Microviscosity is a key parameter controlling the rate of diffusion and reactions on the microscale. One of the most convenient tools for measuring microviscosity is by fluorescent viscosity sensors termed 'molecular rotors'. BODIPY-based molecular rotors in particular proved extremely useful in combination with fluorescence lifetime imaging microscopy, for providing quantitative viscosity maps of living cells as well as measuring dynamic changes in viscosity over time. In this work, we investigate several new BODIPY-based molecular rotors with the aim of improving on the current viscosity sensing capabilities and understanding how the structure of the fluorophore is related to its function. We demonstrate that due to subtle structural changes, BODIPY-based molecular rotors may become sensitive to temperature and polarity of their environment, as well as to viscosity, and provide a photophysical model explaining the nature of this sensitivity. Our data suggests that a thorough understanding of the photophysics of any new molecular rotor, in environments of different viscosity, temperature and polarity, is a must before moving on to applications in viscosity sensing.

To date, the concept of DNA-based asymmetric catalysis has been successfully applied to various synthetic transformations by way of hybrid catalysts involving either an intercalator or an integrated ligand anchored through supramolecular interactions. We report here a new anchoring strategy based on the well-known groove-binder Hoechst 33258. The interaction between calf thymus DNA (ct-DNA) and poly­[d­(A-T)2] with a series of Hoechst 33258-derived ligands was studied by UV–vis absorption spectroscopy, thermal melting analysis, fluorescence emission, CD spectroscopy, mass spectrometry, and molecular docking. The results clearly show that a groove-binding anchoring strategy can be envisioned for DNA-based asymmetric catalysis, offering additional mechanistic insight on how the intrinsic chirality of DNA can be transferred to a reaction product. Most importantly, this new anchoring strategy offers interesting compartmentalization possibilities and provides a new way to reverse the enantioselectivity outcome of a given reaction.

In a little over a decade, the unique chirality of oligonucleotides has allowed the development of a variety of asymmetric synthetic transformations. The concept lies in embedding an achiral transition metal catalyst in a DNA double helix, which provides the necessary chiral microenvironment to selectively form one enantiomer of a given reaction product. The most recent efforts at unveiling new reactivities have been accompanied by the desire to understand the mechanisms by which the chirality is transferred and the influence of the interaction between DNA and the metallic co-factor on the selectivity. By offering a complete overview of the field, this review aims to highlight the intricate correlation between the structure of the chiral bio-inorganic scaffold and its catalytic efficacy.

The challenge in DNA-based asymmetric catalysis is to perform a reaction in the vicinity of the helix by incorporating a small-molecule catalyst anchored to the DNA in a covalent, dative, or non-covalent yet stable fashion in order to ensure high levels of enantio-discrimination. Here, we report the first generation of a DNA-based catalyst bound to a cellulose matrix. The chiral biomaterial is commercially available, trivial to use, fully recyclable and produces high levels of enantioselectivity in various Cu(II)-catalyzed asymmetric reactions including Friedel-Crafts alkylations and Michael additions. A single-pass, continuous-flow process is also reported affording fast conversions and high enantioselectivities at low catalyst loadings thus offering a new benchmark in the field of DNA-based asymmetric catalysis.

We report here a highly selective copper(II)-catalysed asymmetric Friedel–Crafts conjugate addition/enantioselective protonation, which owes to a careful positioning of a bipyridine ligand within a DNA framework.

The recent development of biohybrid catalytic systems has allowed synthetic chemists to reach high levels of selectivity on a wide variety of valuable synthetic transformations. In this context, DNA-based catalysts have emerged as particularly appealing tools. Interestingly, while long RNA sequences (ribozymes) are known to catalyse specific biochemical reactions with remarkable efficiencies, RNA-based catalysts involving a catalytically active metal complex interacting in a non-covalent fashion with short sequences have never been evaluated to date. We report here our results, which have led to the first example involving a short RNA-based catalyst.

We report here a general method for the synthesis of quaternary and tertiary difluoromethylated compounds and their vinylfluoride analogues. The strategy, which relies on a two-step sequence featuring a C-selective electrophilic difluoromethylation and either a palladium-catalyzed decarboxylative protonation or a Krapcho decarboxylation, is practical, scalable and high yielding. Considering the generality of the method and the attractive properties offered by the difluoromethyl group, this approach provides a valuable tool for late-stage functionalization and drug development.

Biosynthetic considerations inspired us to harness the templating properties offered by DNA to promote a [2+2] photoinduced cycloaddition. The method was developed based on the dimerization of (E)-aplysinopsin, which was previously shown to be unproductive in solution. In sharp contrast, exposure of this tryptophan-derived olefin to light in the presence of salmon testes DNA (st-DNA) reproducibly afforded the corresponding homo-dimerized spiro-fused cyclobutane in excellent yields. DNA provides unique templating interactions enabling a singular mimic of the solid-state aggregation necessary for the [2+2] photocycloaddition to occur. This method was ultimately used to promote the prerequisite dimerizations leading to both dictazole B and tubastrindole B, thus constituting the first example of a DNA-mediated transformation to be applied to the total synthesis of a natural product.