binding sites on the polyA chains were unoccupied, with implications for the assembly of high-valence systems.

Statistical thermodynamics in reversible clustering of gold nanoparticles. A first step towards nanocluster heat engines

“…the locus point upon dv ! 0 þ ) [37]. A 'transient equilibrium mapping' model was thereby derived to justify hysteresis of cooling/heating paths and to determine thermodynamic data of slowly (non-covalent) monomer dis/assembling.…”

“…Heating of the sample reverses the process. To gain a more quantitative insight into the hysteretic response we performed the socalled transient equilibrium mapping [37], a spectroscopic method that comprises the rising and lowering of the sample temperature to allow the system to pass through the transient equilibrium on each up-and down-scan (Fig. 2a).…”