Extreme sensitivity of circular dichroism to long-range excitonic couplings in helical supramolecular assemblies.

Circular dichroism (CD) spectroscopy is an ideal tool for studying the self-assembly of helical supramolecular assemblies since it is very sensitive to extended excitonic couplings between chiral chromophores. We show that the CD spectrum retains its high sensitivity to long-range interactions even in the presence of extreme disorder and strong interaction with vibrations when excitations are mainly localized on individual molecules. We derive a universal expression for the first moment of the CD spectrum of helical assemblies in terms of a modulated sum over excitonic couplings, which is independent of the strength of the energetic disorder, the spatial correlation of the disorder, and the strength of the interaction with vibrations.

Optical spectra and stokes shift in double-stranded helical supramolecular assemblies.

We study the photoluminescence from helical MOPV4 aggregates using a model that includes excitonic coupling, exciton-phonon coupling, and spatially correlated disorder in the chromophore transition energies. The helical aggregates consist of stacked dimers of MOPV4 chromophores. We have modeled these helical stacks as double-stranded aggregates, allowing us to investigate the effect of correlated disorder within the dimers on emission.

Photoluminescence spectra of self-assembling helical supramolecular assemblies: a theoretical study.

The reversible assembly of helical supramolecular polymers of chiral molecular building blocks is known to be governed by the interplay between mass action and the competition between weakly and strongly bound states of these building blocks. The highly co-operative transition from free monomers at high temperatures to long helical aggregates at low temperatures can be monitored by photoluminescence spectroscopy that probes the energetically lowest-lying optical excitations in the assemblies. In order to provide the interpretation of obtained spectroscopic data with a firm theoretical basis, we present a comprehensive model that combines a statistical theory of the equilibrium polymerization with a quantum-mechanical theory that not only accounts for the conformational properties of the assemblies but also describes the impact of correlated energetic disorder stemming from deformations within the chromophores and their interaction with solvent molecules.