A Diastereodynamic Probe Transducing Molecular Length into Chiroptical Readout

Abstract

Nature takes advantage of molecular conformational changes to express functions such as signaling across cellular membranes or allosteric protein activation. At the synthetic level, molecular recognition events have been used to induce conformational changes able to trigger functions such as catalysis or sensing. In this context, transduction of stereochemical information has been the leading strategy. In particular, stereodynamic elements have been extensively employed to amplify and/or transduce chiral information. In this article, we report a chiral supramolecular cage with two stereodynamic units, which invert their helicities according to the length of the molecular guest confined within the system. Interestingly, achiral information is transduced by the supramolecular system to different diastereomeric states that have opposite chiroptical absorptions. This is the first example in which it is possible to produce a continuous modulation of the chiroptical output of a system by varying a physical achiral molecular property (viz. molecular dimension). This phenomenon can be exploited for the establishment of novel methods to program conformational control, for the development of innovative sensors and/or for transduction of molecular properties into chiroptical information.

Chirality transfer in a cage controls the clockwise/anticlockwise propeller arrangement of the tris(2-pyridylmethyl)amine ligand

“…Furthermore, very lately, a length-dependent inversion of the TPA helicity upon guest-binding in a supramolecular cage has been described. 8 We present herein a new approach to build TPA-based architectures displaying a predictable and controlled propellerlike arrangement of the pyridines through its capping with a chiral C 3 symmetrical unit.…”

Control and Transfer of Chirality Within Well-Defined Tripodal Supramolecular Cages

“…It is therefore reasonable to expect that such way of generating, controlling, and propagate chirality will be further applied to other class of supramolecular architectures, and will result in the preparation of new kinds of stereoselective and adaptive hosts. In particular, aiming at mimicking the allosteric properties of biological receptors, the chirality dynamics in well-defined cages is the key to develop challenging on-demand control of the hosts chirality, dictated by the nature of the encapsulated guest (Bravin et al, 2019 ; Pavlovic et al, 2019 ).…”

“…Aiming at providing a general view about recent progress in the preparation of chiral tripodal cages displaying chirality dynamics, this mini-review summarizes current knowledge on how the chiral information can propagate along such tridimensional architectures. Control of the chirality within tripodal cages upon chiral sorting (Henkelis et al, 2014 ; Schaly et al, 2016 ; Jedrzejewska and Szumna, 2017 ; Schulte et al, 2019 ; Séjourné et al, 2020 ), or guest binding (You et al, 2012 ; Bravin et al, 2019 ; Pavlovic et al, 2019 ) are beyond the scope of this work.…”

Mixed Multimetallic tris(2‐pyridylmethyl)amine Based Complexes: Synthesis and Chiroptical Properties

“…Recently, we have been working in the application of tris(2‐pyridylmethyl)amine ( TPMA ) [18] metal complexes both in catalysis [19–21] and supramolecular chemistry [22–25] . In particular, we exploited the sensor capabilities of a series of TPMA based molecular architectures in the determination of the enantiomeric excess of chiral molecules, using Circular Dichroism (CD), [26–31] Vibrational Circular Dichroism (VCD), [32] and Circular Polarised Luminescence (CPL) [30] .…”