Energy transfer between FRET pairs is employed herein to reveal novel intermolecular interactions between self-assembled macrocycles, built via Watson–Crick pairing between complementary dinucleosides, and mononucleoside competitors.

Modern supramolecular chemistry relies on the combination of diverse analytical techniques that can provide complementary information on complex self-assembly landscapes. Among them, resonance energy transfer, monitored by fluorescence emission spectroscopy, arises as a sensitive and convenient phenomenon to report binding intermolecular interactions. The use of molecular probes labelled with suitable complementary energy-transfer pairs can provide valuable information about the thermodynamics, kinetics and self-sorting characteristics of a particular self-assembled system. The objective of this work is to generate a set of nucleoside FRET probes that can be reliably employed to prove and analyse quantitatively H-bonding interactions between complementary Watson-Crick pairs. We first describe the preparation of a set of lipophilic nucleosides that are linked to a π-conjugated functional fragment. The bases include guanosine and 2-aminoadenosine as purine heterocycles, and cytidine and uridine as complementary pyrimidine bases. The π-conjugated moiety comprises either a short phenylene-ethynylene oligomer, a bithiophene, or a BODIPY dye. We then demonstrate that the last two chromophores constitute an energy donor-acceptor couple and that donor emission quenching can be related to the ratio of molecules bound to the complementary acceptor pair. Hence, fluorescence spectroscopy in combination with resonance energy transfer, is shown here to be a useful tool to study and quantify the association and self-sorting events between complementary and non-complementary nucleosides in apolar aromatic solvents, where the binding strength is considerably high, and sensitive techniques that employ low concentrations are demanded.

Self-sorting phenomena are the basis of manifold relevant (bio)chemical processes where a set of molecules is able to interact with no interference from other sets and are ruled by a number of codes that are programmed in molecular structures. In this work, we study, the relevance of chelate cooperativity as a code for achieving high self-sorting fidelities. In particular, we establish qualitative and quantitative relationships between the cooperativity of a cyclic system and the self-sorting fidelity when combined with other molecules that share identical geometry and/or binding interactions. We demonstrate that only systems displaying sufficiently strong chelate cooperativity can achieve quantitative narcissistic selfsorting fidelities either by dictating the distribution of cyclic species in complex mixtures or by ruling the competition between the intra-and intermolecular versions of a noncovalent interaction.

High‐fidelity production of a single self‐assembled species in competition with others relies on achieving strong chelate cooperativities, which can be quantified by the effective molarity parameter. Therefore, supramolecular systems displaying very high effective molarities are reliably formed in a wide range of experimental conditions and exhibit “all‐or‐none” phenomena, meaning that the assembly is either fully formed or fully dissociated into the corresponding monomeric components. We summarize here our efforts in the study and characterization of one of these synthetic systems exhibiting record chelate cooperativities: the self‐assembly of rod‐like dinucleoside molecules into tetrameric macrocycles through hydrogen‐bonding Watson‐Crick interactions.

Rodlike π‐conjugated molecules in which two OPV fragments are connected through a diacetylene bond self‐assemble in aqueous and organic media. Optical spectroscopy and AFM measurements indicated that, in water, strong hydrophobic interactions between π‐cores promote aggregation into robust, uniform micellar structures. In contrast, in apolar solvents, a fibrilar morphology is obtained by coiling of columnar stacks. These stacks are formed in a nucleation‐elongation process with degrees of cooperativity of 0.006, that is influenced by the low rotation barriers around the σ‐bonds in the diacetylene linker.